Encyclopedia Astronautica
EMPIRE Lockheed



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Empire
Credit: © Mark Wade
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Empire Comparison
Comparison of Empire designs, from left to right:
Credit: © Mark Wade
American manned Mars flyby. Study 1962. Lockheed's manned Mars flyby spacecraft design of 1962 had a total mass of 100 metric tons.

Taking advantage of Apollo technology, it would be launched into low earth orbit with a single launch of a Saturn V booster. The 22-month mission would be launched toward Mars on 24 September 1974.

EMPIRE was the first series of Mars mission studies conducted under NASA's auspices. The goal of the studies was to identify mission alternatives and estimate spacecraft masses for initial manned Mars flyby and orbiter missions. The primary objective was to identify payload requirements for Nova, the series of super heavy lift launch vehicles planned after the Saturn series. A secondary objective was to identify stage and engine requirements for NERVA, the AEC/NASA nuclear thermal engine program. The Marshall Space Flight Center's Future Projects Office, led by Heinz Koelle, let contracts for the studies to industry in May 1962. Three contractors were selected: Aeronutronic, General Dynamics, and Lockheed.

In the Lockheed fly-by design, two flyby trajectory alternatives were considered. A high energy alternative would put the probe in a solar orbit with a perihelion inside the earth's orbit (with a Venus flyby where possible), then out to Mars, and back to intersect earth's orbit - total mission time 18 months. The lower-energy alternative would put the probe in an orbit that went from earth, past Mars, and out into the asteroid belt before returning to earth 22 months after launch. Lockheed proposed that the low energy path be used, and that the launch mass be further reduced by using a nuclear thermal rocket stage and aerodynamic braking on the return to earth. This would reduce total payload requirement to two Saturn V launches (somewhat at variance with the study's objective to justify and define the requirements for the follow-on Nova superbooster!)

Lockheed's preferred spacecraft design consisted of a rotating spacecraft in order to provide artificial gravity force on the crew during the long mission. The spacecraft would telescope out after boost toward Mars and separation from the nuclear trans-Mars injection stage. At one end of the boom would be a modified Apollo Command-Service Module (for re-entry into the earth's atmosphere at the end of the mission), at the other end would be a habitation module (living quarters during the transit). At the hub would be a large solar collector to drive a solar thermal power generating system, a radiation shelter, and the robot probes that would be dropped to the Martian surface during the flyby.

Characteristics

Crew Size: 3. Habitable Volume: 113.00 m3.

AKA: Early Manned Planetary - Interplanetary Roundtrip Expedition.
Gross mass: 100,000 kg (220,000 lb).
Height: 65.00 m (213.00 ft).
Diameter: 3.00 m (9.80 ft).
Thrust: 1.78 kN (401 lbf).
Specific impulse: 800 s.

More... - Chronology...


Associated Countries
Associated Engines
  • Nerva DoE nuclear/lh2 rocket engine. 266 kN. Study 1968. Early version of Nerva engine proposed for use in Saturn and RIFT configurations in 1961. Isp=800s. More...

See also
  • Mars Expeditions Since Wernher von Braun first sketched out his Marsprojekt in 1946, a succession of designs and mission profiles were seriously studied in the United States and the Soviet Union. By the late 1960's Von Braun had come to favour nuclear thermal rocket powered expeditions, while his Soviet counterpart Korolev decided that nuclear electric propulsion was the way to go. All such work stopped in both countries in the 1970's, after the cancellation of the Apollo program in the United States and the N1 booster in the Soviet Union. More...

Associated Manufacturers and Agencies
  • Lockheed American manufacturer of rockets, spacecraft, and rocket engines. Lockheed Martin, Sunnyvale, CA, USA. More...

Associated Propellants
  • Nuclear/LH2 Nuclear thermal engines use the heat of a nuclear reactor to heat a propellant. Although early Russian designs used ammonia or alcohol as propellant, the ideal working fluid for space applications is the liquid form of the lightest element, hydrogen. Nuclear engines would have twice the performance of conventional chemical rocket engines. Although successfully ground-tested in both Russia and America, they have never been flown due primarily to environmental and safety concerns. Liquid hydrogen was identified by all the leading rocket visionaries as the theoretically ideal rocket fuel. It had big drawbacks, however - it was highly cryogenic, and it had a very low density, making for large tanks. The United States mastered hydrogen technology for the highly classified Lockheed CL-400 Suntan reconnaissance aircraft in the mid-1950's. The technology was transferred to the Centaur rocket stage program, and by the mid-1960's the United States was flying the Centaur and Saturn upper stages using the fuel. It was adopted for the core of the space shuttle, and Centaur stages still fly today. More...

Bibliography
  • Miller, Ron, The Dream Machines, Krieger, Malabar, Florida, 1993.
  • Portree, David S. F., Humans to Mars: Fifty Years of Mission Planning, 1950 - 2000, NASA Monographs in Aerospace History Series, Number 21, February 2001.

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