The Soviet Union declared in 1955 that it would place a satellite into Earth orbit during the 18-month International Geophysical Year (1957-1958). Few in the West took this claim seriously, however, until the Soviets test-launched the world's first intercontinental missile, the R-7, on 21 August 1957. The Soviets then used modified R-7 rockets to launch Earth's first and second artificial satellites, respectively 184-pound Sputnik 1 (4 October 1957) and 1118-pound Sputnik 2 (3 November 1957).
The relatively enormous mass the R-7 could loft into Earth orbit startled U.S. rocketeers. The first successful U.S. satellite, Explorer 1 (31 January 1958), weighed just 31 pounds, while the third Soviet satellite, Sputnik 3, launched four months later, weighed nearly 100 times as much (2926 pounds).
Even as the U.S. launched its first satellite, two new heats in the space race began: the race to hit the moon with an automated probe, and the race to launch a man into orbit. In a presentation to the American Astronautical Society in August 1958, Dandridge Cole and Donald Muir, engineers with The Martin Company in Denver, Colorado, proposed in effect to combine these two races by launching a man around the moon.
They warned that the "Russians may have such a long lead. . .that they will have made landings on the moon before. . .our first circumlunar flight," and predicted that the Soviet Union would be capable of a manned circumlunar flight in 1963, four years before the United States. Cole and Muir added, however, that "on the technical side, at least, there seems to be no reason why this goal could not be accomplished [by NASA] by 1963." In 1958, many in the U.S. perceived that American spaceflight was held back mainly by a lack of political will on the part of President Dwight D. Eisenhower.
Cole and Muir proposed a four-stage launch vehicle ("Missile B") for their circumlunar flight. They estimated that a 160,000-pound-thrust U.S. missile ("Missile A") could be expected by 1963; for their circumlunar flight, they proposed clustering four such missiles to create a first stage with 610,000 pounds of thrust. Their circumlunar rocket would also include a second stage comprising one 160,000-pound thrust missile, a third stage with a 40,000-pound-thrust rocket, and a fourth stage with a 10,000-pound-thrust rocket.
The bucket-shaped circumlunar capsule would weigh 9000 pounds. Though a two-week circumlunar trip would have required the least energy (and thus a smaller launch vehicle), Cole and Muir opted for a three- or four-day trip for psychological reasons. "For one man alone in a tiny sealed capsule on a journey of 250,000 miles from the earth," they explained, "the difference between three or four days and two weeks might approach infinity." Reduced trip time would also trim the quantity of life-support supplies needed on board the capsule. The energy needed to reduce the trip time from two weeks to four days would be modest, they estimated, though reducing it still further would require a prohibitive amount of energy.
The capsule's circumlunar path would have three parts. The outbound leg would last 35.4 hours. It would be followed by a 9.3-hour "hyperbola" past the moon. The capsule would pass 10 miles over the moon's Farside, where the "synthesizing power of the human brain [would] permit collection of more accurate and more meaningful data than could be obtained by photographic techniques alone." The third leg of the mission, the 35.4-hour fall back to Earth, would mirror the outbound leg. The circumlunar voyager would be treated to a magnificent view of Earth rising over the lunar horizon as he began his journey home (image at top of post).
The heat shield for high-speed Earth-atmosphere reentry would weigh just 500 pounds. As Earth filled the capsule's view ports, the pilot's "bathtub-type" couch would fill with water to cushion him from the powerful forces of reentry deceleration. A lid with a window would prevent the water from escaping in zero-G before deceleration commenced. Cole and Muir wrote that, because "the water would be needed only in the last phase of the trip, it could be reserve drinking or washing water." Despite the potential mass savings, they hesitated "to suggest that it might be water. . .already used for drinking or washing."
The capsule would enter Earth's atmosphere nose first. As deceleration began, the bathtub couch would pivot so that the pilot faced the capsule's flat aft end. This would cause him to feel deceleration through his back, enabling him to withstand greater sustained deceleration loads.
After fiery atmosphere reentry, the capsule would deploy fins for steering. Landing would be by parachute at sea or on U.S. soil. Cole and Muir ended their paper with rousing words: "Time may well prove that the man who climbs out of this capsule to receive the cheers of the recovery crew. . .made a voyage of greater importance to the human race than that of Columbus."
The Soviet Union's 858-pound Luna 2 probe became the first human-made object to strike the moon on 14 September 1959, and cosmonaut Yuri Gagarin rode Vostok 1 to Earth orbit in 12 April 1961 to become the first human in space. Gagarin's flight - combined with the geopolitical setback of the failed CIA-sponsored Bay of Pigs invasion of Cuba - inspired new U.S. President John F. Kennedy to call upon NASA to land a man on the moon by 1970 (25 May 1961).
For a time, NASA planned a piloted circumlunar flight as an early mission in the Apollo lunar landing test program. In the event, it jumped straight from its first Earth-orbital Apollo test-flight (Apollo 7, 11-22 October 1968) to its first lunar-orbital test-flight (Apollo 8, 21-27 December 1968).
The Soviet Union tested Zond circumlunar spacecraft - modified piloted Soyuz spacecraft - without crews on board from 1966 until 1970. Most Zond flights suffered failures serious enough to have killed cosmonauts, had any been on board. Fears that the Soviets might steal America's thunder by launching a Zond crew around the moon in December 1968 helped to prompt the Apollo 8 mission.
The first (and, so far, only) piloted circumlunar flight was the result of an accident. On 13 April 1970, the Apollo 13 Command and Service Module Odyssey suffered an oxygen tank explosion which forced NASA to scrub its planned lunar landing. Astronauts James Lovell, Fred Haise, and Jack Swigert used the descent engine of the Lunar Module Aquarius to change their course so that they passed behind the moon on 15 April 1970 without entering orbit and fell back to Earth, splashing down safely on 17 April 1970.
Reference:
"Around the Moon in 80 Hours," Dandridge M. Cole and Donald E. Muir, Advances in Astronautical bet365体育赛事s, Vol. 3, pp. 27-1 - 27-30; Proceedings of the Western Regional Meeting of the American Astronautical Society, August 1958.
