Asteroid passing close to Earth could contain $5.4 trillion of precious metals by Robert Hackett @FortuneMagazine July 20, 2015, 2:05 PM EDT E-mail Tweet Facebook Google Plus Linkedin Share icons Miners looking for a bonanza shouldn’t set their sights solely on the ground. The sky is laden with riches, too. Last night an asteroid—2011 UW158, in the scientific nomenclature—passed by Earth at around 6:00 P.M. eastern standard time. The space rock, which is roughly half a kilometer long, might contain anywhere between $300 billion to more than $5 trillion in precious metals, according to the online telescope service Slooh. The asteroid, which careened 1.5 million miles away from this planet—six times further than the Moon—could be seen by telescope only, not the naked eye. “What makes this unusual is the large amount of platinum believed to be lurking in the body of this space visitor,” noted astronomer Bob Berman, as quoted in the International Business Times. “Can it be mined someday, perhaps not too far in the future?” The asteroid is spectrally classified as “X-type,” meaning the light it emits indicates a metallic object. The rock could contain, reports the mining news site Mining.com, 90 million metric tons of platinum and other precious metals. Asteroid mining may turn out to be a lucrative business for private space companies. While Earth’s gravity has pulled the planet’s heavy metals into Earth’s core, making them rare and valuable in the crust layer, these metals are more diffuse throughout less massive, lower gravity asteroids. Companies have taken note. Last week Planetary Resources, the astronautics firm based in Redmond, Wash., launched a spacecraft from the International Space Station on a 3-month-long mission to test the technology required for extraterrestrial prospecting. The Arkyd 3 Reflight, as its rocket is called, originally left the Earth onboard a SpaceX Falcon 9 rocket last April. In November 2014, the European Space Agency’s Rosetta spacecraft successfully landed on a comet, providing a tantalizing proof of concept for hopeful asteroid miners at companies like Planetary Resources and Deep Space Industries. Scientists expect that when this particular asteroid returns in Sept. 2017, it will be even nearer to Earth. In the meantime, there are plenty of other potentially resource rich asteroids out there just waiting to be exploited.