Water has long been the limiting factor for humans in space. But now, NASA is developing a rover that can make water on the Moon. Such a capability will be necessary for any serious attempt at the permanent settlement of Mars, or any other long-term space voyage. If successful, it will inaugurate a new, critical area in space exploration, where resources from other worlds can be harnessed and used.
Presently, everything we use in space is made on Earth. Consider the big, visible parts of human exploration of the solar system, rockets like the Space Launch System (SLS), under construction and set for its maiden voyage in 2018. There’s also the Orion capsule, tested previously and set to fly atop SLS (without astronauts). Then there’s work on habitats: Scientists are currently working on manufacturing artificial habitats for the International Space Station, but soon will be working on one for the Martian surface. A huge part of this kind of pioneering the solar system, however, concerns not just what we bring to other worlds, but what we leave behind. The Lunar Resource Prospector is the first big step in striking that balance.
The real problem of colonization is mass. It’s very expensive to send something to space, and the heavier it is, the more it costs. It takes hundreds of kilograms on the launch pad to put a single kilogram on the surface of Mars, and Martian settlers will need many, many metric tons of commodities to survive. Practically speaking, they can’t take everything they will need from Earth. To colonize the solar system, they will have to learn how to use the resources of the solar system.
The good news is that everything in the solar system is a potential resource for settlers. In-situ resource utilization, or ISRU, is the concept of mining resources on other worlds and turning them into useful commodities, as well as recycling waste created on other worlds. (Waste conversion solves two problems: It creates new useful things and eliminates garbage. The ISS dumps its garbage, allowing it to burn up in the atmosphere. But surface dwellers on Mars won’t have such a convenient disposal service.)
Energy is an important part of ISRU, and from a settlement perspective, energy is very cheap. The Sun is a giant fusion reactor in the sky, after all, and to harness it, all pioneers need are a few solar panels that they bring from home. Those panels will provide energy for a very long time—energy that can be used for ISRU.
Mars is the most likely current spot for future human settlement, so consider what resources might be available there: Settlers could extract oxygen from Mars’s soil, known as regolith. Water could be extracted from volatiles in the soil, essentially baking them off. There is also carbon dioxide in the Martian atmosphere. Combine carbon with electrolyzed water and settlers can make methane, which could be used as fuel.
Settlers won’t need to take building material to Mars; they could easily glue soil together and make bricks. Metals could also be extracted from Martian regolith to build things. Because Mars is rich with carbon, hydrogen, and oxygen, settlers could even make plastic. What would they build first? Probably greenhouses, for starters. Growing crops for food will also be useful for water purification and oxygen generation.