kragenpoboxcom kragen sitaker eugen leitl writes apart twiddling surface albedo might enough currently dont ion drives enough power least cant develop deploy time estimate worst case 17 years 54e8 seconds move one earth radius 6000 km 6e6 t22 x remember right 2xt2 12e7 m29e17 s2 41e11 ms2 large acceleration roughly equivalent gravitational acceleration parts divided 200000000000 assuming 2kmwide 20 000 decimeterwide spherical asteroid specific gravity 10 43 pi r3 says would volume 4e12 cubic decimeters thus mass 4e13 kg force wed apply achieve acceleration would roughly equivalent weight 200 kg earth yeah ion drives probably nogo unless screwed calculations think force typically exert four orders magnitude small wanted hit today enough impulse would miss us 17 years later wed need accelerate 11 cms oneton 1000kg mass would need hit 4e9 ms ten times speed light achieve thats possible could actually put enough work oneton mass approached speed light would mass could still oneton mass dont anything approaching speed impulse required inversely proportional remaining time impact hit half time elapsed wed need accelerate around 22 cms instead gravitational force earthsized mass could provide sufficient deflection mass 45e5 times far away asteroid earths center 27e9 0018 times distance earth sun 0018 au mass stayed nearby 17 years effects continuous acceleration benefit greatly planning ahead since scale t2 thus needed acceleration scales 1t2 half time elapsed wed need four times much acceleration make miss earth start accelerating numbers little low earth presents slightly easier target physical size suggests due gravity well much easier depends speed projectile ways dont understand theyre also little high assume force applied purely right angles asteroids current path slightly suboptimal scenario although velocity changes five orders magnitude smaller relative velocity difference probably insignificant assume effects asteroids path electrical charges could electrically charge asteroid another nearby asteroid perhaps electron beams provide needed acceleration course calculation could applied direction want sock moon colony oneton asteroid could tiny amount force applied twentyfive years adjust orbit spam im sorry admit havent implemented better solutions im afraid ill allow nonsubscriber fork mail detained scanning hope measure reversed soon time implement better measures often noted posters measures reduce spam sent fork list significantly decrease spam load forkposters since vast majority spam received forkposters sent directly fork list kragen sitaker silence may golden least quiet dont speak unless improve silence often regretted speech never silence ancient philosopher syrus via adam rifkin httpxentcommailmanlistinfofork thu 25 jul 2002 045639 0400 edt asteroids anyone