Earth Return Vehicle
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The Earth Return Vehicle (ERV) forms a part of the Mars Direct humans-to-Mars mission concept first developed by Doctor Robert Zubrin and David Baker in the early 1990s.
It is a vehicle designed to return a crew of astronauts from the surface of Mars to Earth at the conclusion of their stay on Mars. It is used in conjunction with the Mars Habitat Unit to enable the human exploration of Mars.
[edit] Description
The ERV is a two-stage vehicle, with the upper stage comprising the living accommodation for the crew during their six-month return trip to Earth from Mars.
The lower stage of the ERV contains the vehicle’s descent / ascent engines and a small chemical production plant.
The ERV is launched atop a heavy lift launch vehicle, possibly derived from the space shuttle. It is unmanned, and only carries sufficient fuel to safely reach the surface of Mars following aerobraking in the planet's atmosphere on its arrival in orbit.
Once on the surface of Mars, a small nuclear generator is used to power the chemical production plant carried by the ERV. This in turn uses some six tonnes of hydrogen feedstock aboard the ERV. together with the carbon dioxide of the Martian atmosphere to generate up to 112 tonnes of methane and oxygen, to be used as propellants for the return trip to Earth. These are manufactured through a number of simple chemical reactions, e.g., the Sabatier reaction or water electrolysis.
[edit] Specifications
| Round trip payload | |
| Crew compartment | 7,100 kg |
| Reaction control system | 400 kg |
| Biconic brake | 2,450 kg |
| Stage 1(dry) | 6,330 kg |
| Stage 2 (dry) | 1,770 kg |
| Mars-bound payload | |
| Hydrogen for propellant production | 5,810 kg |
| SP-100 Reactor | 4,500 kg |
| Earth-bound payload | |
| Crew | 450 kg |
| Suits | 300 kg |
| Consumables (dry food) | 2,000 kg |
| Soil Samples | 150 kg |
| Stage 1 propulsion system | |
| Usable propellant (methane / oxygen) | 70,160 kg |
| Dry mass | 8,850 kg |
| Total engine thrust | 85,237 kgf (835.89 kN) |
| Specific impulse | 373 s (3.65 kN·s/kg) |
| Stage 2 propulsion system | |
| Usable propellant (methane / oxygen) | 25,000 kg |
| Dry mass | 2,560 kg |
| Total engine thrust | 9,059 kgf (88.84 kN) |
| Specific impulse | 373 s (3.65 kN·s/kg) |
