Encyclopedia Astronautica
STCAEM Cryogenic AeroBrake

Credit: © Mark Wade
Credit: NASA
American manned Mars expedition. Study 1991. The STCAEM cryogenic / aerobrake (CAB) concept was used as the NASA reference vehicle.

It offered conceptual continuity with the mainstream Mars transportation studies performed over the previous several years. Its only major new technology development was high-energy aerobraking (HEAB) for planetary capture, but the concept also required a high-thrust cryogenic space engine. Being able to land on Mars using the CAB concept required a successful rendezvous between separately captured vehicles in Mars orbit. The vehicle consisted of three main elements: the Mars Excursion vehicle (MEV), the Mars Transfer Vehicle (MTV) and the Trans-Mars Injection Stage (TMIS).

STCAEM (Space Transfer Concepts and Analyses for Exploration Missions) was a major NASA funded study produced by Boeing in 1991. It provided an exhaustive trade analysis of mission profiles and trajectories for manned Mars missions using four different propulsion technologies (cryogenic chemical with aerobraking, nuclear thermal, nuclear electric, and solar electric). Within each study alternate mission profiles using split/sprint missions, flyby rendezvous, and additional aerobraking were examined. Only the baseline for the Cryogenic AeroBrake mission is presented here. The nominal baseline mission was as follows:

  • The vehicle was assembled, checked out and boarded in LEO
  • The TMI burn occurs and the TMIS was jettisoned
  • MTV/MEV coast to Mars
  • MTV and MEV separate 50 days prior to Mars capture
  • The MEV aerocaptures robotically a day ahead of the MTV, providing last minute verification of atmospheric conditions and targeting
  • The MTV captures, followed by rendezvous in the parking orbit with the MEV
  • The landing crow transfers to the MEV and checks it out
  • The MEV descends to the surface, jettisoning its aerobrake prior to landing
  • After surface operations, the ascent vehicle (MAV) leaves its descent stage and surface payloads, ascends to orbit and docks with the MTV for crew transfer
  • The MAV was jettisoned in Mars orbit, and the TEl burn occurs
  • The MTV coasts back to Earth
  • The crew transfers to a modified ACRV (MCRV), jettisons the MTV and performs a direct entry at Earth (optional: the entire MTV aerocaptures into a LEO parking orbit for refurbishment and reuse).

STCAEM Cryogenic AeroBrake Mission Summary:

  • Summary: Major NASA funded study produced by Boeing in 1991; focus on in-space propulsion
  • Propulsion: LOX/LH2
  • Braking at Mars: aerodynamic
  • Mission Type: opposition
  • Split or All-Up: all up
  • ISRU: no ISRU
  • Launch Year: 2016
  • Crew: 4
  • Mars Surface payload-metric tons: 25
  • Outbound time-days: 350
  • Mars Stay Time-days: 30
  • Return Time-days: 200
  • Total Mission Time-days: 580
  • Total Payload Required in Low Earth Orbit-metric tons: 800
  • Total Propellant Required-metric tons: 500
  • Propellant Fraction: 0.62
  • Mass per crew-metric tons: 200
  • Launch Vehicle Payload to LEO-metric tons: 140
  • Number of Launches Required to Assemble Payload in Low Earth Orbit: 8
  • Launch Vehicle: Shuttle Z

Gross mass: 801,000 kg (1,765,000 lb).
Height: 50.00 m (164.00 ft).
Span: 30.00 m (98.00 ft).
Specific impulse: 475 s.

More... - Chronology...

Associated Countries
Associated Spacecraft
  • STCAEM Cryogenic AeroBrake TMIS American space tug. Study 1991. The Trans-Mars Injection Stage (TMIS) consisted of a core unit with four advanced space engines (ASE), avionics and cryogenic propellant tanks, and provision for up to four "strap-on" propellant tank sets. More...
  • STCAEM MEV American manned Mars lander. Study 1991. The reference Mars Excursion vehicle (MEV) was a manned lander that could transport a crew of four to the surface. More...
  • STCAEM Cryogenic AeroBrake MTV American manned Mars orbiter. Study 1991. The Mars Transfer Vehicle (MTV) configuration consisted of a transit habitat sized for four crew, an aerobrake, and a TEl Propulsion system. 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 American agency overseeing development of rockets and spacecraft. National Aeronautics and Space Administration, USA, USA. More...
  • Boeing American manufacturer of rockets, spacecraft, and rocket engines. Boeing Aerospace, Seattle, 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...

  • Boeing Aerospace and Electronics, Space Transfer Concepts and Analyses for Exploration Missions, NASA Contract NAS8-37857.
  • NASA Report, STCAEM Cryogenic Propulsion / Aerobrake Variant, Web Address when accessed: here.

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