Robotic achievements in the shadow of Apollo

TIMELINE: DEC 1968-APR 1970

The flight of Apollo 8 in December 1968 marked the beginning of the end for the Soviet Union’s campaign to put cosmonauts on the Moon. The Zond circumlunar flight test series had been plagued by problems. Even the successful flight of Zond 5 suffered so many subsystem anomalies that engineers were very reluctant to trust a spacecraft to a manned mission. The crash of Zond 6 made beating Apollo 8 to the Moon almost impossible, and the circumlunar program endured a further setback on January 20, 1969, when the next Zond test flight fell victim to yet another launcher failure. Any chance that cosmonauts could reach the Moon in competition with the Americans was dealt a severe blow on February 21, 1969, when the counterpart of the Saturn V, the N-l, failed spectacularly on its maiden flight. It had been intended to deliver a modified Zond into lunar orbit. The second attempt to qualify the N-l on July 3, 1969, less than a fortnight ahead of the launch of Apollo 11, resulted in the biggest explosion in the history of rocketry and destroyed the pad facilities. The last of the scheduled Zond flight tests, Zond 7, was a success in August, 1969, but by then the race was over. Instead of following up with a manned circumlunar mission the Soviets added another automated flight, which flew successfully in October 1970 as Zond 8. After two further attempts to qualify the N-l in June 1971 and November 1972 also failed, the manned lunar program vras canceled.

However, the Soviets countered the Apollo program with a series of robotic lunar missions using a new, large spacecraft that was originally designed to land a rover for a cosmonaut to employ on the lunar surface. When in late 1968 and early 1969 it became clear that the Americans were likely to beat them to the Moon, the Soviets opted to use this robotic landing system to try and upstage Apollo by being the first to return a lunar sample to Earth.

While the sample return system was being developed for use with the lander, the first launch of the new’ lander with a rover was attempted on February 19, 1969, but it was lost when the payload shroud failed shortly after the Proton launcher lifted off’. The first sample return spacecraft was launched on June 14, but lost when the

W. T. Huntress and M. Y. Marov, Soviet Robots in the Solar System: Mission Technologies and Discoveries, Springer Praxis Books 1, DOl 10.1007/978-1-4419-7898-111,

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fourth stage failed. Rushing to beat Apollo 11 to the Moon, another sample return mission was launched on July 13, 1969, ten days after the devastating N’-l explosion and 3 days before Apollo 11 was launched. This spacecraft, Luna 15, successfully reached lunar orbit 2 days ahead of Apollo 11 and Westerners, uninformed of its intentions, viewed it with suspicion. Shortly after the lunar module of Apollo 11 set down on the Moon on July 20 and its astronauts made their historic moonwalk, the Soviet spacecraft crashed attempting to land in the Sea of Crises, some distance cast of the Apollo 11 site in the Sea of Tranquility. The next three attempts through the middle of 1970 to return samples from the Moon with this type of spacecraft were all lost to launch vehicle failures.

In early January 1969 the Soviets followed up their 1967 success at Venus with two launches of spacecraft similar to Venera 4 but modified to descend through the atmosphere more rapidly, and thereby provide data from deeper levels than before. Although Venera 5 and Venera 6 worked well, they imploded far above the surface.

The Soviets were ready with a new spacecraft designed for Mars in March 1969. Like the new Luna for delivering rovers and sample return spacecraft, these were heavy spacecraft that needed the Proton launcher. They had been designed Lo be able
to enter orbit around Mars and dispatch a lander, but for the 1969 window they were to release a probe to get the data on the atmosphere that was required to design that lander. When the probe was deleted owing to development and test problems it was decided to equip the two spacecraft for this window as orbiters. Neither survived its launcher. These spacecraft and their launch attempts were virtually unknown in the West until after the Cold War. Blissfully unaware of this potentially overwhelming competition, the IJS dispatched two more flyby missions to Mars in 1969, Mariners 6 and 7, both of which were successful.