Milestones in Space Exploration: The Redstone Rocket

Originally built as a short-range nuclear missile, the Redstone rocket didn’t play much of a role in the Cold War, but it was central to the early parts of the American space program.

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Mercury-Redstone on display at the Kennedy Space Center

In 1944, as Allied troops crossed France after the D-Day landings, German V-2 missiles rained on London. One by one, American and British units overran the launch sites, eventually pushing the Germans out of range. The “vengeance weapon” that Hitler hoped would win the war, was a strategic failure.

But the American Army recognized the enormous military potential of ballistic missiles, and as it captured the technology, sent it back to the US for study. In November 1944, the General Electric company was asked to begin a program to use captured V-2 parts and drawings to produce American rockets for a variety of tasks, including anti-aircraft, cruise missiles, and surface-to-surface ballistic missiles. The project was known as “Hermes”. One of the requirements was for a surface-to-surface artillery rocket, like the V-2, that could carry a high-explosive warhead (and, after 1945, an atomic bomb) to a range of several hundred miles. This missile was known as the Hermes C. GE worked on it till the end of the war, but was unable to solve many of the technical difficulties.

When the Nazis surrendered in May 1945, one of the US Army’s first priorities was to hunt down and capture as many of the German technical staff as possible, particularly in the fields of rocketry and jet engines, and the Americans managed to find the greatest prize of all: Dr Wernher von Braun, the V-2’s designer, and much of his team.

Von Braun was packed to the US, where he agreed to work on American rocketry. His first project was an early cruise missile, which mated a pair of wings to a modified V-2 rocket engine. Called “Navajo”, the missile was designed to cruise along just above the ground before dropping onto its target.

In 1950, shortly after the Soviet Union had tested its own nuclear weapon, the Korean War broke out and the Cold War began in earnest. Although both sides produced long-range heavy bombers capable of reaching each other, they each realized that the future of nuclear warfare lay in long-range Inter-Continental Ballistic Missiles (ICBMs), that were impossible to shoot down and could reach their targets in a very short time.

The Americans established a testing site at Huntsville AL, called the Redstone Arsenal, and moved von Braun and his team there with orders to take over the work on Project Hermes C. As the basis for his new rocket, von Braun chose the very reliable modified V-2 engine that he had used in the earlier Navajo cruise missile. It burned 75% alcohol and liquid oxygen as its fuel, and produced 75,000 pounds of thrust. The finished Hermes C rocket would carry the new W-39 nuclear warhead, which weighed almost four tons and had an explosive yield of 4 megatons, to a distance of 500 miles. First called “Ursa” and then “Major”, it was soon designated “Redstone”, after the arsenal where it was designed.

At the same time, von Braun also began work on a lengthened version of the Redstone that had three upper stages fitted onto it to give it a longer range (1500 miles), that he called “Jupiter C”. Because of a bureaucratic fight with the Air Force, however, the Army was limited to rockets with a range of no more than 200 miles (ICBMs and other long-range rockets were the domain of the Air Force). The Huntsville team was ordered to turn over the “Jupiter C” to the Air Force, and to reduce the designed range of the Redstone.

The Redstone had several new technical improvements over the V-2. The V-2 was essentially unaimed, and there was no way to accurately hit a small target with it. The Redstone, however, had an inertial guidance system and movable steering fins at the tail which allowed it to fall within 150 yards of a selected target. Unlike the V-2, the Redstone also had a detachable warhead, which allowed the dead weight of the rocket body to fall away after launch and reduced the stresses on the re-entering warhead, allowing for greater accuracy.  The new missile stood 69 feet 4 inches tall, was 6 feet in diameter with 3-foot steering fins, and had a loaded weight of about 30 tons.

Flight tests were conducted from 1953 to 1956, and the first operational missiles reached Europe in 1958. In all, about 120 Redstones were produced. It was the first large nuclear missile to be deployed by the US. But as a military weapon, the Redstone had severe shortcomings. Each missile group required a fleet of 20 heavy vehicles, ranging from the missile carriers themselves to liquid-fuel trucks, fire-control vehicles, and water tankers. Once a firing site was reached, it took eight hours to assemble the missile, set up and level the launch vehicle, calibrate the inertial guidance system, and prepare the rocket for launch–and once the launch order was given, it took a further 15 minutes to load the final liquid fuel. The Army responded to all of this by beginning work on a solid-fuel replacement, called the Pershing, which was much quicker to set up and launch. When the Pershing was deployed to Europe in 1964, the Redstones were withdrawn and retired.

Well, not quite retired….

When the Soviet Union launched its Sputnik satellite in 1957, the United States raced to catch up. Although von Braun’s Juno rocket, a slightly-modified version of the Jupiter C (which was itself a derivative of the Redstone), was capable of reaching orbit, President Eisenhower had geopolitical reasons for not using a military missile as a launch vehicle; it wasn’t until the failure of the civilian Vanguard rocket that von Braun was finally allowed to launch America’s first satellite, Explorer, on a Juno.

The next step was to put a human into space, and the US, embarrassed by the success of the Soviet Sputnik, was eager to beat the USSR in a manned flight. To save time, NASA decided to utilize an existing rocket as the launch vehicle for its proposed Mercury space capsule. The Redstone was not powerful enough to put the 1.5-ton Mercury into orbit, but it was capable of a suborbital  space flight, going up and down in an arc and boosting the capsule to an altitude of about 55 miles. In 1958, von Braun and his team were assigned to NASA, and in January 1959, eight new Redstone rockets were ordered for use in the Mercury project. The Mercury-Redstone was modified by stretching the rocket body to 83 feet and using the lengthened fuel tanks from the Juno’s first stage, to give a longer burn time and more thrust.

The Mercury-Redstone made six flights, with one launch failure. Three of the launches carried instruments, one carried the space chimp Ham, and the last two carried astronauts Alan Shepard and Gus Grissom on suborbital flights.

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