Mining rocks in space: science fiction or fact?

There has been much debate in the media, and in my department recently about the possibility of using spacecraft to mine precious minerals and metals from asteroids and return them back to Earth. I thought it might be an idea to write a little blog on this because I think the idea is absolutely amazing, but it sounds like something we only see in the movies. Let’s look at the ideas.

Mining an asteroid: the announcement

The announcement by NASA, backed by President Barack Obama, earlier this year centred around the plans to launch a mission (in 2019) that would be capable of ‘capturing’ or ‘lassoing’ a small asteroid in space and dragging it into Earth orbit (Moon’s high orbit to be precise). Once safely positioned in this location the plan is to send manned missions (Orion spacecraft, in 2021) to the asteroid to carry out mining activities. I’m imagining Bruce Willis in Aramageddon but maybe it won’t be exactly like that! With the involvement of private companies, it is said that it would be possible to return precious minerals and metals mined from the asteroid back to Earth.

Well this all sounds quite fantastic, and did you note the proposed dates? If these audacious plans can be pulled off in that timeframe then it would be unbelievably fast on space discovery timescales. In order for all this to come together in time, it would have to be assumed that the required technologies are, at least, in the development phase. This is not currently clear. However, with the involvement of private companies, bringing more money to the plans, it might just be possible. But what are the technologies that are required, and can an asteroid really provide all the precious materials that would be needed to make the plans useful (for science) and economical (for the private companies)?

The plan: Pros and Cons

The initial plan is to capture a small asteroid (maybe 5-10m diameter would be safe). One issue of starting with a small asteroid is that, at the moment, it is hard for astronomers to actually observe this size of object in space from the Earth (unless it is very close, i.e. about to collide with Earth). However, if we can locate an appropriately sized rock in space then there are pros and cons to capturing something so small. The Pros are that if the relocation of a small captured asteroid from it’s current orbit to one nearer the Earth goes slightly wrong, and it ends up colliding with Earth, then it would most likely burn up in the atmosphere and not hit our planet’s surface. The Cons are that a small asteroid would not yield as much useful resource and so it may be necessary to capture more asteroids in order to make the process anywhere near economical, if it can be at all. I am by no means a business-minded person so I won’t comment on that! Initially though, capturing a small asteroid may be adequate as a ‘proof of concept’, simply to test if the technology and mission plans are successful. If so, even more exciting and ambitious plans could begin, and the rest of space is ours for the taking.

Technology development

There are some very useful aspects to an asteroid capture mission and these would be in the technology development required to carry out the asteroid capture, the movement of the asteroid from its current course and the zero-gravity mining, to name just a few that spring to mind. The space industry is already well known for developing many technologies that have also been useful on Earth (spin-off technologies, I won’t go into them here, there are loads (perhaps another blog post at some point)).

In the NASA asteroid mining plans, it is proposed that ion thrusters would be capable of shifting the captured asteroid from its natural course in order to ‘park’ it next to the Moon. Such thrusters have already been employed on the NASA Dawn mission but only to power the spacecraft itself, not to move a separate object in space. If ion thrusters were proven to be successful in shifting objects in space then governments may consider using them in the future if we were at threat from an asteroid impact. Although there’s a good chance that we’re safe from a large asteroid impact on Earth for at least the next 100 years, there is a small chance that a large asteroid is heading for us that we simply haven’t seen yet. If this was the case then we might want to think about launching a spacecraft to deflect the asteroid away from the Earth. There are actually various options being discussed on how this might be achieved. One of the wildest involves painting one side of the asteroid white to use the Sun’s heat to cause the asteroid to rotate off its current course. However, the most plausible options probably involve either the use of explosives to break the asteroid up into smaller pieces (which may then collide with Earth but if small enough would burn up in the atmosphere), or ion thrusters to nudge the asteroid onto a new course. So, asteroid mining could have the potential to provide us with the technology to save all of humanity!

The development of technology for mining in zero-gravity would also be a huge step forward for science research. If such technology was developed then it would be much easier for scientists to design sample return missions to collect material from comets and asteroids for study on Earth, allowing us to learn more about these objects. Currently most sample return missions to comets and asteroids have employed, or will employ, more of a touch and run approach to sample collection, without the requirement for landing on the object itself. While this obviously makes things a little simpler and cheaper, it does mean that we don’t have a good control on what material is sampled, and it can only ever come from the top surface of the object when it would be nice to sample down into the interior.

Asteroid as a filling station

Another benefit of developing asteroid mining missions is that the captured asteroid could also act as a filling station to fuel a spacecraft to make a journey further into space. It is in fact the water contained in the asteroid that could be used as a propellant, so we would effectively be creating our own fuel in space, which sounds fairly economical. This would mean that the exploration of other planets, such as Mars, could be done with less energy because the spacecraft needs to initially just carry enough fuel to get to the asteroid before it can refuel and continue its journey.

So, do we want to mine an asteroid?

Even if we put aside all the, as yet, undeveloped and/or untested technologies, is space mining something we should, and want, to do as a global community? On the whole I am feeling fairly positive about the idea of mining asteroids, but mostly for selfish reasons in the hope that it would result in more samples for my research. However, we do need to think of the lasting effects this type of mining could have. Despite the fact we have plenty of asteroids at our disposal, the question is whether we want to start using them? In terms of mining in space in general, I would personally have a problem with a large-scale mining effort on another planet and this is for two reasons. The first is because of the high chance of contamination of Earth bugs onto the planet meaning that science research in the future could be compromised. This is always one of the main considerations, and something that is taken very seriously, when planning any scientific missions to other planets at the moment. The second reason is that the mining activities would probably leave a very obvious and lasting effect on other planetary surfaces that could never be erased. Planetary exploration so far has been to such a small degree, and done with such care for science research, that it isn’t causing a big problem for the future. However, in terms of asteroids, we have plenty of them (and most of them we’ve never even seen) so I think it’s reasonable to mine a few because the masses of rock we are talking about are extremely small in comparison to planets.

Returning space rock back to Earth

So far as a global community we’ve only managed to return very small amounts of material from asteroids and comets to Earth. This is because it is very expensive to return space rock, you effectively need double the technology (spacecraft to get to, and maybe land on, the object and some more to collect and return a sample to Earth). In fact the NASA Stardust mission was relatively cheap in space terms (~$200 million) but only returned about 1 milligram of material. Despite these small masses returned, Stardust remains as the only sample return mission from a comet so as a scientist whose worked on such samples, I will take anything I’m given, even if the particle is smaller than the width of a human hair (as often they are!). So, for research I would obviously welcome the return of material mined from an asteroid because it sounds like there is the potential for much larger masses to be returned than is currently possible with science research missions. However, would a private company be happy to provide scientists with samples? And would they be happy to collect and store the samples in the conditions that scientists require in order to really understand the rocks (i.e. ultra-clean). For science though, having samples we truly understand because they are from a known object in space, is one of our biggest priorities. So I say good luck to the space miners, and please may I have some rock when it comes back?!