Part 4

Two types of ion engines represent the most fully developed electric propulsion systems. In contact ion engines, a propellant gas (mercury or cesium, for example) is ionized, or given an electrical charge, by passage through a hot porous metal. The resulting ions are accelerated out of the engine by an electrical field. The charged ions are neutralized as they approach the nozzle to form an exhaust beam that imparts the thrust. Bombardment ion engines rely on the bombardment of the propellant gas by electrons from a cathode, or negative electrode, to create ions. The ions are accelerated from the engine in the same manner as in the contact ion engine.

A Cesium Ion Rocket Engine

This small contact ion engine produces .0009 kilogram (.002 pound) of thrust by passing vaporized cesium through hot tungsten. On Earth this amount of power is scarcely enough to lift a one-carat jewel an inch off a table, but in the frictionless vacuum of space, it is sufficient to provide attitude control for satellites. It can also accelerate a spacecraft to high interplanetary velocities by operating continuously for thousands of hours.

An ion engine of this type was first tested in space in 1964. On that occasion, it provided .0009 kilogram (.002 pound) of thrust for 2 hours, 10 minutes. It was able to control the attitude of the attached instrument package.

This ion engine is a gift from Electro-Optical Systems, Inc., the company that developed it.

Project Orion

[Illustration: 57. The Project Orion test vehicle was used to explore the feasibility of a unique type of propulsion which utilized successive nuclear explosions behind the rear pusher plate.]

Project Orion was an attempt to solve the problems of propulsion for long-term manned journeys to other planets by creating an engine that would use successive nuclear explosions to propel very large space vehicles. The Orion spacecraft was designed to carry many small nuclear explosive systems which would be ejected sequentially from the rear of the vehicle. These units would explode some distance behind the spacecraft. The expanding debris, in the form of high-velocity, high-density plasma, would strike a pusher plate at the rear of the Orion vehicle.

Work on Project Orion was halted in 1963 when the Limited Nuclear Test Ban Treaty, which prohibited atmospheric tests of the propulsion system, was signed.

The Project Orion Test Vehicle—on display—demonstrated the basic principle of intermittent thrust from explosive charges. Test data provided by this model would have assisted engineers in developing the full-scale spacecraft.

The test vehicle carried five high-explosive plastic charges which were ejected from the rear of the craft. Compressed nitrogen powered the ejection system. Each charge was attached to the vehicle by a .9-meter (3-foot) cord. A microswitch exploded the individual packages. The Project Orion Test Vehicle was first flown successfully in October 1959.

From the Gulf Energy and Environmental Systems, Inc.

The Plug-Nozzle Rocket Engine

Although this engine is a liquid-propellant rocket, it substitutes a series of small combustion chambers and nozzles for the traditional single large chamber and nozzle to achieve additional thrust. This innovative combustion system features chambers and nozzles mounted on an annular ring at the base of the engine. Thrust is derived from the expansion of the exhaust gases against a large segmented plug in the center of the engine. Flight control is achieved by varying the amount of propellant introduced into the individual chamber sections. The engine on exhibit burned liquid oxygen and kerosene to provide a thrust of 22,680 kilograms (50,000 pounds).

The plug-nose rocket engine was developed at the General Electric Company’s Malta Test Station in 1961.

The engine on exhibit is from the New York State Atomic and Space Authority.

Space Suits

[Illustration: 58. Astronaut John Glenn is assisted with his suiting-up.]

Modern space suits are direct descendants of the simple “pressure suits” designed as early as 1907 for deep-sea divers. In 1911 an English respiratory physiologist, J. S. Haldane, proposed the use of an oxygen pressurized suit for ascent to high altitudes. The first U.S. patent was granted for a pressure suit in 1918.

