1991-1992 Europe & Asia in Space, Nicholas Johnson and David Rodvold, U.S. Air Force Phillips Laboratory, 1993, pp. 63; Mir Hardware Heritage, NASA RP 1357, David S. F. Portree, March 1995, p. 128.
April 5
STS-37/Atlantis launch
The U.S. resumed piloted spaceflight on September 29, 1988, with the launch of Discovery on mission STS-26, but no EVA was scheduled until this flight. As it turns out, the first U.S. EVA after the January 1986 Challenger accident was a contingency EVA ahead of the planned EVA. On April 6 cabin pressure aboard Atlantis was reduced to 10.2 psi ahead of a possible contingency EVA to assist in Gamma Ray Observatory (GRO) deployment and release. On this date, as GRO checkout proceeded prior to release, astronauts Jerry Ross (who participated in the last U.S. EVA in 1985) and Jay Apt checked out their EMUs, with assistance from IV crewman Kenneth Cameron and prebreathed pure oxygen for 1 hr. Linda Godwin used the RMS to lift the 15,750-kg (35,000-lb) GRO from its cradle in Atlantis' payload bay. The observatory's solar panels were commanded to open to their full span of 21 m (69 ft). The high-gain antenna unlatched, but its 5-m (16.4-ft) boom did not deploy. Cameron and STS-37 Commander Steve Nagel helped Ross and Apt put on their suits. The crew attempted to open the high-gain by shaking GRO with Atlantis' thruster jets and the RMS. The first U.S. spacewalk since November 1985, and the first unscheduled spacewalk since April 1985, began with Ross moving down the starboard slidewire and Apt moving down the port. Seventeen min into the spacewalk, with Atlantis passing through night, Ross shoved loose the boom by exerting about 27 kg (60 lb) 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 WETF. The procedure involved removing a pin, pulling the antenna to fully deployed position, and using a wrench to lock the boom. Apt monitored Ross' movements so that he did not inadvertently damage GRO. Both astronauts had difficulty finding handholds on GRO in darkness. As Atlantis emerged into daylight, 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. 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.
STS-37 Flight Crew Report, Steven Nagel, Kenneth Cameron, Linda Godwin, Jerry Ross, and Jerome Apt, February 4, 1992, pp. 7-9; "Astronauts Give GRO a Helping Hand," Roelof Schuiling and Steven Young, Spaceflight, June 1991, pp. 197, 199-201; STS-37 EVA Lessons Learned Report, Lead EVA Flight Control Team, July 11, 1991; "Shuttle Astronauts Perform EVAs to Free Satellite, test New Hardware," James Asker, Aviation Week & Space Technology, April 15, 1991, p. 26; interview, David S. F. Portree with Linda Godwin, June 13, 1996; interview, David S. F. Portree with Jerry Ross, January 11, 1996.
April 8
1991 EVA 5
World EVA 89 U.S. EVA 53 Shuttle EVA 15
Duration: 5:47 Spacecraft/mission: STS-37 Crew: Steven Nagel, Kenneth Cameron, Jerry Ross, Jerome Apt, Linda Godwin Spacewalkers: Jerry Ross, Jerome Apt Purpose: Test CETA cart and other EVA equipment
Ross and Apt assembled a 14.6-m (46-ft) track down the port side of Atlantis' payload bay while freefloating and attached the Crew and Equipment Translation Aid (CETA) cart device. The astronauts 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. The 5000-series EVA gloves Ross wore proved a disappointment even though they provided superior performance on the ground. Ross, standing in the CLIP-equipped MFR on the RMS, 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, RMS-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 EMU has excessive cooling capacity." They warned of trouble during Space Station Freedom (SSF) assembly, when temperatures might plummet to minus 84 deg C (minus 120 deg F) if the worksite was pointed away from Earth at night. In their post-mission report, the STS-37 crew noted that:
Over the five years since the last EVAs, much of the EVA expertise in hardware design, fabrication, and testing, EVA planning and training, flight control, and crew operations had been lost. While this mission helped to regain some of this expertise, there were also many indications that additional EVAs are required to establish the robust level of EVA capabilities that will be necessary at all levels to support assembly and operation of the SSF.
The crew recommended that at least one or two EVA missions be conducted each year to build EVA experience and aggressively flight test EVA systems ahead of SSF assembly. Despite the success of their EVAs, Ross and Apt recommended that EVAs on consecutive days be avoided.
STS-37 Flight Crew Report, Steven Nagel, Kenneth Cameron, Linda Godwin, Jerry Ross, and Jerome Apt, February 4, 1992, pp. 9-13; STS-37 EVA Lessons Learned Report, Lead EVA Flight Control Team, July 11, 1991; "Astronauts Give GRO a Helping Hand," Roelof Schuiling and Steven Young, Spaceflight, June 1991, pp. 203-204; interview, David S. F. Portree with Linda Godwin, June 13, 1996; interview, David S. F. Portree with Jerry Ross, January 11, 1996.
