Two and half months after Leonov’s spacewalk, Edward White performed the first American EVA. The Gemini 4 hatch had opened at about 14:34 EDT. White's first tasks was to install a 16-mm movie camera and to place an umbilical guard on the hatch sill. Seven minutes later, he was standing on the seat fitting together the two halves of the Hand-Held Maneuvering Unit (HHMU) ? or 'gun' ? that would propel him around the outside of the spacecraft, and placing on the front of it a small camera through which he would take shots of the vehicle.  Twelve minutes after the hatch opened, White drifted up through the rectangular hatch door. He gently squeezed the trigger on his maneuvering unit, literally pulling himself out in a tractor mode but slightly higher than he wanted to go. Within seconds, he was about 2½ meters from the spacecraft, out past the nose of Gemini IV.  A gentle movement with the HHMU put him into a slow tumble. “O.K. I rolled off and I'm rolling to the right now,” said White. “Under my own influence - here goes. Looks like a thermal glove Jim [McDivitt, Gemini IV Commander],” as a small object drifted up through the hatch. It was the right hand over-glove that White had elected not to wear in the hope of improving his hold. “All right. Now I'm coming above the spacecraft. I'n down now. I'm under my own control. O.K. I'm must be worth a million dollars! I'm coming back tc works real good Jim.”  White was in a very slow turn at the nose of the spacecraft when he tugged gently on the tether. It carried him back across the top of the vehicle and put him in the area of the adapter, far behind the re-entry module. just where he did not want to be. Stable again in attitude, White decided he would give the maneuvering unit a good workout and, with his left hand out, put the HHMU into a line with where he thought his center gravity was located and fired a long burst. It carried him straigh down the center between the two hatches, along the extend rendezvous and recovery section, and out past the nose. Stopping himself with another burst on the pusher nozzle, he performed a few yaw tests and then squeezed the trigger to move across the spacecraft. No luck, the small supply of oxygen gaz was totally expended “O.K. I think I've exhausted my air now. I have very gool control with it, I just needed more air… Capcom, it was very easy to maneuver with the gun, the only problem I have is I haven't enough fuel. This is the greatest experience, it's just tremendous… Right now, I'm standing on my head and I'm looking right down and looks like we're coming up on the coast of Califormia… as I go on a slow rotation to the right. There is absolutely disorientation associated with it.” White ran out of compressed oxygen for his maneuvering gun about four minutes after pulling himself out of the hatch. He thus spent the rest of his time using the camera and learning the difficulties associted with tether dynamics. “O.K. I'm drifting down underneath the spacecraft. There's no difficulty with recontacting the spacecraft… particularly as long as you move nice and slow… Feel very grateful to be having the experience to be doing this. I'll bring myself in and put myself out of your view.” With no other means of attitude conrol, he had little alternative but to use the long, snaking line to pull himself around. In the weightless void, it was an almost mpossible task; White was going everywhere but in the actual lirection he wanted to.  And it was an exhilarating experience. The capsule cornicator had been trying for a few minutes to get the attention of very preoccupied pilots. Gemini IV would soon be out of range of tracking stations as the vehicle moved across the continental United States heading for an Atlantic pass. “The Flight Director says, get back in!,” said Mission Control. “It’s the saddest moment of my life,” later said White.

Counted the period between hatch opening and closing, the spacewalk lasted 36 minutes, with White physically outside the spacecraft for about 21 minutes.

Gemini 8’s pilot David Scott was supposed to execute the second U.S. spacewalk to test space suit improvements, one of which being the addition of an Extra Vehicular Life Support System (ELSS) that will extend the availability of reserve oxygen, improve the thermal control characteristics, and raise the efficiency of suit flow and pressurization.  Scott also was to test more maneuvering control with a Hand Held Maneuvering Unit (HHMU) “space gun.” He was to use a larger capacity tank placed into his back-pack Extra Vehicular Support Package (ESP). The ESP was mounted in the rear of the Gemini‘s adapter equipment section within a cradle. Upon reaching that location, the spacewalker would seat himself on the cradle and back on to the ESP, securing it to his suit by a nylon strap which would come across his shoulders and fasten to the front of the chest-pack.  Additional equipment prepared for this mission included two tethers. A 7.6-meter umbilical, similar to that used by White, carried an oxygen line, a nylon tether, and an electrical line for communication and bio-instrumentation. A second umbilical, 23 meters length and contained within a bag attached to the top of the back pack in the adapter, comprised a nylon tether and an electrical hardwire with connections for communications and bio-instruments from the astronaut's body. Donning the chest pack and fitting up the short umbilical, Dave Scott was to open his hatch about 20 hours and 30 minutes into the flight, emerging from the craft at sunrise eleven minutes later on the 13th revolution. He was first to mount a camera, retrieve a package from the side of Gemini set up to study cosmic radiation, move across to the Agena and retrieve a micrometeoroid detection pack. He would then return to the spacecraft, change film in the camera, point it in an aft facing direction and move to the rear of the adapter.  Checking that the back-pack and tether bag were still in their affixed location, the spacewalker was then to return to a plate on the side of the adapter's retrograde section and demonstrate the use of a special power tool designed to be used in weightlessness. (in that environment, a normal power tool would turn the astronaut rather than the chuck and the Defense Department had developed a non-torque power tool for evaluation.) Returning again to the adapter, Scott was to don the ESP back pack and, at second sunrise, wait while Gemini 8 Commander Neil Armstrong undocked from the Agena and moved 18 meters out of plane to station-keep on the target. Scott was then to move out from behind the adapter and position himself in increments to the full extent of the 23-meter tether. Across at the Agena, he would wait as Armstrong maneuvered the spacecraft up to him, and then follow as the command-pilot gently pulled back from the Agena to a distance of 76 meters, hauling Scott along in the process. The spacewalker was to get back in the Gemini spacecraft after an EVA of about 2 hr. 10 min. Unfortunately, this spectacular spacewalk was cancelled when, following the first docking between two spacecrafts – Gemini 8 and an Agena target vehicle – some rocket-engine problems force the crew to abort the mission and return in emergency to Earth.  This spacewalk was very ambitious – in fact, way too much ambitious – considering, as we will learn with the following Gemini’s EVAs, the difficulties of working in space suit in weightlessness outside a spacecraft.   Adapted from: David Barker, The History of Manned Spaceflight, Crown Publishers, 1982, Chapter 13, p. 228-229.

Gemini 8's spacesuit improvments. Gemini's adapter (left), where EVA  equipment would be stored. The rear of a Gemini spacecraft,  where EVA equipment were stored. Gemini 8's Agena docking target  shortly before docking.

This spacewalk is one of the most significant one ever done because it revealed how much it is difficult to work outside a spacecraft. Up to that day, engineers and ground controllers thought that spacewalking astronauts could do about anything, but Eugene Cernan's EVA revealed the opposite: the simplest task needs to be carefully planned in advance. Cernan nearly lost his life — more than once — during his spacewalk! After the troublesome Gemini 8 mission, during which David Scott was to have performed an EVA, Gene Cernan became the second U.S. spacewalker on this Gemini 9 mission. He is the first to have made an entire orbit around the world out of a spaceship, to have sense both day and night in space.   In his biography, Cernan told: “When I pumped my suit up to three and one half pounds of pressure per square inch, the suit took on a life of its own and became so stiff that it didn't want to bend at all. Not at the elbow, the knee, the waist, or anywhere else.  It was as if I wore a garment made of hardened plaster of Paris, from fingertip to toe. “When the hatch stood open, I barely pushed against the floor of the spacecraft and my suit unfolded from the seated position. I grabbed the edges of the hatch and climbed out of my hole until I stood on my seat. “And, oh, my God, what a sight. Nothing had prepared me for the immense sensual overload. I had poked my head inside a kaleidoscope, where shapes and colors shifted a thousand times a second. I did not have the words to match the scene.  No one does. “While Tom [Gemini 9 Commander Tom Stafford ] held my foot to anchor me, I positioned a sixteen-millimeter Mauer movie camera on its mount and retrieved a nuclear emulsion package that recorded radiation data and measured the impact of space dust. Then I stretched forward and planted a small mirror on the nose of the spacecraft. Using it, Tom could watch when I started my trek back to the AMU [Astronaut Maneuvering Unit “space scooter”]. “My only connection with the real world was through the umbilical cord, which we called the "snake," and it set out to teach me a lesson in Newton's laws of motion. My slightest move would affect my entire body, ripple through the umbilical, and jostle the spacecraft. We were forced into an unwanted game of crack-the-whip, with Tom inside the Gemini and me on the other end of the snake. “Since I had nothing to stabilize my movements, I went out of control, tumbling every which way, and when I reached the end of the umbilical, I rebounded like a Bungee jumper, and the snake reeled me in as it tried to resume its original shape. I hadn't even done anything yet and was already losing the battle. There had been no advance warning on the difficulties I was having because everything I did was new. I was already beyond the experiences of White and Leonov, moving into uncharted territory. Nobody in history had ever done this before. “I felt as if I was wrestling an octopus. I was looping crazily around the spacecraft, ass over teakettle, as if slipping in puddles of space oil, with no control over the direction, position or movement of my body, and all the while the umbilical was trying to lasso me. Without a stabilizing device, I had no control over the umbilical, and it pretty much did whatever it wanted. "I can't get to where I want to go," I told Tom in exasperation. "The snake is all over me." “I fought it for about thirty minutes before deciding that this snake was perhaps the most malicious serpent since the one Eve met in the Garden of Eden. “I took a short break before moving to the rear of the spacecraft, where the backpack was stowed, and again was faced with the enormity of what lay before my eyes, a feast for the senses.  “I needed to reach the rear of the spacecraft while I still had sunlight, then check out the backpack and strap it on during darkness. Then I would exchange the umbilical connected to my chest pack for the power and oxygen contained within the AMU, and tether myself to the spacecraft with a 125-foot-long [38 metres] piece of thin nylon line. So the next time the Sun popped up, Tom would flip a switch, the single bolt holding the backpack to the Gemini would shear, and I'd be off, rocketing around on my own, the first human to be an independent satellite. Master of the Universe. But first, I had to get to where the backpack was folded up like some bizarre bird in a nest. My space suit fought my every move, and I needed both flexibility and mobility, the two things it did not have. It was blown up like a balloon figure in the Macy's Thanksgiving parade, and tried to hold that shape, no matter how I sought to bend it. Push in on a party balloon and it will resume its original shape when your finger pressure is removed. Same thing in outer space. My heartbeat increased with the effort, and I was breathing hard, trying to find leverage. “I worked my way hand-over-hand along a small railing, we entered darkness over South Africa. I unfolded the restraining bars alongside the backpack, and clicked on a pair of tiny lights for illumination. Only one lit up, providing less help than a candle. Lord I was tired. My heart was motoring at about 155 beats per minute, I was sweating like a pig, and I had yet to begin my real work.  “I could barely see anything at all as I worked through the thirty-five different functions required to make the thing ready to fly. What seemed simple during our Earth simulations was nearly impossible in true zero gravity. Sweat beaded on me and stung my eyes. The helmet prevented me from wiping them. Eventually I flipped the final switch and the backpack powered up. Almost time to fly. “I was having a hard time seeing things, but it took a while to realize that it wasn't just because of the darkness. I was working so hard that the artificial environment created by the space suit simply could not absorb all of the carbon dioxide and humidity I was pumping out. Vision through my helmet was as mottled as the inside of a windshield on a winter morning, and I told Tom, "This visor is sure fogging up." “The work was more than hard, and I was panting for breath as my heartbeat soared to 180 beats per minute. Since the visor was fogged on the inside, and I obviously couldn't remove the helmet to wipe it dry, my only choice was to rub my nose against the inside of the shield to make a hole through which I could see. “Although my mask was cold, my lower back was scalding hot. During the somersaults of daylight umbilical dynamics, I had ripped apart the rear seams on those seven inner layers of heavy insulation and the Sun had baked the exposed triangle of unprotected skin. Now I had a major sunburn and nothing could be done about it until I took off the suit, which would be at least another day. I had a lot bigger things to worry about at the moment, so I disregarded the fiery sensation.” […]

Gemini 9 Commander Thomas Stafford (left) and Pilot Eugene Cernan. A spacewalking astronaut with an AMU. Artist rendition of the Gemini flight, with a spacewalk and an Agena dcoking target. Cernan in his spacesuit (before the flight). One of the rare photo of Cernan outside his spaceship. (There are no good pictures of Cernan's historic EVA because, at the end of the walk, the camera with which Stafford took pictures fled out of the spacecraft.) Cernan and Stafford before the flight.