Through the early 1960s, all such suits were pressure containers. Project Mercury astronauts wore suits adapted from the U.S. Navy MK-IV pressure suit. It consisted of an inner layer of neoprene-coated fabric and a restraint layer of aluminized nylon fabric. The garment design provided a fair degree of mobility, although the suit could not bend with the full hinge motion of the human elbow or knee because it folded in at the joints, reducing overall volume and increasing internal pressure. The Mercury suit would have been pressurized only if spacecraft cabin pressure had been lost.

Space suits require a great deal of sophistication. They must meet many vital criteria, including low leakage, thermal control, comfort, stowage, and protection from micrometeoroid strikes.

_Gemini 4_ was the first American mission to explore the problems of man functioning outside his spacecraft, with only his space suit for protection. This extravehicular activity required the space suit to be a prime system rather than a precautionary measure.

[Illustration: 59. Apollo space suit.]

Designed and created primarily for moon-walking, the 28.6-kilogram (63-pound) Apollo space suits, with backpack environmental and communication systems, enabled the lunar astronauts to dispense with the tether used on the Gemini “spacewalks.” The suit’s 21 layers are materials such as teflon fabric, nonwoven dacron, and aluminized mylar. These alternating layers of specialized materials protected the astronauts from the extreme temperatures of space and possibility of micrometeroids striking. Boots and gloves contain a stainless steel cloth to protect against abrasion. Suits had to fit the wearers so precisely that 67 anthropometric measurements were required of each astronaut.

[Illustration: 60. Astronaut White takes the first “spacewalk” with only his suit for protection from the space environment.]

When the astronauts ventured outside the spacecraft and explored the lunar surface, the following equipment was worn under the suit: a fecal containment system for emergency containment of solid-waste material; a liquid-cooling garment; a bio-belt assembly, urine collection and transfer system. Together with a portable life-support system, this constituted the complete Environmental Mobility Unit (EMU).

The liquid-cooling garment consists of an outer layer of nylon spandex material, a network of polyvinyl-chloride tubing, and a nylon-chiffon comfort liner. Even spacing of the plastic tubing permitted the efficient transfer of body heat to the cooling liquid (water) as it circulated through the suit.

The bio-belt assembly, worn over the liquid-cooling garment, contains preamplifiers for sensors placed next to the skin. The sensors acquired electrical signals which determined respiration rate and electrocardiograms of the astronauts. The preamplifiers relayed the signals to the spacecraft telemetry system for transmission to Earth.

The urine collection and transfer assembly provided for emergency containment of liquid waste when spacecraft facilities were not available. Liquid waste was subsequently transferred from the collection assembly to the spacecraft waste-management system.

The portable life-support system (PLSS) created and maintained a livable atmosphere inside an astronaut’s space suit during activity on the lunar surface. Worn as a backpack, the PLSS could be used for as long as four hours at a time.

The PLSS supplied oxygen for breathing purposes, suit pressurization, and ventilation. It also removed contaminants from oxygen circulating through the suit and supplied water and oxygen for body cooling. Conversion of exhaled carbon dioxide into oxygen was accomplished through a lithium-hydroxide cartridge also contained in the PLSS. An emergency supply of oxygen was contained in the oxygen purge system mounted on top of the PLSS.

When fully charged, the pack weighs 38 kilograms (84 pounds) on Earth or 6.3 kilograms (14 pounds) on the Moon.

The space suit on exhibit is from the National Aeronautics and Space Administration.

V-2 (A-4)

[Illustration: 61. British-supervised postwar launch of V-2 in Germany.]

[Illustration: 62. V-2.]

The German V-2, originally designated A-4, represents the beginning of modern rocketry. The V-2 was the first proof that large rockets of the sort described by the space-flight pioneers of the early twentieth century could be successfully built and flown. It was also the forerunner of the intercontinental ballistic missile system.

Developed by a team of engineers working under the direction of Dr. Wernher von Braun at Peenemunde, Germany, the V-2 work laid the foundation for the Redstone missile through the Saturn series of space launch vehicles.

