The Zond That Pushed Apollo to the Moon

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The Soviet Union began two lunar programs in the 1960s. Luna, which culminated with the twin Lunokhod rovers in the 1970s, was designed to robotically explore the the lunar surface and environment. Zond was an exploration probe with both a lunar and a planetary version.

Zond 1 launched towards Venus while Zonds 2 and 3 went towards Mars, the latter taking pictures of the Moon on its way. Zonds 4 through 8 were aimed squarely at the moon. These were the preliminary tests for manned circumlunar missions. Zond 5 stands out as the first to carry a living payload.

The first of the lunar Zonds, Zond 4, was a flight worthiness test. The spacecraft was aimed away from the moon, possibly to avoid the complications of translunar trajectories on a shakedown cruise. Its successor, Zond 5, took things up a notch.

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An additional test flight of Zond’s manned capabilities, it proved the spacecraft could keep animals alive on a round trip mission. Zond 5 had a rag-tag crew of sorts. Crammed inside were turtles (properly steppe tortoises), wine flies, meal worms, plants, seeds, bacteria, and other living matter. There was also a human analogue on board. In the pilot’s seat sat a 5 foot 7 inch, 155 pound dummy filled with radiation detectors.

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The 11,850 pound Zond 5 launched from Tyuratam on Sept. 14, 1968. Fifty-six minutes after launch, the spacecraft’s Block D stage fired and started it on its translunar journey. The coast took three-days. Zond 5 took high quality photographs of the Earth from more than 55,000 miles away before reaching the moon on Sept. 18. It flew around the farside coming within 7,363 miles of the surface before starting its return to Earth.

Like most early flights of a new spacecraft, Zond 5’s mission had some hiccups. On the way to the Moon, contamination on the optical surface of the stellar attitude control system rendered it useless; the spacecraft switched to backup sensors. Before reentering the Earth’s atmosphere on Sept. 21, the gyroscopic stabilizing platform went offline and an attitude control sensor failed. But without a self-destruct command the spacecraft hurtled unfettered towards the Earth. Unable to make a guided reentry, the passengers aboard Zond 5 pulled upwards of 20 Gs as the spacecraft fell on a ballistic path to a backup splashdown area in the Indian Ocean.

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Even off target, help was nearby. Soviet recovery forces a little more than 62 miles away found the spacecraft the next day and recovered its passengers. Everyone on board was fine. The turtles had lost about 10 percent of their body weight, but they were active and hadn’t lost their appetites. The flight was survivable, and a manned followup mission was clearly in Zonds future.

But NASA was already a step ahead of the Soviets. On August 12, the space agency had decided that Apollo 8 would go to the Moon in December. It would fly with just a Command Module since the Lunar Module was behind schedule but Apollo couldn’t sit around and wait. Besides, the agency needed deep space and lunar orbital experience. Zond 5 just added an external pressure to NASA internal drive to get to the moon by the end of the year.

Image: A Zond 4 commemorative stamp (public domain)