Apollo 10

• 1. The Dress Rehearsion Decision

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  NASA designated Apollo 10 as an F-mission in May 1969 to serve as a full dress rehearsal for the first lunar landing. Mission planners debated whether to attempt the actual Moon landing on this flight or to treat it strictly as a practice run. George Mueller, a NASA official known for his aggressive approach, favored attempting the landing immediately. He argued that bringing astronauts so close to the surface without landing was senseless if they could do it. However, Director of Flight Operations Christopher C. Kraft and others opposed this idea. They felt new procedures needed development for a rendezvous in lunar orbit. Incomplete information regarding the Moon's mass concentrations also worried them. Lieutenant General Sam Phillips, the Apollo Program Manager, listened to both sides before deciding a dress rehearsal was crucial. The decision ensured all spacecraft components and procedures were tested short of actual descent and landing.

• 2. Veterans Of The Gemini Era

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  Thomas P. Stafford served as commander of Apollo 10 at age thirty-eight when the mission launched. A 1952 graduate of the Naval Academy, he had previously flown as pilot of Gemini 6A and command pilot of Gemini 9A. John Young commanded the Command Module Pilot role and was also thirty-eight years old during the flight. He graduated from Georgia Tech in 1952 and became a test pilot in 1959. Gene Cernan flew as Lunar Module Pilot and was a Navy commander who graduated from Purdue University in 1952. These three men formed the most experienced crew to reach space until the Space Shuttle era. Their combined experience included five prior flights among them. This group represented the first American space mission where every crew member was already a spaceflight veteran. Backup crews included Gordon Cooper and Donn F. Eisele, though Deke Slayton later replaced them with Alan Shepard and Stuart Roosa due to training concerns.

• 3. Rough Launch And Color Broadcasts

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  Apollo 10 lifted off from Kennedy Space Center on the 18th of May 1969, at 16:49:00 UTC. The launch window opened for four and a half hours to secure optimal lighting conditions for the upcoming lunar landing site photography. About twelve minutes after liftoff, the spacecraft entered low Earth orbit but experienced pogo oscillations that shook the vehicle. All systems appeared normal during the review period before the crew restarted the third stage engine. The vehicle shook again while executing the trans-lunar injection burn, causing Cernan concern about potential abort scenarios. Apollo 10 became the first mission to carry a color television camera inside the spacecraft. Mission controllers watched as John Young performed the transposition maneuver and separated the Command Module from the Saturn V rocket. Soon thereafter, a large television audience viewed color images of Earth from space. A minor issue occurred when fiberglass insulation spilled into the cabin tunnel after a mylar cover pulled loose from the hatch.

• 4. The Low Pass Over Tranquility

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  Stafford and Cernan flew the Lunar Module Snoopy to within seven point eight nautical miles of the Sea of Tranquility surface. This distance marked the point where powered descent for landing would begin on a future landing mission. They completed four orbits around the Moon before rejoining Young in the Command Module Charlie Brown. During their solo flight phase, they photographed Apollo Landing Site 2 under proper sunlight conditions. Stafford described the terrain as similar to the desert surrounding Blythe, California. He noted that Apollo 11 could face rougher terrain if it approached off-target. Based upon these observations from relatively low altitude, NASA mission planners confirmed ALS-2 as the target site for Apollo 11. The crew spent approximately eight hours flying the LM apart from Young while orbiting the Moon.

• 5. Tumbling In The Dark

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  An uncontrolled tumble of the Lunar Module ascent stage occurred during the solo flight phase in lunar orbit. Alarmed by the gyration, Cernan exclaimed profanity into a hot mic that broadcast live to Earth. Stafford discarded the descent stage about five seconds after the tumbling began and fought to regain control manually. He suspected an open thruster or a thruster stuck firing was causing the issue. The problem traced back to a switch controlling the mode of the abort guidance system. Both crew members had switched it, returning it to its original position instead of advancing it. Had they fired Snoopy in the wrong direction, they might have missed the rendezvous with Charlie Brown or crashed into the Moon. Stafford regained control of the ascent stage in about eight seconds before rejoining the Command Module.

• 6. Speed Records And Return Trajectory

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  The Smithsonian has been accountable for the Command Module Charlie Brown since 1970. It was placed on loan to the London Science Museum in 1978 after displaying in several countries. The Saturn V third stage became space debris and remains in heliocentric orbit as of recent counts. The ascent stage of the Lunar Module Snoopy jettisoned into a heliocentric orbit and its whereabouts remained unknown until amateur astronomers began searching for it in 2011. A group determined that small Earth-crossing asteroid 2018 AV2 is likely to be the spacecraft with ninety-eight percent certainty. This makes it the only once-crewed spacecraft known to still exist in outer space without a crew. The descent stage of the LM jettisoned in lunar orbit and may have eventually crashed into the Moon due to orbital decay caused by mass

• 7. Lost Hardware In Helio Orbit

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  concentrations.