Luna 15 and Apollo 11: A Near-Miss on the Moon?

It was mid-day on July 21, 1969. Engineers at Mission Control in Houston were preparing for Apollo 11's departure from the moon. Neil Armstrong and Buzz Aldrin's excursion onto the moon's surface was over, and they were stowing equipment in preparation for liftoff early in the afternoon. Meanwhile, a Soviet probe, Luna 15, crash landed on the moon!

Apollo 11. Source: Wikipedia.

Luna 15 was launched three days before the Apollo 11 lift-off. Its aim was to land on the lunar surface, collect rock samples, and return to Earth. If all went well, it could have arrived back on Earth the same day the astronauts came home: a small victory for the Soviets (whose Luna 2 spacecraft was the first human-made object to reach the moon, in 1959). But after several dozen orbits of the moon, the probe's landing didn't go as planned. It stopped transmitting four minutes into its descent, and crashed at Mare Crisium.

A Luna probe. Source: Wikipedia.

I was curious about how far the Luna crash was from the Apollo 11 Lunar Module. Mare Crisium is the "sea" directly north of Mare Tranquilltatis, site of Apollo 11's landing. According to Yahoo Answers (maybe not the most reliable source?), the two crafts were a little over 740 miles apart. 

Was the Apollo 11 mission ever in danger of a collision with Luna 15? Were the Soviets aiming to crash their probe into the Lunar Module? We know now that the answer to both questions was "no." But apparently back in 1969 NASA officials had some concerns. Astronaut Frank Borman put a call into one of the leaders of the Soviet space program, Dr. Mstislav Keldysh, asking him to confirm that the probe posed no threat to Apollo 11's mission. In what some describe as the very first instance of U.S.-Soviet cooperation in the space race, the Soviets released Luna 15's flight plan to NASA officials, allaying fears that it was on a collision course with the Lunar Module or the Command Module. 

During their mission, Armstrong, Aldrin, and Michael Collins were kept apprised of Luna 15's status. Apparently there were others tracking the craft as well. Astronomers at the University of Manchester Jodrell Bank radio telescope eavesdropped on Luna 15's final minutes. Their recordings were released in 2009; you can listen to a British scientist narrate the craft's crash here.

Jodrell Bank Observatory. Source: Space Today.

So the space race effectively ended that day. Americans were first to walk on the moon, hours before an unmanned Soviet landing failed. But, in the process, the U.S. and the U.S.S.R. first cooperated in space!

Sources: Yahoo Answers (always reliable???); Wired; NASA; Collect Space;