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Lunar Encore Leads to First Precision Extraterrestrial Landing

In an address to Congress in 1961, President John F. Kennedy challenged the nation to “land a man on the moon and return him safely to Earth” before the end of the decade. With the flight of Apollo 12, 45 years ago this month, NASA achieved that goal a second time.

The crew of commander Charles “Pete” Conrad, command module pilot Richard Gordon and lunar module pilot Alan Bean were all U.S. Navy officers. Their training included simulations at NASA’s Kennedy Space Center in Florida. They practiced a pinpoint landing within walking distance of the robotic Surveyor 3 spacecraft that touched down on the slope of a shallow crater in the moon’s Ocean of Storms region on April 20, 1967.

Apollo 12 astronauts visiting Surveyor 3 spacecraft on lunar surface.
In history’s first attempt at precisely landing humans on another celestial world, the Apollo 12 lunar module, on the rim of a crater in the background, landed a scant 538 feet from the Surveyor 3. Apollo 12 commander Pete Conrad is seen checking out the robotic probe’s television camera. The television camera and several other pieces were taken from Surveyor 3 and brought back to Earth for scientific examination. Surveyor 3 soft-landed in the moon’s Ocean of Storms region on April 19, 1967.
NASA/Alan Bean

After months of processing in Kennedy’s Vehicle Assembly Building, Apollo 12’s Saturn V rocket rolled to Launch Pad 39A on Sept. 8, 1969. Liftoff took place during a rain shower on Nov. 14, 1969. At 36 seconds into the flight, the vehicle triggered a lightning discharge. All three fuel cells briefly went offline, along with much of the command/service module instrumentation. The quick action by Electrical, Environmental and Consumables manager John Aaron in Mission Control and by the crew allowed the vehicle to continue flying without further problems.

On the mission’s fifth day, Gordon remained in the command module, named Yankee Clipper, while Conrad and Bean descended to the moon’s surface aboard the lunar module, Intrepid. Bean began looking for landmarks and quickly noted they were right on target.

“Hey! Look at that crater,” he said, “right where it’s supposed to be!”

As Intrepid neared touch down, Conrad noted at about 35 feet, the exhaust from the lunar module began kicking up the regolith on the surface. It appeared to be more that that experienced by fellow astronaut Neil Armstrong, commander of the first lunar landing four months earlier.

“I think we’re in a place that’s a lot dustier than Neil’s,” he said. “It’s a good thing we had a simulation, because that was an IFR (instrument flight rules) landing.”

Portrait of the prime crew of Apollo 12. Charles Conrad Jr., Richard F. Gordon Jr., and Alan L. Bean pose in front of the lunar module.
The Apollo 12 crew pose in front of a full-scale mockup of a lunar module. From the left are commander Charles “Pete” Conrad Jr., command module pilot Richard Gordon Jr., and lunar module pilot Alan Bean.

Instrument flight rules include regulations established to govern flight under conditions in which visual references are not possible. During a post-flight debriefing, Conrad explained that the dust was worse than expected.

“At that point, the dust was bad and I had absolutely no attitude reference by looking at the horizon (out the window).”

Using the lessons of the Apollo era and robotic missions to Mars, NASA scientists and engineers at Kennedy are studying how to avoid such hazards in future extraterrestrial landings.

Minutes after the lunar touchdown, Conrad and Bean received a message from overhead.

“Intrepid,” Gordon said, “congratulations from Yankee Clipper!”

The first moonwalk began a few hours later with Conrad descending the lunar module’s ladder and making note of Armstrong’s iconic words as he first stepped onto the moon four months earlier.

“Whoopee,” Conrad said, “Man, that may have been a small one for Neil, but that’s a long one for me.”

He then looked behind Intrepid to see if they had, indeed, succeeded in landing near Surveyor 3.

In this high-angle view at the Kennedy Space Center, the Saturn V rocket for the Apollo 12 mission rolls out of the Vehicle Assembly Building.
In this high-angle view at the Kennedy Space Center, the Saturn V rocket for the Apollo 12 mission rolls out of the Vehicle Assembly Building on Sept. 8, 1969. Mounted atop its mobile launch tower, the rocket is heading for Launch Pad 39A.

“Guess what I see sitting on the side of the crater,” Conrad said. “The old Surveyor. It can’t be any farther than 600 feet from here. How about that?”

In history’s first attempt at precisely landing humans on another celestial world, Conrad nailed it. Images taken in 2011 by NASA’s Lunar Reconnaissance Orbiter indicated Intrepid landed a scant 538 feet from the Surveyor.

The primary mission of the first moonwalk, which lasted three hours and 56 minutes, was to set up the Apollo Lunar Surface Experiments Package, or ALSEP, which was left on the moon’s surface to gather seismic and other scientific data. Seismic readings of moonquakes would tell scientists much about the makeup below the lunar surface. Conrad and Bean also collected rock and soil samples.

When checking the Surveyor 3 during their second moonwalk, they first believed its white color had been changed by exposure to the sun. However, upon further examination, they realized it was covered by lunar dust.

“We thought this thing had changed color, but I think it’s just dust,” Bean said. “We rubbed into (Surveyor’s) battery, and it’s good and shiny again.”

Pete Conrad and Al Bean chat during a training session in the command module simulator
Apollo 12 commander Pete Conrad, left, and lunar module pilot Alan Bean are shown in the Apollo Lunar Module Mission Simulator during training at the Kennedy Space Center on Oct. 22, 1969.

During Intrepid’s landing, the descent engine blew lunar dust onto the probe. The spacecraft was covered by a thin layer of dust giving it a tan hue.

Conrad and Bean removed Surveyor’s television camera and other parts for examination and study to learn how materials respond to years of exposure on the moon. Following three hours and 49 minutes on the surface, the explorers returned to the lunar module with parts from Surveyor and additional geological samples.

Once all the material collected on the moon was secure, Conrad and Bean began preparing for the lunar liftoff, completing 31.5 hours on the moon.

After the rendezvous with Gordon aboard the command module, the lunar collections were transferred to Yankee Clipper. Intrepid’s ascent stage was later dropped back to the moon’s surface for an early test of the ALSEP experiments they left behind. Scientists reported that the seismometers registered the vibrations for more than an hour.

Apollo 12 Lunar Module configured for landing in lunar orbit with vast lunar surface below
The Apollo 12 lunar module, Intrepid, backs away from the command module, Yankee Clipper, prior to its descent on Nov. 19, 1969.
NASA/Richard Gordon

The crew remained in lunar orbit an additional day taking photographs. On the return trip to Earth the crew also photographed a solar eclipse. However this one was of the Earth eclipsing the sun.

Yankee Clipper splashed down in the Pacific Ocean on Nov. 24, 1969, and was recovered by the aircraft carrier USS Hornet.

One of the primary achievements of the second lunar landing was an exercise in pinpoint targeting. Apollo 12 succeeded in landing at its intended objective, perfecting a skill that would prove crucial for upcoming Apollo missions. Precision landings in future Apollo missions would foster exploration in regions where the lunar surface is fraught with landscapes including obstacles such as mountains and canyon-like rills. These sites provided some of the most geologically valuable findings, unlocking secrets to better understand both the moon and planet Earth.

Apollo 12 lunar module pilot Alan Bean deploys components of the Apollo Lunar Surface Experiments Package during the first Apollo 12 moonwalk.
NASA/Pete Conrad