Nearly all asteroids are so far away and so small that the astronomical community only knows them as moving points of light. The rare exceptions are asteroids that have been visited by spacecraft, a small number of large asteroids resolved by NASA's Hubble Space Telescope or large ground-based telescopes, or those that have come close enough for radar imaging. When seen by optical telescopes, these individual sources of reflected sunlight can provide some very valuable but also very basic information -- for example, the asteroid's orbit, a ballpark estimate of its size, sometimes an approximation of its shape, and perhaps an idea of its physical makeup. But to learn more about these elusive and important celestial objects requires a different type of instrument. An infrared sensor can, in the right circumstances, not only provide data on an asteroid's orbit and data that can be used to more accurately measure its size, but also chemical makeup and sometimes even its surfac...