biological experiment, the Microbial Ecology Evaluation Device (MEED), an experiment unique to Apollo 16, to evaluate the response of microbes to the space environment. The crew carried out various housekeeping and maintenance tasks aboard the spacecraft and ate a meal before concluding the day. The penultimate day of the flight was largely spent performing experiments, aside from a twenty-minute press conference during the second half of the day. During the press conference, the astronauts answered questions pertaining to several technical and non-technical aspects of the mission prepared and listed by priority at the Manned Spacecraft Center in Houston by journalists covering the flight. In addition to numerous housekeeping tasks, the astronauts prepared the spacecraft for its atmospheric reentry the next day. At the end of the crew's final full day in space, the spacecraft was approximately from Earth and closing at a rate of about . When the wake-up call was issued to the crew for their final day in space by CAPCOM England, the CSM was about from Earth, traveling just over . Just over three hours before splashdown in the Pacific Ocean, the crew performed a final course correction burn, using the spacecraft's thrusters to change their velocity by . Approximately ten minutes before reentry into Earth's atmosphere, the cone-shaped command module containing the three crewmembers separated from the service module, which would burn up during reentry. At 265 hours and 37 minutes into the mission, at a velocity of about , Apollo 16 began atmospheric reentry. At its maximum, the temperature of the heat shield was between . After successful parachute deployment and less than 14 minutes after reentry began, the command module splashed down in the Pacific Ocean southeast of the island of Kiritimati 265 hours, 51 minutes, 5seconds after liftoff. The spacecraft and its crew was retrieved by the aircraft carrier . The astronauts were safely aboard the Ticonderoga 37 minutes after splashdown. Scientific results and aftermath Scientific analysis of the rocks brought back to Earth confirmed that the Cayley Formation was not volcanic in nature. There was less certainty regarding the Descartes Formation, as it was not clear which if any of the rocks came from there. There was no evidence that showed that Stone Mountain was volcanic. One reason why Descartes had been selected was that it was visually different from previous Apollo landing sites, but rocks from there proved to be closely