Encyclopedia Astronautica
EMPIRE Aeronutronic

Ford Nucleonics Emprie Design
Credit: © Mark Wade
Empire Comparison
Comparison of Empire designs, from left to right:
Credit: © Mark Wade
American manned Mars flyby. Study 1962. Aeronutronic's Mars flyby spacecraft design of 1962 had a total mass of 170 metric tons and would be launched into low earth orbit with a single launch of a Nova booster.

The 21-month mission would be launched toward Mars during a 28 day window opening on 19 July 1970.

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.

Aeronutronic's flyby spacecraft had a total mass of 170 metric tons, a length of 47 m, and would be launched into low earth orbit by a Nova booster with a payload capability of 227 metric tons. The 21-month mission would be launched toward Mars during a 28 day window opening on 19 July 1970. A single nuclear thermal engine of 182 metric tons thrust would fire for 1000 seconds at trans-Mars injection. Two sets of 8 propellant tanks surrounded the nuclear stage and the upper spacecraft. The four lower tanks were jettisoned as depleted during the engine burn. The four upper tanks around the spacecraft were retained to provide additional meteoroid and radiation protection during the trip to Mars and back. The nuclear stage was jettisoned after burnout. The spacecraft then deployed two primary living modules on booms. The spacecraft would then be spun up to 3 rpm to provide 0.3 G gravity for the crew during the mission. The crew was provided with a total of 4500 cubic meters of living space in the living modules, together with 300 cubic meters in a radiation 'storm cellar' at the center of the spacecraft, for use during solar flares.

Aft of the spacecraft large radiator panels would deploy to dissipate heat from a SNAP-8 radioisotope thermal power generator, which provided power. At the forward end of the spacecraft a lifting-body re-entry vehicle was docked. During the mission midcourse corrections were provided by conventional chemical rocket engines. As the spacecraft neared the earth, the crew would enter the re-entry vehicle. A two-stage conventional braking rocket would slow the RV to an acceptable velocity for re-entry. A follow-on mission that would swingby both Mars and Venus with a 1972 launch was also proposed.

EMPIRE Aeronutronic Mission Summary:

  • Summary: First contractor study to NASA for design of a Mars flyby spacecraft
  • Propulsion: Nuclear thermal
  • Braking at Mars: flyby
  • Mission Type: Crocco
  • Split or All-Up: all up
  • ISRU: flyby
  • Launch Year: 1970
  • Crew: 6
  • Total Mission Time-days: 630
  • Total Payload Required in Low Earth Orbit-metric tons: 227
  • Mass per crew-metric tons: 37
  • Launch Vehicle Payload to LEO-metric tons: 330
  • Number of Launches Required to Assemble Payload in Low Earth Orbit: 1
  • Launch Vehicle: Nova MM 1B


Crew Size: 6. Habitable Volume: 4,800.00 m3.

AKA: Early Manned Planetary - Interplanetary Roundtrip Expedition.
Gross mass: 170,000 kg (370,000 lb).
Height: 47.00 m (154.00 ft).
Diameter: 14.00 m (45.00 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
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...

  • 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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