The Cow jumped over the moon (1957)

In June 1957, launch of the U.S. Vanguard 1 satellite (bottom image above) was thought imminent. That month, Krafft Ehricke and George Gamow wrote in Scientific American magazine that, after the artificial satellite reached orbit, "the next interesting target in space" was the moon. They estimated that, with "luck and sufficient effort," an automated probe could reach the moon by 1963.

Ehricke and Gamow proposed a design for such a probe, which they dubbed "Cow" in tribute to the moon-jumping nursery rhyme character. Cow would have a mass of between 400 and 800 pounds. A 100-foot-tall, 120-ton rocket would boost it to a speed of 23,827 miles per hour on a path toward the moon. If the Earth existed in isolation, Cow would then enter an elliptical orbit around the Earth taking it 280,000 miles out into space - that is, about 40,000 miles beyond the moon. The gravitational attraction of the moon and Sun meant, however, that Cow would follow a "distorted" path to a point 1281 miles from the moon 75.6 hours after launch. The probe would then swing around the moon, collecting data all the while, and fall back to Earth.

Cow would strike Earth's atmosphere moving at 25,000 miles per hour 157 hours after launch. Though high-speed reentry would drive Cow's skin temperature to 5000° Centigrade, Ehricke and Gamow maintained that "preventing the capsule from burning up by means of insulation and a cooling system" would not be "technically prohibitive." This would enable recovery of photographic film and recorded data.

Ehricke and Gamow then proposed a follow-on lunar sample-collection mission that would employ two probes launched on a "Cow-type" trajectory. The lead probe would drop an atomic bomb on the moon, blasting a debris cloud far into space; then, through "a miracle of electronic guidance," the trailing probe would "dive into the cloud, collect some of the spray and emerge from its dive by means of an auxiliary jet." It would then fall to Earth for recovery.



On October 4, 1957, the Soviet Union launched the first Earth satellite. Vanguard exploded on its launch pad on December 6, 1957, so the U.S. Army's Explorer 1 became the first U.S. Earth satellite (January 31, 1958). Soon after, both the U.S. and U.S.S.R. began to launch probes toward the moon (see link below). The Soviet Luna 2 spacecraft became the first human-made object to strike the moon on September 13, 1959, and Luna 3 imaged the moon's hidden Farside on October 6, 1959. No spacecraft would fly Ehricke and Gamow's Cow-type trajectory until the Soviet Zond 5 (an unmanned test of a manned circumlunar spacecraft) in September 1967, and none would return samples of lunar surface material until the first manned moon landing (Apollo 11, July 16-24, 1969).

A Rocket Around the Moon, K. Ehricke and G. Gamow, Scientific American, Volume 196, Number 6, June 1957, pp. 47-53.



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