were to be used on later missions. The crew was able to track the Pegasus 3 satellite (launched in 1965) as well as the ascent stage of Spider. The sixth burn of the SPS engine took place on the sixth day, though it was postponed one orbit as the reaction control system (RCS) thruster burn needed to settle the reactants in their tanks was not properly programmed. The SPS burn lowered the perigee of Apollo9's orbit, allowing for improved RCS thruster deorbit capability as a backup to the SPS. Considerable testing of the CSM took place, but this was principally Scott's responsibility, allowing McDivitt and Schweickart leisure to observe the Earth; they alerted Scott if anything particularly noteworthy was upcoming, letting him leave his work for a moment to look at Earth too. 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 orbital lifetime. It shifted the apogee of the orbit to the Southern Hemisphere, allowing for a longer free-fall time to entry when Apollo9 returned to Earth. The burn was extended to allow for testing of the propellent gaging system, which had been behaving anomalously during earlier SPS burns. Once it was accomplished, Apollo9'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. The landing was delayed one orbit because of unfavorable weather in the primary landing zone some ESE of Bermuda. Instead, Apollo9 splashed down east of the Bahamas, about from the recovery carrier, the USS Guadalcanal, after a mission lasting 10 days, 1hour, 54 seconds. Apollo9 was the last spacecraft to splash down in the Atlantic Ocean for a half century, until the Crew Dragon Demo-1 mission in 2019, and last crewed splashdown in the Atlantic until Inspiration4 in 2021. Hardware disposition The Apollo9 Command Module Gumdrop (1969-018A) is on display at the San Diego Air & Space Museum. Gumdrop was formerly displayed at the Michigan Space and Science Center, Jackson, Michigan, until April 2004, when the center closed. The service module, jettisoned shortly after the deorbit