Autor Wątek: [AS] 'Old Reliable': 60 Years Since a Weapon of War Became a Rocket for Space  (Przeczytany 65 razy)

0 użytkowników i 1 Gość przegląda ten wątek.

Offline Orionid

  • Weteran
  • *****
  • Wiadomości: 8301
  • Very easy - Harrison Schmitt
'Old Reliable': 60 Years Since a Weapon of War Became a Rocket for Space
By Ben Evans, on January 13th, 2019

One of the earliest rockets to be launched from Cape Canaveral was the Army’s Redstone missile, which later evolved into the vehicle seen here delivering America’s first man into space. Photo Credit: NASA

Sixty years ago, this week, a weapon of war became a rocket for space. On 8 January 1959, the U.S. Army Ballistic Missile Agency (ABMA) received the go-ahead to convert its fearsome Redstone missile—a direct outgrowth of Nazi Germany’s infamous V-2—into a vehicle which would someday transport the first American astronaut into space.

A U.S. Army test team elevates a Redstone missile for flight. Photo Credit: U.S. Army

As a potential weapon, the Redstone was employed by the U.S. Army as a medium-range ballistic missile to conduct the United States’ first live nuclear tests during Operation Hardtack, launched out of Johnston Island in August 1958. It remained operational through 1964, earning repute as a service workhorse and, as a non-military launch vehicle, gained the moniker of “Old Reliable”. Its production—by prime contractor Chrysler—had begun at the Michigan Ordnance Missile Plant in Warren, Mich., in 1952, whilst the Rocketdyne division of North American Aviation built its Model A-7 engine, Ford Instrument Company provided its guidance and control systems and Reynolds Metals Company fabricated the fuselage. As a potential weapon of war in the deepest freeze-years of the Cold War, the Redstone could carry 500 megatons of TNT of a 3.75-megaton nuclear warhead. Indeed, batteries of Redstones remained stationed in West Germany until 1964.

A direct outgrowth of the Redstone was the Jupiter-C intermediate-range ballistic missile, which might have beaten the Soviet Union by putting an artificial satellite into orbit, ahead of Sputnik 1, had it not been for the Eisenhower Administration’s emphasis upon a civilian launch vehicle. Eventually, on the night of 31 January/1 February 1958, a Jupiter-C successfully lofted the United States’ first satellite, Explorer 1.

America’s journey into space begins at 10:48:16 p.m. EST on 31 January 1958, with the launch of Explorer 1. Photo Credit: NASA

In spite of its reliability as a tactical missile, the Redstone required extensive modification to be safe enough to launch astronauts during Project Mercury, the United States’ effort to put a man into space. Following the January 1959 go-ahead for ABMA to convert it to a suborbital launch vehicle, the Space Task Group (STG) at Langley Research Center in Hampton, Va.—then a facility of the National Advisory Committee for Aeronautics (NACA)—requested the implementation of an effective launch-abort mechanism. In June, ABMA submitted a response to the STG and throughout the remainder of that year, and into 1960, the design of a man-carrying Redstone was finalized and implemented. An automated system would be capable of shutting off the rocket’s engine and transmitting a separation-abort signal to the conical Mercury capsule in the event of a contingency.

However, in the event of a major emergency during ascent, a range-safety officer—saddled with the unenviable role of remotely destroying the booster—was placed in a particularly tricky position, for there existed a three-second time-lag between transmitting the abort command and the actual destruction of the Redstone. If the most dire of launch emergencies should rear its head, there would exist only a hair’s-breadth of time to pull the Mercury capsule and its astronaut clear of the ensuing conflagration.

The Launch Escape System (LES) fires after Mercury-Redstone (MR-1) aborts on 21 November 1960. Photo Credit: NASA

Other contingencies, it was recognized, could occur too rapidly for missions to be manually aborted and ABMA engineers studied over 60 Redstone flights and identified dozens of critical components which could conceivably fail. On the other hand, many malfunction scenarios—including loss of attitude-control and velocity, a lack of proper combustion-chamber pressures or power problems—produced similar results and ABMA found it could install relatively few abort sensors.

