Space-faring robots could be extracting gold and platinum from asteroids within 10 years if a new venture backed by two Silicon Valley titans and Canadian filmmaker James Cameron goes as planned.

Outside experts are skeptical about the project, announced at a news conference in Seattle Tuesday, which would likely require untold millions, or perhaps billions of dollars and huge advances in technology. But the same entrepreneurs pioneered the selling of space rides to tourists — a notion that seemed fanciful not long ago, too.

"Since my early teenage years, I've wanted to be an asteroid miner. I always viewed it as a glamorous vision of where we could go," Peter Diamandis, one of the founders of Planetary Resources, said at a news conference at The Museum of Flight in Seattle.

"The vision of Planetary Resources is to make the resources of space available to humanity."

The inaugural step, to be achieved in the next 18 to 24 months, would be launching the first in a series of private telescopes that would search for the right type of asteroids.

'It is the stuff of science fiction, but like in so many other areas of science fiction, it's possible to begin the process of making them reality'—Thomas Jones, Planetary Resources adviser

The plan is to use commercially built robotic ships to squeeze rocket fuel and valuable minerals out of the rocks that routinely whiz by Earth. One of the company founders predicts they could have their version of a space-based gas station up and running by 2020.

Several scientists not involved in the project said they were simultaneously thrilled and wary, calling the plan daring, difficult — and very pricey. They don't see how it could be cost-effective, even with platinum and gold worth nearly $1,600 an ounce. An upcoming NASA mission to return just two ounces (60 grams) of an asteroid to Earth will cost about $1 billion.

But the entrepreneurs behind Planetary Resources Inc. have a track record of profiting off space ventures. Company founders Eric Anderson and Diamandis pioneered the idea of selling rides into space to tourists, and Diamandis' company offers "weightless" airplane flights.

Investors and advisers to the new company include Google CEO Larry Page and Executive Chairman Eric Schmidt and explorer and Cameron, the man behind the blockbusters Titanic and Avatar.

Anderson says the group will prove naysayers wrong. "Before we started launching people into space as private citizens, people thought that was a pie-in-the-sky idea," Anderson said. "We're in this for decades. But it's not a charity. And we'll make money from the beginning."

The mining, fuel processing and later refuelling would all be done without humans, Anderson said.

"It is the stuff of science fiction, but like in so many other areas of science fiction, it's possible to begin the process of making them reality," said former astronaut Thomas Jones, an adviser to the company.

Target-hunting telescopes cost about $10M

The target-hunting telescopes would be tubes less than a meter long, weighing only a few dozen kilograms and small enough to be held in your hand. They should cost less than $10 million, company officials said.

The idea that asteroids could be mined for resources has been around for years. Asteroids are the leftovers of a failed attempt to form a planet billions of years ago. Most of the remnants became the asteroid belt between Mars and Jupiter, but some pieces were pushed out to roam the solar system.

This NASA photo shows the north pole of the asteroid Eros. Space exploration has taken on renewed interest of late. (Associated Press)

Asteroids are made mostly of rock and metal and range from about seven metres wide to nearly 16 kilometres long. The new venture targets the free-flying asteroids, seeking to extract from them the rare Earth platinum metals that are used in batteries, electronics and medical devices, Diamandis said.

Water can be broken down in space to liquid oxygen and liquid hydrogen for rocket fuel. Water is very expensive to get off the ground so the plan is to take it from an asteroid to a spot in space where it can be converted into fuel. From there, it can easily and cheaply be shipped to Earth orbit for refuelling commercial satellites or spaceships from NASA and other countries.

In the past couple of years, NASA and other space agencies have shifted their attention from the moon and other planets toward asteroids. Because asteroids don't have any substantial gravity, targeting them costs less fuel and money than going to the moon, Anderson said in a phone interview.

'Maybe the time has come'

There are probably 1,500 asteroids that pass near Earth that would be good initial targets. They are at least 50 metres) wide, and Anderson figures 10 per cent of them have water and other valuable minerals.

"A depot within a decade seems incredible. I hope there will be someone to use it," said Andrew Cheng at Johns Hopkins University's Applied Physics Lab, who was the chief scientist for a NASA mission to an asteroid a decade ago. "And I have high hopes that commercial uses of space will become profitable beyond Earth orbit. Maybe the time has come."

Space experts said such the bold endeavour has huge startup costs. Diamandis and Anderson would not disclose how much the project will cost overall. Diamandis said by building and launching quickly, the company will operate much cheaper than NASA.

Harvard's Tim Spahr, director of the Minor Planet Center, said getting drilling equipment into space and operating safely sounds "expensive and difficult."

"It would be awfully hard to make money on it," Spahr said.

Richard Binzel, professor of Planetary Science at MIT, said he hopes Planetary Resources is successful, adding "this effort may be many decades ahead of its time. But you have to start somewhere."