Little Joe 1B (LJ-1B) marked the fourth successful launch in a series of suborbital missions aimed at evaluating key components of the Mercury flight systems. The primary objectives of the Little Joe booster tests were to: (1) analyze capsule dynamics at increasing altitudes; (2) assess the capsule escape system under peak dynamic pressure conditions; (3) validate the parachute deployment system; and (4) confirm the effectiveness of search and recovery procedures.
The LJ-1B mission objectives mirrored those of its predecessors, Little Joe 1 and Little Joe 1A. Specifically, the LJ-1B flight sought to: (1) test the Mercury escape system design and hardware under maximum dynamic pressure expected in a Mercury Atlas launch; (2) evaluate the impact of simulated Atlas abort accelerations on a small primate; (3) gather additional reliability data on the Mercury spacecraft's drogue and main parachute functions; (4) verify the operational efficiency of helicopter-based spacecraft recovery; and (5) retrieve the escape system assembly (escape motor and tower) for post-flight analysis to check for any structural failures or component malfunctions.
Aboard LJ-1B was a female rhesus monkey named Miss Sam. Like Sam, who flew on LJ-2, her name originated from the initials of the U.S. Air Force School of Aviation Medicine, the organization responsible for developing the biological payloads for the Mercury test flights. During the brief but intense flight, Miss Sam was tasked with psychomotor performance tests.
Miss Sam successfully completed her assigned tasks, responding to visual cues and operating a lever as trained, with the exception of a 30-second lapse following the activation of the escape rocket. Despite experiencing extreme g-forces and higher-than-expected noise levels in the capsule, she was recovered in excellent condition. However, she exhibited rapid, involuntary eye movements ("nystagmus") after the escape rocket fired and again upon splashdown. This raised concerns about potential impairments to an astronaut's ability to serve as a backup for the parachute system.
The escape system functioned as expected, activating at maximum dynamic pressure ("max q") and propelling the capsule to an altitude of approximately 9.3 statute miles, with a downrange distance of about 11.7 statute miles. The total flight duration was 8 minutes and 35 seconds, during which Miss Sam experienced 28 seconds of weightlessness. Following splashdown, a Marine helicopter quickly retrieved the capsule and returned it to Wallops Station within 30 minutes of launch. The LJ-1B mission successfully confirmed the aerodynamic feasibility of the Mercury abort system.
Launch Details:
Date: January 21, 1960
Launch Vehicle: Little Joe
Launch Site: Wallops Island, United States