Slashdot Mirror

← Back to Stories (view on slashdot.org)

US To Shoot Down Dying Satellite

Posted by Zonk on from the we-who-may-be-about-to-reenter-orbit-salute-you dept.

A user writes "US officials say that the Pentagon is planning to shoot down a broken spy satellite expected to hit the Earth in early March. We discussed the device's decaying orbit late last month. The Associated Press has learned that the option preferred by the Bush administration will be to fire a missile from a U.S. Navy cruiser, and shoot down the satellite before it enters Earth's atmosphere. 'A key concern ... was the debris created by Chinese satellite's destruction -- and that will also be a focus now, as the U.S. determines exactly when and under what circumstances to shoot down its errant satellite. The military will have to choose a time and a location that will avoid to the greatest degree any damage to other satellites in the sky. Also, there is the possibility that large pieces could remain, and either stay in orbit where they can collide with other satellites or possibly fall to Earth.'"

2 of 429 comments (clear)

  1. China's debris to remain for thousands of years... by KH2002 · · Score: 5, Informative

    The satellite the Chinese shot down was in a much higher orbit, and that debris is likely to stay up for *hundreds* of years... It's worse than that -- according to MIT space security expert Geoffrey Forden, "China's debris will be in orbit for thousands of years (and I mean that literally). ... [The US shoot-down] would create a debris field but no where near the sort of debris catastrophe that China created last year."

    The two shoot-downs are not equivalent, which of course won't prevent agenda-driven comparisons...

  2. Re:Target practice or....? by Anonymous Coward · · Score: 5, Informative

    Short answer: No

    Longer answer: The orbit of a satellite can be determined by the position and the velocity at any time. Orbits are changed by changing the velocity of a satellite, but the old and new orbits will continue to intersect at the point where the velocity was changed.

    Changing to a higher orbit will require two changes in velocity and uses a transfer orbit that intersects both orbits. One velocity change puts the satellite into the transfer orbit and one velocity change puts it into the final orbit. Usually, the two velocity changes are at opposite sides of the transfer orbit (half an orbit period apart).

    I assume that this will use a warhead instead of a rocket motor for a single change of velocity, but there will only be one change of velocity. If the intercept takes place at lowest point of the current orbit then any debris will be in an orbit that will return the debris to the point of intercept. If it is already brushing the atmosphere then reentry is inevitable and the time to reentry will only depend on the ratio of the mass to air drag of the object (small heavy objects will stay in orbit longer).

    Normal precautions of staying out of the temporary orbits of the debris does apply.

    _Richard