Astronautics and Aeronautics 1972, NASA SP 4017, 1974, p. 416; To a Rocky Moon, Donald Wilhelms, 1993, pp. 319-322; Apollo 17 Preliminary Science Report, NASA SP 330, 1973, p. 2.4, 6.6-6.7; Apollo Lunar Surface Journal, Eric Jones, 1995 (http://www.hq.nasa.gov/office/pao/History/alsj/); A Man on the Moon, Andrew Chaikin, 1994, pp. 513; interview, David S. F. Portree with John Young, June 13, 1996.
December 12
1972 EVA 6
World EVA 28
U.S. EVA 26
Lunar Surface EVA 14
Duration: 7:37 Spacecraft/mission: Apollo 17 Crew: Eugene Cernan, Harrison Schmitt, Ronald Evans Moonwalkers: Eugene Cernan, Harrison Schmitt Purpose: Geological traverse to South Massif
Apollo 16 CDR John Young developed and radioed to Schmitt and Cernan a procedure for repairing the LRV fender using folded traverse maps and two lamp clamps. After completing the repair, the Apollo 17 explorers set out on their second geological traverse. At survey stops they deployed 0.06-, 0.12-, and 2.8-kg (1/8-, 1/4-, and 6-lb) explosive packages. Cernan abandoned some of the caution shown on Apollo 15 and 16 and drove as fast as he could. The astronauts skirted Camelot and Lara craters, and 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. In their section of the Apollo 17 Preliminary Science Report the astronauts comment on this, stating that one can conceive of many samples... left uncollected at this remarkable locality. However, few of our experiences in the Apollo Program better illustrate the inherent quality of scientific investigation that is possible from the integrated effort of so many in so short a time.
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 Challenger 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 (11.4 mi).
Astronautics and Aeronautics 1972, NASA SP 4017, 1974, p. 416-417; To a Rocky Moon, Donald Wilhelms, 1993, pp. 322-327; Apollo Lunar Surface Journal, Eric Jones, 1995 (http://www.hq.nasa.gov/office/pao/History/alsj/); Apollo 17 Preliminary Science Report, NASA SP 330, 1973, p. 2.5. 5.16, 6.7; A Man on the Moon, Andrew Chaikin, pp. 514.
December 13
1972 EVA 7
World EVA 29
U.S. EVA 27
Lunar Surface EVA 15
Duration: 7:16 Spacecraft/mission: Apollo 17 Crew: Eugene Cernan, Harrison Schmitt, Ronald Evans Moonwalkers: Eugene Cernan, Harrison Schmitt Purpose: Traverse to North Massif
The astronauts recovered the cosmic ray detector before starting their final traverse because a small solar flare threatened to flood it with low-energy solar protons. Fortunately the flare was not powerful—neither the thin-walled LM cabin nor their EMUs could protect them from a powerful flare. Cernan and Schmitt 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.
Schmitt and Cernan expected to be the last humans on the Moon until the late 1980s, so they 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. Challenger's ascent stage lifted off on December 14 carrying 115 kg (253 lb) of samples and 2120 photos.
Astronautics and Aeronautics 1972, NASA SP 4017, 1974, p. 416-417; To a Rocky Moon, Donald Wilhelms, 1993, pp. 327-331; Apollo Lunar Surface Journal, Eric Jones, 1995 (http://www.hq.nasa.gov/office/pao/History/alsj/); Apollo 17 Preliminary Science Report, NASA SP 330, 1973, p. 2.5, 6.7; A Man on the Moon, Andrew Chaikin, pp. 542-543.
December 17
1972 EVA 8
World EVA 30
U.S. EVA 28
Deep Space EVA 3
Duration: 1:07 Spacecraft/mission: Apollo 17 Crew: Eugene Cernan, Harrison Schmitt, Ronald Evans Spacewalker: Ronald Evans Purpose: Retrieve film from SIM bay of CM America
Ron Evans performed the last deep space EVA to date, making three trips to CM America's SIM bay to retrieve film and floating free for a time on his 7.7-m (23-ft) tether.
Astronautics and Aeronautics 1972, NASA SP 4017, 1974, p. 416-417.
