What do those in the know make of the bold plans dreamed up by wannabe asteroid miners and Chris Lewicki of ? Few outfits are more familiar with asteroids than the at Harvard University. Paul Marks asked its director Tim Spahr if he thinks the operation will succeed
Read more: 鈥�Meet the asteroid miners鈥�
What was your reaction when you first heard about 鈥� plan to mine the asteroids?
My interest was initially piqued by the fact that they also want to study space objects with their small space telescopes. That鈥檚 my background: the discovery of these bodies and their orbits. I view mining asteroids as quite difficult. A lot of the technology required to do that has not yet been demonstrated. Of course, that鈥檚 what somebody would have told you about brain surgery or heart surgery before it was actually done. So while this hasn鈥檛 been demonstrated yet, the only way to do so is to throw a whole lot of money at the problem and to undertake a lot of experiments on Earth and in space.
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Well, with their Google billionaire backers I guess they have the money?
Potentially. You never know exactly how such things will go. People who thought they had a lot of money from donors in 2008 when the markets collapsed found they did not have so much after all.
Planetary Resources mention the concept of moving an asteroid nearer to Earth to make mining it more economically feasible? Is that possible?
It would take an awful lot of energy. And that鈥檚 one calculation that鈥檚 rather easy to do. We know the speed of every object that we observe because that鈥檚 part of the calculation of the orbit. And you know what energy you need to supply to alter that speed. And so you can sit down, with your pen and paper, or your computer, and compute the integral and see what it is. But it鈥檚 certainly a long way from my comfort zone, figuring out how much propellant is required to do that. I suspect that鈥檚 a lot of energy.
Why does it take so much energy to change the orbit of an asteroid?
Because the sun is in charge of the dynamics of the solar system. It is the sun you are messing with at that point. If you wanted to park an object in orbit around the Earth that鈥檚 going to take quite a bit of energy, because you鈥檒l have to alter the velocity of the object so that it is no longer orbiting the sun.
If you do coax an asteroid back towards the Earth and you mine it, reducing its mass, could that change its orbit, too?
Well, that鈥檚 your standard recoil problem. If you鈥檙e standing in your slippers in the middle of an ice hockey rink and you shoot your shotgun, you鈥檙e going to move. That is simple momentum transfer. You鈥檝e flung a piece of yourself away, in this case, the bullet at high velocity, and so the recoil pushes you a little bit. Those are minor issues though. Again, you compute what sort of thing you鈥檙e doing, how much mass you鈥檙e moving away when you take off with what you鈥檝e mined. I suspect that would not be much of a problem. They would know what they鈥檙e moving and what the reaction would be. My intuition is this would be a very small factor.
Should we worry that bringing asteroids closer to Earth and making some kind of trajectory error might damage constellations of key satellites, like the GPS network, or worse, hit the Earth?
Honestly, I view a lot of this kind of talk as sort of alarmist. We have a giant belt of spacecraft up there right now. None have ever been hit by anything despite the fact that we have marble-sized junk flying at the Earth all the time. The International Space Station has never been decompressed and the danger is not from something we鈥檙e going to bring into the area; the real danger is the fact that there is little stuff the size of baseballs and footballs flying in the Earth鈥檚 vicinity literally every day. The US air force keeps track of everything down to small sizes in the vicinity of the Earth anyway, so they know where everything is.
Planetary Resources鈥� co-founder Eric Anderson makes the point that we already have the 417,289 kilogram ISS up there and it could cause great damage on Earth if it accidentally re-entered and yet no-one considers that a risk.
Yes. Whoever will be doing the orbital mechanics for the asteroid project would be well aware of what sort of uncertainties there are. And again, I tend to remind most people that hitting the Earth is a damn hard thing to do.
Do you think they鈥檒l mostly go to an asteroid, sit on it and mine it, rather than move it anywhere?
I suspect that would be the first thing to do. And that presents a number of extremely difficult challenges. Think of Newton鈥檚 law of equal and opposite reactions: there鈥檚 no gravity on the asteroid. How do you actually dig a shovel in? It鈥檚 not like you鈥檙e going to put a front-end loader or a John Deere tractor up there and start scraping the surface, because the instant you do that, the opposite reaction is going to fling you right off of that. You鈥檙e going to have to find a way to bolt your mining material down.
And your robots and your people of course鈥�
Yes, in an environment where the average, small near-Earth asteroid rotates in several minutes, not hours, but minutes
So putting a spacecraft into orbit next to it will be tough?
That will be hard. I鈥檓 quite sceptical. I think that they face a lot of challenges and this will certainly be a multi-decade, multibillion dollar endeavour just to get it off the ground. They鈥檙e not going to just spend 500 million bucks, fly up there, mine the asteroid and make $1 trillion. That will not happen.
