were removed, which meant the oxygen quantity gauge was no longer accurate. This required adding a third tank so that no tank would go below half full. The third tank was placed in Bay1 of the SM, on the side opposite the other two, and was given an isolation valve that could isolate it from the fuel cells and from the other two oxygen tanks in an emergency and allow it to feed the CM's environmental system only. The quantity probe was upgraded from aluminum to stainless steel. All electrical wiring in Bay4 was sheathed in stainless steel. The fuel cell oxygen supply valves were redesigned to isolate the Teflon-coated wiring from the oxygen. The spacecraft and Mission Control monitoring systems were modified to give more immediate and visible warnings of anomalies. An emergency supply of of water was stored in the CM, and an emergency battery, identical to those that powered the LM's descent stage, was placed in the SM. The LM was modified to make transfer of power from the LM to the CM easier. Aftermath On February 5, 1971, Apollo 14's LM, Antares, landed on the Moon with astronauts Alan Shepard and Edgar Mitchell aboard, near Fra Mauro, the site Apollo 13 had been intended to explore. Haise served as CAPCOM during the descent to the Moon, and during the second EVA, during which Shepard and Mitchell explored near Cone crater. None of the Apollo 13 astronauts flew in space again. Lovell retired from NASA and the Navy in 1973, entering the private sector. Swigert was to have flown on the 1975 Apollo–Soyuz Test Project (the first joint mission with the Soviet Union) but was removed as part of the fallout from the Apollo 15 postal covers incident. He took a leave of absence from NASA in 1973 and left the agency to enter politics, being elected to the House of Representatives in 1982, but died of cancer before he could be sworn in. Haise was slated to have been the commander of the canceled Apollo 19 mission, and flew the Space Shuttle Approach and Landing Tests before retiring from NASA in 1979. Several experiments were completed during Apollo 13, even though the mission did not land on the Moon. One involved the launch vehicle's S-IVB (the Saturn V's third stage), which on prior missions had been sent into solar orbit once detached. The seismometer left by