Apart from ECLSS (Environment Control and Life Support Systems) and space vehicles, ISRU is one of the most important capabilities we need to develop in order to settle Mars.
“In Situ Resource Utilisation”, or “ISRU”, simply means using local resources. To illustrate: when European settlers sailed the ocean blue to new lands past the edge of the world, they did not take everything with them that they’d need for their new life. To do so would have been entirely impractical. On arrival at new lands, explorers drank water from local streams, plucked ripe fruits from local trees and hunted local wildlife. They used wood and stone from near the settlement sites to build homes and other structures. In other words, they utilised resources from their current location, hence, In Situ Resource Utilisation (“in situ” is Latin for “on site” or “at location”).
This is one of the main categories here is because ISRU is a crucial capability for Mars exploration and settlement. (Also because it’s a large and interesting topic.) Launching anything into space from the surface of Earth is extremely expensive, costing between $2,000 and $15,000 per kilogram, depending on the vehicle. Considering that everything needed to send even a small crew of humans to Mars – spacecraft, life support systems, food, fuel, and other supplies and equipment – could weigh 50-100 tonnes or more, that’s a significant cost.
Furthermore, the more mass you need to deliver to the surface of Mars, the more fuel is needed to launch that mass to Earth orbit and then onwards to Mars – and the fuel itself has mass. Rockets also have limits in terms of mass and volume; therefore, more mass can mean a greater number of launches. Thus, as mass increases, costs tend to compound in an exponential way, rather than linear.
Anything we can obtain from the Martian environment therefore translates to a significant reduction in mission cost and therefore an increased likelihood that the mission will be flown; or, a greater number of missions that can be flown. For those of us who would prefer to see H2M happen sooner rather than later, developing ISRU capability on Mars is therefore considered crucial.
Mars has plenty of oxygen, nitrogen, carbon, water, metals and energy that can potentially be used by human explorers and settlers. The challenge is accessing it, which is dependent on technology and scientific knowledge.
For the past half-century we’ve been accumulating the necessary scientific knowledge – characterising the atmosphere, climate, the crust and every other aspect of the planet that we can perceive – in order to determine what resources are available. We now have reasonably detailed understanding of the Martian atmosphere and surface, including an awareness of the large quantities of water available across the surface of Mars.
The atmosphere is by far the most accessible resource on Mars, since air can easily be drawn into a system designed to extract substances from it. The next most easily accessible resource is the regolith – the loose top layer of dust and dirt on the Martian surface.
The topic of Martian ISRU can be organised into two sections:
ISRU Level 1
This refers to the most basic resources that we need to obtain from the local environment for the purposes of survival, and simply in order to make H2M feasible. These ISRU processes are likely to be developed at bases during early exploration of Mars (Stage 1 of Mars settlement).
ISRU Level 2
This refers to advanced ISRU processes to produce materials and other substances necessary for manufacturing and industrial processes. While the full list of potential resources that will eventually be produced on Mars would be far too long to list exhaustively, some of the most obvious include:
- Bricks and blocks
- Metals (iron, steel, light engineering metals, platinum group metals, precious metals)
- Wood, bamboo and hemp
- Cement and concrete
- Glass and ceramics
Some of these will be covered in greater detail in future posts.