Cernan thus moved to the Astronaut Maneuvering Unit (AMU) stowed at the rear of his spacecraft but handrails, velcro pads and loop foot restraints failed to help him control his movements. As he struggled, he broke off an experiment antenna mounted on the Gemini spacecraft and tore the outer layers of his suit. (Photo: Cernan and Stafford in their spacesuit, before the flight.)

His exertions exceeded the capacity of his suit’s environment control system to remove moisture, fogging his faceplate and blinding him. Cernan donned the AMU by touch, but Gemini 9 Commander called him back inside. The crew thus abandoned the $10 million Air Force had paid to build the AMU without a try. (Eighteen years will pass before an advanced AMU will be tested by Space Shuttle astronauts.)

After returning to Earth, Cernan conducted underwater simulations of his EVA and reported that neutral buoyancy simulation nearly duplicated actual spacewalk conditions, helping to validate it as a training tool. At the time of his flight, Cernan feared that since he had “failed his EVA”, it could be his first and only spaceflight. But his experience revealed so much about spacewalking that Cernan made two Apollo lunar missions, becoming the last man to walk on the Moon. His Gemini 9 EVA, he said, was the most strenuous experience of his life.

Mike Collins’ full EVA was scheduled to last 90 minutes, more than a full daylight pass around the globe. Five minutes after sunrise, the spacewalker opened his hatch and stood up. He was restrained by a tether approximately 15 meters in length carrying oxygen in addition to providing a tension-pull inhibiting stress on the life support line. The line also included a nitrogen hose which would he connected to a Hand Held Maneuvering Unit (HHMU) “space gun”. About 5 kg of nitrogen was available for use. The first order of business was for Collins to float out the hatch, unfolded a handrail and move back along the Gemini rear adapter to retrieve a micrometeoroid package and place it back in the cabin. Then, he would connect the nitrogen line to the port on the side of the spacecraft.  Momentarily drifting back down into the open hatch, the spacewalker paused for a moment, fired a few squirts from the hand gun to assure himself it worked, and prepared to move back out and across to the Agena target vehicle. Commander John Young had maneuvered his spacecraft close to the docking end of the Agena 8 target vehicle so that it was hanging above the hatches, about 1½ meters distant, sloping away at a 45° angle behind the adapter. Collins gave Young final instructions to position Gemini and, while the commander held his craft at a fixed distance from the Agena, the walker pushed off and up, floating to the rounded lip of the docking cone under the impetus of his own mass. Working his way round the cone, Collins found great difficulty in using the blunt lip for control, several times nearly slippi ng off as he moved counter-clockwise to where the micrometeoroid pack had been sitting exposed to space for four months. Reaching the micrometeoroid package, he attempted to stop his forward motion, but his lower body momentum left him “turning lazy cartwheels somewhere above and to the left of everything that matters.” Unable to stop when he wanted to, the inertia of his body carried him head over heels as his legs just kept on going. Drifting off the Agena, he could make his way back either with the hand gun or by pulling on the umbilical. Pulling up on the nitrogen line until the floating maneuvering unit came into his heavily gloved hand, Collins grasped it firmly and squeezed the trigger, sending bursts of nitrogen spurting into space from the small nozzles.

An Agena target vehicle as viewed from Mike Collins' Gemini 10 window. The micrometeorid package retrieved by Mike Collins from the Agena 8. Note: there are no picture of Mike Collins making his spacewalk since the camera used was lost at the end of the EVA.

More by luck than judgement, the spacewalker found himself flying straight down upon Gemini and feet first in the hatch, promptly coming to a halt on the seat. However, his movement had pulled the craft out of attitude with the Agena and Young gently blipped the hand controller to nudge Gemini back into position with the target vehicle hanging overhead.

For the second time, Collins drifted up to the docking cone, preferring to use the HHMU this time but, in trying to correct a pitching moment, he translated too high and narrowly missed grabbing hold of the docking cone. Instead of trying to do it the planned way, he fumbled for bunches of wires in the back of the cone, firm hand grips with which to pull himself up and over to the micrometeoroid package. During this activity, his heart rate never exceeded 120 beats/min and his respiration was a steady 20 breaths/min. 

But now, having retrieved the plate he had been working for ten minutes to get, it was time to return to the Gemini spacecraft. He was supposed to emplace another package for possible retrieval on a later flight, but he abandoned that idea when it became clear that in using his hands to clamber around the cone he would probably lose the one he had just removed.

Using the umbilical to pull himself back in, Collins was prevented from giving the maneuvering gun a good workout because Gemini propellant was getting low and Young was cautioned about station-keeping on the Agena. So that was that. The EVA would have to be terminated so that Gemini 10 could pull back from its target and drift, far away from the danger of a collision with the Agena. 

But the process of getting back in caused Collins great difficulty. First, he became wound up in the umbilical, then he had difficulty moving arms and legs within the pressurized suit. Finally, a combined operation freed the pilot and the hatch was closed. Collins discovered that he had lost his camera, then the long umbilical caused problems again, preventing Young from seeing the control panel so he could report fuel usage to Missin Control and causing Collins to accidentally shut off the radio.

This spacewalk shows that without some sort of handholds or restraining devices, a large percentage of the astronaut’s time is devoted to torquing his body around until it is in the proper position to do some useful work. Denied the opportunity to test the HHMU fully, Collins had, nevertheless, retrieved a valuable package that would tell scientists about particles moving in the vicinity of Earth and contribute toward an understanding of near-space environmental conditions. (The hatch was opened for a third time, to eject EVA equipment no longer required.)

Aldrin emerged in orbital daylight with an enthusiastic “Man, look at that!” and installed the S13 ultraviolet astronomical camera. He evaluated SEVA dynamics until after dark, then performed astronomical photography. 

He installed a camera to record his activities, then prepared for the next EVA by installing a handbar and unfolding a handrail. He changed a diffraction grating on the S13 camera and removed the S12 micrometeoroid package from behind the cockpit. Aldrin resumed astronomical photography as darkness fell again. He witnessed a second orbital sunrise before closing the hatch on his successful first EVA.

Aldrin moved to a similar work station on the Agena docking adapter where he tested an Apollo torque wrench with and without tethers. He wiped Lovell’s window and observed thruster firings on Gemini 12, then closed the hatch on the world’s first successful complex EVA.

Adapted from: David S. F. Portree and Robert C. Treviño, Walking to Olympus: An EVA Chronology, NASA Monographs in Aerospace History Series #7, October 1997, p. 10.

While inside the orbital module, Soyuz 5 Commander Boris Volynov checked out Khrunov and Yeliseyev’s life support and communications systems before returning to the descent module. He then sealed the hatch and depressurized the orbital module. 

Khrunov went out first, transferring to the Soyuz 4 orbital module while the docked spacecraft were out of radio contact with the Soviet Union over South America. Yeliseyev transferred while the spacecraft were over the Soviet Union. They closed the Soyuz 4 orbital module hatch behind them, then Soyuz 4 Commander Vladimir Shatalov repressurized the module and entered to help Khrunov and Yeliseyev get out of their suits. 

The spacewalkers delivered newspapers, letters, and telegrams printed after Shatalov lifted off to help prove that the transfer took place. Soyuz 4 and 5 separated after only 4 hr, 35 min. together. 

On mission day 4, Schweickart and Commander James McDivitt entered the Lunar Module (LM). The astronauts depressurized the two spacecrafts and McDivitt opened the LM’s hatch. Since Schweickart was feeling better than expected, McDivitt allowed him to egress and place his feet in the “golden slipper” foot restraint on the LM’s porch (photo 2).

Schweickart took photographs while Divid Scott opened the Command Module hatch, emerged partially, and retrieved thermal exposure samples from the exterior (photo 3). Scott’s SEVA was designed to demonstrate his ability to prepare for contingency EVA transfer from the LM to the CM in the event of docking or transfer problems. 

Schweickart performed well in the foot restraint, so McDivitt permitted him to test handrails and retrieve thermal samples on LM’s exterior. Movement using the handrails was easier in space than during training(photo 4). Schweickart reported. He returned to the LM and the astronauts closed the hatches and repressurized the two spacecraft.

Bean removed the camera from the LM side and put it on a tripod, in the process pointing it at the Sun. The camera’s vidicon tube was damaged, ending EVA TV for Apollo 12. 

The moonwalkers planted the U.S. flag and collected rocks near the LM, then deployed the Advanced Lunar Science Experiment Package (ALSEP), north of Surveyor Crater, about 180 metres from the LM. Dust kicked up by the astronauts stuck to the ALSEP instruments. The dust was not slippery, though Conrad took a harmless spill because of uneven footing. 

The astronauts had some difficulty removing from the LM side the plutonium fuel cartridge for ALSEP’s nuclear power source. The cartridge was hot enough to melt a hole in a space suit. Conrad and Bean had to dust each other off before climbing back into the LM for the night. 

First, the moonwalkers store the TV camera damaged during the first EVA so it could be returned to Earth for examination.

The 1.8-km traverse had three major objectives:  site exploration, geological sample collection, and Surveyor 3 inspection. They moved to the ALSEP site, collected a core and a trench sample, then they they collected two cores. Along the way they saw spatters of cooled molten glass on rocks and occasional brightly colored rocks. They also noted that the surface was gray or brown depending on Sun angle and direction. 

Two hr into the EVA they received a “go” for a 4-hr EVA. The astronauts stated later that they felt little fatigue and could have continued for twice as long as the three and half hr originally scheduled. 

They skirted the south rim of Surveyor Crater. Surveyor 3 sat on a 12-degree slope, 45 m inside the crater. The moonwalkers were puzzled by the apparent change in Surveyor’s white color caused by a fine coating of tan lunar dust. It looked brown to them. 

They then collected pieces of Surveyor 3 for study by scientists interested in the long-term of effects on equipment of lunar surface conditions. They removed Surveyor 3’s TV camera, sample scoop, and samples of wire, glass, and metal.

Then they moved back to the Lunar Module, stowed the rock boxes, and closed out EVA 2. They reported that fighting the internal pressure of their gloves made their hands tired. 

Mission Control used the code phrase “We’d like an EMU check” to warn the moonwalkers to slow down after their heart rates reached about 160 beats/min. They reported that the thermal meteoroid garments of their spacesuit were severely worn by lunar dust abrasion. Lunar dust became a problem during the return home, floating in weightless, making breathing difficult for the astronauts without their helmets. During the flight home, they had to clean lunar dust off the air filter screens every 2 to 3 hr.
     After their return back to Earth, the moonwalkers had difficulty telling themselves apart in their more than 500 photos. (Markings on the Commander's suit will be add on the next flights.)

After Edgard Mitchell joined him on the surface, the astronauts collected a 19.5-kg contingency sample, then deployed the TV camera (taking care not to point it at the Sun), S-band dish antenna, and U.S. flag. Shepard’s suit had red stripes at the knees and shoulders so he could be identified in photographs. His helmet also bore a red stripe. A hinged center shade section was added to the LEVA, providing additional eye protection when the astronaut walked toward the Sun under low Sun-angle conditions. 

The astronauts deployed the ALSEP experiments about 150 metres west of their Lunar Module, then set up the laser ranging retroreflector 30 metres beyond that. The EVA was extended by 30 minutes to partly compensate for the late start. In all, the astronauts covered about 550 metres before returning to the LM to eat and rest.

