http://games.groups.yahoo.com/group/sfconsim-l/ SFCONSIM-L Sat, 21 Nov 2009 00:08:43 GMT michael scott http://games.groups.yahoo.com/group/sfconsim-l/message/82309 http://games.groups.yahoo.com/group/sfconsim-l/message/82309 remember Kahoutec, the big head with no tail? how many gas poor comets of interstellar origin might we have missed over the last 400 years? ... [Non-text Fri, 20 Nov 2009 23:42:24 GMT Erik Max Francis http://games.groups.yahoo.com/group/sfconsim-l/message/82308 http://games.groups.yahoo.com/group/sfconsim-l/message/82308 ... Sure, the velocities _could_ be high, and usually would be. But my point was they don't _have_ to be. Lack of hyperbolic comets with very high hyperbolic Fri, 20 Nov 2009 22:34:24 GMT Henry Cobb http://games.groups.yahoo.com/group/sfconsim-l/message/82307 http://games.groups.yahoo.com/group/sfconsim-l/message/82307 ... Yes and no relativistic packages from the home system are needed for the harvesting. Assuming magsail drive you can launch the "impactors" at ZERO delta-v Fri, 20 Nov 2009 22:14:03 GMT linguofreak http://games.groups.yahoo.com/group/sfconsim-l/message/82306 http://games.groups.yahoo.com/group/sfconsim-l/message/82306 ... Actually, I think this is something Henry got right in this whole exercise. Even the nearest stars, which are (with the exception of a few halo stars) Fri, 20 Nov 2009 22:10:18 GMT Isaac Kuo http://games.groups.yahoo.com/group/sfconsim-l/message/82305 http://games.groups.yahoo.com/group/sfconsim-l/message/82305 I now think that the ideal candidates for interstellar colonization are stars with close orbiting companions--either a warm Jupiter or close orbiting star. Fri, 20 Nov 2009 21:25:43 GMT Erik Max Francis http://games.groups.yahoo.com/group/sfconsim-l/message/82304 http://games.groups.yahoo.com/group/sfconsim-l/message/82304 ... Not necessarily. Depends entirely on the original orbit of that comet. A comet in a similar orbit around the Galaxy to the Sun's would be observed to have Fri, 20 Nov 2009 21:16:20 GMT Erik Max Francis http://games.groups.yahoo.com/group/sfconsim-l/message/82303 http://games.groups.yahoo.com/group/sfconsim-l/message/82303 ... I don't specifically know either, but I agree the logical answer is probably "both." -- Erik Max Francis && max@... && http://www.alcyone.com/max/ Fri, 20 Nov 2009 19:22:35 GMT Brian York http://games.groups.yahoo.com/group/sfconsim-l/message/82302 http://games.groups.yahoo.com/group/sfconsim-l/message/82302 ... Interestingly, that paper derives an upper limit of 6e-4 solar masses per cubic parsec which, given the density I suggested (1.83e8 comets per cubic Fri, 20 Nov 2009 18:53:31 GMT Henry Cobb http://games.groups.yahoo.com/group/sfconsim-l/message/82301 http://games.groups.yahoo.com/group/sfconsim-l/message/82301 ... I'd be more ready to lean inwards such that it has to have a visible tail, but at that point you've got all of recorded history to work from. ... What's Fri, 20 Nov 2009 18:28:27 GMT Brian York http://games.groups.yahoo.com/group/sfconsim-l/message/82300 http://games.groups.yahoo.com/group/sfconsim-l/message/82300 ... Not at all. What I'm saying is that, at the moment, there's no evidence that, even if other stars on average lost the same fraction of their comets as we Fri, 20 Nov 2009 17:03:11 GMT Henry Cobb http://games.groups.yahoo.com/group/sfconsim-l/message/82299 http://games.groups.yahoo.com/group/sfconsim-l/message/82299 ... My bad. 30 million out of a trillion is only 0.003% So Sol is a very special case as it has had exactly the right qualities to generation lots and lots of Fri, 20 Nov 2009 16:56:35 GMT Henry Cobb http://games.groups.yahoo.com/group/sfconsim-l/message/82298 http://games.groups.yahoo.com/group/sfconsim-l/message/82298 ... So only three percent of all comet-bodies are shed by each star throughout its lifetime? -HJC Fri, 20 Nov 2009 16:30:12 GMT Brian York http://games.groups.yahoo.com/group/sfconsim-l/message/82297 http://games.groups.yahoo.com/group/sfconsim-l/message/82297 ... Well, let's do a bit of back-of-the-envelope calculating to see what we would expect to find. Let's say that we would detect a comet if it came within a Fri, 20 Nov 2009 16:19:18 GMT David McMillan http://games.groups.yahoo.com/group/sfconsim-l/message/82296 http://games.groups.yahoo.com/group/sfconsim-l/message/82296 ... I assume it wasn't *carried* on the tether. Actually, that doesn't sound like a terribly bad idea, as long as the separation tests showed consistent Fri, 20 Nov 2009 15:43:32 GMT linguofreak http://games.groups.yahoo.com/group/sfconsim-l/message/82295 http://games.groups.yahoo.com/group/sfconsim-l/message/82295 ... We see lots of comets being shed by Sol because they all have to come in close enough to interact with one of the planets to be shed. But once it's been