How are asteroids like the Apophis tracked?

Question

What are the limitations in current technology?

Answer 1

The six stations mentioned by Nick S are 36" telescopes. They are monitored by people and computers to look for anything that moves relative to the stars or anything that doesn't belong where it is.

Once an object is discovered, a call goes out to other observatories to zoom in on it and get exact fixes on its location. With several precise sightings, we can approximate the orbit and project it into the future until it passes close enough to a planet to have its orbit altered.

When the gravity of a planet alters the orbit of an asteroid, certainty goes out the window. We calculate the full range of possibilities, given our present knowledge of the orbit. If it looks like a collision with Earth is possible, then we give it a higher priority and try to reduce our uncertainty enough to rule out any possible collision with Earth. When an asteroid comes close enough, we can detect it with long-range radar, which improves our certaintly still more.

In the case of Apophis, we have not completely ruled out a possible collision with "Earth on April 13, 2036; so NASA is considering whether to launch a mission to place a radio transponder on Apophis. This would greatly improve our accuracy. Such a mission would have to be done within about a decade, so it can tell is if we should attempt to deflect Apophis away from Earth. The last opportunity to deflect it will be April 13, 2029. After than, it will take a much greater shove to have an appreciable effect.

Answer 2

It is all done with CCD technology now with half dozen stations worldwide reporting to NASA.

Basically photos are taken of all parts of the sky constantly, and the computers compare the pics taken at different times of the same piece of sky and identify objects that have changed location. The positions of the identified objects are checked against the database of known objects, and if one is a newly identified object, it is tracked over time to ascertain its orbit.

The equipment is not limited. What is limited is the amount of stations, and the amount of money put into the quest - a tiny fraction of the space budget for soemthing that could save millions of lives.

See http://neo.jpl.nasa.gov/cgi-bin/neo_ca

for the site that shows all the identified near-Earth asteroids.

Answer 3

Well, if they continue to shortchange science in this country, we'll be limited to saying "There it is!" as the rock comes burning into the atmosphere.

Answer 4

I am really not sure. I will stay up tonight and look for a clue to this mystery.