The EVA was planned as a 3-km traverse - probably the longest practical for an astronaut wearing a lunar spacesuit if useful work was to be performed along the way and a safety margin maintained. Their objective was the rim of Cone Crater, a meteoroid impact pit 300 metres wide. Geologists saw it as a natural excavation laying bare eons of lunar geological history. Reaching the elevated rim was considered important because it should have contained the oldest rocks.

Al Shepard and Ed Mitchell headed east toward the crater, taking turns towing the MET. They began climbing the blanket of loose debris around Cone 90 minutes into the EVA, about 850 metres from the crater rim. The MET had a tendency to tip and became difficult to pull as the number of boulders increased. The moonwalkers finally resorted to carrying it. Mitchell noted problems with dust, saying that, “we’re filthy as pigs… everything’s going to be covered with dust before long.” Shepard’s heart rate climbed to 150 beats per min and Mitchell’s right EMU backpact wrist cable broke, impeding his hand movements. 

Shepard said after the EVA that the worst problem was “the undulating terrain where you simply couldn’t see more than 100 to 150 metres away from you. Consequently, you were never quite sure what landmark would appear when you topped the next ridge. We were very surprised when we… approached the ridge which we thought to be the rim of Cone Crater, to find there was another one behind it… I think if we had wanted to reach the top of the crater and did nothing else, that we could have done that within the time period allotted.” 

The astronauts received a 30-minutes extension, but were finally compelled to abandon their quest for the rim. They obtained only one of three planned core tubes, 16 photographs, and 10 kg of samples during their Cone traverse.

Pulling his shoulders through the top hatch, he got his bearings at the complex Hadley-Apennine landing site ahead of the surface EVAs.  He told Edgar Mitchell in Mission Control that the site was “exactly like what you had on Apollo 14. It’s very hummocky, and, as you know, in this kind of terrain, you can hardly see over your eyebrows.” 

Scott reported that 5-km Mt. Hadley glowed gold and brown in the lunar morning sunlight, and that there were no large boulders to hinder the progress of the Lunar Roving Vehicle during the next day’s scheduled traverse south to St. George Crater.

At the start of the EVA, David Scott set up the improved TV camera while James Irwin collected the contingency sample. They tended to move using two-footed kangaroo hops rather than slow-motion loping. 

Unstowing and deploying the Lunar Roving Vehicle took longer than the 20 minutes allotted. Though it was planned as a one-man task, under lunar conditions, unfolding the vehicle required both astronauts. During LRV deployment, Irwin took the first of several harmless falls. The astronauts found that the rover had no front-wheel steering, but Scott managed to maneuver the vehicle using only rear steering. The astronauts also found that their seatbelts barely fit around their pressurized EMUs.

About 3 hours into the EVA, they set out on a 10.3-km traverse south along the rim of Elbow Crater to the 2-km-dia. St. George Crater, near Hadley Rille. During the traverse, the astronauts reduced suit cooling to avoid becoming cold while their metabolic rates were low. They had some difficulty with light reflected from the landscape opposite the sun, which made obstacles difficult to discern.

The astronauts used a rake to collect “walnut-sized samples” near St. George Crater. Flight controllers operated the LRV camera so geologists on Earth could explore the lunar landscape telerobotically and guide the astronauts in collecting samples.

The moonwalkers then drove back to the Lunar Module to deploy the ALSEP science instrument package. They located the central station 110 metres west of the LM and drilled a hole in the ground for a heatflow experiment probe. But the task was extremely difficult, Scott discovering that the lunar ground is very hard. In his effort, he used so much oxygen that flight controllers had terminated the EVA thirty minutes early and considered cutting back the second EVA.

Both astronauts suffered pain in their fingers caused by their fingernails pressing hard against their glove fingertips. Irwin needed help to remove his gloves, and elected to trim his nails before the second EVA. Scott left his fingernails as they were to avoid reducing his dexterity.

When they did reach the surface, David Scott and James Irwin were delighted to discover that Lunar Roving Vehicle front steering had become operational. They began a 12.5-km traverse southeast to the foot of the Hadley Delta mountain and back. The LRV climbed Hadley Delta’s slopes at 10 km/hr. with no difficulty. 

The moonwalkers climbed 100 metres above the Lunar Module, which was more than 5 km away. Soft material on the slopes provided poor footing, and the LRV began to slide while parked. Irwin held the rover while Scott hopped off to collect a green crystalline rock. 

At Spur Crater, they collected the “Genesis Rock,” which today is still believed to be a piece of original lunar crust more than four billion years old. Scott called Spur a “gold mine” of interesting geological samples, so their time there was extended to 49 min. 

The elevation clutch on the LRV camera began to slip. Irwin’s vertical PLSS antenna snapped off, and Scott taped it on horizontally. The astronauts collected so many samples at Spur that the LRV bounced when they dropped the rock box on it. 

They then had to rush because they were approaching the “walkback” limit of their suit reserves. In contrast to the first EVA, Scott used about as much oxygen as expected. The astronauts found navigating back to the LM difficult until they encountered their own outbound tracks. 

Back at the LM, Scott drilled a core hole, encountering much resistance and hurting his hands. Then the 3-metre-long core tube could not be removed. On advice from Mission Control, the astronauts abandoned the tube until the next EVA. They planted the U.S. flag at the EVA’s end.

David Scott and James Irwin managed to free the core tube which became stuck on EVA 2, but could not take it apart to stow it because the LRV vise was assembled backwards on Earth. They used a wrench and lost 28 minutes. 

They then started their traverse 1 hr. 20 min into the EVA. They drove 5 km  west to Scarp Crater, then turned northwest to Hadley Rille, with stops at Rim Crater and a feature called The Terrace. This EVA marked the first time Apollo astronauts passed out of sight of their LM. 

With this EVA, the fifth of his career, Scott became the record-holder for number of EVAs. His record was not beaten until 1984 by Soviet cosmonauts onboard Salyut 7. During the three traverses, the LRV was used to collect nearly 80 kg of samples and covered almost 50 km.

Using handrails and foot restraints, he had no difficulty making three round trips to the Scientific Instrument Module (SIM) bay built into the side of Service Module. Irwin guided his 8.3-m tether from Command Module hatch. 

Worden first retrieved the 39-kg Itek panoramic camera cassette, which he tethered to his arm and carried to Irwin at the hatch. Though Worden’s metabolic rates remained acceptable throughout the EVA, Mission Control warned him not to rush. 

On the second trip, Worden removed the 10-kg cassette from the Fairchild mapping camera. he made an unplanned third trip to inspect the SIM bay instruments which had malfunctioned. 

Then, Duke had trouble getting into his lunar suit because he had grown 4 cm  in weightlessness. Then, a problem with the LM’s steerable antenna delayed EVA start by an hour and prevented Young’s first steps on the Moon from being televised. 

Finally, on the Moon, the astronauts deployed the U.S. flag and ALSEP deployment. Duke used an improved drill to collect a 2.6-metre core. He inserted the heat flow probe, which was linked to the ALSEP central station by a cable. But Young accidentally walked over the cable, tearing it loose from the central station. Mission Control began study of a possible repair during the second EVA. Also, the deployment lanyard on the cosmic ray experiment broke, leaving the crew uncertain as to whether the instrument was fully deployed. 

The moonwalkers deployed the Lunar Roving Vehicle but they discovered that it had no rear steering and one of its batteries read low. Fortunately, rear steering returned and the battery read normal 40 minutes into the traverse.  En route, Young and Duke collected an 11.7-kg rock. The LRV bounced a great deal during the traverses.

Following the traverse, Duke operated a movie camera while Young performed LRV traction tests known jocularly as the famous “Grand Prix.” 

When Mission Control relayed the news that Congress approved Space Shuttle funding, John Young leaped one metre and saluted the flag. (Nine years later, he went on to command the first Shuttle mission.) Duke jumped too, but slipped and fell on his PLSS. 

After the EVA the astronauts reported the usual dust problems: stuck zippers glove disconnects and indicators scratched and difficult to read.

Onboard the rover, the moonwalkers climbed Survey Ridge to Stone Mountain. They collected core samples on Stone Mountain and reported that the view of their landing site was “just dazzling.” The LM was barely visible in the distance. 

During descent toward the LM, the rover’s pitch meter pegget 20° of slope. The astronauts collected a thin layer of surface material using adhesive plates. As with most lunar EVAs, some activities and stops were deleted because of insufficient time. 

(Prior to the second EVA, Mission Control vetoed repair of the heat flow cable because it would take too much time and possibly short-circuit the ALSEP central station.) 

John Young and Charles Duke drove to the foot of Smoky Mountain, near North Ray Crater, where they spent 1 hr. 20 min. sampling and taking magnetic field readings using the Lunar Portable Magnetometer. They found the largest remnant magnetic field discovered on the Moon. 

They commented on the thick dust they kicked up and the generally shattered appearance of the area. Geologists in the back room asked Young to look at North Ray’s bottom, but he turned down the request, saying that: “That rascally rim slopes about 10 or 15 degrees… then all of a sudden… I’ve got to go 100 yards down a 25 to 30 degree slope and I don’t think I’d better.” The astronauts collected samples off 10-metre-high, 20-metre-long House Rock, the largest boulder sampled during Apollo. 

Young found that by hopping into the air and landing on his feet, the weight of his suit overcame the suit’s internal pressure, so he could get to his knees and pick up rocks without using geological tools. 

The LRV suffered temporary navigational computer failure, but the moonwalkers knew where they were from the Sun’s position. They trended back toward their outbound tracks so they could follow them back to the LM, but spotted their spacecraft before they found their tracks. The LRV reached its highest speed on the Moon - 22 km/hr - rolling down a 15-degree slope during return to the LM. 

Young left the LRV parked 50 metre east of the LM, then helped Duke load 96.6 kg of lunar samples into the spacecraft. Controllers on Earth used the rover camera to track the LM ascent as it left Descartes behind. (The avionics cooling water ran out as it completed docking with the Command Module.)

Mattingly made two leisurely trips along Apollo’s Service Module. He inspected the spacecraft’s exterior and exposed the Microbial Ecological Evaluation Device to space for ten minutes. 

Before returning to the cabin, he opened his visor briefly so he could see the stars, taking care not to look in the direction of the Sun.

The astronauts deployed and tested their Lunar Roving Vehicle, then planted a U.S. flag which had hung in Mission Control since Apollo 11. Cernan accidentally knocked off part of one of the rover’s fenders and repaired it with tape. The astronauts set up the ALSEP 185 metres northwest of the LM.

Cernan drilled two holes 2.5 metres deep holes and inserted two heat flow probes. He also drilled a core sample hole 2.8 metres deep. Collecting the core required 1 hour, the core device stuck despite the long-handled jack designed to ease removal. Cernan’s oxygen consumption climbed rapidly as his pulse hit 145 beats per minutes. Schmitt extracted the core by throwing his weight on the jack handle, but fell and scattered equipment. In general, the Apollo 17 astronauts treated their space suits roughly - experience gained on earlier flights left them with little fear of suit damage. Cernan then inserted a cosmic-ray probe into the hole left by the core. Encumbered by his suit, 

The damaged rover fender fell off on the way to the first geological survey station, so the astronauts were showered with dust. Schedule pressure forced deletion of a trek to Emory Crater in favor of a shorter trip to Steno Crater. The astronauts placed 0.45-kg and 0.23-kg explosive packages during the traverse. The explosives were set off after Cernan and Schmitt departed and recorded by geophones in the Apollo 17 ALSEP. 

Schmitt at first had trouble picking up rocks, which he admitted was “a very embarrassing thing for a geologist.” Cernan drove so Schmitt could do science. The geologist carried a new long-handled scoop which allowed him to sample from the rover seat, saving time. 

Back at the LM, Cernan reported that his tussle with the core tube bruised his arms and burst blood vessels under his fingernails. Dust tracked into the LM gave Schmitt a mild hayfever attack. However, dust catchers on the floor mitigated some of the dust difficulties experienced by previous crews. 

