Near Earth Objects
Near-Earth objects (NEOs) are meteoroids, asteroids, and comets whose orbits lie close to -- and sometimes cross -- Earth’s. Impact craters on Earth bear witness to the destructive potential of NEOs. The hazard posed by NEOs has captured the professional attention of not just astronomers but also geologists, biologists, mission planners, aerospace engineers, and even the United States Department of Defense. The public is increasingly aware that Earth resides within a cosmic shooting gallery. The crash of Comet Shoemaker-Levy 9 into Jupiter in 1994 provided proof that cosmic collisions do occur.
Yet NEOs also represent a hitherto untapped resource for the future exploration of our solar system. Lying close to Earth in space and having negligible gravity, NEOs represent an abundant source of raw materials such as metals and water waiting to be harvested for space-based construction.
What are NEOs? How many are there? Where do they come from? Do any of them pose any real threat to Earth? What do we do if one is found to be on a collision course? Can we move them? Can they provide viable space resources? These questions are now under investigation by planetary scientists.