# Redirecting asteroids on an impact course by momentum transfer **URL:** \ **Category:** Factual Questions\ **Created:** [December 17, 2017, 4:53pm UTC](https://boards.straightdope.com/t/redirecting-asteroids-on-an-impact-course-by-momentum-transfer/804718 "2017-12-17T16:53:54Z")\ **Posts on this page:** 1\ **Showing post:** 56
**Author:** ![SamuelA](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@SamuelA](https://boards.straightdope.com/u/SamuelA)\ **Post date:** [December 19, 2017, 8:43pm UTC](https://boards.straightdope.com/t/redirecting-asteroids-on-an-impact-course-by-momentum-transfer/804718/56 "2017-12-19T20:43:45Z")
> [@Machine\_Elf](#): > > So…ten years’ warning? Even assuming sufficient motivation, it’ll be at least two years before your first nuke leaves the earth, and it’ll be several more years before it gets to the asteroid. At which point the asteroid is no longer ten years out, it’s more like four years out, and now needs a pretty big nudge to assure a miss. But the rest of your nukes are going to arrive later, when the asteroid is even closer. I think it’s pretty optimistic to believe that we could build/launch rockets the size of the Saturn V at intervals shorter than six months, so you’re only going to get a handful of nukes up to the asteroid before it lands in your front yard. I think this is a reasonable analysis. Obviously this is a bad case scenario. My main point was really that each nuke you set off is getting you more push per kilogram of payload mass. Also, I had implicitly assumed you were going to spend the propellant to brake, but your idea is better - just fly by and set off the nuclear shaped charge at the right nanosecond. And yeah, you would have to pick the patch you set it off next to carefully, apparently the material type matters. --- _[View the full topic](https://boards.straightdope.com/t/redirecting-asteroids-on-an-impact-course-by-momentum-transfer/804718)._