Space access
Space access is the ability for persons to leave a planet's surface. This page is an introduction on basic principles and technology of getting from the Martian surface to an orbit or into free space.
Motivation
A human colony on Mars can be established with or without space access. The fight against the strong gravitational pull requires large amounts of energy. Since the gravity of Mars is smaller than Earth and the atmosphere is thinner, space access is easier. However, the energy resources of such a colony are limited. Using parts of the available energy for space access reduces other project's progress.
So, why should the colonists spend the effort? Assuming, the colonists went to Mars to stay there and build their own civilization, there still might be some additional tasks to do:
- Trips to Low Mars Orbit and possible space stations residing there for scientific reasons
- Trips to Phobos and Deimos for scientific and mining reasons.
- Ferry persons to and from space craft that have arrived from, or are heading for, Earth, or other celestial bodies.
- Possible satellite repair, not a dissimilar task as to what was imagined for the space shuttle in the 1970's
Conventional rocket crafts
The craft should be:
- Reusable
- Single Stage to Orbit (SSTO)
- Use propellants that can be obtained from Mars.
- Able to share components with other machines
It has proved very difficult to build an SSTO launcher on Earth, but the lower Martian gravity would be of assistance to any launching spacecraft. If the craft uses multiple stages, these will all have to be recovered separately, which complicates the process of reuse.
Hydrogen and oxygen propellants can be obtained from Martian ice. The attitude control thrusters could use gaseous oxygen and methane, kept under pressure.
Early landers will probably be non-reusable or only partially reusable. The decent stages of these landers could be dismantled and reused.
The guidance systems on the lander need not be hi-tech. The Apollo spacecraft flew to the Moon using less computing power then a pocket calculator. A simple computer, or a pneumatic system could be used. Although there are advantages with hi-tech systems, lo-tech systems could be included as a backup.
Speculative concepts
- Supersonic in ground effect may be used for a winged shuttle even in the thin Martian atmosphere to help reduce costs.
- A space elevator is an interesting alternative both for Luna and Mars. Probably, it allows even more cost reduction.
- A mass driver is powered electrical and requires no chemical fuels. While on Earth this would not work for lifting people to orbit, the conditions of Mars might allow it.
