Asteroids in Cold Space: To See Them, Feel the Heat
by Todd Jackson
Here we are, days past the Mayan apocalypse and none the worse for it. Of the ways we all studied as potential means for that globe-bestriding destruction, there’s one that’s been sure to get headlines: massive near-earth asteroids. Part of the danger – for apocalypse-scenario enthusiasts, part of the fun – has always been the problem that comparatively small objects against open cold space are so hard to see. Now a private group, the B162 Foundation, is making plans to join NASA efforts to use the heat signatures the asteroids generate as they move through space as a way to spot them decades before they, as it were, spot us.
The ascension of infrared in spotting asteroids is part of the legacy of NASA’s Wide-field Infrared Survey Explorer, which operated in 2010 and 2011, taking nearly two billion images. Able to “see through” dust that obscures visible light, and able to see dark-bodied asteroids, WISE contributed profoundly to our understanding of asteroids. While its sensors weren’t as advanced or sensitive as those aboard the Spitzer Space Telescope, the European Herschel Space Observatory, or the upcoming James Webb Space Telescope, WISE had the advantage of being able to take a panoptic, wide view of a great breadth of space all at once. This is much more effective for spotting NEOs than the 1%-of-sky slow crawl approach favored by most telesopes peering into deep space for very distant objects. The WISE mission suggested a population of between 3200 and 6200 asteroids larger than 100 meters. We have currently identified no more than 30% of them. We feel safe that nothing the size of a Tu is likely zeroing in on us for at least the next 40 years.
Now, a private group, the B162 Foundation, intends to build upon the principles of WISE and give us the most comprehensive view of near-Earth asteroids yet. B162 looks to launch its Sentinel space telescope aboard a SpaceX Falcon by 2018. It aspires to
catalog 90 percent of the asteroids larger than 140 meters in Earth’s region of the solar system. The mission should also discover a significant number of smaller asteroids down to a diameter of 30 meters
The heat picked up by infrared telescopes is not like just the result of the slow effect of sunlight, but because objects moving through space generate an electrical charge. The results of the 2005 NASA Deep Impact collision into Comet Tempel 1 have further ramifications concerning the origin of comets and meteors, and indeed whether there is any distinction between them. For our purposes, what matters is that we have an enhanced ability to spot them using infrared.
As long as we have years, and particularly decades, of forewarning against any meteor impact, moving it off-course appears to be a simple, if not easy, proposition. The favored idea is to nudge it slightly off-course, using either charges or rockets. NASA is even considering capturing an asteroid in open space and placing it in a stable orbit around the Moon.
Interest in asteroids exceeds the mere threat they might pose to Earth. They also offer great stores of water and mineral wealth – though the results of Deep Impact might sober us of our expectations for finding water. Asteroids are known to contain great caches of iron, nickel, cobalt, and platinum-grade metals, as well as an abundance of other substances. These could provide raw materials for Earth, or they could provide raw materials to be used off-Earth without the great trouble of sending those materials through expensive rocket launches overcoming Earth’s massive gravity well.
Now a private space company is looking to get a toe-hold into asteroid mining and turn it into a business. Planetary Resources has ambitions for near-Earth asteroids, of which “1,500 are as easy to reach as the Moon and are in similar orbits as Earth.” The company’s first commercial product, a LEO Space Telescope that will contribute to the search for dangerous objects, but whose precision imaging system gives it a particular capacity to prospect asteroids, identifying which are most valuable.
Clearly, the window within which Earth can become seriously impacted by asteroids is narrowing. This leaves us with a wonderful range of potential planetary disasters still intacted for film-makers and nail-biters everywhere. It also leaves us with a greater understanding of the staggering wealth in natural resources than we had ever believed possible.