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Propellant

Rocket propellant from water ice has also been proposed for the Moon, mainly from ice that has been found at the poles. The likely difficulties include working at extremely low temperatures and extraction from the regolith. Most schemes electrolyse the water and form hydrogen and oxygen and liquify and cryogenically store them. This requires large amounts of equipment and power to achieve. Alternatively it is possible to simply heat the water in a nuclear or solar thermal rocket, which seems to give very much more mass delivered to low Earth orbit (LEO) in spite of the much lower specific impulse, for a given amount of equipment.

The monopropellant hydrogen peroxide (H₂O₂) can be made from water on Mars and the Moon.

Aluminum as well as other metals have been proposed for use as rocket propellant made using lunar resources, and proposals include reacting the aluminum with water.

The spacecraft could use the propellant itself or supply a propellant depot.

Rocket propellant

Water

In the context of ISRU water is most often sought directly as fuel or as feedstock for fuel production. Applications include it's use as in life support either directly, for growing food, producing oxygen, or numerous other industrial processes. All of which require a ready supply of water in the environment and the equipment to extract it. Such extraterrestrial water has been discovered in a variety of forms throughout the solar system, and a number of potential water extraction technologies have been investigated. For water that is chemically bound to regolith, solid ice, or some manner of permafrost, sufficient heating can recover the water. However this is not as easy as it appears because ice and permafrost can often be harder than plain rock, necessitating laborious mining operations. Where there is some level of atmosphere, such as on Mars, water can be extracted directly from the air using a simple process such as WAVAR. Another possible source of water is deep aquifers kept warm by Mar's latent geological heat, which can be tapped to provide both water and geothermal power.

Uses

Solar cell production

It has long been suggested that solar cells could be produced from the materials present in lunar soil. Silicon, aluminium, and glass, three of the primary materials required for solar cell production, are found in high concentrations in lunar soil and can be utilized to produce solar cells. In fact, the native vacuum on the lunar surface provides an excellent environment for direct vacuum deposition of thin-film materials for solar cells.

Solar arrays produced on the lunar surface can be used to support lunar surface operations as well as satellites off the lunar surface. Solar arrays produced on the lunar surface may prove more cost effective than solar arrays produced and shipped from Earth, but this trade depends heavily on the location of the particular application in question.

Another potential application of lunar-derived solar arrays is providing power to Earth. In its original form, known as the solar power satellite, the proposal was intended as an alternate power source for Earth. Solar cells would be shipped to Earth orbit and assembled, the power being transmitted to Earth via microwave beams. Despite much work on the cost of such a venture, the uncertainty lay in the cost and complexity of fabrication procedures on the lunar surface.

Rocket propellant

Rocket propellant from water ice has also been proposed for the Moon, mainly from ice that has been found at the poles. The likely difficulties include working at extremely low temperatures and extraction from the regolith. Most schemes electrolyse the water and form hydrogen and oxygen and liquify and cryogenically store them. This requires large amounts of equipment and power to achieve. Alternatively it is possible to simply heat the water in a nuclear or solar thermal rocket, which seems to give very much more mass delivered to low Earth orbit (LEO) in spite of the much lower specific impulse, for a given amount of equipment.

The monopropellant hydrogen peroxide (H₂O₂) can be made from water on Mars and the Moon.

Aluminum as well as other metals have been proposed for use as rocket propellant made using lunar resources, and proposals include reacting the aluminum with water.

The spacecraft could use the propellant itself or supply a propellant depot.

Oxygen to breathe and water to drink

Water ice could replenish a space ship's water tanks. Water is needed for drinking and hygiene, but may also be used for radiation protection in deep space (living quarters inside a double-walled cylindrical water tank). Splitting water allows the creation of rocket propellant, but can also liberate oxygen that could be used to replenish the atmosphere in a closed-loop recycling system.

Metals for construction or return to Earth

Asteroid mining could also involve extraction of metals for construction material in space, which may be more cost-effective than bringing such material up out of Earth's deep gravity well, or that of any other large body like the Moon or Mars. Metallic asteroids contain huge amounts of siderophilic metals, including precious metals.

Building materials

The colonization of planets or moons will require to obtain local building materials, such as regolith. For example, studies employing artificial Mars soil mixed with epoxy resin and tetraethoxysilane, produce high enough values of strength, resistance, and flexibility parameters.