When Apollo 11 met Luna 15 in orbit around the Moon

On July 13, 1969, the mighty Saturn V rocket that would send Apollo 11 to the Moon was on the launchpad. The pre-launch countdown was already underway; technicians were putting the rocket and spacecraft through their pre-flight checks. The final launch countdown wouldn't start for another day and a half. But the big news in space that day wasn't the impending American manned lunar landing attempt, it was the Soviet mission that had launched towards the same target. That mission was the unmanned Luna 15, a mission that marks the Soviet intersection with Apollo as well as the first cooperative effort in space between the two rival nations.

Apollo 11's launch, July 16, 1969.

The Luna Program

The Luna program was conceived by Sergei Korolev, the powerhouse behind the Soviet Union’s early successes in space, in 1955. He wanted to build a multi-stage version of the R-7 rocket (the rocket that launched Sputnik, the first satellite) that would be powerful enough to send a spacecraft to the Moon. He wanted to use this rocket to send orbital probes, landers, and rovers to explore the lunar surface before the Americans. The climax of his program was to be a robotic sample return mission.

The sample return mission would be fairly simple. A modular spacecraft consisting of a descent stage, ascent stage, and Earth return vehicle would land on the lunar surface. An instrument would then collect a surface sample and deposit it into the Earth return vehicle. Then, the ascent stage would ignite, rocketing the sample off the Moon and back towards the Earth, leaving the descent stage on the lunar surface. Years before NASA settled on its modular design for Apollo, Korolev imagined a similar arrangement for Luna.

The Luna program accomplished a number of space firsts: the first spacecraft to go into orbit around the Moon, the first spacecraft to photograph the Moon's far side, and the first spacecraft to land on the Moon were all Soviet Luna vehicles. Some missions were successful, some ended in crash landings on the lunar surface, and others never made it beyond Earth orbit. But progress was steady, and by the end of the decade it was time to begin the sample return missions.

Luna 15 was at least the second attempt at a lunar sample return mission; a previous effort in June had failed to reach Earth orbit. But it wasn't limited to sample return: en route to the Moon, Luna 15 would study circumlunar space, the lunar gravitational field, and the chemical composition of lunar rocks. It would also photograph the Moon's surface.

Frank Borman aboard Apollo 8 in 1968.

Frank Borman and the Soviet Connection

Luna 15 worried NASA not because the mission threatened to overshadow Apollo 11 or get in its way. Rather, the concern was that it might disrupt the agency’s communications with the Apollo 11 crew. If Luna 15’s orbit was too close to Apollo 11, it could interfere with the radio signals between Mission Control in Houston and the spacecraft. From what NASA could tell, based on its launch time and trajectory, it looked like Luna 15 and Apollo 11 would reach the Moon at about the same time.

What NASA needed was trustworthy information about Luna 15’s orbit and mission to be sure it wouldn't interfere with Apollo 11. And to get that information from the notoriously secretive and guarded Soviet space program, it needed an inside connection. It turned out NASA had that inside man in Gemini and Apollo astronaut Frank Borman.

Half a year earlier in December of 1968, Borman had commanded Apollo 8, history’s first manned mission to orbit the Moon. The mission was Borman’s last; he retired shortly after returning to Earth. But he stayed with NASA long enough to score another career first: he was the first NASA astronaut to travel to the Soviet Union. It was a goodwill visit in July of 1969 on which Borman lobbied for a joint U.S. and Soviet mission in space.

Borman returned to the United States on July 10 after ten days abroad, bearing Soviet medals for NASA to leave on the Moon honoring two lost cosmonauts, Yuri Gagarin and Vladimir Komarov. He also returned with Soviet contacts, contacts that became important assets for NASA in trying to learn the details of Luna 15’s mission.

