With two months to go before flight, the Apollo 13 prime crew of James Lovell, Thomas Mattingly, Fred Haise, and backups John Young, John Swigert, and Charles Duke continued to train for the 10-day mission planned to land in the Fra Mauro highlands region of the Moon. Engineers continued to prepare the Saturn V rocket and spacecraft at the launch pad for the April 11, 1970, liftoff and completed the Flight Readiness Test of the vehicle. All six astronauts spent many hours in flight simulators training while the Moon walkers practiced landing the Lunar Module and rehearsed their planned Moon walks. The crew for the next Moon landing mission, Apollo 14, participated in a geology field trip as part of their training for the flight then planned for October 1970. Meanwhile, NASA released Apollo 12 lunar samples to scientists and the Apollo 12 crew set off on a Presidential world goodwill tour.
At NASA's Kennedy Space Center in Florida, engineers completed the Flight Readiness Test of the Apollo 13 Saturn V on Feb. 26. The test ensured that all systems are flight ready and compatible with ground support equipment, and the astronauts simulated portions of the countdown and powered flight. Successful completion of the readiness test cleared the way for a countdown dress rehearsal at the end of March.
One of the greatest challenges astronauts faced during a lunar mission entailed completing a safe landing on the lunar surface. In addition to time spent in simulators, Apollo mission commanders and their backups trained for the final few hundred feet of the descent using the Lunar Landing Training Vehicle at Ellington Air Force Base near the Manned Spacecraft Center, now NASA's Johnson Space Center, in Houston. Bell Aerosystems of Buffalo, New York, built the trainer for NASA to simulate the flying characteristics of the Lunar Module. Lovell and Young completed several flights in February 1970. Due to scheduling constraints with the trainer, lunar module pilots trained for their role in the landing using the Lunar Landing Research Facility at NASA's Langley Research Center in Hampton, Virginia. Haise and Duke completed training sessions at the Langley facility in February.
The astronauts trained for moonwalks with parabolic flights aboard NASA's KC-135 aircraft that simulated the low lunar gravity, practicing their ladder descent to the surface. On the ground, they rehearsed the moonwalks, setting up the American flag and the large S-band communications antenna, and collecting lunar samples. Engineers improved their spacesuits to make the expected longer spacewalks more comfortable for the crew members by installing eight-ounce bags of water inside the helmets for hydration.
During their 35 hours on the Moon's surface, Lovell and Haise planned to conduct two four-hour spacewalks to set up the Apollo Lunar Surface Experiment Package (ALSEP), a suite of four investigations designed to collect data about the lunar environment after the astronauts' departure, and to conduct geologic explorations of the landing site. The four experiments included the:
- Charged Particle Lunar Environment Experiment designed to measure the flexes of charged particles
- Cold Cathode Gauge Experiment designed to measure the pressure of the lunar atmosphere
- Heat Flow Experiment designed to make thermal measurements of the lunar subsurface
- Passive Seismic Experiment designed to measure any moonquakes, either naturally occurring or caused by artificial means
As an additional investigation, the astronauts planned to deploy and retrieve the Solar Wind Composition experiment, a sheet of aluminum foil to collect particles from the solar wind for analysis by scientists back on Earth after about 20 hours of exposure on the lunar surface.
With one lunar mission just two months away, NASA continued preparations for the following flight, Apollo 14, then scheduled for October 1970 with a landing targeted for the Littrow region of the Moon, an area scientists believed to be of volcanic origin. Apollo 14 astronauts Alan Shepard, Stuart Roosa, and Edgar Mitchell and their backups Eugene Cernan, Ronald Evans, and Joe Engle learned spacecraft systems in the simulators. Accompanied by a team of geologists led by Richard Jahns, Shepard, Mitchell, Cernan, and Engle participated in a geology expedition to the Pinacate Mountain Range in northern Mexico Feb. 14-18, 1970. The astronauts practiced using the Modular Equipment Transporter, a two-wheeled conveyance to transport tools and samples on the lunar surface.
On Feb. 13, 1970, NASA began releasing Apollo 12 lunar samples to 139 U.S. and 54 international scientists in 16 countries, a total of 28.6 pounds of material. On Feb. 16, Apollo 12 astronauts Charles Conrad, Richard Gordon, and Alan Bean, accompanied by their wives and NASA and State Department officials, departed Houston's Ellington Air Force Base for their 38-day Bullseye Presidential Goodwill World Tour. They first traveled to Latin America, making stops in Venezuela, Peru, Chile, and Panama before continuing on to Europe, Africa, and Asia.
The groundbreaking science and discoveries made during Apollo missions has pushed NASA to explore the Moon more than ever before through the Artemis program. Apollo astronauts set up mirror arrays, or "retroreflectors," on the Moon to accurately reflect laser light beamed at them from Earth with minimal scattering or diffusion. Retroreflectors are mirrors that reflect the incoming light back in the same incoming direction. Calculating the time required for the beams to bounce back allowed scientists to precisely measure the Moon's shape and distance from Earth, both of which are directly affected by Earth's gravitational pull. More than 50 years later, on the cusp of NASA's crewed Artemis missions to the Moon, lunar research still leverages data from those Apollo-era retroreflectors.
