50 years ago Apollo 10 paved the way to landing on the moon

June 10, 2019

By David Chudwin MD

Fifty years ago, the Apollo 10 crew of Thomas Stafford, John Young and Eugene Cernan blasted off from the Kennedy Space Center to practice the steps necessary to land on the Moon. Four days later, Stafford and Cernan successfully flew the Lunar Module to within 50,000 feet of the lunar surface while Young remained in orbit aboard the Command & Service Modules (CSM).

The Apollo 10 mission served as a dress rehearsal for the first landing on the Moon two months later by Apollo 11 astronauts Neil Armstrong and Buzz Aldrin.

A Saturn V rocket launched Apollo 10 to the Moon on 18 May 1969. With a nod to the Peanuts comic strip, the CSM, with the radio call sign ‘Charlie Brown’, and the attached Lunar Module, radio call sign ‘Snoopy’, went into lunar orbit three days later.

On 22 May Stafford and Cernan entered the Lunar Module, separated from the CSM and fired the descent engine to place the Lunar Module in an orbit with a low point of about 50,000 feet above the Moon’s surface. The pair tested the Lunar Module’s engines, radar and other systems and inspected the prospective Apollo 11 landing spot on the Sea of Tranquility, which is found in the Tranquillitatis basin of the Moon.

The descent engine was jettisoned, as planned, but after the ascent engine was fired the Lunar Module suddenly began to rotate. Cernan famously swore “son of a bitch!” into an open microphone. The crew had improperly entered commands into the primitive Lunar Module computer. Along with Mission Control in Houston, Stafford and Cernan did some fast troubleshooting and the problem was fixed. Firing of the ascent engine raised the Lunar Module’s orbit so it could rendezvous and dock with John Young in the CSM orbiting overhead.

This manoeuvre was successful and the three astronauts reunited aboard ‘Charlie Brown’. The Service Module engine later fired to change the path of Apollo 10 to send it back towards Earth. The crew reached a speed of 24,791 mph during its return trajectory to Earth, making Stafford, Young and Cernan the fastest humans ever in history – a record that still stands. The men and their spacecraft were recovered from the Pacific Ocean by a US Navy ship, the USS Princeton, on 26 May.

The success of Apollo 10 led Apollo Program officials to designate the next flight—Apollo 11—as the first attempt to land men on the Moon. Apollo 10 played a crucial role in that momentous decision.

About the Author

David Chudwin MD is the author of I Was a Teenage Space Reporter: From Apollo 11 to Our Future in Space to be released by LID Publishing 2 April in the US and a month later in the UK.



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