A team of researchers are planning to send robotic spacecraft into outer space, land near asteroids hurtling through the abyss and mine them for water, metals and other elements that will make colonizing space that much easier. Science columnist Torah Kachur explains.

Why do we need to mine asteroids?

Quite simply because the current economics of space flight are untenable. It costs approximately $10,000 US per kilogram every time we want to send something up to the International Space Station. Imagine $10,000 for a litre of water. Elon Musk and Space X are trying to cut those costs down by having reusable rockets, but still, the price is exorbitant.

The reason why it is so expensive is because of the gravity of Earth; we have to propel a rocket with its payload away from Earth and out of the atmosphere and that takes a lot of energy. But once you are in outer space, there are smaller space bodies with less, if any, gravity that may contain stuff that we need for human habitation or just visits to space.

What kinds of things are going to be mined?

Pretty much anything we can find. I spoke with J.L. Galache. He's an entrepreneur and has a startup called ATEN engineering. He wants to be one of the first to mine asteroids.

"Being able to get water while we're in space, building materials, to be able to build spaceships and habitats up in space with materials that we've harvested in space — that's what's going to enable us to spread throughout the solar system," says Galache.

The primary thing to find is actually water, because it's is heavy to get from Earth, but also plentiful in space on asteroids. So it's not unreasonable to think that a lander spacecraft of some kind (there are a few designs in progress) would come near an asteroid, suck up some ice or water and bring it back to the ISS or any other human dwelling in space. This would make space travel much more affordable.

Think of a water-logged asteroid as a little gas station in the sky, - Torah Kachur

Not only that, water can be used for more than just drinking; it can be split into oxygen for breathing and hydrogen for rocket fuel. Think of a water-logged asteroid as a little gas station in the sky.

How do researchers know if one of these asteroids contains water?

That's the hard part and the focus of the scientific establishment right now. There are three broad categories of asteroids, all of which have potential for mining. But we need to know which is which before we embark on missions.

"There are the C-types, which are carbonaceous. They have very primitive materials that have been unchanged since they were formed close to when the solar system was formed," says Galache.

"Some of them are water rich, up to 20 per cent by weight. Then we have the S-type aspirates which are stoney. These have gone through some changes due to heating since they were formed and they're rather dry. And then we have a smaller minority of asteroids that are metallic."

That means the first targets are the C-type asteroids. Right now the teams and companies that are in the Wild West of asteroid mining are using data from telescopes run by NASA (such as the Hubble) to map and characterize different asteroids that come near Earth's orbit.

Near Earth Asteroid Eros, visited by NASA. (NASA)

The scientists use spectroscopic imaging, which allows them to determine the chemical composition of a space object.

The next steps will likely be taken using independent telescopes and imaging apparatuses, because then the companies interested in space travel won't be limited just to where NASA wants to look, but instead can explore the regions that look the most profitable.

There has been some coverage in the news — and some people might have heard this — that asteroid mining involves finding diamond-rich asteroids in space, or gold-rich asteroids and bringing them back down to Earth. Is that the plan?

No, actually not at all. It simply doesn't make economic sense to do that because we already know, with the Space X failures and successes, how hard it is to land things from space onto Earth because of the increased gravity once you enter the atmosphere. Instead, the vision is way crazier and ambitious than just mining space for uses on Earth.

"The whole idea is that we create an in-space economy, so, materials are harvested in space, they are sold in space and they are used in space," says Galache.

"All the money made in the current space economy is made down here on Earth."

The idea is that we would have permanent human inhabitants in space, or to start, even just permanent robotic missions in near Earth orbit. These could leapfrog from one asteroid to the next, from one space body to the next, collecting minerals and water to use for things like building spaceships in space. Or building little houses or tools or machines in space.

Near Earth Asteroid Itokawa, visited by The Japan Aerospace Exploration Agency. (The Japan Aerospace Exploration Agency )

There's no reason that everything for space has to be built on Earth and sent up. Instead, we could 3D print with materials extracted from space objects like asteroids, use the fuel that is already there, and even make a diamond ring to propose to a space girlfriend.

That is ambitious to say the least. So what is the timeline?

Can I say 20 years like I always do? That's what the experts think. They say that within five years there will be a privately financed asteroid mining operation sent into space. From there, depending on its success, humans can follow shortly. There is a long way before there are schools in space to raise kids who drink water mined from asteroids, but it's not out of reach. I guess we literally are reaching for the stars.