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Our SpaceFlight Heritage: Apollo 10 paves way for 1st human lunar landing

Eugene Cernan, left, Thomas Stafford, center, and John Young, the crew of Apollo 10. Photo credit: NASA

Eugene Cernan, left, Thomas Stafford, center, and John Young, the crew of Apollo 10. Photo credit: NASA

As NASA takes aim on the Moon with its Artemis program, it is important to remember the missions that paved the way for the agency’s first manned landing. One of the most critical of these – was Apollo 10.

The Lunar Module ascent stage as it approaches the Apollo 10 Command Module following its landing rehearsal. Photo Credit: NASA

Carried out 50 years ago Apollo 10 was the final dress rehearsal before Neil Armstrong and Buzz Aldrin made their first steps on the Moon two months later in July of 1969. Before they could do this there were several features of the Lunar Module that still needed to be practiced and refined.

This requirement fell on the crew of Apollo 10. At 12:49 p.m. EDT (16:49 GMT) May 18, 1969, NASA astronauts Thomas Stafford, John Young and Eugene Cernan launched atop the fifth Saturn V rocket which had been selected to send the the fourth manned Apollo mission on its way to the Moon.

Once placed on a trans-lunar trajectory by the Saturn V’s S-IVB upper stage, the command module, nicknamed Charlie Brown, separated. Young, the command module pilot, then performed the transposition, docking and extraction maneuver to pull the Lunar Module, nicknamed Snoopy, away from the booster.

Three days later, using the command and service module’s SPS engine, the trio entered orbit around the Moon, becoming the fourth, fifth and sixth humans to orbit another world.

Apollo 10's Command Module orbits the Moon in May of 1969. Photo Credit: NASA

Apollo 10’s Command Module orbits the Moon in May of 1969. Photo Credit: NASA

On May 22, Stafford (the mission’s Commander) and Cernan (the Lunar Module pilot) boarded the lander, undocked and fired the descent stage engine to bring the low point of its orbit down to about 50,000 feet (15,000 meters) above the Sea of Tranquility, This was the part of the mission flight profile where the powered descent phase of a landing would begin. The task of landing was given to the next Apollo crew.

According to NASA, Apollo 10 was designed to gather data related to the Moon’s gravity, check out the lander’s programmed trajectories and radar, as well as its lunar flight control systems.

After surveying the landing site for Apollo 11, the descent stage of the Lunar Module was jettisoned. This part of the flight did not go as smoothly as the rest of the mission had. 

After the descent stage had separated an accidental duplication of commands sent to the flight controller caused the LM to roll. As one might imagine the crews selected to complete the Apollo Program’s objectives were highly-trained and the situation was quickly resolved. It did however result in some colorful language from the duo. Reports have stated that if the vehicle had continued in this manner, it would have crashed on the Moon and Cernan and Stafford would have been killed. 

Once sorted, the LM’s ascent stage made its way back to the command and service module to re-dock.

After the crew transferred back to Charlie Brown, Snoopy was again undocked and remotely commanded to fire its engine to depletion, placing it into an unknown heliocentric orbit.

Then on May 24, the command and service module engine performed a trans-Earth injection burn, placing the trio on a two-day return trip home.

Just before entry interface, the capsule separated from the service module and began to re-enter Earth’s atmosphere before splashing down at 12:52 p.m. EDT (16:52 GMT) May 26, some 460 miles (740 kilometers) east of American Samoa.

The crew of Apollo 10 still holds the record for the highest speed attained by a human spacecraft at 24,791 mph (39,897 kph) just before re-entry—or as Stafford says, 0.0037% the speed of light.

Video courtesy of NASA

 

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Derek Richardson has a degree in mass media, with an emphasis in contemporary journalism, from Washburn University in Topeka, Kansas. While at Washburn, he was the managing editor of the student run newspaper, the Washburn Review. He also has a blog about the International Space Station, called Orbital Velocity. He met with members of the SpaceFlight Insider team during the flight of a United Launch Alliance Atlas V 551 rocket with the MUOS-4 satellite. Richardson joined our team shortly thereafter. His passion for space ignited when he watched Space Shuttle Discovery launch into space Oct. 29, 1998. Today, this fervor has accelerated toward orbit and shows no signs of slowing down. After dabbling in math and engineering courses in college, he soon realized his true calling was communicating to others about space. Since joining SpaceFlight Insider in 2015, Richardson has worked to increase the quality of our content, eventually becoming our managing editor. @TheSpaceWriter

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