Reports from the second trienniel Planetary Defence Conference. Sounds good ! :-). In this case the baddies are large "Near Earth Objects" over 140m in diameter that pass within 1.3 earth-sun distances from the sun. I like "One of the complications is just getting to the asteroid, which is much harder when it chooses us, as opposed to us choosing it. " Russell _______________ Some interesting material. Outline material only but no doubt enough information for Gargoyle to use: Various methods of interception and deflection are discussed. " ...On the question of how to protect against an identified threat, the opinions seemed to fall toward using the gravity tractor or the ballistic impact in preference to nuclear explosives. ..." " All three of these deflection technologies need to be developed, however, since they have very different capabilities, and we are dealing here with a huge range of NEA sizes and orbits. One of the complications is just getting to the asteroid, which is much harder when it chooses us, as opposed to us choosing it. The gravity tractor must match orbits (rendezvous) with the target. In contrast, the kinetic impactor does not need to slow down near the asteroid, but it does have to hit a small target at high speed. Nuclear charges would normally be used from a rendezvous spacecraft, but in extreme cases might be deployed like kinetic impact, with a high-speed intercept. There is no "one size fits all" solution. " " Mark Boslough (Sandia) discussed interesting simulations of atmospheric explosions such as Tunguska. Noting that the fireball from a meteor explosion has considerably downward momentum (unlike the classic mushroom cloud from a nuclear explosion), he concludes that the Tunguska impactor exploded higher and was smaller (energy of order 5 megatons) than usually inferred." ___________________ From: > -- NASA ARC NEO News (03/09/07) Planetary Defense Conference Part 2 > http://www.spaceref.com/news/viewsr.nl.html?pid=23570 > -- NASA ARC NEO News (03/07/07) Planetary Defense Conference > http://www.spaceref.com/news/viewsr.nl.html?pid=23569 > -- NASA Near-Earth Object Survey and Deflection Analysis of > Alternatives Report to Congress > http://www.spaceref.com/news/viewpr.nl.html?pid=22088 > > "The objectives of the George E. Brown, Jr. NEO Survey Program are > to detect, track, catalogue, > and characterize the physical characteristics of NEOs equal to or > larger than 140 meters in > diameter with a perihelion distance of less than 1.3 AU > (Astronomical Units) from the Sun, > achieving 90 percent completion of the survey within 15 years after > enactment of the NASA > Authorization Act of 2005. The Act was signed into law by President > Bush on December 30, > 2005." -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist