Free Astronomy Magazine July-August 2018

JULY-AUGUST 2018 ardous asteroids − the only goal of these surveys is to determine the orbits, and not the composition, of those objects. The sec- ond factor is that NEAs are generally discov- ered only when they are at their maximum brightness. Because their apparitions are very fleeting, there is usually no opportunity to observe the brightened NEAs long enough and deepen our knowledge of their chemi- cal and surface properties before they be- come invisible to any telescope. Without spectroscopic observations, it is impossible T he possible mining of a small asteroid could involve its entrainment in a region of space easily reachable from the Earth, as is the vision of Deep Space Industries. This strategy avoids having to follow the object in its orbit around the Sun.