Near-Earth Asteroids -- Solar System Dynamics
or Fun with Cosmic Cannonballs
One application of PEP that may someday be supremely "practical" is the
study of orbits of "near-Earth" asteroids. The Earth is continually
encountering interplanetary debris of various sizes. Although the rarity
increases with size, we know there are asteroids big enough to cause a
catastrophe if they collided with the Earth. Because of the perturbing
influence of the major planets, the asteroid orbits tend to "wander", and
the calculation of whether (or when) a particular object might impact the
Earth may require extremely accurate knowledge of the orbit, such as can be
provided by radar observations. On several occasions, we have collaborated
in efforts to use radar to observe newly-discovered objects approaching
very near the Earth. Such objects are generally within range only for a
matter of days or weeks, and we must race to gather enough optical
observations to predict the positions and velocities well enough to point
the radar systems at the targets. Some of these efforts have been
spectacularly successful. Eventually, as more powerful radars become
available, it may be possible to set up a sort of "cosmic early warning"
system.
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