Little Joe 1 (LJ-1) was a failed launch of a Little Joe by

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, a solid fuel

rocket A rocket (from it, rocchetto, , bobbin/spool) is a vehicle that uses jet propulsion to accelerate without using the surrounding air. A rocket engine produces thrust by reaction to exhaust expelled at high speed. Rocket engines work entirely fr ...

that was designed for a Max Q abort and

launch escape system A launch escape system (LES) or launch abort system (LAS) is a crew-safety system connected to a space capsule that can be used to quickly separate the capsule from its launch vehicle in case of an emergency requiring the abort of the launch, suc ...

test for the Mercury capsule. The objective was to determine how well the escape rocket would function under the most severe dynamic loading conditions anticipated during a Mercury-Atlas launching. The vehicle was in height, weighed approximately , and was in diameter with a fin span of . The Little Joe booster consisted of four Pollux and four

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clustered, solid-fuel rockets, could develop a

thrust Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that sys ...

of , and could lift a maximum payload of . The escape system, using a Grand Central 1KS52000 rocket motor, weighed . On 21 August 1959, LJ-1 was being prepared for launch from the Wallops Flight Facility,

Wallops Island Wallops Island is a island in Accomack County, Virginia, part of the Virginia Barrier Islands that stretch along the eastern seaboard of the United States of America. It is just south of Chincoteague Island, a popular tourist destination. W ...

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. At 35 minutes before launch, evacuation of the area had been proceeding on schedule and the batteries for the programmer and destruct system in the test booster were being charged. Suddenly, half an hour before launch time, an explosive flash occurred. When the smoke cleared it was evident that only the capsule-and-tower combination had been launched, on a trajectory similar to an off-the-pad abort. The booster and adapter-clamp ring remained intact on the launcher. Near apogee, at about 610 m, the clamping ring that held tower to capsule released and the little pyro-rocket for jettisoning the tower fired. The flight time was 20 seconds. The accident report for LJ-1, issued 18 September 1959, blamed the premature firing of the Grand Central escape rocket on an electrical leak, or what missile engineers call transients or ghost voltages in a relay circuit. The fault was found in a coil designed to protect biological specimens from too rapid an abort.Reference NASA SP-4201 p. 208 According to the 18 September 1959 accident report, the unexpected triggering of the launch escape system was caused by a transient or electrical leak; analysis showed it to be due to the rapid-abort system being wired directly into the destruct arming

busbar In electric power distribution, a busbar (also bus bar) is a metallic strip or bar, typically housed inside switchgear, panel boards, and busway enclosures for local high current power distribution. They are also used to connect high volt ...

. The batteries were shipped from England to the U.S. uncharged and shorted; on charging at the pad, the batteries, when enough charge was reached, actuated the sequencer for the abort system, and sensing insufficient altitude, fired the squibs in the abort motor. Insufficient power in the batteries then failed to initiate the tower jettison motor and capsule parachute recovery charge, and both crashed into the sea.

Notes and References

External links

This New Ocean: A History of Project Mercury—NASA SP-4201
{{Project Mercury Project Mercury 1959 in spaceflight