In its original guise, the single-stage Redstone stood 83.3 feet (25.4 meters) tall and weighed 8,200 pounds (3,720 kg). Ignition of its engine was ground-initiated and liftoff commenced when approximately 85 percent of its total thrust had been achieved. Its Model A-7 engine, fueled by a mix of ethyl alcohol and liquid oxygen, and powered by a hydrogen peroxide-fed turbopump, achieve an all-out yield of 78,000 pounds (35,380 kg), but was extensively modified for piloted flights. Lengthened propellant tanks benefited from thicker walls to handle the increased loads of the Mercury capsule and efforts were set in place to improve the reliability of electrical components aboard the Redstone. Steel ballast was added to compensate for the aerodynamic instabilities caused by this additional weight and metal “stringers” were implemented to support the weight of the spacecraft.

In early 1961, the Mercury Seven were ready to begin the United States’ first missions into space. However, the need to conduct a final unpiloted Mercury-Redstone mission caused America to lose the race to beat the Soviet Union into space. Photo Credit: NASA

The first Mercury-Redstone launch—dubbed “MR-1”—was intended to test the abort system and achieve a velocity of around Mach 6, which the United States’ first astronaut might experience, as well as demonstrating the ability of the spacecraft to separate from the rocket. On the morning of 21 November 1960, its A-7 roared to life, but as the Redstone made to leave Pad 5 at Cape Canaveral, a pair of tail-plug sensors separated in the wrong order and the engine shut down. The result was one of the United States’ most visually embarrassing launch mishaps: the vehicle rose 4 inches (10 cm) from the pad surface, then settled delicately back onto its pedestal.

Worse yet, the shutdown signal caused the Launch Escape System (LES) tower to fire, producing copious quantities of smoke which momentarily hid the Redstone from view. Flight Director Chris Kraft was astonished by what he initially perceived as tremendous acceleration…until the smoke cleared, and the rocket was still on the pad. Ironically, although the LES had fired successfully—shooting away to an altitude of 0.7 miles (1.2 km) and alighting safely on the ground about 1,100 feet (360 meters) away—it had not pulled the boilerplate Mercury capsule with it, as the rocket’s automated brain calculated that the acceleration was insufficient and blocked the initiation of a separation signal. Future Mercury astronaut Wally Schirra, watching the proceedings, described it as “a memorable day, especially for someone who likes sick jokes”. To make matters worse, the drogue parachute popped out of the Mercury capsule’s nose, together with a cloud of green marker-dye and an auxiliary chute. All three fluttered pathetically to the ground.

Haunting view of Gus Grissom on his way toward the Redstone rocket, ahead of becoming America’s second man in space. Photo Credit: NASA

A month later, the same Mercury capsule was recycled and successfully flown on the MR-1A mission, after which a chimpanzee—Ham, named for his handlers at Holloman Aerospace Medical Center, based at Holloman Air Force Base, near Alamogordo, N.M.—flew a 16-minute suborbital mission in late January 1961. Despite several problems during Ham’s flight, the reliability of the Mercury-Redstone was rated at somewhere between 78-84 percent, with a 98-percent probability that an astronaut would survive a mission. A final booster development flight took place in March and the first manned flight into space, to be conducted by Navy Commander Alan Shepard, was targeted for late April.

Unfortunately, in one of those quirks of history and of fate, on the 12th of that month, the Soviet Union launched the first man into space. Not only that, but Yuri Gagarin accomplished a full orbit around the Earth, a feat for which the Redstone was wholly incapable. So it was that when the Redstone successfully launched Shepard on a 15-minute suborbital “hop” on 5 May, it established the United States as a player in human spaceflight, but positioned them firmly in second place behind the Soviets. And that undesired “secondness” would lead directly to America’s decision to aim for bootprints on the Moon before the end of that same decade.