This page no longer updated from 31 October 2001. Latest version can be found at www.astronautix.com
Class: Manned. Type: Mars Expedition. Nation: USA. Agency: NASA. Manufacturer: Martin Marietta.
In 1991 Martin Marietta and NASA Ames ()ubrin, Baker, and Gwynne) proposed 'Mars Direct' - a Mars expedition faster, cheaper, and better than the standard NASA plan. Key features included:
Mars Direct would be completed in two launches of the proposed Ares heavy lift booster. The first launch would deliver an unfuelled and unmanned Earth Return Vehicle (ERV) to the Martian surface. After landing an on-board production plant would generate methane/oxygen propellants. A second launch would deliver the four-person crew. Following eighteen months of extensive exploration of the surface, they would enter the ERV and return directly to Earth. The same launch vehicles and spacecraft developed for Mars Direct could also support a lunar base.
- Direct flight to and from the Martian surface. Artificial gravity provided en route. No earth orbit or lunar orbit rendezvous; no zero-G assembly operations or crewed monitoring of spacecraft in Mars orbit.
- Fuelling of the Earth Return Vehicle using propellant generated on Mars from the atmosphere.
- Extended operations on the Martian surface (555 days) as opposed to the 20 days for NASA 'fast' missions.
Launch 1: In December 1996, a single Ares launch vehicle would place an unmanned 40 tonne payload onto a direct trans-Mars trajectory. The payload would consist of:
Launch 2: In 1999 an Ares would launch a manned 80 tonne payload. This would consist of:
- ERV - Earth return vehicle. This unfuelled, unmanned vehicle would eventually be used by the manned crew to ascend from the Martian surface and return to earth
- Automated chemical processing unit and set of compressors. This would manufacture rocket propellant for the ERV using the Martian atmosphere.
- 100 kWe nuclear reactor mounted on a methane/oxygen propelled light truck. This would power the chemical processing unit. After the ERV propellant was generated it would provide power to the base.
- 6 tonnes of liquid hydrogen. This would be catalytically reacted by the processing plant with Martian atmospheric carbon dioxide to produce methane and water. The water would then be electrolysed to produce oxygen and more hydrogen, which would be recycled through the plant. The process would provide 24 tonnes of methane and 48 tonnes of oxygen rocket propellants. An additional 36 tonnes of oxygen would be produced through direct reduction of Martian carbon dioxide. The total propellant produced was to be 107 tonnes - 96 tonnes for the ERV and 11 tonnes to fuel surface vehicles.
- Small scientific rovers
- Aerobrake/landing engine assembly
These two launches would constitute the main Mars Direct expedition. But a backup return vehicle would be available, since in 1999 a payload identical to Launch 1 would also be put on a trans-Mars trajectory. If for any reason the Launch 1 ERV was unusable, this payload would provide a backup for the Launch 2 crew. If all went well, it would be used as the return vehicle for the next crew, to be launched in 2001. In this way two ERV's would always available for crew return as missions were sent out every two years. During the eighteen months on the Martian surface, the crew would use the ground vehicle to traverse 22,000 kilometres of Martian terrain within 500 km from the base.
- Habitation module with a crew of four and supplies for three years. Artificial gravity would be provided for the crew during the coast to Mars by unreeling a tether between the spacecraft and the spent Ares third stage. The habitation module is 8.4 m in diameter, 4.9 m tall, and consists of two floors: the lower floor, with cargo and the ground rover; and the upper floor, with the crew quarters. Total mass is 35 tonnes.
- Pressurized methane/oxygen driven ground rover. This was to be fuelled with a one-way surface range of up to 1000 km. If for any reason the crew landed far from the ERV, it could be used to reach it for the return home. Normally it would be refuelled from the propellants at the ERV site.
- Aerobrake/landing engine assembly. This would be used to land at the Launch 1 site, guided by a beacon on the ERV.
The same equipment could be used to establish a lunar base - in fact it could be tested comprehensively on the moon before committing to the Mars expedition. In the lunar scenario the Ares booster could launch a 59 tonne payload consisting of the standard Habitation Module with a Lunar orbital capture and lunar descent (LOC/LD) stage. The LOC/LD stage would land the Habitation Module on the Moon. A crew could then be flown to the Moon using an ERV with an LOC/LD stage. This ERV used only the second stage of the Mars ERV for Earth return direct from the lunar surface.
Use of a nuclear thermal rocket (NTR) third stage on the Ares would increase trans-Mars payload by 50%. The NTR stage would have a specific impulse of 900 s, a power of 900 MWth, and a thrust of 45,000 lb. Use of a NIMF (Nuclear rocket using Indigenous Martian Fuel) stage on the lander would provide the Habitation Module with the capability of leaping from one location on the Martian surface to another, using compressed Martian carbon dioxide from the atmosphere as propellant. This would allow 18 sites on the surface to be visited within the 550 days of surface time, as opposed to just one for the baseline expedition.
Craft.Crew Size: 4. Design Life: 3 years. Total Mass: 160,000 kg.
Mars Direct Chronology
01 January 1991
Martin Marietta and NASA Ames (Zubrin, Baker, and Gwynne) proposed 'Mars Direct' - a Mars expedition faster, cheaper, and better than the standard NASA plan.
- 465 - Zubrin, Robert, Baker, David A, and Gwynne, Owen, Mars Direct: A Simple, Robust, and Cost Effective Architecture for the Space Exploration Initiative, AIAA-91-0328, 1991. HTML when accessed: http://mars.nw.net/
Back to Index
Last update 12 March 2001.
Contact Mark Wade with any corrections or comments.
Conditions for use of drawings, pictures, or other materials from this site..
© Mark Wade, 2001 .