Asteroid 4179 Toutatis Will Miss Earth, This Time

EtherAlchemist writes "National Geographic News reports in this story that a giant, peanut shaped asteroid known as 4179 Toutatis will pass within 1 million miles of Earth on Weds, the 29th. When it does, it will be the closest any known object of this size (3 miles) has passed near Earth in this century. No worry about impact yet, it should pose no threat until at least 2562. An interesting note: the asteroid believed to have caused Earth's biggest mass extinction is thought to have been between 3.7 and 7.5 miles as reported here in 2001." 2004 FU162 came closer, but is a much smaller object.

Comments

what if...?

[rokzy]

what if we knew for sure we would be hit in 500 years? that's long enough to be none of our problems. so would people say "fuck them" and just leave it to some other generation to sort out, or be willing to pay for a huge programme to deflect/destroy it?

it's a similar problem to global warming, except there are no asteroid-impact-dependent business models funding research and laws like with oil.

Moon?

[OgGreeb]

Does anyone ever run trajectory calculations for a strike on the Moon, rather than Earth? And what size Moon strike would cause problems here? Could the moon eject a chunk in our direction sufficiently large to be a problem? For that matter, what would happen to the Moon in that situation?

Too many questions -- no idea of the impact (pun intended.)

What painting does

[Engineer-Poet]

There are a few matters of physics that you have to know for this to make sense:

1. Both solar and thermal radiation exert pressure.
2. The incoming solar radiation pushes away from the Sun, but the thermal re-radiation from the asteroid pushes away from the hottest parts.
3. Asteroids rotate, so the thermal-radiation pressure is not directly away from the Sun but away from the "afternoon" part. The lower the albedo (darker) and the greater the thermal conductivity (lag between peak insolation and peak temperature), the greater the difference between the direction to the Sun and the thrust vector.

By painting the asteroid whiter (or, in theory, darker) you change the amount of heat absorbed and thus the ratio between the thrust from the reflected light (tracks exactly with incoming light) and the thrust from the radiated heat. Given enough time this will let you change the orbit of the rock enough to miss (or possibly hit) what you want it to. This works best with smaller bodies and long (very long) lead times.