Extraterrestrial Resources


Returning platinum group metals to earth seems possibly promising. Lunar oxygen has potential but doesn't have many existing potential customers. Helium 3 is not promising any time soon.

In General

The potential uses for extraterrestrial resources expand greatly if you use them in situ. However, that provides merely a better way to operate on an extraterrestrial body, rather than a reason for going there in the first place, so the rest of this page is directed at returning materials to the earth or earth orbit.

Platinum Group Metals

Returning platinum and other valuable substances to earth may be profitable. I haven't really researched this, but here are a bunch of references (which I haven't looked at myself; comments are from the usenet post where I got the references):

In addition the CSTS, section, page 367, briefly mentions mining platinum but does not offer details. They assert that having additional platinum on the market would reduce prices significantly but don't support or quantify the assertion.

Those are the resources I am aware of which are most focused on markets (as far as I know); a lot more has been written on asteroid mining (particularly the technology), one nice site with good descriptions and lots of references is P.E.R.M.A.N.E.N.T., Mark Prado. Note in particular the discussion there about what the concentration of platinum group metals might be; finding some ores with concentrations much higher than on earth is presumably going to be a requirement for profitably shipping platinum group metals to earth.

Some rough numbers:

If you take your favorite choice from the above numbers, guess about the up-front costs to develop the hardware and so on, you can come up with an answer for whether a business would make sense. One catch is that most mission scenarios would take a significant amount of time to return the material. It seems like it may work at launch prices in the ballpark of $100/kg to $1000/kg to LEO, but there are lots of uncertainties and risks here.

Lunar Oxygen

One brief sketch of supplying oxygen to space stations in earth orbit is "Resupply of the International Space Station", Artemis Data Book, section 3.4. However, it doesn't have numbers on how much oxygen space stations would need. One can also imagine supplying oxygen for use as propellant to earth-orbit spacecraft, but I haven't seen any numbers on that either.

Helium 3

Helium 3 is present in minute concentrations on the moon (but larger than on earth). Generally considered for use in generating electricity via fusion. Fusion research has generally been a long-term prospect. Some 1990s estimates of when it might have progressed to the stage where commercial reactors are worth considering ranged from the years 2015 to 2030 (CSTS, section, page 364). There is a small market for using helium 3 in cryogenic applications (it behaves noticeably differently from helium 4 at those low temperatures). According to WebElements the size of the cryogenic market is "thousands of liters" annually. They also list uses as a neutron counter in nuclear application, and for magnetic resonance imaging (without market sizes).

Best web site I've seen on lunar helium 3 is NEEP 602 at the University of Wisconsin. Lecture 27 (Helium 3) contains much information about comparing helium 3-based fusion reactions to other reactions, references to published sources on the technologies involved, etc. Lecture 37 (Economics of Large Space Projects - 3) is about economic analysis of helium 3 mining. I didn't review it in detail, but the basic summary is that to make it work, the utilities need to be willing to pay $500-800 per gram of helium 3, there needs to be significant government subsidies of one sort or another, and some of the costs of lunar operations need to be shared with other operations such as volatile extraction or science.

The main competitive source of Helium-3 is from the decay of Hydrogen-3 (Tritium). I believe that producing Hydrogen-3 to yield Helium-3 for fusion reactors would take too much energy (spallation sources need about 50 MeV of input energy per neutron, and the fusion yields less than 20 MeV.)

About 1.38 x 10^-6 of naturally occurring Helium is He3 (source: Spectra gases). I'm not sure whether this is a source of currently commercially available He3, or what quantity would be available via these means.

This page is part of Jim Kingdon's space markets page.