At survey stops, they deployed explosive packages. Cernan abandoned some of the caution shown on Apollo 15 and 16 and drove as fast as he could. They spent an hour sampling South Massif landslide material at Nansen Crater. They then explored Shorty Crater, which was suspected (at this time) of being a volcanic vent. Schmitt kicked up orange and crimson soil which appeared to confirm this hypothesis, so the astronauts, Mission Control, and Earth-based geologists rapidly adjusted the tight traverse schedule so Schmitt could collect unplanned core and trench samples. 

Apollo scientific and technical ground-based support was sufficiently refined by this time to permit flexible responses to EVA challenges and opportunities. Later, the astronauts comment that one can conceive of many samples “left uncollected at this remarkable locality.”
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The astronauts saw more orange soil at later stops. The soil turned out later to be ancient volcanic glass blasted to the surface when Shorty was formed about a million years ago, not a sign of recent volcanism as originally hoped. 

Before returning to the Lunar Module, Schmitt went back to the ALSEP site to check the orientation of the Lunar Surface Gravimeter. On this EVA, the longest of the Apollo program, the astronauts drove the LRV for 19 km.

The moonwalkers traversed to North Massif. They deleted the last geological survey stop to return to the ALSEP to adjust the Lunar Surface Gravimeter, which was still not functioning properly. They then extracted the cosmic-ray neutron probe and set more explosive packages. 

Finally, they unveiled a plaque on Challenger, which read: Here man completed his first exploration of the Moon, December 1972 A.D. May the spirit of peace in which we came be reflected in the lives of all mankind. 

Since they expected to be the last humans on the Moon until the late 1980s, Schmitt and Cernan were eager to keep working but, by EVA closeout Schmitt’s hands were so tired from lack of glove mobility during the long EVAs that he could barely move them. They left the lunar surface carrying 115 kg of samples and 2120 photos.

The crew improvized a Stand-up EVA, trying to open up the solar array. They moved their Apollo Command Module close to the jammed array. Paul Weitz then stood with his upper body through the hatch and assembled a 4.5-metre pole with a shepherd’s hook on the end from three 1.5-metre sections handed to him by Joe Kerwin. He hooked and pulled on the array while Kerwin gripped his legs. Charlers Conrad had to hold the CM steady because Weitz’s efforts pulled it toward the workshop. 

Weitz replaced the hook with a universal prying tool when the strap did not budge, but to no avail.  Their efforts thwarted, the astronauts docked with Skylab and closed out a 22-hour day.

On June 7, Pete Conrad went outside Skylab’s airlock and Joe Kerwin passed him the six 1.5-metre poles, helped him assemble the cable cutter, and then moved in position. Conrad handed him the cable cutter assembly, then carryied the BET. The plan called for Kerwin to hook the cable cutter assembly on the strap holding wing 1 closed. Conrad would then crawl down the assembly to wing 1 and attach the BET.

However, Kerwin had difficulties finding a firm foothold because Skylab unexpectedly differed from the mockup in the tank in Huntsville. He was forced to hold on with one hand while attempting to position the pole with the other. After a frustrating half hour, he shortened his tether by doubling it. This held him more firmly against Skylab and allowed him partial use of his other hand. He finally succeeded in hooking the aluminum strap. 

Conrad attached the BET large hook to the discone antenna, then climbed along the cable cutter assembly pole. He attached one of the two BET small hooks to bolt holes on wing 1. Again, Skylab differed from the ground mockup; the second small hook would not fit. Kerwin tightened the BET using a cleat, then cut the strap holding the array closed. Conrad placed the BET over his shoulder, put his feet against the workshop’s hull, and strained against to pull open the array. Kerwin joined him. Finally the hydraulic damper holding the array closed gave way. 

As Conrad later described it: “I was facing away from it, heaving with all my might, and Joe was also heaving with all his might when it let go and both of us took off. By the time we got settled down… those panels were out as far as they were going to go.”  Needles on electricity meters on the ground and inside Skylab jumped, signaling success. 

Before going inside, the astronauts serviced the ATM astronomical instruments, changing out film in a malfunctioning camera and pinning open a balky solar telescope aperture door.  The astronauts had difficulty restowing the life support umbilicals in their spherical stowage containers.

Astronauts used single and dual handrails, the latter resembling ladders without rungs. According to them, the single handrails worked well, while translation using the dual rails was as easy as “driving on the freeway.” All handrails were painted blue for visibility and provided with “road signs” - alphanumeric designators. The blue faded rapidly in the strong sunlight of space however, and the designator labels proved difficult to see. 

Their film changeout tasks completed, Conrad and Weitz removed space exposure samples launched on the workshop’s exterior to return them back to Earth. 

They then used a brush to clean the White Light Coronograph occulting disk, which was producing glare. Conrad then moved to Circuit Breaker Relay Module 15. Acting on instructions from the ground, he hit it with a hammer to free a stuck relay. This low-tech solution succeeded and soon the module was feeding electricity into the Skylab power system again.

At the start of the EVA, Owen Garriott assembled two poles, each made up of 11 1.5-metre sections, and passed them to Jack Lousma, who attached them to a base plate he installed on a hand rail, unfurled the sunshade fabric, and attached a reefing line to make the shade lie flat. He swiveled the completed shade to cover the station, then returned to the airlock to get equipment for the next phase of the EVA. 

Lousma ascended the Apollo Telescope Mount again, installed film. He then inspected Apollo Command Module thruster quads A and B from his position on the ATM. The quads were leaking, but Lousma saw no obvious signs of leakage and they later stopped, so Skylab 3 could run its scheduled 56-day duration. 

Lousma removed a telescope aperture door ramp to keep the door from sticking, which required removal of two bolts not designed for EVA. Then, he deployed the Micrometeoroid Particle Collection experiment. This experiment was originally intended for deployment from the science airlock blocked by the parasol, but was redesigned for EVA deployment and launched with the Skylab 3 crew.

The Airlock Module suit cooling system was inoperative because of leaks, so no water flowed through the umbilicals to the astronauts’ suits. Air cooling proved adequate for the undemanding tasks at hand, Garriott reported becoming slightly warm, while Bean’s hands were warm throughout the EVA.

They also attached the Trans-Uranic Cosmic Ray Experiment detector to the clipboard; pinned open a malfunctioning aperture door; installed space exposure samples; and repaired the Microwave Radiometer/ Scatterometer/Altimeter antenna, which was on the Earth-facing side of station where no EVA handrails or foot restraints existed. The astronauts had difficulty keeping their umbilicals separated.

They also took 40 pictures of Comet Kohoutek; partially replaced ATM film, retrieved space exposure samples, and pinned open another malfunctioning aperture door. 

The astronauts then returned to the Airlock Module to stowed equipment while crewman Edward Gibson maneuvered Skylab to the proper attitude for far UV comet photography. The Far UV camera took three sequences of 10 photos each, then returned the instrument to the airlock. 

Finally they repaired a telescope filter wheel, which involved fine work made challenging by their stiff space suit gloves. They used a dental mirror and penlight to look into the aperture, then carefully positioned the filter wheel with a screwdriver. Leaking cooling water, colored yellow by chromate corrosion inhibitor, formed ice on the front of Carr’s belly-mounted pressure control unit. The leak lacked sufficient volume to deplete the cooling water supply. Yellow ice flaked off as Carr moved.

The astronauts then mounted the Micrometeoroid Particle Collection experiment on the ATM. NASA hoped that the experiment could be collected by Space Shuttle astronauts during a Skylab visit in the early 1980s (which never happen). 

Gibson’s suit cooling system sprang a leak, so he switched to minimum cooling and continued work. At the end of the EVA he reported that he was “tired and hungry.”

Grechko opened the front docking port and pulled himself halfway out so that he could inspect and manipulate the outer surfaces of the docking mechanism using special tools. He found everything to be in perfect working order.  (Airlock depressurized time was 88 minutes, but SEVA time [hatch open/close] was only 20 minutes.) 

For years, Soviet spaceflight observers believed that mission Commander Yuri Romanenko, in his eagerness to look out the open hatch, nearly drifted free of the station, and that only quick action by Grechko prevented him from being lost in space. Grechko now denies categorically that his commander was ever in danger, and adds ruefully that “Yuri was very angry about the story.” Romanenko says that the story had its start in a “bad joke” Grechko told which was misunderstood, and adds that, even though his short safety tether was not secured, his electricity/communications umbilical firmly fastened him to Salyut 6. 

Ivanchenkov positioned himself on the Yakor (“anchor”) foot restraint near the airlock hatch, while Kovalyonok floated with his feet in the transfer compartment. The cosmonauts rested during the 35-minute orbital night, and were treated to the sight of a brilliant meteor burning up below them in Earth’s atmosphere. 

Ivanchenkov removed three space exposure cassettes launched on Salyut 6’s exterior and handed them to Kovalyonok for stowage in the transfer compartment. He then replaced meteoroid dust collectors and installed radiation sensors. Ivanchenkov photographed the Black Sea, Kazakhstan, and China. 

Mission Control ordered them to return inside just before Salyut 6 passed from radio range, but Kovalyonok decided, while out of radio contact, that they could stretch the EVA 20 minutes longer to enjoy the view of Australia’s Great Barrier Reef and New Zealand.

With difficulty, Valeri Ryumin opened a handrail recessed into the station’s hull, then gripped it with one hand for 30 minutes until orbital sunrise. As Ryumin moved aft along the station, Vladimir Lyakhov took his place at the handrail.

Ryumin had to use a wire-cutters designed for onboard use to cut through four 1-mm steel cables and free the antenna. Each time he cut at a cable, the 10-metre-dia antenna pitched toward him, threatening to cut his suit (as it had cut thermal insulation blankets on the station’s aft bulkhead) or smash him. Lyakhov positioned himself so he could warn Ryumin of the dish’s movements. Ryumin’s heart rate reached 146 beats/min while he worked. 

Finally, the last cable was cut and Ryumin pushed the KRT-10 antenna away with a “forked stick.”  The antenna flops loosely at the rear of the station. When communication was restored with the ground, the cosmonauts reported that they had completed their task and, at first, were not believed [since it tok them so little time]

Then, the spacewalkers returned to the exterior of the transfer compartment, where Ryumin wiped a porthole with a cloth to collect samples of obscuring “space dust.” They also collected space exposure experiment cassettes mounted just outside the EVA hatch. After the EVA, Ryumin found a small puncture in his suit’s primary bladder, possibly caused by a sharp wire on the KRT-10 antenna.

Anatoli Berezevoi spent most of the EVA standing in the hatch passing equipment to Valentin Lebedev, who positioned himself in the Yakor foot restraint. Lebedev’s activities were aimed at preparing for Salyut 7 solar array augmentation EVAs and other space assembly tasks. The Pamyat experiment tested “thermomechanical joining of pipeline sections in outer space,” while Istok tested “threaded connectors” made of different materials.

Lebedev also tested an experimental wrench, which worked well, but his hand went numb because his wrist pressed against his suit wrist ring during tool use. Lebedev complained that the improved Orlan-D cooling system made his feet cold. 

He collected and replaced 20 space exposure cassettes containing gasket rubber, insulating coatings, glass for ports and lenses, and other materials. He also replaced micrometeoroid detectors. He then described the EVA for Soviet TV viewers as he stood on Salyut 7’s hull while Berezevoi televised the station’s exterior and the Earth below.

While preparing for STS-6 EVA, Story Musgrave and Donald Peterson “stood” face to face in the airlock, which lead to thrashing and noise. Despite this, they managed to doze during the 3-hour in-airlock prebreathe. They then left the airlock to assess space suit mobility by translating aft along the handholds inside the payload bay door hinge of the Orbiter. Musgrave climbed to the top of the payload bay aft bulkhead and looked back over the Orbiteur’s engine bells.

