Encyclopedia Astronautica
1969.11.19 - Apollo 12 makes a precision landing on the lunar surface

Conrad and Bean reentered the LM, checked out all systems, and at 10:17 p.m. EST on November 18 fired the reaction control system thrusters to separate the CSM 108 (the Yankee Clipper) from the LM-6 (the Intrepid). At 1:55 a.m. EST November 19, the Intrepid landed on the moon's Ocean of Storms, about 163 meters from the Surveyor III spacecraft that had landed April 19, 1967.

Six hours into the fourth day, Conrad and Bean prepared to enter and activate the lunar module. Both were having trouble with their biomedical sensors; Conrad's were blistering his skin and Bean's were producing erratic signals. Both men cleaned and reattached their electrodes, then finished donning their space suits and began preparing Intrepid for departure.

For the next several hours Conrad and Bean in Intrepid and Gordon in Yankee Clipper were busy setting up their guidance and navigation computers and exchanging data with the ground. When all was ready, Gordon turned the spacecraft so that the long axis of the command and service module was perpendicular to the flight path with the lunar module outward from the moon, retracted the docking latches, and fired his attitude-control thrusters to move Yankee Clipper away from Intrepid. The landing craft was 5 miles (8 kilometers) north of its intended ground track - largely as a result of an error in the landing site location and the inability to adequately correct for the moon's irregular gravity field. This and other errors would be removed by the instructions transmitted to the guidance computer after the lunar module headed down for its landing.

On the back side of the moon in the 13th revolution, the computer triggered a 29-second firing of the descent engine, bringing the low point of Intrepid's orbit to 8.1 nautical miles (15 kilometers). As the lander passed north of Mare Nectaris, Conrad turned it on its back with the descent engine pointed along the flight path and switched the engine on to begin the final approach. Everything went exactly as expected, and after two minutes Conrad commented that it "feels good to be standing up in a g-field again." Three minutes later the module's attitude-control thrusters began firing busily - more than Conrad thought they should - but Houston assured him that all was well.

After seven minutes Intrepidnosed over into a near-upright position and for the first time Conrad could see the lunar surface. The principal landmark identifying his landing point was a pattern of craters the astronauts called "Snowman"; Surveyor III lay halfway up the eastern wall of the crater that was the Snowman's torso, and Intrepid was targeted for the center of the crater. As soon as he could see out the window, Conrad cried delightedly, "Hey, there it is [Snowman]! There it is! Son of a gun! Right down the middle of the road!" Then, as Bean called out altitude, velocity, and quantity of fuel remaining; Conrad maneuvered the craft with his hand controller to pick a smooth spot to land on. The engine exhaust began kicking up dust about a hundred feet (30 meters) above the surface and by the time Intrepid reached 50 feet ( 15 meters) the cloud obscured the surface completely. At 1:54:36 a.m. EST on November 20, Pete Conrad made a blind landing - exactly where, he could not tell, but certainly close to the intended spot.

Conrad was naturally anxious to determine where he had set Intrepid down, and while he and Bean went through the post-landing check list they occasionally looked out the windows for landmarks that would allow Houston to pinpoint their location, but without success. After changing his mind a time or two, Conrad finally concluded, "I'm not sure that I'm not sitting fight smack on the other side of the Surveyor crater, just a little bit past it." Two hours later, Dick Gordon in Yankee Clipper confirmed Conrad's guess when he sighted both Intrepidand Surveyor III through his sextant as he passed over the site. He told Houston that the lunar module was "on the left shoulder of the Snowman... , about a third of the way from the Surveyor crater to the head. Postmission calculations placed Intrepidon the northwest rim of the Surveyor crater, 535 feet (163 meters) from the inert spacecraft. Had there been windows in the back of the lunar module, Conrad could have spotted the Surveyor as soon as the dust settled.

After postlanding checks of systems, Conrad and Bean described what they could see from their spacecraft. Intrepidhad landed in undulating terrain pocked with craters ranging from a few feet to several hundred feet across, the larger ones rimmed by large blocks of rock. Numerous boulders, up to 20 feet (6 meters) in size, were scattered around the site, most of them angular rather than rounded, many showing fillets of dust around the base. Immediately in front of the landing craft Bean saw an area of "patterned ground" - parallel cracks in the surface soil perhaps an eighth of an inch (3 millimeters) deep. From the lunar module the crew could distinguish no color differences in the rocks or soil; everything seemed the same bright white.

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