STS-37/Atlantis landing
April 25
1991 EVA 6
World EVA 90 Russian EVA 37 Space Station EVA 45
Duration: 2:25 Spacecraft/mission: Mir PE-8 Crew: Viktor Afanaseyev, Musa Manarov Spacewalkers: Viktor Afanaseyev, Musa Manarov Purpose: Inspect damaged Kurs antenna on Kvant
Progress-M 7, an automated cargo ship, approached the Mir station aft port on March 21. About 500 m (1640 ft) out, the spacecraft's Kurs automated guidance system was unable to lock on a corresponding antenna on the Kvant module, and the Progress drifted past Mir. A second docking attempt on March 23 ended with a flight controller aborting the docking after noting a "catastrophic error" in the robot ship's orientation just 20 m (65.6 ft) from the station. Progress-M 7 passed within 7 m (23 ft) of Mir, narrowly missing solar arrays and antennas. On March 26 Manarov and Afanaseyev undocked their Soyuz-TM 11 spacecraft from Mir's front port and approached the aft port using the Kurs system. Their spacecraft imitated Progress-M 7's performance, allowing them to localize the problem in the Kurs antenna on Kvant. They completed a manual docking at the aft port. Progress-M 7 docked automatically at the forward port on March 28. Afanaseyev and Manarov spent April 23 checking their Orlan-DMA suits for an EVA to inspect Kurs. On this date the EVA was delayed 15 min while Afanaseyev reconnected a cable in the Kvant 2 airlock. The cosmonauts set up an experimental thermo-mechanical joint outside Kvant 2 early in the EVA. The experiment was designed to provide data supporting Sofora truss deployment on Kvant during the next Mir Principal Expedition. Afanaseyev put the camera taken inside Mir on January 7 back into service on Kvant 2's movable platform. Meanwhile, Manarov clambered a distance of about 30 m (100 ft) to inspect the balky Kvant Kurs antenna. By doing so he violated the Soviet EVA "buddy policy" which required that Afanaseyev accompany him. Manarov televised images of the Kurs antenna to engineers in the TsUP. One 23-cm (9.2-in) 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 EVA cosmonauts in finding their way around Mir's expanding exterior. They collected the thermo-mechanical joint installed at the start of EVA before returning to the Kvant 2 airlock. Manarov later received a rebuke for moving off alone to inspect the Kurs antenna.
Vremya newscast, April 25, 1991 (translated in JPRS Report, Science & Technology, USSR: Space, JPRSUSP-91-003, June 26, 1991, p. 1; TASS in English, in JPRS Report, Science & Technology, USSR: Space, JPRS-USP-91-003, June 26, 1991, p. 1; 1991-1992 Europe & Asia in Space, Nicholas Johnson and David Rodvold, U.S. Air Force Phillips Laboratory, 1993, pp. 64-65; Mir Hardware Heritage, NASA RP 1357, David S. F. Portree, March 1995, p. 129; "Progress-M 7: Catastrophe Avoided," Neville Kidger, Spaceflight, June 1991, p. 192.
April 28–May 6
STS-39/Discovery
May 18
Mir/Soyuz-TM 12 PE-9 launch
May 26
Mir/Soyuz-TM 11 PE-8 landing
June 5–14
STS-40/Columbia
June 25
1991 EVA 7
World EVA 91 Russian EVA 38 Space Station EVA 46
Duration: 4:48 Spacecraft/mission: Mir PE-9 Crew: Anatoli Artsebarski, Sergei Krikalev Spacewalkers: Anatoli Artsebarski, Sergei Krikalev Purpose: Replace damaged Kurs antenna on Kvant; test new joint ahead of Sofora assembly
Progress-M 8 delivered tools and equipment for the planned 6-hr Kvant Kurs antenna repair EVA on June 1, and Artsebarski and Krikalev practiced the planned repairs inside Mir on June 14. The work was considered unusually delicate and complex because it involved small tools, such as a dental mirror, and many small parts not designed for EVA handling. In addition, there were few handholds and footholds at the Kvant work site. Getting into proper working position required a full hour when the repair was simulated in the Hydrolaboratory. Artsebarski and Krikalev rested during orbital night when visibility was too poor to permit delicate work. After repairing Kurs, the cosmonauts 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. Sofora was expected to be more durable than the URS truss tested on Salyut 7 (May 1986), which employed a mechanical hinged joint system. 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..."
"Troubled Night On Board Mir," S. Leskov, Izvestiya, June 26, 1991, p. 1 (translated in JPRS Report, Science & Technology, USSR: Space, JPRS-USP-91-004, September 20, 1991, p. 2); abstract of Vremya TV news report, July 10, 1991, in JPRS Report, Science & Technology, USSR: Space, JPRS-USP-91-004, September 20, 1991, p. 3; 1991-1992 Europe & Asia in Space, Nicholas Johnson and David Rodvold, U.S. Air Force Phillips Laboratory, 1993, pp. 67-68.