First landing in the central lunar highlands.
First spacewalk during the return journey to Earth.
Launch: April 16, 1972
Lunar Orbit Insertion: April 19, 1972
Lunar Landing: April 20, 1972
Lunar Surface Departure: April 24, 1972
Recovery on Earth: April 27, 1972
This was the fifth mission in which astronauts walked on the lunar surface, but it was far from routine. Apollo 16 changed the way scientists think of the Moon.
On April 21, 1972, Commander John W. Young and Charles M. Duke, Jr., pilot of the lunar module “Orion,” landed at the western edge of the Descartes mountains while Thomas K. Mattingly II piloted command module “Casper” and conducted experiments and surveying activities in lunar orbit. Their descent was delayed by almost six hours because of a malfunction that affected the command and service module’s propulsion system. As a result, their stay on the lunar surface would be slightly shortened, and after they returned to the command module, a day would be shaved off the orbital part of the mission.
The destination this time was quite different from those of the previous Apollo missions, three of which were in mare regions (the lunar “seas”) and one of which was in ejecta from the Imbrium impact. This was the central lunar highlands, which was considered representative of three-fourths of the lunar surface. Based on photos taken from space by earlier missions, it was thought to be the product of volcanic eruptions in the Moon’s ancient past. But measurements and samples taken by the Apollo 16 astronauts disproved that hypothesis, to the great surprise of scientists on Earth. The Moon still held major mysteries for the scientists to unravel.
As in the preceding mission, Young and Duke had a rover at their disposal, enabling them to cover nearly 17 miles (27 kilometers) and to collect nearly 212 pounds (96 kilograms) of rock and soil from 11 different sites. Their haul included two anorthosite samples that were bigger and older than the “Genesis rock” recovered by Apollo 15. They also deployed or conducted nine experiments and took numerous photographs.
Gremlins on the Moon
However, another mishap occurred as the astronauts were setting up the Apollo Lunar Surface Experiments Package (ALSEP), the fourth in a network of lunar surface scientific stations. Young accidentally tore a cable loose from the heat-flow experiment, rendering it inoperable.
Young and Duke lifted off of the Moon on April 24 after spending 71 hours on the lunar surface, more than 20 of which were outside Orion. They rejoined Mattingly in the command module and jettisoned the lunar module, intending to crash it into the lunar surface as previous missions had done to test the seismometers that had been left there. But Orion began to tumble, apparently because a circuit breaker for the guidance and navigation system had been left open. Unable to control Orion’s attitude, they left it in lunar orbit, where it remained until its uncontrolled crash about a year later.
Ironically, the subsatellite that was intended to orbit for a year lasted only about a month before crashing into the Moon. Because of the reduced mission time caused by the earlier problem with the propulsion system, a maneuver to reshape their orbit was canceled. They released a subsatellite virtually identical to the one which Apollo 15 had placed in lunar orbit, but its orbit was unstable and it met a premature demise.
Particle and Fields Subsatellite
Nearly identical to its predecessor, the Apollo 16 Particles and Fields Subsatellite was ejected from the Apollo 16 Command and Service Module about 4 hours prior to the crew’s trans-Earth injection burn which sent them home from the Moon. Because of problems with the Apollo CSM main engine, the crew were forced to release the subsatellite in a low lunar orbit of 62 x 62 miles (100 × 100 kilometers) at 10° inclination.
The probe eventually crashed onto the lunar surface after 34 days in orbit rather than the planned one year mission. Impact point was at 10.2° N / 112° E at 21:00 UT on May 29, 1972. Because of its low orbit, the spacecraft did, however, return some valuable low-altitude data.
Return to Earth
Apollo 16 set new records for time spent on the lunar surface, time spent on lunar-surface EVAs, samples recovered from the Moon and number of photos taken. The mission succeeded with nine out of 10 experiments on the lunar surface and 15 from lunar orbit, and with numerous biological experiments and engineering trials and demonstrations. And it disproved what had been the prevailing hypothesis about the central lunar highlands.
During the return trip to Earth, Mattingly conducted a spacewalk to retrieve film cassettes from the Scientific Instrument Module bay at the rear of the service module. While outside the spacecraft, he set up a biological experiment with the Microbial Ecology Evaluation Device, which was used only on this mission.
The command module splashed down in the Pacific Ocean on April 27, 1972 after a mission elapsed time of 265 hours, 51 minutes, 5 seconds. The splashdown point was 215 miles (346 kilometers) southeast of Christmas Island and 3 miles (5 kilometers) from the recovery ship USS Ticonderoga.
This was the fourth spaceflight for Young, who had flown on Gemini 3 and 10 and on Apollo 10. It was the first for Duke and Mattingly.
The backup crew for this mission consisted of Fred Haise, Stuart Roosa and Edger Mitchell. Command module Casper is on display at the Alabama Space and Rocket Center in Huntsville, Alabama.
- Credit: NASA