The afternoon after Luna 15 launched, Borman was passing through Washington when he received a message from Chris Kraft. The Apollo flight director, who was in Houston preparing for Apollo 11’s launch, implored Borman to use his contacts and get in touch with someone who could confirm that Luna 15 wouldn't disrupt Apollo 11’s communications. Kraft needed as much information on the mission as Borman could get.

Borman called the offices of Mstislav V. Keldysh, head of the Soviet Academy of Sciences. But as his call was made at the unfortunate hour of 2AM Moscow time, he left a message. Early the following morning in America, Borman received a reply from an English speaker in Keldysh’s office saying the information he’d asked for was on its way. Within hours, two identical telegrams arrived at Borman’s home and the White House, containing specific details about the Luna 15 mission. The massage specified Luna 15’s intended orbit, confirming that the spacecraft wouldn't get in the way of Apollo 11’s radio signals.

Borman and Kraft appeared at a press briefing together the next afternoon, assuring the country that the Soviet mission wasn't a threat to the manned lunar landing attempt.

The Eagle lander returns to Luna orbit, around the time that Luna 15 crashed into the Moon's surface.

A Dramatic Intersection

Luna 15 reached the Moon and entered into orbit on July 17, two days before Apollo 11 arrived. And while the world waited with baited breath for news of the American landing attempt, astronomers at the Jodrell Bank Observatory in Manchester had a front row seat to the dramatic intersection of the two missions. Using the Lovell radio telescope, they were able to listen to communications between Houston and Apollo 11, as well as communications between Moscow and Luna 15.

On July 20th, about two hours before Neil Armstrong and Buzz Aldrin in the Eagle separated from the Command Module Columbia, Luna 15 entered its 39th orbit around the Moon. The Jodrell astronomers listened as both the Eagle and Luna 15 adjusted their orbits. A little over an hour and a half later, as it began its 40th orbit, Luna 15 adjusted itself into a lower orbit; at the same time, the Eagle adjusted its orbit in preparation for landing.

When the Eagle landed, Luna 15 was still in orbit, as it was when Neil Armstrong took his first steps on the Sea of Tranquility. The Soviet spacecraft didn't being the dramatic climax of its mission until Armstrong and Aldrin were back inside the Eagle after finishing their two hour walk on the surface.

As the first men on the Moon prepared to launch from the lunar surface, the Jodrell astronomers heard commands being sent up to Luna 15 from Moscow. The Soviet spacecraft was beginning its 52nd orbit and adjusting its trajectory to a path that would take it towards the surface. It was at this point the English astronomers realized the craft was designed to land.They tracked the spacecraft in real time as it began its landing sequence, and followed along as it sped towards the surface. They listened as Luna 15 gained speed, traveling far too fast to survive any landing. They were still listening when the Soviet lander crashed, somewhat appropriately, in Mare Crisium, the Sea of Crises.

"I say, this has really been drama of the highest order,"remarked one Jodrell Bank astronomer when it was all over.

Cooperation in Space

Had Luna 15 landed successfully and returned a lunar sample to the Earth, it still wouldn't have overshadowed Apollo 11. Not only was the American mission manned where the Soviet mission was robotic, but Luna 15 was on a trajectory that would have had it land on Earth after the Apollo 11 astronauts had splashed down. Even a perfect mission wouldn't have enabled the Soviets to secure the honor of having returned the first lunar sample.

Failure aside, the intersection between Luna 15 and Apollo 11, which is rarely if ever mentioned when discussing history’s first lunar landing, is an important moment. That the Soviets readily shared their mission’s orbital path to avoid any conflict with Apollo was significant. It was also safer to divulge this information than be accused of trying to interfere with an Apollo mission, which would almost certainly have led to some kind of international incident. So while Luna 15's role in Apollo 11 might not be the most exciting part of the mission, it is an important episode in the Space Race.

Further Reading: Jodrell Bank Centre for Astrophysics; Countdown: An Autobiography by Frank Borman and Robert Serling

Necessary Listening: The Jodrell Bank recording from July 1969.

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