Encyclopedia Astronautica
Design Reference Mission 4 SEP



zdrm3sep.jpg
DRM 3 SEP
Credit: NASA
American manned Mars expedition. Study 1998. In 1998 NASA Lewis studied a Solar Electric Transfer Vehicle for use in a Mars Expedition. This would never leave earth orbit yet provide most of the delta-V to send a spacecraft toward Mars.

Only five shuttle-derived vehicles would be required to put the expedition into low earth orbit versus eight required in the 1997 Design Reference Mission. Removing the backup habitat lander saved two of these launches. The other launch was saved by eliminating the four nuclear thermal rocket stages needed in the 1993 and 1997 DRM's and replacing them with SETV's and three chemical stages.

The SETV itself had a starting mass of 123 metric tons and was 194.6 m across its solar arrays. The solar cells powered two Russian-built Hall thrusters. Due to the long time spent in the radiation belts during the slow spiral away from the earth, each SETV was expected to last for two missions only before it had to be abandoned. Only perigee burns would be made to boost the orbit, and it would take six to twelve months for the SETV to move its payload - a cargo vehicle and a small chemical trans-Mars injection stage - into a 300 km x 400,000 km orbit. The chemical stage would then boost the cargo vehicle on a six month transfer trajectory to Mars. Then the SETV would begin the long process of bringing itself back down to a 300 km circular orbit of the earth. The second mission would place an unmanned Mars landing vehicle into the same 300 x 400,000 km orbit. The crew would be launched separately in a lightweight taxi to rendezvous and dock with the spacecraft prior to the chemical stage's boost toward Mars. In this way the long period of zero-gravity and radiation exposure during the SETV's long ascent would be avoided.

Design Reference Mission SEP Mission Summary:

  • Summary: Refine DRM 3.0; SEP Prop Option
  • Propulsion: Solar Electric
  • Braking at Mars: aerodynamic
  • Mission Type: conjunction
  • Split or All-Up: split
  • ISRU: ISRU
  • Launch Year: 2011
  • Crew: 6
  • Outbound time-days: 180
  • Mars Stay Time-days: 570
  • Return Time-days: 150
  • Total Mission Time-days: 900
  • Total Payload Required in Low Earth Orbit-metric tons: 400
  • Total Propellant Required-metric tons: 130
  • Propellant Fraction: 0.32
  • Mass per crew-metric tons: 66
  • Launch Vehicle Payload to LEO-metric tons: 75
  • Number of Launches Required to Assemble Payload in Low Earth Orbit: 6
  • Launch Vehicle: Magnum

More... - Chronology...


Associated Countries
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...

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.
  • Griffin, Brand; Thomas, Brent; Vaughan, Diane, A Comparison of Transportation Systems for Human Missions to Mars, AIAA 2004-3834, 40th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit ,11-14 July 2004.

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