SEATTLE >> 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 filmmaker James Cameron gets off the ground as planned.

Outside experts are skeptical about the project because it would probably 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, told a news conference Tuesday at the Museum of Flight in Seattle. The company’s vision "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.

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. Company leaders predict 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 2 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. Diamandis and co-founder Eric Anderson 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 Cameron, the man behind the blockbusters "Titanic" and "Avatar."

Anderson said the group will prove naysayers wrong. He said asteroids will be mined for water, as well as precious metals. Extracting water is key to deep space exploration, as well as for driving costs down, he said.

The water can be used for drinking and growing food but also for fuel, which is made by separating the hydrogen and oxygen, Anderson said.

He acknowledged the many potential pitfalls.

"There will be times when we fail. There will be times when we have to pick up the pieces and try again," Anderson said.

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

The target-hunting telescopes would be tubes only a couple of feet long, weighing only a few dozen pounds 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.

Asteroids are made mostly of rock and metal and range from a couple of dozen feet wide to nearly 10 miles 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 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 refueling 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.

There are probably 1,500 asteroids that pass near Earth that would be good initial targets. They are at least 160 feet (50 meters) wide, and Anderson figures 10 percent 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 John 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."

Diamandis and Anderson would not disclose how much the project will cost overall. By building and launching quickly, their company hopes to operate much more cheaply 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 the Massachusetts Institute of Technology, said the effort "may be many decades ahead of its time. But you have to start somewhere."

Anderson said the benefit to humanity — and investors — is worth it.

"We do understand that the pot of gold at the end of this rainbow, if it’s successful, will be big."

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Borenstein reported from Washington.