The spacewalkers demonstrated contingency payload bay door closure without actually closing them. They had difficulties rewinding the payload bay door EVA winch and considered cutting the winch cable, but Mission Control vetoed this and the cable came free. They also went through the motions of lowering a jammed satellite tilt table. Musgrave reported that his fingers were cold.

Vladimir Lyakhov, who thus became the first Russian to perform a second EVA, and Alexandr Alexandrov forst set up a TV camera on a movable arm so flight controllers could monitor the EVA. Then they took up position in foot restraints and removed the add-on array from its container.

Forty min into the EVA, the spacewalkers passed out of range of Soviet ground stations and tracking ships for 50 minutes. Much of the time out of range was spent in darkness, so they awaited orbital sunrise to resume work. 

A total of 48 operations were needed to deploy the array nominally. Lyakhov and Alexandrov used a special winch to unfurl the add-on array along one side of the existing array. The 5-metre-long, 1.5-metre-wide add-on array increased available power by 25 percent. 

Lyakhov received a reprimand from Mission Control for releasing bits of junk to watch them float away - the glittering objects could interfere with Salyut 7’s star sensors.

During the EVA, Leonid Kizim and Vladimir Solovyov simultaneously simulated the work in the neutral buoyancy facility. In the event of difficulties, they could give us assistance with their recommendations. 

This spacewalk marked the first time the Soviets performed two EVAs in one mission.

During EVA preparations, while spacewalkers pre-breath in the airlock, to help relieve the thrashing and banging which occurred during airlock depressurization on STS-6, Bruce McCandless pointed his head toward the airlock floor while Robert Stewart pointed toward the ceiling.

Outside in open space, McCandless spent 90 minutes checking and donning his MMU, then tested it in the payload bay by maneuvering precisely around equipment. He found that the backpack shuddered and shook when forward movement was initiated in attitude hold. He then moved 45 metres out from the Orbiter, returned to the payload bay, flew out to 96 metres and returned, then moved out again to about 99 metres. MMU nitrogen propellant use was higher than in simulations. McCandless reported later that he was chilled when out away from the payload bay.

Mission Commander Vance Brand noted that the MMU’s tracking lights were inadequate for finding the astronaut if he strayed away during orbital night. He ordered McCandless to hurry back to the payload bay before the Orbiter passed into darkness.

Then, Robert Stewart installed a Manipulator Foot Restraint on the Canadarm robot arm, but had to postpone a test ride because the EVA was behind schedule. 

When McCandless returned to the payload bay, Stewart attached in front of the MMS (between its control arms) the Trunnion Pin Attachment Device (TPAD) to be used to snare Solar Maximum Mission satellite retrieval, scheduled for the next flight. McCandless practiced docking with a trunnion pin mounted next to a mockup of the Solar Max main electronics box in the payload bay. 

Stewart then flew the MMU 93 metres from the Orbiter. Commander Brand noted that Stewart was traveling at 0.5 km/h about 90 metres from the Orbiter, so warned him to slow down. Stewart tested the MMU for 65 minutes. 

Finally, McCandless became the first astronaut to ride a foot restraint at end of robot arm. The arm proved more stable for EVA work than expected.

Unfortunately, the Canadarm manipulator arm suffered wrist joint and elbow TV camera malfunctions prior to this EVA. The camera problem meant that engineering film coverage of the EVA was not as comprehensive as planned. The joint failure was much more serious: it meant that the RMS could not release a rotating Shuttle Pallet Satellite above the Orbiter’s payload bay, depriving the MMU astronauts of a spinning target for practice docking using the TPAD. The ability to dock with a rotating target was considered crucial to the Solar Max repair. The astronauts practiced docking with fixed targets instead. 

Then, Stewart performed a hydrazine transfer experiment to help validate the Orbiter’s proposed role as a satellite tanker. Freon dyed red for visibility filled in for poisonous hydrazine. 

Finally, a foot restraint worked itself loose.  Commander Vance Brand maneuvered the Orbiter and McCandless moved down the starboard sill to retrieve the errant hardware. NASA called this an unplanned test of the Shuttle’s ability to rescue an astronaut stranded by MMU failure.

Outside, in the Orbiter’s payload bay, George Nelson, assisted by James van Hoften, donned the MMU, then attempted to dock with Solar Max using the TPAD mounted between the hand controller arms. He bounced off Solar Max after the TPAD jaws failed to close on one of the satellite’s berthing docking pins. Solar Max began to spin. 

Twice more he attempted to latch onto the satellite with the TPAD, each time adding to the slow spin. (His difficulties were later traced to an obstructing grommet on Solar Max which did not appear in its blueprints.)

Nelson then tried to stabilize the satellite by gripping one of its two solar arrays and activating the MMU’s automatic attitude hold feature, but this reversed the spin and started an unpredictable tumble about two axes. Solar Max lost its lock on the Sun and began draining its batteries. He was forced to return to the Orbiter when his MMU nitrogen propellant supply ran low. 

Mission Control considered changing MMUs and TPADs and trying again, but the Orbiter’s rendezvous fuel was running low, threatening the orbiter’s ability to recover a stranded MMU astronaut. 

A subsequent attempt by Terry Hart to capture the satellite using the Canadarm robot arm failed because of the tumble. The astronauts returned to the airlock. 

At the end of the day, it seemed that the Space Shuttle had failed to live up to one of its development justifications: payload retrieval and refurbishment.
 

Then, during their second spacewalk on April 11, James van Hoften and George Nelson completed replacement of the satellite’s 225-kg attitude control and main electronics box 1 hour ahead of schedule.  Van Hoften reported that the EVA “tools are working great - haven’t had one glitch yet.” The spacewalkers praised the Module Servicing Tool, which was developed specifically for MMS servicing. 

The failed attitude control module and main electronics box of the satellite were stowed for return to Earth, where they would be analyzed to determine the cost-effectiveness of satellite refurbishment in orbit.

They also stowed thermal blankets and various aluminum parts for analysis by orbital debris researchers on Earth. The salvaged components acted as impromptu debris catchers during their 4 yr in space. 

Before returning to the airlock, Nelson stepped into an foot restraint and rode the Canadarm above Solar Max to examine and photograph the satellite from all angles. Van Hoften then took the MMU on a short test flight in the payload bay.

The ODU was located in unpressurized aft equipment compartment of the station. There were no handholds near it, so ground engineers attached a special work platform with foot restraints to the Progress forward dry cargo module. Mission Control extended the platform by remote control prior to the EVA. Total distance between the Salyut 7 airlock hatch and the worksite was 15 metres. However, the spacewalkers’ progress over the station’s hull was impeded by the 40 kg of equipment they carried, including a tool caddy, cutting tools, wrenches, bypass pipes, a waste container and, most encumbering of all, a ladder for reaching the worksite. 

During their first of two planned EVA – which had the goal of preparing worksite for ODU repair -, Leonid Kizim and Vladimir Solovyov drove anchor pins into the equipment compartment’s plastic skin to attach the ladder and tool containers, then unfolded the ladder to its full 5-metre length before closing out the spacewalk.

They pulled aside thermal blankets and cut through the station’s plastic skin to reach the oxidizer plumbing. They then located and replaced a valve on a “shut-off part of the reserve line,” but only after a nut locked by epoxy resin thwarted their efforts for 2 hours. 

The oxidizer system was then pressurized with nitrogen to check their work, revealing that the ODU still leaked. The cosmonauts asked for and received an extension to complete work on the reserve line. But, when the extension lapsed, Mission Control had to order them back inside Salyut 7.

First, they finished work on the line they repaired during their second EVA, then installed a bypass line between two fill tubes, creating a new conduit to the main oxidizer supply. After they completed their work, nitrogen was again pumped through the system to check its integrity. To the dismay of all, the ODU plumbing still leaked. 

The spacewalkers replaced the thermal blankets and returned inside the station while troubleshooters on the ground resumed efforts to localize the leak. 

With this EVA, Kizim and Solovyov became the first Soviet spacewalkers to conduct three EVAs in one flight.

The spacewalkers were then dismayed to discover that they lacked tools adequate to complete the repair. They replaced the thermal blankets and returned inside Salyut 7, their efforts again thwarted. (The Progress 20 undocked on May 6, taking the special extension and foot restraints with it.

Leonid Kizim and Vladimir Solovyov left the airlock toting tools and the two solar array extensions, each in a separate container. They discarded the containers after removing the panels. From foot restraints, they assembled each 4.56-square-metre extension, then attached the first and winched it into position.

Onboard Salyut, Oleg Atkov used controls to turn the port array 180 degrees so it presented its other side to the cosmonauts. They then attached and winched into place the second add-on panel. 

Then, Solovyov struggled to tie two knots in wire bundles linking the arrays to the station’s main external power panel, a task he later compared to “trying to thread a needle in boxing gloves.” The new panels contained cells made of gallium arsenide that were more efficient at producing electricity than the silicon cells launched with Salyut 7. They added 1.2 kW to Salyut 7’s power supply. 

Adding the port array extensions required only one EVA, demonstrating the benefits of EVA experience (this was Kizim and Solovyov’s fifth EVA) and of applying lessons learned from the previous solar array add-on EVA in November 1983. With this EVA, they tied David Scott’s record for total number of EVAs.

Vladimir Dzhanibekov opened the Salyut 7 airlock and unfolded than stood in a Yakor foot restraint. He then set up a worksite lamp. Svetlana Savitskaya handed out the URI, which Dzhanibekov set up and attached to an external power outlet. He then traded places with Savitskaya, who set up a TV camera. 

Savitskaya began work with URI, first cutting a 0.5-milimetre-thick titanium sample. In all, she performed six cutting, two silver spray coating, and six soldering experiments. Savitskaya and Dzhanibekov then traded places again so he could test URI. Dzhanibekov said later that “the tool is very handy and I’m sure we’ll be using it a lot.” After finishing, he took down URI and handed the device and experiment samples to Savitskaya. 

Dzhanibekov then removed Ekpozitsiya cassettes from the station’s exterior and handed them to Savitskaya, who handed back a Meduza biopolymer cassette for installation. Products of the welding experiment returned to Earth.

This walk marked the tenth EVA for the Orlan-D suits. Perhaps because it was old, Solovyov’s suit suffered cooling water pump failure. He compensated by operating primary and backup circulating fans simultaneously and resting periodically to cool off. 

Before returning inside, the spacewalkers removed a sample of silicon solar cell material so engineers could study its degradation. They used a special holding tool to avoid contaminating it with their suit gloves. (It was later reported that the men’s hands were in bad shape after the EVA “as if they had been in a fist fight.”)

With this EVA, their sixth together, Kizim and Solovyov broke David Scott’s 1971 record for total EVAs and completed a record 22 hr. 50 min. of EVA in a single mission.

Before going inside, they manually stowed the Orbiter’s Ku-band antenna, which had given trouble earlier in the flight, and inspected the Shuttle Imaging Radar-B (SIR-B) antenna, which had not closed properly and had had to be pushed shut using the RMS. The spacewalkers found that insulation caught between the antenna sections was a possible cause. 

As they prepared to close out the EVA, the airlock hatch cover escaped. While Commander Crippen maneuvered the Orbiter to pursue, Leestma somersaulted from the middle of the bay and snatched it.

The goal of the first EVA was to recover the 555-kg Palapa B-2. In the payload bay, Joe Allen donned the MMU (“space sccoter”) and attached a grapple stinger to its arms. He then flew to Palapa, inserted the stinger into the spinning, drum-shaped satellite’s Apogee Kick Motor bell, and activated the MMU’s automatic attitude hold feature to stop the spin. 

Allen and Dale Gardner than cut off Palapa’s omnidirectional antenna, and Gardner, standing in an foot restraint fixed on the Canadarm, attempted to attach the 2.44-metre A-frame device. But the device stubbornly resisted his efforts.

The spacewalkers thus fell back on the backup plan: Gardner grasped and held the satellite, while Anna Fisher, on the command of the Canadarm, guided him to the stowage frame intended to hold Palapa in the Orbiter’s payload bay. (Gardner’s gloves became abraded during the EVA because of friction from a knurled tool handle.)

