> lumps of asteroid aren't exactly known for being aerodynamic, making reentry calculations pretty unreasonable. As long as you're cutting it, you could make i

> lumps of asteroid aren't exactly known for being aerodynamic, making reentry calculations pretty unreasonable. As long as you're cutting it, you could make it somewhat aerodynamic. However, you have to remember a lot of the time you want reentry vehicles (or rocks) to be round so that they get down in good condition. In addition, you don't need to just fire it off into earth; you can attach a computer and small rockets to it so it can subtly and cheaply correct its own course. The energy you would need for this can be arbitrarily small: http://en.wikipedia.org/wiki/Edward_Belbruno http://en.wikipedia.org/wiki/Edward_Belbruno