AKA: Little Joe 1 2C. Status: Retired 1961. First Launch: 1959-08-21. Last Launch: 1961-04-28. Number: 8 .
During the countdown of the first programed Little Joe launching (LJ-1 beach abort test) at Wallops Island, the escape rocket fired prematurely 31 minutes before the scheduled launch. The spacecraft rose to an altitude of 2,000 feet and landed about 2,000 feet from the launch site. Premature firing was caused by a faulty escape circuit.
Little Joe 1-A (LJ-1A) was launched in a test for a planned abort under high aerodynamic load conditions. This flight was a repeat of the Little Joe (LJ-1) that had been planned for August 21, 1959 (escape rocket fired 31 min before the intended launch of the Little Joe launch vehicle). After lift-off, the pressure sensing system was to supply a signal when the intended abort dynamic pressure was reached (about 30 sec after launch). An electrical impulse was then sent to the explosive bolts to separate the spacecraft from the launch vehicle. Up to this point, the operation went as planned, but the impulse was also designed to start the igniter in the escape motor. The igniter activated, but pressure failed to build up in the motor until a number of seconds had elapsed. Thus the abort maneuver, the prime mission of the flight, was accomplished at a dynamic pressure that was too low. For this reason a repeat of the test was planned. All other events from the launch through recovery occurred without incident. The flight attained an altitude of 9 statute miles, a range of 11.5 statute miles, and a speed of 2,021.6 miles per hour.
Little Joe 1-B (LJ-1B) was launched from Wallops Island with a rhesus monkey, 'Miss Sam,' aboard. Test objectives for this flight were the same as those for Little Joe 1 (LJ-1) in which the escape tower launched 31 minutes before the planned launch, and Little Joe 1-A (LJ-1A), wherein the dynamic buildup in the abort maneuver was too low. A physiological study of the primate, particularly in areas applying to the effects of the rapid onset of reverse acceleration during abort at maximum dynamic pressure, was also made. In addition, the Mercury helicopter recovery system was exercised. During the mission, all sequences operated as planned; the spacecraft attained a peak altitude of 9.3 statute miles, a range of 11.7 statute miles, and a maximum speed of 2,021.6 miles per hour. Thirty minutes from launch time, a Marine recovery helicopter deposited the spacecraft and its occupant at Wallops Station. 'Miss Sam' was in good condition, and all test objectives were successfully fulfilled.
Little Joe 5 with a Mercury production spacecraft was launched from Wallops Island to test the spacecraft in an abort simulating the most severe launch conditions. At 15.4 seconds after liftoff, the escape rocket motor and tower jettison motor ignited prematurely. Booster, capsule, and tower remained mated through ballistic trajectory until destroyed on impact.
Mercury Little Joe 5A (LJ-5A), the sixth in the series of Little Joe missions, was launched from Wallops Island. This flight was intended to satisfy test objectives, which were not met previously because of the failure of the spacecraft to separate from the launch vehicle during the Little Joe 5 (LJ-5) mission flown on November 8, 1960. For reference, the purpose of this test was to demonstrate primarily the structural integrity of the spacecraft and the escape system during an escape maneuver initiated at the highest dynamic pressure anticipated during an Atlas launch for orbital flight. Little Joe 5A (LJ-5A) lifted off normally, but 19 seconds later the escape tower fired prematurely, a situation closely resembling the November 1960 flight. The signal to initiate the abort maneuver was given; and the launch vehicle-adapter clamp ring was released as intended, but the spacecraft remained on the launch vehicle since the escape motor was already expended. The separation was effected by using the retrorockets, but this command was transmitted before the flight had reached its apex, where separation had been planned. Therefore, the separation was rather violent. The parachutes did deploy at about 40,000 feet, and after recovery it was found that the spacecraft had actually incurred only superficial structural damage. In fact, this spacecraft was later used for the subsequent Little Joe 5B (LJ-5B) flight test. Test objectives of the Little Joe 5A (LJ-5A) were not met.
Little Joe 5B (LJ-5B) was launched from Wallops Island to test the Mercury escape system under maximum dynamic pressure conditions. At the time of lift-off, one of the launch vehicle rocket motors did not ignite until after 4 seconds had elapsed. This delay caused the launch vehicle to pitch into a lower trajectory than had been planned, with a result that the abort maneuver experienced greater dynamic pressures than had been specified in the flight test plan. Other than this, all other sequential systems operated according to plan, and after landing, a normal helicopter recovery was accomplished. Thus, all test objectives were met and were actually exceeded because the spacecraft withstood the higher dynamic pressures.