[7] On January 27, 1967, Grissom's crew was conducting a launch-pad test for their planned February 21 mission, which they named Apollo 1, when a fire broke out in the cabin, killing all three men.

[24] Scott, also Air Force, was selected in the third astronaut group in 1963 and flew alongside Neil Armstrong in Gemini 8, on which the first spacecraft docking was performed.

Flight Director Gene Kranz deemed the Apollo 9 crew the best prepared for their mission, and felt Scott was an extremely knowledgeable CMP.

They took part in the vehicle checkouts for the CSM at North American Rockwell's facility in Downey, California, and for the LM at Grumman's plant in Bethpage, New York.

They each spent more than 300 hours in the CM and LM simulators at Kennedy Space Center (KSC) and at Houston, some involving live participation by Mission Control.

The LM arrived from Grumman in June 1968 and was subjected to extensive testing including in the altitude chamber, simulating space conditions.

The inner core of the F-1 engine chamber in the first (S-IC) stage was removed, thus saving weight and allowing for a slight increase in specific impulse.

[41] Small cracks in LM-3's aluminum alloy structure due to stresses such as the insertion of a rivet proved an ongoing issue; Grumman's engineers continued working to fix them until the LM had to be mounted on the Saturn V in December 1968,[42] where it was housed inside the Spacecraft-Lunar Module Adapter, numbered as SLA-11A.

[44] The Apollo astronauts were provided with early versions of the Sony Walkman, portable cassette recorders intended to allow them to make observations during the mission.

[48] Personnel in NASA public relations thought the names were too informal, but the call signs ultimately gained official sanction.

[51] This included the Portable Life Support System (PLSS), providing oxygen to the astronaut and water for the Liquid Cooling Garment (LCG), which helped prevent overheating during extravehicular activity.

[53] During his stand-up EVA,[b] Scott did not wear a PLSS, but was connected to the CM's life support systems through an umbilical, utilizing a Pressure Control Valve (PCV).

[56] Originally scheduled to launch on February 28, 1969, the liftoff of Apollo 9 was postponed because all three astronauts had colds, and NASA did not want to risk that the mission might be affected.

[66] The flight plan for the third day in space was to have the commander and lunar module pilot enter the LM to check out its systems and use its descent engine to move the entire spacecraft.

[68] The flight plan was thrown into question when Schweickart, suffering from space adaptation sickness, vomited, while McDivitt felt queasy as well.

They had been avoiding sudden physical motions, but the contortion-like maneuvers to don their space suits for the LM checkout caused them to feel ill.

The experience would teach the doctors enough about the sickness to have the astronauts avoid it on the lunar landings, but at the time Schweickart feared his vomiting might endanger Kennedy's goal.

The hatches were then closed, though the modules remained docked, showing that Spider's communications and life support systems would work in isolation from those of Gumdrop.

[59] The lunar module lacked the capability to return the astronauts to Earth;[41] this was the first time space travelers had flown in a vehicle that could not take them home.

[75] At a distance of 115 miles (185 km), Spider fired to lower its orbit and thus begin to catch up with Gumdrop, a process that would take over two hours, and the descent stage was jettisoned.

[76] McDivitt brought Spider close to Gumdrop, then maneuvered the LM to show each side to Scott, allowing him to inspect for any damage.

[79] Apollo 9 was to remain in space for about ten days to check how the CSM would perform over the period of time required for a lunar mission.

[81] With the main goals of the mission accomplished, the hatch window was used for special photography of Earth, using four identical Hasselblad cameras, coupled together and using film sensitive to different parts of the electromagnetic spectrum.

[82] Such photography allowed different features of the Earth's surface to appear, for example, tracking of water pollution as it exits mouths of rivers into the sea,[57] and the highlighting of agricultural areas using infrared.

[83] The photography was successful, as the ample time in orbit meant the crew could wait to allow cloud cover to pass, and would inform Skylab's mission planning.

[3] Scott used a sextant to track landmarks on the Earth, and turned the instrument to the skies to observe the planet Jupiter, practicing navigation techniques that were to be used on later missions.

[86] The seventh burn of the SPS system took place on the eighth day, March 10; its purpose was again to aid RCS deorbit capability, as well as extending Gumdrop's orbital lifetime.

It shifted the apogee of the orbit to the Southern Hemisphere, allowing for a longer free-fall time to entry when Apollo 9 returned to Earth.

[30][87] Once it was accomplished, Apollo 9's RCS thrusters could have returned it to Earth and still allowed it to land in the primary recovery zone had the SPS engine failed.

The eighth and final SPS burn, to return the vehicle to Earth, was accomplished on March 13, less than an hour after the ten-day mark of the mission, after which the service module was jettisoned.