In designing a mission to Mars, it is important that the plan be simple
and cost effective yet be able to complete the mission requirements. One
alternative that fits these criteria is known as the "Mars Direct"
plan. In Mars Direct there will be two launches involved. The first will
deliver an unfueled and unmanned Earth Return Vehicle (ERV) to the Martian
surface. It will then manufacture methane/oxygen propellant out of resources
found on Mars. The second launch will deliver the crew to the planet where
they will explore and experiment for 1.5 years before returning to Earth
in the ERV.
Key points in keeping a Space Exploration Initiative (SEI) mission to
Mars low-cost but effective include the following:
- The mission should not depend upon and LEO stations as it is costly
to build and maintain such a station and difficult to repair.
- To be highly effective, astronauts must have these three elements once
they reach their destination: time, mobility, and power. Astronauts must
have time to perform their experiments at their destination and explore
the surface of Mars. Most Martian mission plans have about 1.5 years of
flight time with only a few weeks on the surface. Mobility is needed for
the exploration of the Martian surface and to perform experiments on the
surface. On Mars, power can be produced using methane/oxygen or carbon
monoxide/oxygen combinations. Rocket thrust for the propulsion in the return
flight can be produced by using carbon dioxide propellant heated in a nuclear
thermal rocket engine.