December 19
Apollo 17 splashdown
1973
May 25
Skylab 2 launch
May 25
1973 EVA 1
World EVA 31
U.S. EVA 29
Space Station EVA 1
Duration: 0:40 Spacecraft/mission: Skylab Orbital Workshop (Skylab 1)/Skylab 2 Crew: Charles Conrad, Joseph Kerwin, Paul Weitz Spacewalker: Paul Weitz Purpose: Free jammed Skylab solar array
Skylab was damaged about one minute after its May 14 liftoff on a Saturn V. The astronauts reported that solar array wing 2 and most of the meteoroid shield were gone. Solar array wing 1 appeared intact, but a metal strap held it closed. Later analysis determined that a design flaw, an opening at the top of the meteoroid shield, allowed air to enter between the station's skin and the shield during ascent. This created an overpressure which ripped away the shield, which in turn snagged and tore away solar array wing 2. On this date Skylab 2 CDR Charles Conrad, CMP Paul Weitz, and Science Pilot (SPT) Joseph Kerwin rendezvoused with the Skylab Orbital Workshop 6 hr after launch on a Saturn IB rocket. The Skylab astronauts wore a modified Apollo A7LB EMU. When used during EVA from the Skylab Airlock Module, the A7LB featured an Astronaut Life Support Assembly (ALSA) belly-pack instead of a PLSS. The ALSA consisted of an oxygen control unit generally similar in function to the Gemini G4C Ventilation Control Module; an 18.3-m (60-ft) insulated umbilical; and a leg-mounted package holding a 30-min emergency oxygen supply in two tanks. Oxygen and cooling water were pumped from the Airlock Module through the umbilical to the ALSA control unit, which distributed them to hose connectors on the front of the suit. For this EVA, however, the astronauts used shorter umbilicals to link them to the CM life support system. The astronauts moved the Skylab 2 CM close to the jammed array. Weitz then stood with his upper body through the hatch and assembled a 4.5-m (15-ft) pole with a shepherd's hook on the end from three 1.5-m (5-ft) sections handed to him by Kerwin. He hooked and pulled on the array while Kerwin gripped his legs. 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-hr day. Conrad was blunt about the likelihood of freeing array wing 1—he told Mission Control that "we ain't gonna do it with the tools we got." Once inside the station, the Skylab 2 crew deployed a solar shield parasol through a small scientific airlock. They commenced their research program on May 29, but the four Apollo Telescope Mount (ATM) "windmill" arrays proved insufficient to maintain the station.
Living and Working in Space: A History of Skylab (NASA SP-4208), W. David Compton and Charles D. Benson, 1983, pp. 269-271; "Skylab EVA," Robert Kain, Crew Training and Procedures Division, NASA JSC, no date; Skylab Experience Bulletin No. 27: Personnel and Equipment Restraint and Mobility Aids: EVA, JSC 09561, NASA JSC, May 1975.
June 7
1973 EVA 2
World EVA 32
U.S. EVA 30
Space Station EVA 2
Duration: 3:25 Spacecraft/mission: Skylab Orbital Workshop (Skylab 1)/Skylab 2 Crew: Charles Conrad, Joseph Kerwin, Paul Weitz Spacewalkers: Charles Conrad, Joseph Kerwin Purpose: Free jammed Skylab solar array
A team led by Russell Schweickart developed an EVA solar array repair procedure, which NASA management approved on June 4. Mission controllers sent EVA instructions to Skylab's teleprinter and the astronauts fabricated tools from onboard materials. They screwed together six 1.5-m (5-ft) rods, attached a cable cutter at the other, then tied 6 m (20 ft) of rope from the SEVA Sail backup solar shield to the cutter pull rope. This permitted the EVA astronaut to operate the cutter from 9 m (30 ft) away—the distance from the edge of area around Skylab's airlock hatch (the EVA Bay) to the strap holding shut array wing 1. An EVA waist tether was hooked to the cable cutter assembly to attach it to the base of Skylab's discone antenna. The cable cutter assembly also served as a handrail for translation to the solar array wing. Engineers believed that a hydraulic damper for slowing normal wing deployment had frozen, so Schweickart's team devised the Beam Erection Tether (BET) to force it open. The BET was a 9.8-m (32-ft) piece of SEVA sail rope tied to the middle of a 1.8-m (6-ft) rope. Two small hooks from waist tethers were tied to the ends of the 1.8-m rope, and a large hook designed originally to secure the SEVA sail to Skylab's exterior was tied onto the opposite end of the 9.8-m rope. The two small hooks were attached to holes in the wing array, while the large hook was attached near the discone antenna. Because footholds were scarce, the astronauts could not deploy the array by pulling on one end of the BET. Instead, they would stand with the middle of the BET over one shoulder to hold them against Skylab's hull and break the damper by straining upwards and pulling. The BET would thus serve both to open the array and restrain the astronauts. On June 6 Kerwin and Conrad rehearsed the planned EVA inside Skylab, and on this date depressurized the Skylab Airlock Module, which was made cramped by their burden of tools. Conrad left the airlock through its surplus Gemini hatch and stepped into the Pressure Garment Assembly foot restraint at the Fixed Airlock Shroud work station. Kerwin passed him six 1.5-m (5-ft) poles, helped him assemble the cable cutter assembly, then moved to the discone antenna using the ATM girders and other projections in the EVA Bay as mobility aids. Conrad handed him the cable cutter assembly, then moved to the discone antenna carrying 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 near the discone 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, Kerwin shortened his 1.8-m (6-ft) 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 the flight Skylab differed from the ground mockup; the second small hook would not fit. Kerwin tightened the BET at the discone end 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 the BET 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. The astronauts serviced the ATM before going inside, 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. The primary EVA heat exchanger module suffered minor clogging during the EVA, leading engineers to design a new module to serve as a backup. The module reached the station in July with the second Skylab crew.