Four-thousand V-2s were fired against Allied targets in England and on the continent in 1944 and 1945. After World War II, captured V-2 rockets were used to train American technicians in missile launch procedures and to carry the first payloads of scientific instruments into the upper atmosphere in the United States.

The operational V-2 rocket structure consisted of three sections. The nose housed the warhead and control mechanisms. The fuel tanks carried liquid oxygen and alcohol propellants. The rocket engine, turbopumps, and control surfaces were contained in the tail section.

Jet deflector vanes positioned in the stream of exhaust gases and external vanes maintained attitude and directional control during the powered portion of flight.

Length 14 m. (46 ft., 1 in.) Diameter 1.6 m. (5 ft., 5 in.) Propellants Alcohol and liquid oxygen Thrust 25,400 kg. (56,000 lb.) Velocity 5633 km./hr. (3500 mi./hr.) Altitude Peak of operational trajectory, 89 km. (55 mi.)

V-1

[Illustration: 63. Illustration from World War II intelligence report.]

GERMAN PILOTLESS AIRCRAFT Warhead: approx. 1000 kg. Fuel filler cap Lifting lug Fuel tank. (Capacity 130 galls. petrol) Wirebound spherical compressed air bottles Grill incorporation shutters & petrol injection jets Impulse duct engine Light alloy nose fairing probably containing compass Launching rail Steel tubular main spar passing through fuel tank Pressed steel wing ribs Sheet steel wing covering Automatic pilot: 3 airdriven gyros: height & range setting controls Pneumatic servo mechanism operating rudder & elevators

The German-developed V-1 was an automatically controlled pilotless aircraft for use against Allied cities during World War II.

The missile was launched from ground ramps. Once in the air, automatic controls on board the craft took over. The V-1 climbed to a predetermined altitude, followed a compass course, and dove to the ground after a preset distance had been covered.

This mid-wing monoplane was powered by a unique pulsejet engine above the rear portion of the fuselage.

The relatively low speed of the missile made it easy prey for antiaircraft guns or fighters.

The V-1 on exhibit is from the U.S. Air Force, Park Ridge Depot.

German Antiaircraft Missiles

[Illustration: 64. Rheintochter R-I (Rhine Maiden).]

Rheintochter I

The Rheintochter I (Rhine Maiden) was intended for use against Allied bomber formations late in World War II. The German ground-to-air rocket was fin-stabilized, and controlled by radio. The flight of the two-stage vehicle was controlled by the four movable vanes on the nose of the craft.

The first stage carried the missile away from the launching rail, while the second stage brought the missile up to full speed and propelled it to the target.

Both the booster and sustainer engines used solid fuel. After a six-tenths of a second burn, the booster dropped off and the sustainer motor ignited. The missile warhead was housed at the rear of the sustainer stage. Exhaust gases were expelled through six nozzles located between the main fins.

The program was abandoned in December 1944, after 82 Rheintochter I rockets had been test fired. By then it had become apparent that the missile could not reach the operational altitude of modern bomber aircraft.

Hs-298

[Illustration: 65. Hs-298.]

The Hs-298 was designed to combat the Allied bomber threat to wartime Germany. This air-to-air missile could be launched from either fighter or bomber aircraft and was in quantity production early in 1945.

It carried 45.4 kilograms (100 pounds) of high explosives that were detonated by proximity fuse when the missile was within 9.1 meters (30 feet) of an enemy airplane.

X-4

[Illustration: 66. X-4.]

The fin-stabilized X-4 air-to-air missile was guided to its target by means of electrical impulses which passed through two wires connecting the rocket to the launch aircraft until detonation. Once the missile was on its way to the target bomber, the fighter pilot directed its course with a separate small control stick in his cockpit. Because the control wires streamed out ahead of the launching aircraft, the pilot was prevented from evasive maneuvering.

Launched from German fighter aircraft, usually a FW-190, the X-4 was powered by either a solid-propellant engine or a bi-propellant liquid-rocket engine. It carried a 20-kilogram (44-pound) warhead.