Finally, they removed a bracket clamp from the A-frame during EVA closeout and took it into the airlock for examination in the crew compartment. (Later investigation revealed that the A-frame was blocked by a Palapa waveguide extension that did not appear in the spacecraft blueprints.)

The spacewalkers left the omnidirectional antenna intact to serve as a handling aid. While Allen held the satellite on the Canadarm, Fisher moved him to the back of the payload bay where they secured it for return to Earth. 

A torque wrench escaped when Gardner bumped a tether release button, but he was soon alerted and he captured it before it could drift out of reach. 

In their postflight debrief, the crew noted that the EVAs were physically and mentally exhausting for all five crewmembers. They suggested that Shuttle crews of at least six were desirable for missions with complex EVAs. Allen and Gardner reported that satellites were relatively easy to handle; in fact, they were easier to handle in some ways than the long, lightweight A-frame. Allen added that “As objects get smaller in space, they become more difficult to handle. It’s really extraordinary how much easier it is to move more massive objects like satellites.”

Ironically, this EVA marks the final flight of the MMU. The two flight units had flown a total of 10 hr. 22 min. in space.

Three days before, the crew had deployed two satellite from the Orbiter payload bay, one of them being the Syncom-IV/Leasat 3 geosynchronous communications satellite. Unfortunately, this craft remained inert after deployment, and engineers quickly determined that a likely culprit was a faulty switch on the satellite’s side. 

They thus hatched a plan in which spacewalking astronauts would attach improvised switch-pulling appendages to the Canadarm end effector. Two different switch-pullers (the “lacrosse stick” and the “flyswatter”) were manufactured using materials on board Discovery, including tape and plastic book covers. Then, Rhea Seddon, onboard the Orbiter, would maneuver the arm so that the appendages snag the switch that started an automatic timer. The crew would quickly move away to get clear of the plume from the satellite’s kick motor. 

Before the EVA, Seddon bent the arm at elbow and wrist to bring the its end effector closer to the airlock. At the start of the EVA, Hoffman and Griggs moved to the end effector, which is about halfway down the payload bay, and attached the switch-pullers with a payload retention strap. 

They rested while out of communication range. During night passes, both men became cold. Their work completed, Griggs pushed himself over the starboard payload bay sill toward the Orbiter’s delicate radiator panels. But Commander Karol Bobko warned him to return to the payload bay. The astronauts then returned to the warmth of Discovery’s crew compartment. 

Rhea Seddon snared the switch repeatedly with the switch-pullers, but Syncom IV/Leasat 3 remained inert.

The spacewalkers used the Orlan-DM’s headset lights to continue work during orbital night. They left a small piece of solar cell material outside as an exposure experiment. This completed the series of solar array augmentation spacewalks planned at Salyut 7’s launch to occur over the station’s occupancy. 

Before closing out the EVA, they installed a Soviet/French experiment for collecting meteoritic dust (it was expected to gather dust from Halley’s Comet) and changed space exposure cassettes near the transfer compartment hatch.

Spacewalkers James van Hoften  and William Fisher entered the Orbiter’s payload bay and Van Hoften placed his feet in a foot restraint at the tip of the Canadarm. The 6818-kg drum-shaped satellite rotated very slowly, so he found it easy to install a bar for slowing rotation by hand. However, the EVA fell behind schedule because the handling bar - which included a grapple fixture for the arm end-effector - did not fit at first. 

The astronauts safed the satellite using plugs and specialized tools, then installed a bypass cable harness to work around the faulty switches that prevented activation in April.

They discovered that the satellite’s batteries had not frozen as some had feared. Syncom-IV/Leasat 3’s omnidirectional antenna popped up, indicating a successful repair, and Van Hoften and Fisher closed out the first EVA.  The crew left Leasat 3 safed on the Candarm when they bedded down for the night.

They experienced difficulties handling the satellite, which threatened to collide with the Orbiter. This was largely because they could not see each other from their positions on opposite sides of the 4.3 metre-diameter satellite and thus imparted opposing motions. Van Hoften warned that “if something happens and I’m about to lose it, I’m going to give it a heck of a push and bail out.” Fortunately, the astronauts managed to control the satellite’s motions, however. 

Van Hoften spun up Syncom-IV/Leasat 3 manually to 3 rotation-per-minute and released it. Subsequently,, the satellite proceeded successfully to geosynchronous orbit. 

In their postflight debrief, the spacewalkers recommended against EVAs on consecutive days, and stated that their spacesuit is “unquestionably overcooled.” In his crew report, Van Hoften stated that his fingers became very cold while he held Leasat 3, even with water to his cooling system shut off. But with the water off, his helmet fogged up.

Spacewalkers Jerry Ross and Sherwood Spring first assembled the 3.4-metre Assembly Concept for Construction of Erectable Space Structures (ACCESS) assembly jig in the Orbiter’s payload bay. Each cell was assembled in the jig, then pushed up so that the next cell could be assembled. Ross later called this “a neat way to build a truss.” 

Assembling the ACCESS truss required 58 minutes in the water tank, and the EVA timeline allotted 2 hours for a single ACCESS assembly. However, only 55 minutes were required to build the truss, so the astronauts disassembled it and built it again. 

The Experimental Assembly of Structures through EVA (EASE) task assessed the capabilities of free-floating astronauts, and involved putting together beams weighing 29 kg to make a 3.6-metre three-sided pyramid. EASE was scheduled to be assembled six times, but the astronauts managed eight assemblies. 

During the first four assemblies, the astronauts used foot restraints. Spring noted in his postflight debriefing that his fingers grew numb during the third EASE assembly and very tired during the fourth. 

At the end of the EVA, he assembled and hand-deployed a small target satellite to be used after the EVA as a station-keeping target for the Orbiter, which played the role of an automated orbital maneuvering vehicle in rendezvous software tests.

Jerry Ross and Sherwood Spring assembled nine bays of ACCESS, then placed parts for the tenth bay on the Canadarm. Ross stepped into the foot restraint and Mary Cleave, onboard the Orbiter, positioned him within reach of the top of the ACCESS girder, where he assembled the tenth bay. The parts were not tethered. 

Ross performed a cable run assembly simulation by attaching a tether along the side of the tower while Cleave positioned him. Then Spring released the bottom of the tower so Ross could try to precisely handle the beam from the RMS. He replaced it in the assembly jig where it started, demonstrating astronaut ability to assemble a truss in one place and install it in another. 

Spring then replaced Ross on the foot restraint. He changed a beam on the tower to simulate structural repair, then pointed the truss at the Moon to judge his handling ability. 

They took down ACCESS, and Spring assembled EASE from the arm. Before finishing, he joined two beams to simulate handling a thermal control heat pipe. Ross unlatched the EASE pyramid so that his partner could maneuver it.  Then he replaced Spring on the foot restraint to duplicate the EASE activities. 

The spacewalkers reported that the most difficult part of the EVAs was torquing their own 182-kg masses while holding the EASE beams. Generally speaking, ACCESS worked well, while EASE required too much freefloating. 

They judged that performing 6-hr EVAs every other day over a 5- or 6-day period was feasible, and recommended glove changes to reduce hand fatigue. Ross said in the EVA debrief that the crew had tried to have the MMU (“space sccoter”) manifested for use in the second EVA, because “for certain applications it would be very useful… in particular if you were building portions of a space station attached to the orbiter, then moving those portions farther than the manipulator arm could transport them.” He added that the MMU could be used to attach cable runs and instruments in places out of reach of the robot arm. 

Thus, the 7-time spacewalkers removed and placed inside Salyut 7’s transfer compartment space exposure cassettes and the joint Soviet-French micrometeoroid collector deployed in August 1985. They then attached the cylindrical 150-kg URS space assembly device to the hull outside the airlock hatch. 

The URS device deployed a 20-kg, 12-to-15-metre tubular metal truss held together by hinges and springs. The URS truss was deployable, as opposed to the erectable EASE and ACCESS systems Ross and Spring worked with 7 months earlier. Pravda stated that the truss’ length could be increased to a kilometer or more by adding more folded cassettes. 

Kizim operated the three buttons that controlled deployment, then climbed halfway up the truss. He found it sturdy, with oscillations limited to a few centimeters of amplitude. The top of the URS truss carried the 3-kg Fon (“Background”) device, which assessed the environment around Salyut 7. 

The spacewalkers also installed the BOSS visible light communications system on a work compartment porthole, then refolded the URS girder and closed out the EVA.  Portions of the EVA were televised live to Soviet audiences. 

The spacewalkers extended the URS truss, then used the BOSS device installed on the previous EVA to relay data on truss stability from instruments at the top of the truss. These included a small seismograph for tracking low-frequency (small) vibrations imparted by the station’s acceleration, and the Mayak (“beacon”) experiment, in which a camera tracked high-frequency vibrations by filming the movements of a small orange light attached to the truss. 

Solovyov and Kizim then rigidized the truss by welding portions using the URI tool. After closing and dismantling the truss, they installed the Mikrodeformator device which studied aluminum-magnesium alloy reactions to repeated structural loads under space conditions. 

At the end of the EVA, they brought inside the sample of solar cell material left outside by Savinykh and Dzhanibekov in August 1985.

The astronomy module Kvant arrived at the Mir core module’s aft port on April 10 and achieved a soft docking. But full retraction of the docking probe proved impossible, and the docking collars remained separated by a few centimeters. A contingency EVA was quickly authorized. 

Thus, Yuri Romanenko (who took part in a similar contingency EVA from Salyyt 6 in 1977) and Alexander Laveikin left the transfer compartment at the front of Mir and moved 13 metre along the module’s hull to the aft port. (Laveikin’s space suit registered a minor pressure drop, causing momentary concern, but the problem was quickly traced to an incorrect switch setting.)

Flight controllers extended the docking probe to permit the spacewalkers to examine the docking unit. They discovered an “extraneous white object” jammed between the two spacecraft. This was later identified as a twisted piece of cloth, possibly trash escaped from Progress 28, which had undocked from the aft port on March 26. 

With difficulty, Laveikin freed and discarded the object. The cosmonauts then waited nearby while the Mission Control commanded the Kvant probe to retract, completing hard dock. The cosmonaut returned inside an expanded Mir station.

During the first of two spacewalk planned to installe the solar array, Yuri Romanenko and Alexander Laveikin first attached an extendible “hinged lattice girder” truss to the top of the Mir complex, then attached folded solar panels to both sides of the girder. 

Then, to test their ability to operate without EVA restraints, they employed no foot restraints on this and their next EVA, relying instead on tethers. Laveikin later stated that this gave them “more freedom to maneuver, but we had to cling to the ship with one hand.”

Before going inside, they attached space exposure cassettes to Mir’s exterior. 

By June 23, the cosmonauts completed work inside Mir to connect the new array to Mir’s electrical system. The new array increased available power by 2.4 kW.

This entailed “collapsing” the lower extendible boom to fold shut both solar array sections attached to it. The new section was, like the one it replaced, made up of eight leaves of solar cells. Carbon-plastic composite replaced metal in the new section, however, and six of the leaves used improved solar cells that produced as much power as eight conventional leaves while better withstanding the rigors of space. The remaining two leaves were instrumented and independently replaceable, providing a test site for new solar cell materials. 

The spacewalkers stood in foot restraints while they worked, continuing the EVA restraint tests begun in June 1987. They redeployed the extendible boom, unfolding the new section and exposing it to sunlight. 

To round out the EVA, Manarov and Titov moved back along the Kvant module to inspect the rendezvous antenna on Progress 34 (it was late in opening), televised Mir’s exterior and the Soyuz TM-4 spacecraft for the benefit of engineers on Earth, and replaced space exposure cassettes.

While outside Mir, Vladimir Titov and Musa Manarov cut through 20 layers of thermal insulation to reach the 40-kg detector. Because there were no footholds or handholds at the worksite, they took turns working while the other held him. More clips held the detector in place than expected. Three screws locked in place by resin threw them off timeline; they had to scrape one with a saw blade before it would turn, and the effort required to turn the screws forced them to rest several times. 

