Nine Hundred Asteroids in Near-Earth Orbits

SEWilco writes: "This Discovery.com item points out a new estimate of 900 asteroids in orbits closer than Mars. Cornell University's William Bottke did a new study of The Spacewatch Project's small-object search. This estimate says that we've found 40% of the nearby asteroids. Well, I'm glad that we've started looking before a disaster, unlike 'Rendezvous With Rama'." Or "Lucifer's Hammer."

Comments

Looks Like They wanted to Copy My website

[szyzyg]

Http://szyzyg.arm.ac.uk/~spm/neo_map.html

Delivering a dose of harsh reality to the world for the last 2 years ;-)

The important thing about the asteroid threat is that it's one of the few dangers to the human races that
(a) Can Kill us All
(b) We Understand
(c) We have a remote chance of avoiding using modern technology

But Fundamental to this all is the fact that we need to get as much wartning as possible - that's why we should be spending more money on telescopes and serach programs.

In fact - we're so underfunded that I've been seduced away from my job of 'saving the world' to go and work at myplay.com.....

So you know which Music serivce provider to blame when armageddon comes calling.

Deflecting asteroids

[XNormal]

Ok, you find a dinosaur killer on a collision trajectory with the Earth. It will hit us in 18 months. What do you do now?

It looks like the only technology that could possibly pack enough energy to deflect an object with such momentum is a nuclear bomb. Isn't it ironic that the same technology that brought us the possibility of destroying life on planet Earth could also save it?

A few years ago I did a few back-of-the-envelope calculations to see what would be required to deflect an object a few kilometers in size. Naturally, the delta-V you need to deliver depends on how early you can catch it. If it's still very far you need just a little nudge to ensure it won't collide. It also depends on what margin for error you want to tolerate i.e. how far from Earth do you want it to pass.

It looks like some of the bigger H-bombs have the energy to do it. The problem is how to convert it efficiently to kinetic energy. If you blow up a nuclear bomb in space all you get is a fantastic flash. The relatively small mass of the device itself evaporates and disperses into the vacuum in a matter of milliseconds. You need mass to convert this energy into motion. Using the mass of the asteroid itself is dangerous - if you blow up your bomb too close to the object it could break into many fragments with different orbits. Many of them could still hit the Earth. Splitting it neatly in half Armageddon-style is not very likely :-).

So you need to bring your own reaction mass. The bomb will be accompanied by some big tanks of water. I don't remember the calculations, but you need quite a lot of reaction mass. It appeared to be more than what current launch vehicles can handle.

Have a nice day.


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