Jupiter-C

[Illustration: 67. Jupiter-C launches the first American satellite, January 31, 1958.]

Jupiter-C carried the first successful American artificial earth satellite, _Explorer 1_, into orbit on January 31, 1958. Jupiter-C launched additional Explorer satellites on March 26 and July 26, 1958.

Jupiter-C, or Juno 1, is a modified version of the Redstone Ballistic Missile and a direct descendant of the V-2 (A-4) rocket developed in Germany during the second World War.

The vehicle’s main stage is powered by a rocket engine burning liquid oxygen and a hydrazine mixture. The second and third stages are contained in the “tub” on the nose of the rocket. Both use scaled-down Sergeant solid-propellant rockets: eleven in the second stage and three in the third. A final Sergeant motor is attached to the base of the satellite to provide the velocity necessary to place the vehicle in orbit. An electric motor spun the entire “tub” prior to launch and during the climb into space in order to stabilize the satellite.

The Jupiter-C was built by the U.S. Army Ballistic Missile Agency.

Vanguard

[Illustration: 68. Three-stage Vanguard launch vehicle boosts the second American satellite into Earth-orbit, March 17, 1958.]

Standing 21.6 meters (70.8 feet) high and weighing more than 10,000 kilograms (20,000 pounds), the Vanguard launch vehicle successfully orbited three satellites. The first was _Vanguard 1_, launched on March 17, 1958.

The rocket has three stages. The first-stage motor, burning kerosene and liquid oxygen, operated for 2 minutes and 20 seconds. The second stage carried the vehicle to an altitude of 210 kilometers (130 miles), propelled by white-fuming nitric acid and unsymmetrical dimethylhydrazine (UDMH). With propellants exhausted, the upper stages then coasted to 480 kilometers (300 miles) above the surface of the Earth where the solid-propellant third-stage motor fired to place the satellite into orbit.

The Vanguard was designed and built by the Martin Company for the U.S. Naval Research Laboratory.

Scout

[Illustration: 69. Four-stage Scout vehicle launches satellite from the Western Test Range, California.]

[Illustration: 70. Scout in vertical position prior to the launch of an Explorer science satellite, April 29, 1965.]

On February 16, 1961, Scout became the first solid-propellant vehicle to orbit a satellite (_Explorer 9_). It is a four-stage launch vehicle that can perform a variety of space and reentry research tasks. Its relatively low cost has made it a popular choice for many satellite programs, including Transit navigation satellites, the Small Astronomy and Small Scientific Satellites, the Beacon Explorer, Hawkeye, Micrometeoroid, Meteoroid Technology, and Solrad satellites. The rocket has also been used extensively to launch foreign satellites. ANS-A (Netherlands), GRP-A (Germany), UK-5 (England), Eole (France), San Marco 5 (Italy), and the ESRO satellites for the European Space Research Organization (now European Space Agency) have all gone aloft aboard Scout launch vehicles.

The satellite in the nose of the Scout on exhibit is an INJUN/Air Density Explorer identical to that launched from Wallops Island, Virginia, on August 8, 1968.

Scout was built by the LTV Aerospace Corporation for the National Aeronautics and Space Administration and the Department of Defense.

The Scout is from the National Aeronautics and Space Administration and LTV Aerospace Corporation.

Minuteman III

[Illustration: 71. Minuteman III launch from Vandenberg AFB, California.]

The Minuteman III is the standard U.S. land-based intercontinental ballistic missile. This three-stage solid-propellant missile is launched from underground silos that are 24.4 meters (80 feet) deep and 3.7 meters (12 feet) in diameter. These missiles can be launched either from underground control centers or by an airborne launch control center installed in KC-135 aircraft.

Minuteman III was first test-fired on August 16, 1968, and has since replaced earlier Minuteman series ICBMs in the operational system. This missile was designed by Boeing for the Air Force Strategic Air Command.

