Few asteroids are worth mining, suggests Harvard study

A new study might contain some bad news for companies hoping to mine asteroids for their valuable ores.

In the last couple of years, start-ups - including one backed by Sir Richard Branson - have announced plans to extract resources from space rocks.

But calculations by Dr Martin Elvis suggest our cosmic neighbourhood might not be such a treasure trove after all.

The Harvard astrophysicist argues just 10 near-Earth asteroids might be suitable for commercial-scale mining.

But Eric Anderson, co-founder of asteroid mining company Planetary Resources, told reporters that the values quoted in the study were off - conservatively - by a factor of 100.

Dr Martin Elvis

Dr Elvis, from the Harvard-Smithsonian Center for Astrophysics in Cambridge, US, has developed an equation to estimate the number of asteroids in the Solar System that could be exploited in a cost-effective way.

His research paper is in press at the journal Planetary and Space Science, and has been posted on the pre-print server Arxiv.org.

In 2012, Planetary Resources, backed by billionaire investors including Hollywood director James Cameron as well as Google executives Larry Page and Eric Schmidt, unveiled their vision of using robotic spacecraft to squeeze the chemical components of fuel as well as minerals out of asteroid rocks.

Several months later, the company was joined by a competitor - Deep Space Industries - which plans to use low-cost spacecraft called Fireflies and Dragonflies to reconnoitre and return samples from near-Earth asteroids.

Advocates of asteroid mining say it could turn into a trillion-dollar business, but some experts have been sceptical of the idea.

Concentrating efforts
In the latest study, Dr Elvis worked out the factors that would make an asteroid commercially viable to mine and what fraction of known space rocks met these requirements.

He emphasised there were large uncertainties in the values and called for more thorough surveys of what's out there.

He assumed that mining operations would want to focus on iron-nickel asteroids (known as M-type), considered the most promising targets for finding so-called platinum-group metals.

These include platinum, along with iridium, palladium and others.

These are rare in the Earth's crust because they dissolve in molten iron, instead being mainly concentrated in the planet's core.

Platinum and palladium are the most economically important, having a wide range of uses in industry. But according to the analysis, just 1% of near-Earth asteroids are rich in these elements.

Suitable asteroids also need to be relatively easy to reach, further narrowing the pool by ruling out all but the nearest objects to Earth.

The operative parameter here is delta-v - the change in velocity needed to send mining equipment to the target and return with a larger mass of ore.

The size of the target is also a factor; the paper suggests it wouldn't be worth mining asteroids smaller than about 100m because the total value of the ore they would produce wouldn't be enough to cover the costs of a space mission.

However, Dr Elvis points out that the ore values in his analysis range from a low of $800m to a high of $8.8bn.

"Such a large range of values could greatly change the profitability of a venture, making more accurate assays necessary," he explained.

More Information: How Many Ore-Bearing Asteroids? Arxiv.org

Ijen volcano in Yogyakarta, Indonesia: Sulphur Miners' annual ceremony

A sulphur miner carries a goat's head in a white bag as he climbs to bury the head in the crater as part of an annual offering ceremony on the Ijen volcano in Yogyakarta, Indonesia.

The ritual is performed by the sulphur miners of Mount Ijen who slaughter a goat and then bury the head in the crater. 

The sacrifice is performed to ward off potential disasters for the next year.

The Ijen crater rises to 7,800 feet with a depth of over 570 feet, making it one of the world's largest craters. 

Sulphur mining is a major industry in the region, made possible by an active vent at the edge of a lake, but the work is not without risks as the acidity of the water in the crater is high enough to dissolve clothing and cause breathing problems.

Picture: Ulet Ifansasti /Getty Images

Japan finds rich Rare Earth deposits on seabed

Japanese researchers said Thursday they have found a rich deposit of rare earths on the Pacific seabed, with reports suggesting it could be up to 30 times more concentrated than Chinese reserves.

Mud samples taken from 5,800 metres (19,000 feet) below the waves contained highly concentrated amounts of the precious minerals, which are vital for high-tech manufacturing and used in products including wind turbines and iPods.

The proving of resources is significant for Japan, which currently relies largely on China. China has a near-monopoly hold on Rare Earth elements; around 90 percent of the world's supply of rare earths.

Manufacturers have complained in the past that Beijing restricts exports of the materials at times of tension.

"Rare Earths are necessary for cutting-edge technologies. Japan faces an urgent task to secure stable supplies," said a statement by researchers from the Japan Agency for Marine-Earth Science and Technology and the University of Tokyo.

The samples, taken from the seabed near Minamitori island some 2,000 kilometres (1,250 miles) southeast of Tokyo, were 10 times more concentrated than that of mud collected from the seabed near Hawaii, the researchers said.

The concentration was 20 to 30 times higher than that from Chinese mines, Japanese media said.

Scientists believe the seabed contains about 6.8 million tonnes of the materials, the equivalent of 220 to 230 years worth of rare earths used in Japan.

But despite the desire to move away from dependence on oppressive China, the cost of extracting supplies from such a depth and in such hostile conditions may prove problematic.

In its afternoon edition, the mass-selling news provider Yomiuri Shimbun said there had been no successful commercial mining below 5,000 metres.

The researchers said they plan to continue their survey, which began in January, to further study rare earth resources and find out how extensive the deposits are.