Little Joe II
Little Joe II was an American rocket that flew just five times, between 1963 and 1966, and never carried a single astronaut. Its job was to put Apollo hardware into trouble on purpose. Each flight tested the launch escape system, the emergency equipment meant to pull a crew away from a failing rocket. The rocket also helped verify that the command module parachutes could bring a capsule down safely after such an abort. It was the smallest of the four launch rockets used in the Apollo program, and it borrowed its name from an earlier machine built for Project Mercury. Why did NASA need a purpose-built rocket just to stage emergencies? How do you design a launcher that must be both versatile and cheap? And when the moment of escape came, did the system actually work?
Man-rating the Apollo launch escape system, which means certifying it for human passengers, was supposed to happen early and at minimum cost. No reasonably priced launch vehicle offered the payload capability and range of thrust that the planned tests required. A contract was therefore awarded to develop and build a specialized rocket. It had a precedent in the original Little Joe, which tested the escape system of the Mercury spacecraft in 1959 and 1960.
Cape Kennedy in Florida, home of the Air Force Eastern Test Range, was the first choice of launch site. A heavy schedule of high-priority launches there pushed planners to weigh Wallops Island in Virginia and Eglin Air Force Base in Florida. Launch Complex 36 at White Sands Missile Range in New Mexico won out. It had earlier hosted Redstone missile tests, and it fit the schedule and support needs. It also allowed recovery on land, which was cheaper and less complicated than the water recovery that Cape Kennedy or Wallops Island would have demanded.
The Manned Spacecraft Center in Houston, Texas, now called Johnson Space Center, directed the whole program. General Dynamics/Convair served as prime contractor for the launch vehicle, and North American Rockwell as prime contractor for the spacecraft. White Sands supplied the range services: range safety, radar and camera tracking, command transmission, real-time data displays, photography, telemetry acquisition, data reduction and recovery operations.
Fabrication of detail parts for the first vehicle began in August 1962, and the final factory systems checkout was completed in July 1963. Holding down cost shaped nearly every choice in between. Designers kept the tooling and manufacturing simple, which cut the number of components and the time needed to build each rocket.
Because weight was not a limiting factor, engineers deliberately overbuilt the main structural members. That greatly reduced how many structural proof tests were needed, and how complicated they were. Wherever possible they also chose off-the-shelf parts with a proven record in other aerospace programs. Using such parts trimmed the amount of qualification testing too.
The structure was designed around a gross weight of 220,000 pounds, or 100,000 kilograms, of which 80,000 pounds, or 36,000 kilograms, was payload. The rocket's diameter was sized to match the Apollo service module, and its length was set to suit the Algol rocket motors. Its fins were sized so that the vehicle would be inherently stable. The design came in two forms: an original version with fixed fins, and a later one fitted with flight controls.
Two borrowed motors powered Little Joe II. The booster was a motor developed for the Recruit rocket, and the sustainer came from the Algol stage of the Scout rocket family. Each Algol delivered 465 kilonewtons of thrust, stood 9.1 meters long, and burned for about 40 seconds. A full one weighed 10,180 kilograms, and an empty case weighed 1,900 kilograms.
The Recruit motor, designated Thiokol XM19, was far smaller. It measured 2.7 meters long and 0.23 meters wide, weighed 159 kilograms, and produced 167 kilonewtons. Its burn lasted only 1.53 seconds, so its role was to add a kick at lift-off.
Versatility came from changing how many motors flew. A single airframe could hold as many as seven primary motors, and the number and firing order were tailored to each mission. The structure allowed sequential firing, with a possible 10-second overlap among four first-stage and three second-stage sustainer motors. The first test vehicle carried six Recruit boosters and one Algol. The A-003 vehicle carried six Algols and no Recruits. Across that range, the whole rocket's thrust ran from 49 to 1,766 kilonewtons, and its weight from 25,900 to 80,300 kilograms.
On the 28th of August 1963, the Qualification Test Vehicle made the first Little Joe II launch. Its payload was a dummy, an aluminum shell in the basic shape of the Apollo command module, topped with an inert launch escape system. The flight demonstrated that the rocket would work for the real tests to follow.
The A-001 launch came on the 13th of May 1964. It carried BP-12, a boilerplate command module, which served as a test stand-in for the real spacecraft. This flight performed the first successful abort using a live launch escape system.
On the 8th of December 1964, the A-002 mission flew BP-23. Its goal was to test the escape system under pressures and stresses like those of a Saturn IB or Saturn V launch. The A-003 mission followed on the 19th of May 1965, with BP-22. It was planned as a high-altitude test of the escape system.
The last Little Joe II flew on the 20th of January 1966, carrying CSM-002, the first production spacecraft. It used four Algol sustainers and five Recruit boosters, and it climbed to about 22,600 meters. Its range was 34,630 meters. Separately from these five rocket flights, two pad abort tests fired the escape system at ground level.
The Qualification Test Vehicle ignored the order to destroy itself. Primacord, a detonating cord, had been installed improperly, so the first detonation never reached the shaped charges on the Algol motor case. The rocket otherwise did its job, and the fault was corrected.
The fourth mission, A-003, went out of control about 2.5 seconds after lift-off. An electronic failure had driven one aerodynamic fin fully over to one extreme. The abort that was meant to happen at high altitude therefore took place low instead. Once that problem was fixed, the abort test program was completed.
The tests exposed flaws in the spacecraft as well. Engineers found minor deficiencies in the parachute reefing cutters, in the mountings of the mortars that deploy the drogue and main parachutes, and in the command and service module umbilical cutters. All were corrected before the crewed Apollo flights began. Every command module that flew landed in satisfactory condition, which confirmed that a crew aboard would have survived the abort conditions.
Surviving examples of Little Joe II can be seen at the New Mexico Museum of Space History in Alamogordo, and at Johnson Space Center in Houston, Texas. With the command module, service module and escape system attached, the rocket stood 26.2 meters tall. Without them its body measured 10.1 meters, with a diameter of 3.9 meters. Its fins spanned 8.7 meters, more than twice the width of that body.
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Common questions
What was Little Joe II used for?
It was used from 1963 to 1966 for five uncrewed tests of the Apollo launch escape system. It also verified the performance of the command module parachute recovery system in abort mode.
Why were the tests launched from White Sands Missile Range?
Cape Kennedy had a heavy schedule of high-priority launches. Launch Complex 36 at White Sands suited the schedule and support needs, and it allowed land recovery, which was cheaper and less complicated than water recovery.
What motors powered Little Joe II?
It used Recruit motors as boosters and Algol motors, from the Scout rocket family, as sustainers. The number of motors varied by mission, up to seven in a single airframe.
Did every Little Joe II flight go as planned?
No. The Qualification Test Vehicle did not destruct when commanded because primacord was installed improperly. On the A-003 mission, an electronic failure sent a fin hard over and the vehicle went out of control about 2.5 seconds after lift-off. Both problems were corrected.
Where can a Little Joe II be seen today?
Surviving examples are at the New Mexico Museum of Space History in Alamogordo, New Mexico, and at Johnson Space Center in Houston, Texas.
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