This missile is from the US. Air Force and Boeing Aerospace Corporation.

Poseidon C-3

[Illustration: 72. Launch of Poseidon from nuclear-powered submarine.]

This two-stage solid-propellant Fleet Ballistic Missile is launched underwater from nuclear-powered submarines. The Poseidon is launched by compressed air, with first-stage ignition just after the missile is clear of the hull. Poseidon carried the Mk-3 Multiple Independently targeted Reentry Vehicles (MIRV)—thermonuclear weapons which enable a single missile to cover a number of targets.

The first successful test flight of Poseidon was from Cape Canaveral on August 16, 1968, and the first submarine launch was from the U.S.S. _James Madison_ on August 3, 1970.

The Poseidon C-3 is from the U.S. Navy and Lockheed Aircraft Corporation.

Skylab

[Illustration: 73. Closeup view of Skylab space-station cluster photographed against a black-sky background from the _Skylab 3_ Command Module during the “fly around” inspection prior to docking.]

Launched into earth orbit on May 14, 1973, Skylab was a research center that housed three-man crews on three different visits to the space station. The longest mission lasted nearly three months.

Equipment and experiments on board the orbiting station were designed to accommodate four areas of research: earth observation to further knowledge of natural resources and the earth’s environment; solar observation to increase understanding of solar processes and influences on earth’s environment; study of the effects of long duration weightlessness on man, basic biological processes and adaptability to space flight conditions; and experiments in processing of materials under the unique conditions of weightlessness and vacuum environment of space. All missions were highly successful in obtaining data and photographs.

Skylab consisted of four major components: the Orbital Work Shop (OWS), Airlock Module (AM). Multiple Docking Adapter (MDA), and the Apollo Telescope Mount (ATM).

The cylindrical Orbital Work Shop is 15 meters (48 feet) in length and 6.5 meters (22 feet) in diameter. The workshop is divided into two major areas by an open-grid partition. By wearing special shoes, the astronauts can use this grid to anchor themselves in the weightlessness of space. The lower portion contains the crew quarters, food preparation and dining areas, washroom, and waste processing and disposal facilities.

[Illustration: 74. Orbital Workshop crew-quarters installations.]

I M131 chair control Sleep compartment 70 sq ft II Head 30 sq ft Wardroom 97 sq ft III M507 gravity substitute work bench Experiment compartment 181 sq ft M171 gas analyzer M171 helmet stowage ESS IV M092 LBNPD Electric power control console M131 rotating chair

The upper portion contains a large work-activity area, water-storage tanks, food freezers, film vaults, and experiment equipment.

The Airlock Module enabled spacesuited crew members to make excursions outside the Skylab to replace or adjust equipment, change film, or carry out other extra-vehicular activities. This capability was vital to emergency repairs by the astronauts on the first mission. The Airlock Module was attached to the OWS and passage to the module was accomplished through a hatch which connected the module to the interior of the workshop. When an astronaut entered the module, he would vent the atmosphere of the module into space. When the pressure in the airlock reached zero, the crew member could open the outer hatch and float out into space.

[Illustration: 75. Airlock Module.]

The Multiple Docking Adapter (MDA) was used by crews arriving or departing from the Skylab workshop. The Apollo command/service modules delivered crews to the MDA from which the astronauts could enter Skylab through the hatch in the docking port. In an emergency, two command/service modules could dock at the MDA. The MDA also held equipment for earth resources multispectral photography, materials processing, and astronomy. The Apollo Telescope Mount (ATM) was on top of and controlled by the MDA. It contained six astronomical instruments to obtain information about the Sun.

[Illustration: 76. Multiple Docking Adapter.]

Solar energy is the prime source of electric power on Skylab. Two systems of solar electric-cell arrays—one wing on the OWS and four panels on the ATM—deployed after the Skylab reached orbit. Principal contractors: OWS—McDonnell Douglas Astronautics Company; AM—McDonnell Douglas Astronautics Company; MDA—Martin Marietta Aerospace.

