Science fiction authors and futurists have been musing on the possibility of mining asteroids for decades, but last year a company called Planetary Resources declared its intention to actually do it. That got people thinking about whether or not humanity has really reached the point where asteroid mining could become a reality. A group of astronomers at the University of Strathclyde in the UK have replied with an emphatic, “yes.’ They have identified 12 near-Earth asteroids that could be easily retrieved and mined with current rocket technology.
It’s believed that asteroids could contain large deposits of industrial and precious metals. An unremarkable one-kilometer asteroid could contain upwards of two billion tons of iron-nickel ore, which is three times the global yield on Earth. Then there is the likely presence of gold, platinum, and other rare substances. Planetary Resources claims a 30-meter object of the right composition could contain $25 to $50 billion in platinum.
These numbers spurred the University of Strathclyde team, led by Garcia Yarnoz, to pour over the astronomical data on near-Earth objects to see if any of them could actually be snared. To their surprise, they found 12 small asteroids that pass close enough to Earth that they could be corralled into the L1 or L2 Lagrangian points for mining operations. The researchers dubbed these asteroids Easily Retrievable Objects (EROs).
Lagrangian points are regions of space where the gravity of the Earth and another celestial body balance out. If you place something in a Lagrangian point, it stays put. That’s exactly what you want if you’re going to start drilling into an asteroid. The L1 and L2 Lagrangian points are where the gravity of Earth and the sun are at a draw. They are about 1 million miles from Earth, or about four times the distance to the moon.
The 12 candidate asteroids are in orbits that take them near the L1 or L2 Lagrangian points, so they would need only a small push to get them to the right spot. Yarnoz and his team estimate that changing the velocity of these objects by less than 500 meters per second would be sufficient – some would take substantially less effort. One ERO called 2006 RH120 could be captured by changing its velocity by only 58 meters per second. This could be completed as early as 2026.
One of the important criteria in filtering the database of 9,000 near-Earth objects down to the 12 mineable asteroids was size – we simply don’t have the technology to safely nudge a large asteroid into a Lagrangian point. There will be no mega-sized mining platforms spanning a one-kilometer asteroid in the near future. Most of the EROs identified by the study are in the two to 20 meter range, but that’s still large enough to contain substantial resources.
These 12 objects are probably a small fraction of EROs floating around near Earth. We know where many more of the big space rocks are because they’re much easier to see, but there might be a wealth of resource-rich small asteroids near the Lagrangian points ripe for the picking.
