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.
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):
- M. McKay, D. McKay, M. Duke, eds., Space
Resources:Materials, NASA SP-509, v. 3, US GPO, 1992 (P. 111-120
cover asteroid mining).
- J. Lewis, T. Jones, W. Farrand, "Carbonyl Extraction of Lunar and
Asteroidal Metals", Engineering, Construction, and Operations in
Space (eds. Johnson & Wetzel), p. 111-118. American Society of
Civil Engineers, New York, 1988
- J. Lewis, M. Mathhews, M. Guerrieri, eds., Resources of
Near-Earth Space, U. of Arizona Press, Tuscon, 1993. (Too many
good articles in this one to list).
- J. Kargel, "Metalliferous Asteroids as potential sources of
precious metals", Journal of Geophysical Research, v. 99, no
E10, p. 21129-21141, October 25, 1994. (The first attempt I've seen
at developing price elasticity curves for raw materials)
- C. Meinel has a nice article from the 1985 IEEE EASCON on mass
payback for various asteroidal return scenarios.
- Lewis and Lewis, Space Resources: Breaking the Bonds of
Earth. (Don't have a complete citation for this).
In addition the CSTS, section 22.214.171.124.1, 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
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.
- Prices for platinum group metals: $1000-10000/kg in large
quantities (depends on the platinum group metal and whether one is
planning for a drop from current prices; one source is the monthly
Mineral Industry Surveys, Precious Metals from the USGS; also see their
Minerals Yearbook, Platinum-Group Metals for more on the
- Mass payback of 10 to 100 (that is 1kg delivered to the asteroid
gets 10 to 100 kg back on earth). (Source: usenet).
- Doing the first stages of refining at the asteroid reduces the
mass to be returned significantly. Refining to 0.2% platinum group
metals looks easy; 5% looks hard but possible. (Source: usenet).
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 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 126.96.36.199.2, 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). WebElements lists "NMR,
tracisotopically enriched samples availabler" as applications.
I haven't seen any indication that any of these markets could be large.
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
This page is part of Jim
Kingdon's space markets page.