The Skylab components on display were presented to the museum by the National Aeronautics and Space Administration.

Apollo-Soyuz Test Project

[Illustration: 77. Artist conception of the Apollo-Soyuz Test Project rendezvous.]

On May 24, 1972, President Richard Nixon and Aleksey Kosygin, Chairman of the USSR Council of Ministers, signed an agreement “concerning cooperation in the exploration and use of outer space for peaceful purposes.” The signing represented a formal endorsement of negotiations that had been held between the two nations over several years. The agreement established the Apollo-Soyuz Test Project (ASTP) to develop and fly a standardized docking system “to enhance the safety of manned flight in space and to provide the opportunity for conducting joint scientific missions in the future.”

On July 15, 1975, the afternoon countdown for the Soviet launch was completed and _Soyuz_ lifted off from the Baykonur complex near Tyuratum in Central Asia, some 3200 kilometers (2000 miles) southeast of Moscow. _Soyuz_ carried cosmonauts Alexey Leonov and Valeriy Kubasov.

Taking advantage of _Apollo_’s larger fuel supply for maneuvering, _Apollo_ followed _Soyuz_ into orbit 7½ hours later. _Apollo_ was launched atop a Saturn 1B from Kennedy Space Center, Florida.

After careful maneuvering, the two craft linked up around noon on July 18. Some 225 kilometers (140 miles) above Earth, the astronauts and cosmonauts visited each other’s craft, performed joint experiments, and made further tests of the new docking system.

Following the undocking Saturday, _Apollo_ fired its engines briefly and moved away from _Soyuz_. _Soyuz_ descended from orbit and landed in the south-central USSR early Monday morning, July 21.

Astronauts Stafford, Slayton, and Brand remained in orbit conducting research and making science demonstrations. Splashdown into the Pacific Ocean occurred in late afternoon on Thursday, July 24.

The historic ASTP mission was accomplished by using existing systems and a new docking module. The _Apollo_ spacecraft was made available when the lunar-landing program was curtailed. Since the command module was built with a docking system designed to work only with U.S. spacecraft, a method of incorporating the new docking system had to be devised.

A second important problem was the difference between the spacecraft atmospheres. The _Apollo_ used a pure oxygen atmosphere at about one-third of the atmospheric pressure on earth’s surface; _Soyuz_ used a nitrogen-oxygen mixture at normal atmospheric pressure. To permit crews to pass from _Soyuz_ to _Apollo_ without suffering from the “bends” (a painful condition experienced when nitrogen gas bubbles form in the body fluids), engineers had to design an airlock to equalize the pressure.

[Illustration: 78. The Soviet _Soyuz_ atop a three-stage launch vehicle lifts off July 15, 1975, to begin the joint US-USSR space mission.]

[Illustration: 79. Overhead view of _Soyuz_ in orbit, photographed from the _Apollo_ spacecraft during the joint mission. The three major components of the _Soyuz_ are the spherical Orbital Module, the bell-shaped Descent Vehicle, and the cylindrical Instrument-Assembly Module from which two solar panels protrude.]

[Illustration: 80. View of _Apollo_ spacecraft as seen in Earth-orbit from _Soyuz_. The Command/Service Module and Docking Module are contrasted against a black-sky background and the horizon of the Earth is below.]

The docking module, 3 meters long and 1.5 meters in diameter (10 feet long and 5 feet in diameter), also solved the problem of incompatible docking mechanisms by carrying the new docking system on one end and a system compatible with _Apollo_ on the other.

Prime contractor for Apollo Command Module, Service Module, and Docking Module was Rockwell International.

The _Apollo_ hardware is from the National Aeronautics and Space Administration, and the _Soyuz_ spacecraft is on loan from the USSR Academy of Sciences.

_Apollo_