Little Joe (rocket)
Maxime Faget stood at NASA's Langley Research Center in Hampton, Virginia during 1958. He sketched a rocket design that featured four large fins protruding from its airframe. The engineer recalled the slang term for rolling a four in craps when he looked at those fins. He called the project Little Joe based on that double deuce throw. Paul Purser worked alongside him to detail how to cluster four solid-fuel Sergeant rockets. Their drawings showed four holes which matched the gambling reference perfectly. Later additions of Recruit motors did not change the nickname. The name stuck because the engineering blueprints kept showing those four stabilizing fins.
NASA managers reviewed launch costs for Project Mercury in early 1958. Atlas rockets required approximately US$2.5 million per launch while Redstone vehicles cost about $1 million each. Program leaders realized they needed a far less expensive booster system for numerous test flights. They designed the Little Joe rocket to cost only $200,000 per unit. This price point allowed them to fly many more tests than previous options permitted. The agency could develop and deliver this vehicle with much less time and effort. Wallops Island facilities in Virginia already existed so no new infrastructure was needed. North American Aviation won the contract for seven booster airframes on the 29th of December 1958. The company began work immediately in Downey, California.
Engineers arranged four modified Sergeants called Castor or Pollux rockets into a single assembly. Four supplemental Recruit rockets fired in various sequences to create takeoff thrust variations. Maximum design thrust reached almost 230,000 pounds or 1,020 kilonewtons. The cluster theoretically lifted a spacecraft of about 4,000 pounds on a ballistic path over 100 miles high. Solid fuel powered every motor without any electronic guidance systems. Thiokol manufactured the Recruit motors with a burn time of 1.53 seconds. Castor rockets burned for 37 seconds while generating 58,200 pounds of thrust. The total weight of the booster reached 28,000 pounds with a length of 15.2 meters. Engineers hoped their ungainly rocket would prove the legitimacy of most ballistic capsule design concepts.
Sam flew aboard Little Joe 2 on the 4th of December 1959 as a rhesus macaque. The mission reached an altitude of 53 miles or 85 kilometers before recovery by SE of Wallops Island. Miss Sam followed as a female rhesus monkey during the 21st of January 1960 flight known as Little Joe 1B. That test achieved maximum-q abort and escape conditions with a boiler plate capsule. Both animals survived their flights to validate escape systems before human spaceflight. The Space Task Group used these primate missions to acquire firm empirical data quickly. Measurements included inflight forces and impact forces on the capsule. Telemetry systems recorded noise levels and heat loads during each ascent.
Little Joe 5 became the first flight to carry a real Mercury capsule from the McDonnell production line on the 8th of November 1960. This transition marked a shift from development flight tests with boilerplate models to qualification flight tests. The Space Task Group moved further away from research into operations at that moment. North American Aviation had manufactured seven airframes but one remained in Downey for static loading tests. STG ordered refurbishment of this seventh airframe to have three boosters for the qualification program. Five prototype capsules made in Langley shops were expended by the 21st of January 1960. Only two Little Joe boosters remained for final qualification flight tests after that date.
Electrical malfunction caused the escape tower to ignite hour before launch on the 21st of August 1959. The spacecraft lifted off while the rocket stayed grounded during Little Joe 1. A clamp holding the spacecraft deflected by air pressure during the 8th of November 1960 flight. Incorrect wiring caused the escape tower to ignite too early and fail to separate the spacecraft. Tower fired 14 seconds too soon during the 18th of March 1961 test known as Little Joe 5A. Rescue tower rocket ignited 10 seconds too late during the 4th of November 1959 mission called Little Joe 1A. Engineers corrected these electrical malfunctions and wiring errors through subsequent engineering fixes. The third test with a production spacecraft succeeded on the 28th of April 1961 to conclude the program.
Common questions
Who designed the Little Joe rocket and when did he sketch it?
Maxime Faget sketched the Little Joe rocket design at NASA's Langley Research Center in 1958. He named the project based on a four-in-craps slang term after observing four large fins on his drawings.
What was the cost per unit for the Little Joe booster compared to Atlas rockets?
NASA managers set the Little Joe booster cost at $200,000 per unit to save money compared to other options. Atlas rockets required approximately US$2.5 million per launch while Redstone vehicles cost about $1 million each during early 1958 reviews.
When did Sam fly aboard Little Joe 2 as a rhesus macaque?
Sam flew aboard Little Joe 2 on the 4th of December 1959 as a rhesus macaque. The mission reached an altitude of 53 miles or 85 kilometers before recovery by SE of Wallops Island.
Which company won the contract for seven Little Joe airframes and where did they work?
North American Aviation won the contract for seven booster airframes on the 29th of December 1958. The company began work immediately in Downey, California to manufacture the units.
How much thrust did Castor rockets generate during Little Joe operations?
Castor rockets burned for 37 seconds while generating 58,200 pounds of thrust. Maximum design thrust for the entire cluster reached almost 230,000 pounds or 1,020 kilonewtons.
On what date did the final successful qualification flight test conclude the program?
The third test with a production spacecraft succeeded on the 28th of April 1961 to conclude the program. This flight followed multiple electrical malfunctions that required engineering fixes throughout 1959 and 1960.