20 SEG NEWSLETTER No 65 • APRIL 2006Feasibility <strong>of</strong> Asteroid MiningMichael W. Busch † , Division <strong>of</strong> Geology and Planetary Science, California Institute <strong>of</strong> TechnologyMC 150-21, Pasadena, California 91125SHORT ARTICLESAbout 2% <strong>of</strong> meteorites observed to fall toEarth are near-pure nickel-iron, implyingNiFe objects somewhere in the solar system.Over the last decade, radar observations<strong>of</strong> asteroids have located four suchobjects (Table 1). The NiFe asteroids arethe largest accessible reserve <strong>of</strong> platinumgroupelements (PGEs) in the solar system.Nickel-iron meteorites contain about 60ppm <strong>of</strong> PGEs on average, uniformly distributedin the NiFe matrix. The richestcontain over 150 ppm (Table 2).Carbonyl processing, similar to operationsat the International Nickel plant atSudbury, Ontario, is the best method <strong>of</strong>extracting PGEs from an asteroid on anindustrial scale (Lewis and Lewis, 1987).Since the PGEs are uniformly distributed,the entire mass must be ground andreacted with CO to form carbonyls, whichare then decomposed according to species.This process requires about 40 Mw <strong>of</strong> solarthermal and electrical power to process3.25 million metric tonnes (t)/year. Othermethods, such as thermal separation, arefar more energy-intensive.The largest contributor to the cost <strong>of</strong>any space mission is the total massneeded in Earth orbit, since launch costsare currently about US$15,000/kg (allcosts are in January 2006 U.S. dollars).Therefore, the target should require thesmallest possible velocity change fromEarth orbit, to decrease the mass <strong>of</strong> fuelthat must be brought up from Earth. Thetarget should also have the highest possiblesolar flux, to minimize the mass <strong>of</strong>the power plant. Asteroid 1950 DA is thebest known target.If 1950 DA has an average concentration<strong>of</strong> PGEs, a total system mass <strong>of</strong>about 190 t in Earth orbit is sufficient toprocess 3.25 million t/yr and return theresulting 180 t/yr <strong>of</strong> metal from the asteroidto the Earth’s surface. The carbonylprocess requires a large number <strong>of</strong> moving† E-mail: busch@caltech.eduTABLE 1. Known Nickel-Iron AsteroidsTABLE 2. Precious Metals in Nickel-IronMeteoritesConcentrationElement Average HighestPlatinum 20 ppm 30 ppmPalladium 10 ppm 20 ppmRuthenium 10 ppm 30 ppmGold 5 ppm 20 ppmIridium 5 ppm 20 ppmOsmium 3 ppm 35 ppmAverages over nickel-iron meteoritesfrom Krinov, 1960; the highest PGE contentsare from the type IIA irons(Goldberg et al. 1951, Crocket 1972)parts, however, so a crew is desirable tomaintain the equipment. A crew <strong>of</strong> four tosix in a closed-cycle life support systemadds 60 t to the Earth-orbit mass. The cost<strong>of</strong> such a 250-t spacecraft would likely bein the vicinity <strong>of</strong> $5 billion, including thecost <strong>of</strong> assembly before launch. For comparison,the initial cost <strong>of</strong> an Earth-basedplatinum-palladium mine producing 22t/yr <strong>of</strong> PGE is about $1 billion (ImpalaPlatinum, 2005).The revenue from selling 180 t/yr <strong>of</strong>PGEs in the ratios present in nickel-irondepends on Earth demand. Using priceand production data for the last decade,assuming linear price elasticity andadjusting for inflation, I estimate the revenueat $1.9 to $2.8 billion/yr, with theprice <strong>of</strong> PGEs decreasing by up to 35%.The range represents uncertainty in theEarth production and price elasticity <strong>of</strong>each species. For example, I have notincluded the effects <strong>of</strong> a decrease in PGEprices on Earth-based mining.Because an asteroid mining missionmust be able to operate almost independently<strong>of</strong> Earth, operating costs are muchsmaller than the uncertainty in my revenueestimates. Revenue <strong>of</strong> $1.9billion/yr is sufficient to repay a $5 billioninitial cost within three years,Asteroid Volume Surface Est. PGE Content (troy oz) ∆v Solar(km 3 ) density Pt Pd Au (km/s) flux(g/cm^3)16 Psyche ~3.3×10 6 ~5 1.1×10 16 5.3×10 15 2.7×10 15 14.60 0.12216 Kleopatra ~670,000 ~3.5 1.5×10 15 7.5×10 14 3.8×10 14 14.10 0.131986 DA ~4 ~5 1.3×10 10 6.5×10 9 3.2×10 9 7.13 0.151950 DA ~0.8 ~5 2.6×10 9 1.3×10 9 6.4×10 8 6.86 0.40Notes: PGE contents were computed using the volume and surface density for each objectand the average concentrations