In addition to the fixed-base lunar module simulators in Houston and at the Cape, astronauts also practiced at Langley Research Center on the suspended lunar landing trainer which was equipped with realistic surface views and lighting.
As the lunar module approached, Young saw it through his sextant at a distance of 259 kilometers. Stafford and Cernan got a radar lock on the command module shortly after the insertion burn and watched with interest as the instrument measured the dwindling gap between the vehicles and demonstrated the theories of orbital mechanics in actual practice. Cernan especially liked the steady communications that kept both crews aware of what was happening.
On May 18th 1969, a king, some congressmen, other distinguished guests, and a hundred thousand other watchers waited at scattered vantage points around the Cape area. At 49 minutes past noon, Rocco Petrone’s launch team sent Apollo 10 on its way to the United States’s second manned rendezvous with the moon.
John Young enjoyed the longest career of any astronaut thus far. Over the course of 42 years of active NASA service he made six space flights and is the only person to have piloted, and been commander of, four different classes of spacecraft: Gemini, the Apollo Command/Service Module, the Apollo Lunar Module, and the Space Shuttle.
Thomas P. Stafford was the first member of his Naval Academy Class of 1952 to pin on the first, second, and third stars of a General Officer. He flew six rendezvous in space; logged 507 hours and 43 minutes in space flight and wore the Air Force command Pilot Astronaut Wings. He has flown over 127 different types of aircraft and helicopters and four different types of spacecraft.
Although the contractors had shipped excellent spacecrafts, preparations at Kennedy did not go quickly from the assembly building to the launch pad. Testing was delayed several days in order to stay out of the way of Apollo 9 pre-flight activities. Also during maintenance to the Launch Control Center, the electrical power was switched off to replace a valve. The Apollo 10 launch vehicle’s pneumatic controls sensed the power outage, opened some valves and dumped 20,000 liters of fuel on the launch pad.
The biggest concern before Apollo 9 was the docking maneuver.In early 1969, at NASA there was little confidence in the docking system. At a January program review, Phillips said that problems encountered during probe and drogue testing worried him…
The Command Module probe and the Lunar Module Drogue
McDivitt & Schweickart practice in the LM simulator
Schweickart in the spacesuit with the backpack
Lithograph print of the negative that flew on Apollo 9, with signatures of Grumman engineers and mechanics