On Mar 6, 5:03 pm, bob haller <hall...@aol.com> wrote: > On Mar 6, 12:27 pm, Robert Clark <rgregorycl...@yahoo.com> wrote: > > > Assuming comet C/2013 A1 misses Mars by 37,000 km how much delta-v > > would you need to nudge it to hit Mars? > > > This might not be purely of academic interest. Already we've seen two > > Earth encounters whose likelihood together was one in hundreds of > > millions. > > > This comet to make a close encounter to Mars is *huge*. To put it > > perspective it dwarfs the asteroid that destroyed the dinosaurs. Such > > close encounters to any of the terrestrial planets must be very rare. > > > For instance the puny, in comparison, asteroid 2012 DA14 would be > > expected to get so close to the Earth once in 40 years. That such a > > large comet would get so close to Mars must be much rarer than this. > > So the chance is less than 1 in 40 in a year. Say it happens for > > either of two planets; that's a chance of less than 1 in 20 in a year. > > Say then it happens within a 2 year period; that's 1 chance in 10. > > > Now the chance of the three encounters occurring within such a close > > time span is greater than one in several billion. The unlikelihoods > > begin piling up greater and greater. > > > Then we are left with the disturbing possibility there is a physical > > phenomenon causing these large, close encounters. And the possibility > > arises there is another large, close encounter to the Earth that may > > be upcoming. > > > It would really become important to know then not what's the delta-v > > needed to turn a close miss to an impact, but in fact the reverse. > > > Bob Clark > > Well aiming hazardous comets and asteroids at mars or other planets > may be a good way to get rid of hazards.... > > theres a theory the earth has a planet killer type event every 34 > million years or so. A couple weeks ago I posted we may be entering a > littered part of space.