related to those from the Fra Mauro Formation, Apollo 14's landing site. Geologists realized that they had been so certain that Cayley was volcanic, they had not been open to dissenting views, and that they had been over-reliant on analogues from Earth, a flawed model because the Moon does not share much of the Earth's geologic history. They concluded that there are few if any volcanic mountains on the Moon. These conclusions were informed by observations from Mattingly, the first CMP to use binoculars in his observations, who had seen that from the perspective of lunar orbit, there was nothing distinctive about the Descartes Formation—it fit right in with the Mare Imbrium structure. Other results gained from Apollo 16 included the discovery of two new auroral belts around Earth. After the mission, Young and Duke served as backups for Apollo 17, and Duke retired from NASA in December 1975. Young and Mattingly both flew the Space Shuttle: Young, who served as Chief Astronaut from 1974 to 1987, commanded the first Space Shuttle mission, STS-1 in 1981, as well as STS-9 in 1983, on the latter mission becoming the first person to journey into space six times. He retired from NASA in 2004. Mattingly also twice commanded Shuttle missions, STS-4 (1982) and STS-51-C (1985), before retiring from NASA in 1985. Locations of spacecraft and other equipment The Ticonderoga delivered the Apollo 16 command module to the North Island Naval Air Station, near San Diego, California, on Friday, May 5, 1972. On Monday, May 8, ground service equipment being used to empty the residual toxic reaction control system fuel in the command module tanks exploded in a Naval Air Station hangar. Forty-six people were sent to the hospital for 24 to 48 hours' observation, most suffering from inhalation of toxic fumes. Most seriously injured was a technician who suffered a fractured kneecap when a cart overturned on him. A hole was blown in the hangar roof 250 feet above; about 40 windows in the hangar were shattered. The command module suffered a three-inch gash in one panel. The Apollo 16 command module Casper'' is on display at the U.S. Space & Rocket Center in Huntsville, Alabama, following a transfer of ownership from NASA to the Smithsonian in November 1973. The lunar module ascent stage separated from the CSM on April 24, 1972, but NASA lost control of it. It orbited the Moon