from Table 2; Dv is the approximate velocity changerequired to go from low Earth orbit to the object; the solar flux is averaged over the orbitand expressed relative to Earth; 1986 DA and 1950 DA are on eccentric orbits that bringthem close to the Earth at intervals, while Kleopatra and Psyche never leave the asteroidbelt; volumes and surface densities are derived from radar observations (Ostro et al. 2002)assuming a discount rate <strong>of</strong> 6%. If theinitial cost is higher than $5 billion, thetime to repay increases. Costs up to $14billion would be repaid within a decade.The reserves in 1950 DA are comparableto the Bushveld Complex, althoughthe PGE concentrations are much higher(Cawthorn, 1999). At several times theextraction rate given above, the reserveswould last for centuries. If the pr<strong>of</strong>itsfrom the mission described are appliedexclusively to financing additional missions,the revenue can exceed $7 billion/yrwithin a decade <strong>of</strong> the start <strong>of</strong> thefirst mission.No one has applied carbonyl techniquesin space on any scale, so a technologydemonstration mission would bethe logical first step in a mining venture.One such mission would be a 1/100 th -scale version <strong>of</strong> the mission describedabove, obviously without a crew. Thedemonstration: go to 1950 DA, processsome tens <strong>of</strong> tonnes <strong>of</strong> material andreturn the resulting kilogram <strong>of</strong> PGE toEarth. This smaller spacecraft would costsome hundreds <strong>of</strong> millions <strong>of</strong> U.S. dollars,because fixed costs such as the launchvehicle must be considered.The potential <strong>of</strong> asteroid mining istheoretically great, although the cost <strong>of</strong>any large-scale mission is quite high.There are good launch opportunities to1950 DA throughout much <strong>of</strong> this century.A demonstration mission could belaunched in 2008 or 2010, with the largemission launching a few years later. Thefirst pr<strong>of</strong>its would be made within adecade <strong>of</strong> today.ACKNOWLEDGMENTSThe author thanks Roger Scoon for hishelpful review.REFERENCESCawthorn, R.G., 1999, Platinum and palladiumresources <strong>of</strong> the Bushveld Complex: SouthAfrican Journal <strong>of</strong> Science, Nov/Dec 1999.Crocket, J.H, 1972, Some aspects <strong>of</strong> the geochemistry<strong>of</strong> Ru, Os, Ir and Pt in iron meteorites:Geochimica et Cosmochimica Acta, v.36, p. 517–535.Goldberg, E., Uchiyama, A., Brown, H., 1951,The Distribution <strong>of</strong> nickel, cobalt, gallium,palladium and gold in iron meteorites: Geochimicaet Cosmochimica Acta, v. 2, p. 1-25.Impala Platinum, 2005, 2005 Annual Report:Johannesburg, Impala Platinum.Krinov, E.L., 1960, Principles <strong>of</strong> meteoritics,Oxford, Pergamon Press.Lewis, S.J. and Lewis, R.S., 1987, SpaceResources, Columbia University Press.Ostro, S.J., Hudson, R.S., Benner, L.A.M.,Giorgini, J.D., Magri, C., Margot, J.-L.,andNolan, M.C., 2002, Asteroid radar astronomy,Asteroids III: Tucson, University <strong>of</strong> ArizonaPress, p. 151–168 p. 1
APRIL 2006 • No 65 SEG NEWSLETTER 21EXPLORATION REVIEWSAFRICARegional Correspondent:Judith Kinnaird (SEG 2002)SEG Regional Vice President AfricaSchool <strong>of</strong> GeosciencesUniversity <strong>of</strong> the Witwatersrand,South AfricaTel: +27 11 7176583Fax: +27 11 7176579E-mail: kinnairdj@geosciences.wits.ac.zaANGOLAPetra Diamonds report that kimberliticoccurrences at Alto Cuilo increased toabout 1,323 ha in estimated surfacearea and 33 kimberlitic occurrenceshave now been confirmed by drilling. Athird core drill rig was ordered in 2005to expedite drilling <strong>of</strong> the substantialnumber <strong>of</strong> anomalies and 350 alluvialpits are now complete.BOTSWANAMount Burgess commenced an infilldrilling program at its Kibhabe basemetals project to bring the 2.4-km zone<strong>of</strong> zinc, lead, silver anomaly with copperand vanadium credits into a JORCcompliantresource/reserve. Earlierresults from four drill sections showedaverage grades <strong>of</strong> 3% zinc, 1% lead,and 28 g/t silver.DEMOCRATICREPUBLIC OF CONGOSouth African-based Metorex Ltd hasannounced it will begin cobalt productionat its Ruashi mine by April 2006with an initial output expected to bearound 1,000 tpa.Banro Corporation states thatdrilling results from its wholly ownedNamoya project on the Twangiza-Namoya gold belt include 7.98 m at38.63 