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NASA’s Bold Apollo 9 Plans Made the Moon Landing Possible

Vintage Space iconVintage Space
By Amy Shira Teitel
Mar 1, 2019 7:26 PMOct 15, 2019 3:24 PM


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The crew of Apollo 9 during a pre-flight test. NASA.

Apollo 9 launched 50 years ago, on March 3, 1969, and it might be the most important but least celebrated of the early Apollo missions. In fact, it was so important to NASA’s ultimate lunar landing goal that the space agency had a series of contingency missions in place to ensure it could get as much data as possible if something went wrong.

Apollo 9’s mission wasn’t necessarily glamorous. Commander Jim McDivitt, Command Module Pilot (CMP) Dave Scott, and Lunar Module Pilot (LMP) Rusty Schweickart were charged with running through a full lunar landing mission in the (relative) safety of Earth orbit.

Running through these burns, spacecraft separations, and dockings in orbit was no small order, not to mention Apollo 9 would test spacewalk procedures and other crew factors. As stated in the mission press kit, Apollo 9’s goals were:

  • Launch a full Apollo stack with a crew on board. This would be the first time a Saturn V would launch with both the command-service module (CSM) and lunar module (LM) on board with a full crew. In launch configuration, the LM was stowed beneath the CSM so it would also be the first time the lander was extracted from its stowed position.

  • Fly the LM with a crew. Apollo 9 was actually the second time an LM flew, but the spacecraft’s first flight was on Apollo 5 and that LM was legless and unmanned, so there was still a lot to test with the full vehicle.

  • Demonstrate lunar orbit rendezvous activities. This was a big one. On a nominal landing mission, after flying three days to get to the Moon, the commander and LMP would transfer into the LM then separate from the CSM in lunar orbit. They would land using the big descent engine, stay a while, then leave the Moon’s surface by firing the smaller ascent engine. It would then be up to the crew in the LM to seek out and dock with the CSM waiting in orbit so they could transfer back into the main craft that would take them home.  Related to this objective, Apollo 9 would also do an EVA transfer from the LM to CSM, the emergency measure in the event that the two spacecraft couldn’t dock properly in lunar orbit.



  • Determine whether there were enough consumables on board both spacecraft, i.e. make sure both vehicles could keep the crew alive long enough to get to the Moon and back again.


An artist’s rendition of the EVA transfer. NASA

An artist’s rendition of the EVA transfer. NASA.

Not only was this a busy mission plan, but the stakes were also high. This was March of 1969, just nine months to go before the end of the decade. That meant NASA had just nine months to meet President Kennedy’s ambitious timeline to reach the Moon. Apollo 10 was already on the books as a dress rehearsal for lunar orbit and landing procedures, with Apollo 11 to follow as the first actual landing attempt. Apollo 12 was scheduled for November to give America a second chance at making the landing in case Apollo 11 failed.

If Apollo 9 failed, and NASA had to redo this first dress rehearsal mission, it risked pushing the first landing attempt to Apollo 12, which would take away the wiggle room of a second landing mission before the end of the decade. Short of losing a crew in space, a full failure of Apollo 9 was probably NASA’s worst case scenario kicking off 1969.

To avoid a total loss, NASA devised a series of contingency missions that would squeeze the most experience from a non-nominal Apollo 9 mission. The focus of these contingencies was the Lunar Module; Apollo 8 had proved the CMS could support a lunar mission, so the LM was the big missing piece.

The contingency missions were designed to kick in at any point on the mission timeline when a failure occurred, allowing the crew and mission control to seamless slip into an alternate mission plan. In devising these alternate missions, NASA identified fourteen possible failures that would force one of seven alternate mission plans.

Alternate A: This mission kicked in if the LM was somehow taken out of play. If the third S-IVB stage failed to put the spacecraft into orbit, the CSM’s main Service Propulsion System (SPS) engine would have pick up the slack, but because it was higher in the vertical stack that meant the LM had to be discarded first. Similarly, if the LM got stuck in its adapter it couldn’t be part of the mission. This would force a full-duration CSM only mission with burns of the SPS engine to check its functionality. 

Rusty Schweickart during his EVA. NASA.

Rusty Schweickart during his EVA. NASA.

Alternate B: This mission took over in case there were problems with the SPS engine and/or the CSM and LM. The alternative would be to recover the LM from its launch shroud as planned and do as much with the two spacecraft docked as possible, including the EVA. 

Alternate C: This kicked in if there were any problems with the LM’s descent stage, the big engine astronauts would use to actually land on the Moon. In this case, the crew could still do the EVA transfer as planned and test the LM’s ascent engine; most of the mission would stay on track.

Alternate D: If there were problems with the CSM or LM coolant loops or other mechanical issues, the mission would test as many of the original mission objectives as possible as close to the original timeline as possible.  

Alternate E: If there were problems with the LM descent stage or other coolant, electrical, or radar problems, the rendezvous goals for the mission would be modified or revised into stationkeeping exercises of football rendezvous. 

Alternate F: If the LM guidance and navigation system failed, the descent and ascent engine burns would be cancelled in replaced with SPS burns and stationkeeping with the LM’s ascent stage. The CMS would also perform the active rendezvous with the LM, the contingency in case the LM had problems in lunar orbit.

Alternate G: Engine problems in the LM would remove the descent engine burn and the ascent engine rendezvous. Instead, the big LM test would be a burn of the ascent stage.

Luckily, Apollo 9 was a beautifully smooth mission. There were some communications issues, but these were resolved. Rusty Schweickart experienced some pretty gnarly space sickness that almost cancelled the EVA (throwing up in a spacesuit is not only disgusting, the astronaut risks aspirating his vomit) but he adjusted to weightlessness in time to perform the EVA on schedule. In the end, Apollo 9’s flight played its pivotal role in getting NASA to the Moon before the end of the 1960s.

Source: Apollo 9 Press Kit; NASA Apollo 9 page.

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