# How Much Could You Deflect the Path of a 500 meter Diameter Asteroid with 100 STAR48 Rocket Motors

Assume we detected a 500 meter diameter asteroid hurling toward Earth at 10 Km/sec (about half the speed of the asteroid that wiped out the dinosaurs). Assume it has a density of 2.4 g/cm and that we detected it very far away, so we have 6 months before impact. We send a ship out to match speed and land on it. Fortunately, it's rotating very slowly, say once every two hours. We mount 100 Star48 rocket motors in a position that will be perpendicular to its current direction of travel when we light them. The combined specific impulse for 100 Star48s is 57.5e6 Kgf-sec. If the firing is successful, how much have we deflected its path?

There is currently an active question about a possible extinction level asteroid heading toward Earth. A nuclear explosion might break the asteroid apart. I would like to know if a rather low tech solution has any merit, or not.

• When it comes to deflecting asteroids, 6 months is very little time. For 500 m you'd hope for 10 years, maybe. Sep 30, 2021 at 13:46
• "We send a ship out to match speed and land on it." This will probably take more than 6 months.
– Rodo
Sep 30, 2021 at 16:37
• If it turns out that the real answer to this question is: "If a 500 m diameter asteroid heading toward Earth at 10 Km/sec is discovered just 6 months before impact, there's really not anything you can do about it". That's a depressing, but useful thing to know. Sep 30, 2021 at 16:44
• back of the envelope calc says you can change its velocity by 4mm/s... Sep 30, 2021 at 17:44
• "A nuclear explosion might break the asteroid apart" well, yes. That's not necessarily a bad thing though, as it'll spread the bits out over a range of trajectories man of which won't hit Earth, and the bits that do are less likely to successfully reach the surface. Oct 1, 2021 at 10:34