A Handful of (Lunar) Dust [Part 1]
[This article was written by Sam Ross. He blogs at towerofbuckets.wordpress.com]
This is the landing site of Apollo 17. These pictures were taken on that mission, the last time humans walked on the Moon. For over 40 years it has sat abandoned, in some state of disrepair. I say ‘some state’ because we don’t know what the site looks like today. In fact, we have no idea what any of the Apollo sites look like, because NASA has never deemed it necessary to send anything to look. In fact, NASA has never returned to the Moon’s surface. The only missions to have landed after the date of Apollo 17 are the Soviet vehicles Luna 21 and 24, and the recent Chinese mission Chang’e 3. But none of these missions have gone back to the site of another landing.
It’s time to change that.
PTScientists are a small team (by space standards) based in Germany, but with support from scientists and engineers globally. Their mission is simple. Go back.
I mean, not them personally. A rover that they are building. But that rover will, if all goes according to plan, be studying the remains of the Apollo 17 landing site by 2017. Plus, if all goes according to plan, winning the $30 million Google Lunar X-Prize.
But why the moon? Surely it would be a better use of resources to accelerate the race to a manned landing on Mars? That is, after all, the long-term goal of most space agencies.
But the Moon has something special. It is close, easy to get to, and it has the regolith.
When I use the word regolith, what I basically mean is soil. But regolith sounds much cooler that soil, and is also the technical term for the layer of loose material covering a celestial body. Soil, basically. On the Moon, that means a layer between 3 and 15 metres thick of loose material. The regolith varies in size, from boulders to pebbles to gravel to a fine dust, all of it eroded over millennia by solar radiation and impact from micrometeorites.
That dust, the top few centimetres of the regolith, has some very interesting physical properties. The dust is so fine, it passed through the gloves of the Apollo astronauts and coated their hands in a fine black powder. Some of these particles are less than 2µm across, which is finer than the very finest particles in clay. When this dust is hit by micrometeorites, it sometimes forms tiny glass beads that heat the dust enough for tiny grains of elemental iron to form. Those grains are enough to make some of the grains slightly magnetic, enough to pick them up with a magnet in the low gravity of the Moon.
Regolith is not unique in the solar system. We think that most rocky bodies have it, including Mars, the Moon and comets. But unlike asteroids and comets, the Moon is already in Earth orbit and is easy to get to. And once you get there, you have access to a lot of material. And that material is very useful.
Lunar regolith is useful for three main reasons.
Lunar regolith can be made into rocket fuel.
Lunar regolith is about 7% aluminium, and more than 40% oxygen. Aluminium is a core component in a number of rocket fuels, and can even be mixed with water in particulate form to make a solid propellant (called ALICE). And oxygen can be used, super cooled, to make oxidiser. So in theory, the Moon can be used as a giant fuel depot – for oxidiser and propellant, the 2 components of rocket fuel. We could fuel interplanetary ships or build much larger deep-space probes to go to the outer solar system without having to carry the fuel to orbit. Because, if you want to take any mass into orbit, you need spend a lot of money on the launch vehicle – and a large proportion of the weight of any interplanetary vessel is fuel. But we could reduce those costs massively, by having all the fuel in space already. The costs of getting an empty ship to lunar orbit aren’t massive, and the costs of carrying fuel from the Moon’s surface to orbit are also relatively low. So we could massively increase the number and size of ships (both robotic and, hopefully, manned) leaving Earth for the rest of the Solar System. We could fuel the future of our exploration of the Solar System with the Moon.
Lunar regolith contains minerals that can be sold at vast profits.
Lunar regolith contains, broadly, the same materials as the Earth’s crust. However, it does contain much higher-than-Earth levels of titanium, and helium-3 – a potential fuel for nuclear fusion. And both of those can be sold, at great profit, on Earth. Even if you consider the costs of shipping equipment to the Moon and shipping the products back to Earth, you can still turn a considerable profit.
Now, the prospect of commercial mining of the Moon is advantageous (assuming you think colonisation is a good thing – which I do) for two different reasons.
If mining companies are setting up shop on the Moon, they will probably want to have an extensive operation – multiple sets of mining, refining and returning stations for whatever is being mined. And if you have a complex system in an extreme environment, you will bet that things will go wrong pretty frequently. And at some point, the companies are going to decide that having a crew of engineers living at the station for long shifts is cheaper than using robots. So bingo, suddenly you have a commercial drive to put a permanent human settlement on the Moon. And when there is commercial drive and money to be made, you can bet that things will really get moving.
And secondly, if companies are mining huge amounts of platinum/titanium/helium on the Moon, they’re going to have to sift through a lot of regolith to find it. So there are going to be enormous spoil heaps of aluminium, silicon, nickel and iron oxides (ores) just sitting on the surface of the Moon. And there you have the basic materials for building…basically anything. Computers, spaceships, bases – all sitting there. And then it would just take one company to start exploiting that, and we could have vast manufacturing sites on the Moon. But I’m getting ahead of myself.
I think it would be interesting to see how we, as a society, would respond to a large scale production centre on the Moon. But one thing is certain. If there is profit to be made, and the risks and costs are low enough, mining in space will happen. And some day, in the not too distant future, we might be seeing an advert like this on TV.
Lunar regolith has all the materials for construction
This is, in my opinion, the most exciting use for the abundant supply of lunar regolith – using it to build things. That could be large things, like robots and components for interplanetary ships. But more likely, it will mean building components for bases that are too large or unwieldly to ship from Earth easily - like large antenna or structural components for buildings, or simple roads to make travel quicker. And while this won’t be everything needed to build a colony from the ground up, it opens up the option for much larger-scale construction with lower costs.
The ability to build your own components is great, because shipping everything from Earth is expensive, time-consuming and highly limiting. Using local materials for your own purposes is called In Situ Resource Utilisation, and means you can develop the beginnings of a semi-independent colony – and is the Holy Grail for colonisation programs.
But in-situ construction is about more than colonisation. It opens up the possibility of building entire interplanetary ships on the Moon’s surface (or in orbit), using the iron and aluminium for the exterior of the ship and the silicon for the computers. Sure, we might have to ship some specialist materials and components to lunar space, but we could save on at least half of the weight of the ship (I can’t find reliable numbers for how much of the ISS is these simple elements) if the spacecraft were designed to use these materials. And that is without the considerations of fuel – which could all be delivered from the lunar surface.
But that’s a long way off. As it is, the major goal is finding a safe, reliable and cheap way to convert dust into spaceships – or the basic materials for building spaceships. And as it turns out, there are four main ways (that we know about) of doing that.
[All image credits: NASA]