Little Joe (rocket)

Little Joe was a solid-fueled booster rocket used by NASA for eight launches from 1959 to 1961 from Wallops Island, Virginia to test the launch escape system and heat shield for Project Mercury capsules, as well as the name given to the test program using the booster. The first rocket designed solely for crewed spacecraft qualifications, Little Joe was also one of the pioneer operational launch vehicles using the rocket cluster principle. The Little Joe name has been attributed to Maxime Faget at NASA's Langley Research Center in Hampton, Virginia. He based the name on four large fins, which reminded him of a slang term for a roll of four in craps. A successor, Little Joe II, was used for flight testing of the Apollo launch escape system from 1963 to 1966.

Background

When NASA needed a booster for Project Mercury, the agency found that the Atlas rockets would cost approximately US$2.5 million each and that even the Redstone would cost about $1 million per launch. The managers of the Mercury program recognized that the numerous early test flights would have to be accomplished by a far less expensive booster system, so NASA designed the Little Joe rocket which cost $200,000 each. In January 1958, Max Faget and Paul Purser had worked out in considerable detail on paper how to cluster four of the solid-fuel Sergeant rockets, in standard use at the Wallops Flight Facility in Virginia, to boost a crewed nose cone above the stratosphere. Faget's short-lived "High Ride" proposal had suffered from comparisons with "Project Adam" at that time, but in August 1958 William Bland and Ronald Kolenkiewicz had returned to their preliminary designs for a cheap cluster of solid rockets to boost full-scale and full-weight model capsules above the atmosphere. As drop tests of boilerplate capsules provided new aerodynamic data on the dynamic stability of the configuration in free-fall, the need for comparable data on the powered phase quickly became apparent. So in October 1958, a NASA team prepared new engineering layouts and estimates for the mechanical design of the booster structure and a suitable launcher. As the blueprints for this cluster of four rockets began to emerge from their drawing boards, the designers' nickname for their project gradually was adopted. Since their first cross-section drawings showed four holes, they called the project "Little Joe", from the craps throw of a double deuce on the dice. Although four smaller circles were added later to represent the addition of Recruit rocket motors, the original name stuck. The appearance on engineering drawings of the four large stabilizing fins protruding from its airframe also helped to perpetuate the name Little Joe had acquired. The primary purpose of this relatively small and simple booster system was to save money — by allowing numerous test flights to qualify various solutions to the myriad problems associated with the development of crewed space flight, especially the problem of escaping from an explosion at or during launch. Capsule aerodynamics under actual reentry conditions was another primary concern. To gain this kind of experience as soon as possible, its designers had to keep the clustered booster simple in concept; it should use solid fuel and existing proven equipment whenever possible, and should be free of any electronic guidance and control systems. The designers made the Little Joe booster assembly to approximate the same performance that the Army's Redstone booster would have with the capsule payload. In addition to being flexible enough to perform a variety of missions, Little Joe could be made for about one-fifth the basic cost of the Redstone, would have much lower operating costs, and could be developed and delivered with much less time and effort. Unlike the larger launch vehicles, Little Joe could be launched from the existing facilities at Wallops Island.

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