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Little Joe 1B



Little Joe 1B (LJ-1B) was the fourth successful launch in a series of suborbital flights designed to test various components of the Mercury flight systems. The primary objectives of the Little Joe booster missions were to: (1) study capsule dynamics at progressively higher altitudes; (2) test the capsule escape system at maximum dynamic pressure; (3) qualify the parachute system; and, (4) verify the search and retrieval methods.

Objectives for LJ-1B were the same as those for the earlier Little Joe 1 and Little Joe 1A flights. Specific goals of the LJ-1B flight were to: (1) check out the Mercury escape system concept and hardware at the maximum dynamic pressure anticipated during a Mercury Atlas exit flight; (2) determine the effects of simulated Atlas abort accelerations on a small primate; (3) obtain further reliability data on the Mercury spacecraft drogue and main parachute operations; (4) check out the operational effectiveness of spacecraft recovery by helicopter; and, (5) recover the escape-system assembly (escape motor and tower) for a post-flight examination in order to establish whether there were any component malfunctions or structural failures.

Along for the ride on LJ-1B was a female rhesus monkey, dubbed Miss Sam. As with Sam on the LJ-2 flight, Miss Sam's name was derived from the initials of the institution that was responsible for designing the various biological packages to be used in the Mercury test flights, the U.S. Air Force School of Aviation Medicine. The monkey was to be tested in psychomotor performance tasks during the short but severe flight.

Miss Sam performed her routine well during the flight, watching the light and pulling the lever as trained, excepting a 30 second lapse following the time of the escape rocket firing. Although she was returned in excellent condition, despite the severe g loads and a higher than anticipated noise level in the capsule, she did experience a rapid, involuntary, oscillatory motion of the eyeball ("nystagmus") after the escape rocket firing and after impact on the water. This was of primary concern for it suggested that an astronaut's effectiveness as a backup to the parachute system might be impaired.

The escape system performed as anticipated as did all sequences. The escape rocket kicked in at the point of maximum dynamic pressure ("max q"), propelling the capsule to an altitude of roughly 9.3 statute miles and downrange a distance of about 11.7 statute miles. The total flight time was 8 minutes 35 seconds with Miss Sam experiencing only 28 seconds of weightlessness. The capsule was recovered soon after splashdown by a Marine helicopter and returned to Wallops Station some 30 minutes following launch. LJ-1B succeeded in finally proving the basic aerodynamic viability of the Mercury abort concept.

Alternate Names

  • LJ-1B
  • LittleJoe1B
  • Mercury Little Joe 1B

Facts in Brief

Launch Date: 1960-01-21
Launch Vehicle: Little Joe
Launch Site: Wallops Island, United States

Funding Agency

  • National Aeronautics and Space Administration (United States)


  • Engineering
  • Life Science

Additional Information

Questions and comments about this spacecraft can be directed to: Dr. Edwin V. Bell, II



NameRoleOriginal AffiliationE-mail

Other Sources of LJ-1B Information/Data

LJ-1B information (NASA KSC)
MR-1 Press Release images (NASA JSC)

Project Mercury Drawings and Technical Diagrams (NASA History Office)

On-line version of Project Mercury: A Chronology (NASA History Office)

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