It has been 50 years since NASA first shoved astronauts into a spacecraft that could not return to Earth: say hello to Spider.
At 16:00 UTC on 3 March 1969, NASA sent the second crewed Saturn V into orbit following the success of Apollo 8's Christmas jaunt around the Moon. While this crew would not be travelling quite so far, there was a possibility that two of the Apollo 9 astronauts could be left stranded in a spacecraft that could never return to Earth.
The Lunar Module (LM), dubbed "Spider" by the crew, was designed to land on the Moon, but not to re-enter the Earth's atmosphere.
The LM had suffered delays throughout the programme. The first uncrewed flight model was put through its paces in orbit in January 1968 as part of the Apollo 5 test flight. Though the mission encountered issues with the spacecraft's engine, technicians reckoned it was enough of a success that the next flight could involve a crew.
The goal was to give the LM a thorough workout. The astronauts proved it was possible to rendezvous and dock with the ungainly thing, clamber into the cramped confines of the LM before undocking and check out the spacecraft's systems.
According to the NASA mission report (PDF), the Saturn V deposited the Apollo stack into an orbit of 102.3 by 103.9 nautical miles.
The command-and-service modules (CSM) separated from the S-IVB stage, spun about, and returned to collect the LM. Once docked, the spacecraft backed away from the S-IVB, which was restarted by mission controllers and sent on its merry way to orbit the sun.
Once safely clear of the S-IVB (which, as it transpired, under-performed and would have likely resulted in an aborted lunar mission) the crew – consisting of Commander James McDivitt, Command Module Pilot David Scott and Lunar Module pilot Russell Schweickart – got cracking with the task of checking out the systems.
First up were four firings of the CSM's Service Propulsion System (SPS) to raise the orbit of the Apollo stack and check out just how "hard" the hard docking of the LM and CSM was under the stresses of thrust.
The fun began at the 41-hour mark, when McDivitt and Schweickart were to clamber into the LM in order to test the descent propulsion system (DPS) of the spacecraft. The crew donned pressure suits, and first Schweickart and then McDivitt entered the Moon jalopy.
Shortly after getting the thing activated and running on its own power, McDivitt requested a private chat with Mission Control.
The pilot, Schweickart, was not well.
Space Adaption Syndrome (SAS) was not well understood at that time. Russian and American space agencies had not shared their experiences, and astronauts were reluctant to discuss the onset of nausea resulting from the arrival of micro-gravity. The crews of Apollo 7 and 8 also experienced issues. However, Schweickart was due to perform an Extravehicular Activity (EVA) from the LM and a bout of nausea would not go well for the poorly 'naut.
The team continued testing the systems of the LM, deploying the landing gear, firing the DPS and checking out the landing radar before floating back up the tunnel to the CSM.
The following day, the crew once again donned their pressure suits and Schweickart and McDivitt returned to the LM once again. At the 71:53 mark, McDivitt "assessed LMP condition as excellent", in NASA parlance, and the trio pressed ahead with a modified version of Schweickart's EVA.
The plan had been for the LMP to spend two hours simulating external transfer techniques between the LM and CSM (rather like how Russian cosmonauts would have made their way between spacecraft in lieu of the US internal transfer tunnel). Instead, having depressurised the Apollo stack, Schweickart spent 37.5 minutes on the porch of the LM after popping the hatch for the one and only time it would be opened anywhere but on the lunar surface.
With Scott observing from the open hatch of the CSM, Schweickart checked out foot restraints and the LM's handrails while recording the excitement with 70mm and 16mm cameras.
The following day's activities upped the ante, although this time Schweickart was not required to leave the LM. Instead, the duo undocked the lander (after a failed first attempt thanks to fussy capture latches) and took the module for a spin. With Scott standing by to swoop in and rescue the pair using the CSM, the separation manoeuvre was performed after a short time spent flying the spacecraft in formation.
Once safely away, Schweickart and McDivitt performed more testing of the LM's DPS before the heartstopping step of jettisoning the descent stage. The duo the flew back to the CSM in the LM's ascent stage, continuing their check-out of the LM's systems.
Once the pair were safely aboard the CSM and hatches were sealed, the ascent stage of the LM was jettisoned and sent on a wander until the fuel was depleted.
The trio returned to Earth on 13 March, having accomplished all the major goals of the mission, and setting the stage for Apollo 10's flight to the Moon. Neither McDivitt nor Schweickart flew in space again, the former retiring from NASA in 1972 and the latter serving as backup for the first crewed mission to Skylab before leaving the agency in 1977.
Scott would go on to fly as the commander of Apollo 15 before also retiring from the space agency in 1977.
While there have been many books written about Apollo and the Lunar Module, we'd recommend checking out the "Spider" episode of the HBO series From the Earth to the Moon, which itself will soon be closer to the events it chronicles than to today. ®