g/t , 7 m at 16.01 g/t, 15.74 m at7.46 g/t and 10.4 m averaging 4.5 g/t.GABONSouthernEra Diamonds has commencedmicro-diamond testing <strong>of</strong> kimberlitebodies, confirming the discovery<strong>of</strong> seven new kimberlitic bodies, one <strong>of</strong>which contained five high-pressure G10garnets, while others contained spinels.GUINEAThe government <strong>of</strong> Guinea has granteda mining concession for GlobalAlumina Corp (GAC) to supply itsrefinery. GAC has signed an agreementwith Glencore International AG whichwill take 420,000 tpa <strong>of</strong> alumina over a20-year period. GAC has now secured20-year <strong>of</strong>f-take agreements for 55% <strong>of</strong>the planned 2.8 Mt/yr capacity <strong>of</strong> itsproposed operation, including 40% tobe shipped to Dubai Aluminium Corp.Ltd.LESOTHOLetseng diamond mine, producer <strong>of</strong>some <strong>of</strong> the biggest diamonds in recentyears, produced 19 658 carats whichfetched an average $1,708 per carat inthe six months to September 2005. Therecovered grade was 1.71 ct/100 t.LIBERIAMano River Resources has confirmedthat the kimberlite pipe K007 at Kpo isdiamondiferous. Kpo is being exploredin a joint venture with Trans Hex.Approximately 600 kilos <strong>of</strong> weatheredkimberlite obtained by pitting waswashed, jigged, and concentrated onsite and then examined in Mano’srecently established diamond laboratoryin Monrovia. A single >3 mm gemqualitydiamond weighing 0.4 caratswas recovered from the sample. A3,000-m drilling programme is nowplanned.MADAGASCARPan African Mining Corporation hasdiscovered a nickel-bearing lateriteabove an ultramafic complex in northernMadagascar. The highly weathereddeposit on the company’s Nickel Valleyproperty is about 1 km long and 250 mwide and oval in shape. Sampling byauger-drilling, trenching and pittinghave been completed to depths <strong>of</strong> 10 mwith the best grades being 2 m at 2.6%Ni.Jubilee Mining has intersected 48 m<strong>of</strong> high-grade nickel-copper mineralization15 m below surface in boreholeANT1 on its Antsahabe property on theLondokomanana concession. Bulj-miningweighted average grades are up to0.64% nickel and 0.13% copper.MALAWIPaladin Resources began re-examiningthe Kayelekera uranium deposit in late2004 following the improved uraniumoutlook. Revised resources based onassays and down-hole gamma-logging(after standard radiometric calibration)are given at two cut<strong>of</strong>f grades, as thecompany expects the economic cut<strong>of</strong>ffor any mine developed at Kayelekerawould be between 300 and 600 ppmU 3 O 8 . Measured resources would be 2.20Mt based on 300 ppm with 13.11 Mtindicated and 3.40 Mt inferred. At a cut<strong>of</strong>f<strong>of</strong> 600 ppm, measured resourceswould be 1.58 Mt with 6.98 Mt indicatedand 1.19 Mt inferred.NAMIBIAAfri-Can, a Canadian-based company,has signed an agreement with marinemining contractor International Miningand Dredging Holding Ltd (IMD) toundertake a US$2.5 million <strong>of</strong>fshorediamond exploration program on its994 km 2 Block J marine concession beginningin early 2006. Afri-can currentlyholds a 70% interest in Block J with“black economic empowerment” companyWoduna Mining Holdings owning30%. The concession, which lies 105km north <strong>of</strong> Luderitz, has water depthsranging between 70 and 170 m andwork will begin with a geophysical survey<strong>of</strong> up to 3,100 line-km followed bycollection <strong>of</strong> around 300 large samples.Rio Tinto is to expand the Rossinguranium mine in the Namib desert in aUS$112 M program that will extend thelife <strong>of</strong> mine by seven years. Annual outputwill be increased from 3,600 tpa to4,000 tpa <strong>of</strong> uranium oxide. The mineis unusual in that it extracts primaryuranium from granite dikes rather thansecondary sedimentary-hosted uranium.Paladin Resources has 44,000 t <strong>of</strong>uranium oxide at its Langer Heinrichproject in and it is expected to start producingwithin a year. This new opencastsedimentary-hosted uranium mineis situated about 85 km east <strong>of</strong>Swakopmund, in the Namib NaukluftNational Park. The Park is doing a greatdeal to protect the environment, especiallyaround the site, and there arestrict requirements to ensure the protection<strong>of</strong> plant, animal,and insect life. Thisto pageincludes keeping22 ...EXPLORATION REVIEWS
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