Bringing home the goods

Instead of trying to mine a distant asteroid, how about we bring the asteroid to Earth? NASA’s ill-fated Asteroid Redirect Mission (ARM) was an attempt to do just that. The goal of the mission was to grab a four-metre (13-foot) boulder from a nearby asteroid and return it to cislunar space – between the orbits of Earth and the Moon – where we could then study it at our leisure. To move the boulder, ARM would use solar electric propulsion, with solar panels absorbing sunlight and converting it into electricity. That electricity would power an ion engine. It wouldn’t be fast, but it would be efficient – and it would eventually get the job done. Unfortunately, in 2017, NASA cancelled ARM. Some of the critical technologies wound up in other projects, like the OSIRIS-REx mission to the asteroid Bennu, and NASA continues to investigate and use ion engines.