After the cosmonauts accomplished 70 percent of the task, a special “key” tool for removing a brass clamp snapped. Before they passed out of radio contact, the Mission Control gave the cosmonauts 15 minutes to remove the clamp using other tools. When communication was restored, Titov and Manarov reported that they had given up and returned to the transfer compartment hatch. 

Before entering the airlock, they measured attachment locations for a foot restraint to be used on an upcoming Soviet-French spacewalk.

On Octiber 20, Vladimir Titov and Musa Manarov left one of the transfer compartment berthing ports carrying a new detector for the TTM - the old detector was not designed for replacement. The new one had handling aids and large fasteners easily operated using EVA gloves. 

The detector slid into place with difficulty, but the repair still required about an hour less than expected. 

Titov and Manarov then installed a special foot restraint for the Soviet-French EVA scheduled for December. The restraint was designed and manufactured on the ground using measurements they made during their February EVA.

First outside, Chrétien leaned out of a transfer compartment hatch and unfolded handrails recessed into Mir’s hull. Then, he used springs and hooks to attach the Enchantillons space exposure rack to the handrails. It carried five technological experiments. Chretien attached electrical leads to Mir’s power supply and with difficulty opened sample container lids on the rack. 

Alexandr Volkov then joined him outside to set up the 240-kg ERA, which included a mounting platform, deployable structure and “filming block” for recording deployment. They attached the mounting platform to handrails on the frustum between Mir’s transfer compartment and small-diameter work compartment, then attached the deployable structure. 

Sergei Krikalev commanded ERA to deploy from inside Mir, but it remained stubbornly folded. The frustrated spacewalkers shook the recalcitrant structure, but Mission Control rejected Volkov’s offer to kick ERA.

After consultation with French engineers, Mission Control told the cosmonauts to discard ERA and return inside if it failed to open by remote command. Mir then passed out of radio range, and Volkov kicked ERA several times. When the TsUP reacquired Mir, it learned that the platform was fully deployed. (Fully deployed, ERA measures 3.6 metres wide by 3.8 metres long.) 

Finally, the cosmonauts discarded the structure and returned inside, setting a new Soviet EVA endurance record.

Spacewalkers Alexandr Viktorenko and Alexandr Serebrov exited Mir through one of three unoccupied radial ports in Mir’s transfer compartment. The EVA’s start was delayed 1 hour by a valve that let air escape from Soyuz-TM 8 when the cosmonauts spilled air from the transfer compartment. 

Viktorenko and Serebrov finally egressed during orbital night, just before midnight Moscow time. They had other minor problems: a broken wire in Viktorenko’s suit prevented water temperature monitoring and Serebrov’s coolant loop leaked. 

Despite these minor annoyances, the cosmonauts successfully installed two star trackers - each weighing 80 kg - on “standard points” on Kvant. They also retrieved Meduza samples from Mir’s hull before ending the EVA.

The spacewalkers removed the supports for the French ERA experiment from Mir’s hull, then returned to the transfer compartment. Whline inside the depressurized compartment, they moved the Konus #2 drogue from the +Y port (where Kvant 2 is docked) to the -Y port (opposite Kvant 2) to receive Kristall. This Konus transfer was originally planned to occur during a separate EVA, so this reduced to four the total number of EVAs planned for Viktorenko and Serebrov.

This EVA marked the last use of the Mir's transfer compartment as an airlock (until 1995), the spacewalkers will from now used the Kvant 2 Special Airlock Compartment.

They then removed the obstructing Kvant 2 Kurs antenna ahead of the SPK flight test. Before pulling shut Kvant 2’s large EVA hatch, they installed Ferrit and Danko space exposure cassettes on the module’s hull and installed the Gemma-2 camera on the Kvant 2 tracking platform.

Alexandr Serebrov trained for years in simulator to fly the SPK. For the testin open space, he remained attached to Mir at all times by a 60-metre tether. The slender tether was deemed necessary because the station could not maneuver to retrieve him if he became stranded out of reach. It was attached to an electric winch on the dock installed on the previous EVA. The winch automatically took up slack in the tether to prevent tangling. 

Serebrov flew the SPK out 5 metres from Mir and back three times. He then backed to 33 metres, stopped, and completed various maneuvers. Alexandr Viktorenko videotaped Serebrov. 

During his final test maneuvers, Serebrov determined that he was approaching the dock off course. He corrected, and the tether caused him to flip backwards and rock “like a pendulum.” Despite this, Soviet engineers were pleased by initial results of the SPK test.

Serebrov backed away to 45 metre and did an “aerobatic” roll, covering a total of about 200 metres. He needed help from Alexandr Viktorenko to redock because Spin-6000 blocked his view of the dock. 

According to Vladimir Shatalov, Head of Cosmonaut Training, the SPK was to be used after these first two tests for undefined “practical purposes.” Other officials said that it would be used to inspect Mir’s exterior. In fact, the SPK remained stored inside Mir until February 1996, when it was abandoned at the end of its dock outside the Kvant 2 airlock hatch to make more room in the Kvant 2 SALC. 

(Presumably, Societ controllers arrived at the same conclusions of their U.S. counterparts: the use of SPK and MMU “space scooters” pose a high risk of the trauma of loosing a spacewalker in open space.)

At the start of the EVA, these inexperience (and probably tired) spacewalkers damage the Kvant-2 airlock hatch by opening it before all the air was evacuated. They violated Kvant 2 airlock egress procedure when releasing the hatch hooks prematurely. Air pressure within the lock being at 5 kpascal (0.74 psi), the hatch sprang back against its hinges with a force of 400 kg. 

Oustside, spacewalkers’ traversing Kvant 2’s 13.73-metre length required longer than expected (about 90 minute). (The cosmonauts quipped after the EVA that they had plenty of handholds, but needed street signs.) They rested during orbital night passes. And then, three hours passed before they finished installing a straight ladder bridging the gap between Kvant 2 and the Soyuz, and then a curved ladder to the heatshield and explosive bolts. 

The mood in Mission Control was tense, in part because controllers could not see the cosmonauts - the TV camera cables were not long enough to reach the worksite.

The cosmonauts detected no obvious damage to the explosive bolts and heatshield. They then folded two of the thermal blankets in half, but left the third alone. By this time, more than 5 hours had passed, so they hastened back to the Kvant 2 hatch, leaving ladders and tools at the worksite. 

They entered the Kvant 2 airlock after exceeding the 6-hour’s space suit safety limit, only to find that the hatch would not close! They used the Kvant 2 instrument-science compartment (ISC) as a contingency airlock, leaving the SALC in vacuum. Soviet officials stated that the ISC could be used to extend the main airlock compartment for transferring large equipment outside the Mir station.

So, the spacewalkers depressurized the Kvant 2 instrument-science compartment (ISC) and moved through the unpressurized airlock into space. First, they televised images of the damaged hatch to Mission Control. One hinge was obviously deformed. 

Then, they moved to the Soyuz worksite - more easily this time - and removed the ladders, stowing them on Kvant 2’s hull. 

Meanwhile, engineers on the ground sought a means of closing the hatch. Despite difficulty in gaining sufficient leverage, Balandin and Solovyov forced the hatch shut. They repressurized the airlock and ISC, sealed themselves in the latter, and doffed their suits, leaving the hatch to the airlock compartment  closed. After 24 hours, the external airlock hatch showed no leakage, so Misson Control gave them permission to leave open the hatch connecting the airlock to the rest of the station.

The replacement hinge was designed to be installed by cosmonauts working in pressure suits with EVA tools. The EVA was scheduled to last 4 hours 20 minunutes. But, 4 hours into the EVA, the spacewalkers entered the airlock and closed and sealed the hatch to check their work, then reopened it and egressed to carry out other EVA tasks.

These included moving parts and equipment for the upcoming solar array transfer EVA to Kvant 2’s exterior, removing a camera from the Kvant 2 “video spectrum complex” (the Gemma-2 unit for Earth environment monitoring) for repair inside Mir, and removing for return to Earth a space exposure cassette of superconductive materials.

The task was originally scheduled to occur over two EVAs. This EVA lasted almost 2 hours longer than planned, but concluded with Strela entirely installed. To test the device, Manarov rode the end of the boom while Afanaseyev operated its cranks. 

Before closing out the EVA, the spacewalkers removed the Ferrit space exposure experiment from Kvant 2 and replaced it with the Sprut-5 device for measuring particle flow near Mir.

Thus, the spacewalrk began with Jerry Ross moving down the starboard slidewire and Jerome Apt moving down the port. Seventeen minutes into the spacewalk, Ross shoved loose the boom by exerting about 27 kg of force using his right hand while holding onto a GRO flight support structure trunnion with his left. 

The astronauts then set up a foot restraint so they could continue manual deployment, a procedure they had practiced four times in the neubral buyancy pool. The procedure involved removing a pin, pulling the antenna to fully deployed position, and using a wrench to lock the boom. They had difficulty finding handholds on GRO in darkness. 

Then they performed some of the EVA Development Flight Experiment activities originally scheduled for April 8. They evaluated handrails (the dog bone cross section design proves superior to the round cross-section design); used the Crew Loads Instrumented Pallet (CLIP) to measure forces placed on foot restraints by simple tasks; and moved along a rope extended across the payload bay. 

Finally, they returned to the airlock but did not repressurize it until GRO was successfully away. Ross and Apt stuck their helmeted heads out the airlock hatch to watch GRO shrink into the distance.

They then took turns on CETA, each placing their feet in a CETA foot restraint so that his body was parallel to the bay wall and using a handrail to pull himself the length of the track. Apt reported that “you can give yourself a couple of pulls and go all the way to the end of the bay.” 

An electrical locomotion system with hand cranks for generating electricity for a motor and a mechanical locomotion system with a winch-type pull handle were also tested. 

Ross inadvertently demonstrated that the CETA parking brake did an excellent job of holding the cart in place by forgetting to turn it off before trying to move. The manual cart won out because it required less effort to operate than the electrical (second place) and mechanical versions. 

Ross, standing in the CLIP-equipped foot restraint on the Canadarm, rode far out over the main engines at varying speeds while Apt used strain gauge devices to measure when the arm’s brakes slipped. Ross attempted to perform coarse positioning of the “limp RMS” to see if equipment gripped by the end effector could be positioned with power off - this did not work well. In general, arm-based tasks took longer to perform than expected. 

The astronauts became cold; in their post-mission report they stated that “it is clear that the [space suit] has excessive cooling capacity.” They warned of trouble during Space Station Freedom assembly, when temperatures might plummet to –85° C  if the worksite was pointed away from Earth at night. 

Despite the success of their EVAs, Ross and Apt recommended that EVAs on consecutive days be avoided.

But first, the cosmonauts set up an experimental thermo-mechanical joint outside Kvant 2. The experiment was designed to provide data supporting Sofora truss deployment on Kvant during the next Mir crew. Afanaseyev also put the camera taken inside Mir on January back into service on Kvant 2’s movable platform. 

Meanwhile, Manarov clambered a distance of about 30 metres to inspect the balky Kvant Kurs antenna. By doing so, he violated the Soviet EVA policy which required that Afanaseyev accompany him, and he later received a rebuke for doing so. However, he televised images of the Kurs antenna to engineers at Mission Control: a 23-centimetre parabolic dish was missing, apparently knocked off by an accidental kick during the January 26 EVA. 

The cosmonauts then installed markers (“road signs”) on handrails to assist future spacewalkers in finding their way around Mir’s expanding exterior. Finally, they collected the thermomechanical joint installed at the start of EVA before returning to the Kvant 2 airlock. 

Fortunately, Anatoli Artsebarski and Sergei Krikalev succeeded in installing a new Kurs antenna on Kvant. They rested during orbital night when visibility was too poor to permit delicate work. 

