Looks like we'll just have to be content with our Lego space miners. A new Harvard study says that very few asteroids in our solar system are worth mining.

Several very rich people -- and our government -- are hoping to mine asteroids for precious metals, hydrogen and oxygen. But Dr. Martin Elvis, an astrophysicist, has calculated that only 10 asteroids (or 1 percent) would be suitable and come close enough to Earth for mining. He estimates the value of mined ore from those asteroids could be from $800 million to $8.8 billion. Which is a lot, but building a space mining company from the ground up is pretty expensive. If Elvis is correct, it might not be worth the effort. This is a big blow to the burgeoning space mining industry.

But! Space mining company co-founder Eric Anderson (his Planetary Resources is backed by James Cameron and Larry Page) is not deterred. In fact, he told the BBC, he thinks Elvis's calculations are off. Way off:

"Number one, the author points to an assumption of only wanting to go to M-type asteroids,' he told BBC News.

'Assuming we were only going after platinum-group metals, the most platinum-rich asteroids are the C-class ones.' Fragments of these asteroids are known as carbonaceous chondrites when they fall to Earth.

In addition, Planetary Resources' engineers were prepared to include objects that required a delta-v of 7km/s, a more ambitious limit than the 4.5km/s used in Dr Elvis' study.

'I think the study is probably off by a factor of 100, conservatively, and I think it's off by a factor of 1,000 optimistically,' Mr Anderson added.

(In case you were wondering, delta-v is the change in velocity needed to send space mining equipment to the space mines and then back to Earth, laden with heavy space minerals.)

Not sure why Dr. Elvis went with M-type asteroids when everyone knows the C-class 'stroids hold the big bucks.

A somewhat annoyed-sounding Dr. Elvis told the BBC (emphasis his): "I want to stress that my paper does not mean that there is no commercial future for asteroid mining. It does mean that gold mines are rare, which shouldn't be too surprising. Not every mountain on Earth hides a fortune, and not every flying mountain in space will either."

We'll find out soon enough; NASA is planning to lasso an asteroid in 2019, while Planetary Resources' rival Deep Space Industries hopes to launch asteroid-prospecting spacecraft as early as next year.