Second crew on Skylab: Breaking all records
Sen—A month after the original crew of Skylab had returned to Earth, a fresh trio of astronauts was ready to re-inhabit the first American space station.
The second expedition to Skylab, designated SL-3, (counting the launch of the unmanned outpost itself as SL-1) was scheduled to double the 28-day flight of the SL-2 crew. Moreover, as the ballistic team charted the best suitable return path for the crew, the mission was extended from 56 days to 59 days to place the splashdown closer to the U.S. coast.
As before, from the point of view of space medicine, the mission was heading into a complete unknown, since nobody could predict the reaction of the human body to the effects of prolonged weightlessness. In addition to watching their own health, the second expedition had many tasks including observations of the Earth, astronomy and technical experiments.
The crew included the commander Alan Bean, scientific pilot Owen Garriott, and pilot Jack Lousma.
A Saturn-1B rocket carrying the command and service module of the Apollo spacecraft lifted off from Pad 39B at Cape Canaveral on July 28, 1973, at 7:10 a.m. EDT. The ride to orbit was flawless, but several hours into the mission, Bean reported seeing "some kind of sparklers," while telemetry indicated that one of four clusters with attitude control engines on the service module was leaking propellant. As a result, it had to be urgently turned off. To keep the thrust symmetrical, another engine cluster on the opposite side of the service module also had to be deactivated. The crew also had to re-adjust all their rendezvous maneuvers to compensate for a missing pair of engine clusters.
After some heart-racing maneuvers near the station, the crew finally stabilized their ship right in front of Skylab's living quarters window. "Looks like nobody's home," astronauts radioed to mission control.
The docking was completed successfully, but, unexpectedly, first Lousma and then two of his crew-mates all came down with symptoms of motion sickness. The crew needed between three and four days to fully adapt to weightlessness.
On August 2, as the astronauts finally began productive work, a new emergency interrupted their routine. This time, a second cluster on the Apollo spacecraft docked at the station started leaking. Any further problems with additional thrusters would render useless their transport back to Earth.
After a period of serious concern on the ground, (when mission control pondered an immediate return of the crew relying on just two remaining engine clusters), engineers concluded that the leaks in two engine clusters were coincidental and would unlikely replicate themselves. As a result, there was no reason for urgent actions. However, as a precaution, NASA officials instructed astronauts Vance Brand and Don Lind to prepare for a rescue mission to retrieve their comrades, as it was envisioned for various contingencies.
According to the plan, a backup Apollo spacecraft modified to carry five people, would be prepared for launch at the beginning of September. Two rescue pilots would be sitting on left-hand and right-seat coaches with the third remaining empty. Two extra couches would be installed in the back of the capsule, replacing usual storage lockers. The spacecraft could berth at the second Earth-facing docking port on the Skylab, while the original ship could remain attached at the main axial port.
Fortunately, by mid-August various simulations on the ground proved that the already orbiting Apollo could be safely used for the return to Earth and the rescue crew was allowed to stand down.
In the meantime, the crew aboard Skylab continued their program.
On August 6, Lousma and Garriott ventured on the exterior of the station to install a new version of a makeshift sunshade designed to replace the thermal shielding which was ripped off during Skylab's nearly botched ascent to orbit. After almost four hours of struggle, the accordion-like blanket had been successfully rigged on two 55-foot-long aluminum poles and over the original parasol. Still, the pair of astronauts stayed outside for a total of six hours 31 minutes to complete a number of secondary tasks. It included a visual inspection of the Apollo's troubled service module, which fortunately, revealed no extra leaks.
Back inside the station, the crew also pioneered "student" experiments, made famous by a spider named Arabella, who after short period of confusion by weightlessness proceeded to build her web.
During August, the crew conducted a series of the most ambitious engineering experiments of the expedition, testing a flying chair dubbed the Autonomous Space Maneuvering Unit, ASMU. Thanks to the voluminous working section of Skylab, astronauts were able to "fly" the chair inside the weightless interior of their orbital home.
By that time, the crew began working so efficiently that ground specialists were complaining about problems to keep them fully occupied.
On August 24, the crew conducted its second spacewalk. Lousma reconnected cables to a new set of rate-gyroscope processors for the attitude control system of the station, because previous units showed poor performance. Then Garriott retrieved and replaced exposed cartridges in the station's telescope section, among with other repair and maintenance chores.
The third and final spacewalk of the SL-3 mission was performed on September 22 and, again was mostly dedicated to the maintenance of the scientific instruments.
Thanks to many tasks and a well-prepared exercise routine, the crew remained in good health and high spirits until the end of its record-breaking mission.
On Sep. 25, 1973, the trio boarded their Apollo spacecraft and undocked from the station. Following a braking maneuver, the command module separated from the service module and plunged into the atmosphere. It then successfully parachuted into the Pacific Ocean, some 400 kilometers southwest of San Diego, Ca, at 6:19 p.m. EDT. Due to considerable wind and waves in the area, the command module ended up upside down, but the crew used inflatable bags to put the spacecraft upright.
The second expedition to Skylab lasted record-breaking 59 days one hour and nine minutes. The crew spent 33 hours 44 minutes in three spacewalks, produced 77,600 images with Skylab's solar telescopes and took 14,400 photos of the Earth's surface.