Then, they assembled a prototype thermo-mechanical joint outside Kvant 2 in preparation for the planned Sofora truss assembly EVAs. The joint had sleeve couplings made of titanium-nickel alloy with “memory effect,” which shrank and snugged tight when heated by a hand-held heating and assembly device. 

The newspaper Izvestia stated that: “It is sad that we have of late referred to the Mir orbital complex… almost exclusively in connection with repair work. No one will argue that it is [not] taking ever-increasing effort to maintain the aging orbital complex. Yet it is still not fully equipped…” 

Anatoli Artsebarski and Sergei Krikalev installed TREK and tnan a charged particle detectors, retrieved the thermomechanical joint assembled during the previous EVA, and tested a new TV camera. They used the Strela boom to move around Mir’s exterior and completed the EVA 2 hr ahead of schedule.

The spacewalkers attached the mounting platform moved on the previous EVA to Kvant’s hull, then began Sofora assembly. The truss was put together lying back over Soyuz-TM 12 at the aft port, parallel to the long axis of the Mir core module.  They used the four heating and assembly devices to shrink the memory metal sleeves in the truss joints. They had difficulty seeing their work as the lighting changed, but managed to keep working during orbital night. They were unable to use foot restraints provided because the distance between the restraints and their work was different than on Earth, so they relied on their hands and arms to hold position. 

Krikalev and Artsebarski assembled three Sofora segments before closing out this, their fourth EVA together.

The three remaining Sofora segments were assembled, then the truss was attached to its mounting platform on Kvant and raised so that it was nearly perpendicular to the long axis of the Mir base block. Sofora was sloped 11 degrees toward Mir’s front to place its top above the station’s center-of-gravity. 

Artsebarski climbed to the top of the truss and attached a Soviet flag mounted in a metal frame. Moscow TV stated that, “it is not difficult to understand Anatoli Artsebarski and Sergei Krikalev, who, on their own initiative, placed a Soviet flag atop the girder. After all, our country has not totally fallen apart yet and there are still things which we do better than anyone else in the world.” 

Artsebarski’s helmet visor fogged up because his suit’s heat exchanger ran out of water, so Krikalev had to guide him back to the Kvant 2 airlock.

Then Sergei Krikalev moved off to carry out the remaining EVA tasks by himself, an obvious violation of the Russian EVA “buddy system.”  He removed Sofora assembly equipment and cleaned cameras on Kvant, then collected an experimental solar array section that was added to the Mir core module top array in 1988. 

The EVA required less time than planned despite Volkov’s absence. With the conclusion of this EVA, Krikalev established a new world record for total EVA time of 36 hr. 29 min, which stood for more than four years.

Thuot, who held a capture bar device equipped with a Canadarm grapple fixture, rode the end of the arm. During orbital night, Endeavour completed rendezvous and Thuot attempted to attach the capture bar to the Intelsat. Differences between ground training and actual orbital tasks thwarted his efforts and Intelsat VI began to oscillate. Several times, the arm stopped moving because it was driven into positions its joints could not support. 

After three capture attempts, Endeavour moved off to permit Intelsat controllers to damp its wobble.

Although his alignment was unquestionably correct, the bar refused to seat and the satellite began wobbling again. The Orbiter backed away to allow Intelsat controllers to stabilize it. Thuot later remarked that handling Intelsat VI “was much more dynamic than our training had led us to believe.”

With Pierre Thuo on the Canadarm, Rick Hieb near the starboard payload bay wall, and Tom Akers in the center of the bay (attached to an ASEM strut), Mission Commander Brandenstein edged the Orbiter toward the satellite’s underside. The spacewalkers studied the 14,4-ton satellite’s slow rotation for about 15 minutes, and then together grasped it. 

Hieb then attached the capture bar while Thuot and Akers held Intelsat VI. Then Melnick grappled the bar with the Canadarm to move the satellite into position above the perigee kick motor. The spacewalkers attached the apogee-kick motor, then retreated to the airlock while Kathy Thornton activated springs to propel Intelsat VI out of the payload bay. The craft was finally sent on its way to geosynchronous orbit.

The three spacewalkers returned to the payload bay and cleaned up, stowing foot restraints and a camera. They thus completed the100th EVA in history and also the longest.

Spacewalkers Kathy Thornton and Thomas Akers assembled a pyramidal structure 4.6 metres wide from struts and connectors (“sticks and balls”) carried in the Mission Peculiar Equipment Support Structure (MPESS) in the payload bay. 

After they completed the ASEM structure, Melnick used the Canadarm to position it so the spacewalkers could attach the MPESS. Akers and Thornton fell behind the EVA timeline, so a plan to have each astronaut ride the MPESS as Melnick hoisted it over Endeavour’s nose was abandoned. The exercise was important because the over-the-nose location was an important station assembly area.  Mass-handling exercises using the 1725-kg MPESS were also truncated because of time pressure and because the Intelsat VI retrieval provided needed data. 

The EVA included the Crew Self Rescue (CSR) flight demonstration, which tested equipment to allow an EVA astronaut to safely return to a space station if he or she became untethered. Six self-rescue devices were included, but the extra time spent on ASEM meant that only the Crew Propulsive Device (CPD) could be tested. The CPD was a hand-held nozzle assembly resembling the Gemini HHMU which was fed by a compressed nitrogen tank mounted on the PLSS. It worked as expected, but time constraints meant that it could be evaluated for only about 10 minutes of a planned 15 to 20 minutes. 

The other Crew Self Rescue devices included inflatable and telescoping poles and a rope “bola” device the drifting astronaut could throw to hook to a station strut. The devices were all tested before flight by suited astronauts aboard the KC-135 aircraft.

Alexandr Viktorenko and Alexandr Kaleri used large shears to cut through thermal insulation on Kvant 2 module to reach its gyrodynes. They inspected and televised the gyrodynes for engineers on the ground. 

Before closing out the EVA, they also tested binoculars compatible with a space suit visor for inspecting Mir’s outlying areas.

On this EVA, they installed a locking device on Sofora to hold the truss securely while bent back. They used the Strela boom to move themselves and their equipment about the station. 

They laid a 14-metre power cable along the truss and attached metal braces to the VDU for securing it to Sofora. And working by flashlight during orbital night, they removed the metal frame containing the tattered remnants of the Soviet flag placed atop Sofora in 1991. 

Before returning inside, they removed from the Mir core module top array an experimental solar panel that had been exposed to space for four years. They also removed micrometeorite panels and samples of construction materials from Kvant 2’s exterior for return to Earth.

They tested carrying a large object by carrying each other, demonstrated large tool use with a tool for manually positioning the Tracking and Data Relay Satellite tilt table, and tested their ability to align bulky objects by placing each other in the bracket which holds the EMU in the airlock. 

The EVA was videotaped for study by EVA operations engineers on the ground. The astronauts had to close out their walk at the planned time, despite their late start, because it was assigned a lower priority than observations by one of the Orbiter’s payloads, the Diffuse X-ray Spectrometer, which had to be suspended during the EVA. 

After returning to the cabin Runco and Harbaugh recorded answers to detailed EVA questions. After they returned to Houston, they repeated their tasks in the buoyancy pool to help improve EVA training. 

With some difficulty, the cosmonauts attached one drive to the framework installed on Kvant in 1991, then connected plugs to link it to Mir’s electrical supply. 

Poleshchuk then discovered that one of Strela’s two control handles had come off and floated away from Mir. Their planned second EVA had to be postponed for a month, when the next Progress freighter would deliver a new handle. Solovyov said after the EVA that, “we will be sure to screw the handle on tighter next time.”

It was reported that, for the first time, these cosmonauts worked on a contractual basis, one source reported that they were paid one million roubles for three EVAs.

Then, they used the boom to move the second solar drive container to the worksite on Kvant. In contrast to their first EVA, Manakov and Poleshchuk installed the second drive with few problems. 

They completed the installation ahead of schedule, so they were able to spend several minutes televising images of Mir’s exterior to engineers at Mission Control.

For the first time, spacewalking astronauts left an Orbiter airlock through an extension which linked it to the Spacehab module in the payload bay. 

Outside, David Low pushed on EURECA’s antenna from the Canadarm while controllers on the ground commanded the latches to close. The antenna locked down, and the astronauts turned to the EVA development objectives. 

Thus, Low and Peter Wisoff tested Hubble Space Telescope Servicing Mission-01 and Space Station EVA equipment. They took turns carrying each other while riding the robot arm to judge their ability to move large loads, used a foot restraint while working with tools, and tested safety tethers. 

While away from the payload bay, pointed at space, they got cold enough to shiver, and their hands became numb and painful.

At the back of the bay, Walz investigated damage caused by a pyrotechnic fastener malfunction in the Advanced Communications Technol-ogy Satellite payload. Walz found that the explosion had torn a hole in the Orbiter’s aft payload bay bulkhead, but caused no damage to the payload bay doors or other equipment. He decided not to handle the debris because it might cut his gloves. 

The astronauts then commenced EVA. They conducted a glove-warming evaluation using the payload bay lights, then tested tethers for high- and low-torque work and a Portable Foot Restraint (PFR) designed for HST SM-01. They also compared ground training with actual work on orbit. They reported that their boyanch pool experience was more difficult than the actual EVA. The HST-related tests assured planners that ground preparations for the flight were on a sound footing. 

The astronauts accomplished more than planned and remained ahead of schedule until closeout, when the equipment-bay door refused to close. The EVA thus required 45 minutes more than scheduled.

Spacewalkers Vasili Tsibliyev and Alexandr Serebrov moved equipment from Kvant 2 to Kvant using Strela. They installed a “grate,” then attached a platform behind Sofora. They then moved the container holding the Rapana truss to the attachment site and linked it to Mir’s electrical system. 

The EVA was planned to last more than 4 hours, but had to be cut short when Vasili Tsibliyev’s suit cooling system failed. He stayed near the Kvant 2 airlock while Alexandr Serebrov collected TREK experiment detector plates and videotaped and photographed Mir’s exterior from Kvant 2.  (Serebrov, the first cosmonaut to test the SPK maneuvering device (1990), said later that the SPK should have been used for Panorama.)

Before going inside, Vasili Tsibliyev and Alexandr Serebrov inspected and collected space exposure experiments, installed meteoroid detectors, and spoke with Russian Prime Minister Viktor Chernomyrdin, who was visiting the TsUP. 

They also snapped a few photos for the Panorama survey, but a third EVA had to be scheduled to complete the task. (With that spacewalk, Serebrov matched the old record for most EVAs (9) held jointly by Leonid Kizim and Vladimir Solovyov since 1986.)

Then, they inspected Sofora’s mount and attached another space exposure cassette to Mir’s exterior. They also watched a piece of metal of undetermined origin drift past. Finally, the cosmonauts tossed the Orlan-DMA suit that gave trouble on the last EVA out the Kvant 2 hatch after rigging it so it appeared to be saluting. 

Serebrov set a new career record for most EVAs (10), but Sergei Krikalev’s record for most time spent in EVA (36 hr, 29 min) remained intact. 

The spacewalkers first installed a cover on a low-gain antenna to avoid damaging it, and then changed Rate Sensing Unit 2 and 3, Electronics Control Unit 1 and 3, and four fuse plugs. Musgrave, the shorter of the two astronauts, was able to slip under the HST sunshade to reach the Rate Sensing Units. 

Because they did not have to remove the sunshade, this saved about 1 hour of EVA time. Musgrave unbolted the old Rate Sensing Unit, then Hoffman, in a foot restraint on the Canadarm, slid it out while Musgrave steered it free. 

Up to this point, the spacewalkers were ahead of timeline, but then they had difficulty closing the RSU compartment door, which was deformed due to exposure to temperature extremes during HST’s first 3 years in space. Musgrave pushed on the bottom of the door while Hoffman, on the arm, pushed on the top. This was the only major problem experienced on any of the HST SM-01 EVAs, a fact that surprised, given the history of EVA.

Finally, the astronauts closed out by setting up the payload bay for the next EVA.