Encyclopedia Astronautica
NASA Mars Expedition 1971



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PMRG
Credit: © Mark Wade
American manned Mars expedition. Study 1971. Final NASA Mars expedition before the 1980's. The spacecraft would use shuttle hardware, including SSME engines in the rocket stages.

In its final action after Nixon had killed any possibility of further manned Mars spaceflight work, the nearly-defunct Planetary Missions Requirement's Group called for NASA centers to sum up their work. NASA Houston used the opportunity to take a new look at a Mars mission using expected shuttle hardware in February 1971. A manned expedition to Mars in 1987 lasting 570 days was envisioned. Six Chemical Propulsion System liquid oxygen/liquid hydrogen stages, each equipped with a shuttle SSME engine, would be assembled in low earth orbit. Each stage would be an orbiter payload in place of the manned orbiter, having an empty mass of 27 metric tons and having 245 metric tons of liquid oxygen / liquid hydrogen propellants. The tanks would be topped up in orbit by no fewer than 65 shuttle missions. A 50 metric ton North American MEM lander, capable of supporting three crew for 45 days on the surface, would be used. The transit Mars Module would be lofted in a single shuttle launch, and be 20 m long, using a large solar array for power. The spacecraft would be rotated in transit to provide 1/6 artificial G for the five-member crew. The spacecraft would be placed in a 3200 x 16,000 km Mars orbit. The landing crew would be provided with two single-man rovers, allowing 20,000 square km of the Martian surface to be explored. This was the last of the NASA Mars expedition designs for decades.

NASA Mars Expedition 1971 Mission Summary:

  • Summary: First NASA Mars expedition design to use liquid oxygen/liquid hydrogen propulsion and shuttle hardware elements.
  • Propulsion: LOX/LH2
  • Braking at Mars: propulsive
  • Mission Type: opposition
  • Split or All-Up: all up
  • ISRU: no ISRU
  • Crew: 6
  • Outbound time-days: 340
  • Mars Stay Time-days: 30
  • Return Time-days: 200
  • Total Mission Time-days: 570
  • Total Payload Required in Low Earth Orbit-metric tons: 1900
  • Total Propellant Required-metric tons: 1470
  • Propellant Fraction: 0.77
  • Mass per crew-metric tons: 316
  • Launch Vehicle Payload to LEO-metric tons: 30
  • Number of Launches Required to Assemble Payload in Low Earth Orbit: 71
  • Launch Vehicle: Shuttle

Crew Size: 5.

Gross mass: 1,900,000 kg (4,100,000 lb).
Height: 140.00 m (450.00 ft).
Diameter: 7.31 m (23.98 ft).

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Associated Countries
Associated Engines
  • SSME Rocketdyne lox/lh2 rocket engine. 2278 kN. In production. Isp=453s. Space Shuttle Main Engines; only high-pressure closed-cycle reusable cryogenic rocket engine ever flown. . Three mounted in the base of the American space shuttle. First flight 1981. 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
  • NASA Houston American agency overseeing development of rockets and spacecraft. Houston, Houston, USA. More...

Associated Propellants
  • Lox/LH2 Liquid oxygen was the earliest, cheapest, safest, and eventually the preferred oxidiser for large space launchers. Its main drawback is that it is moderately cryogenic, and therefore not suitable for military uses where storage of the fuelled missile and quick launch are required. 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
  • 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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