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  1. 19567

    Why slam a copper impactor into Comet Tempel 1? Wouldn’t copper vapor contaminate the spray? Why not a high-temperature ceramic? P.M. deLaubenfelsCorvallis, Ore. According to Casey Lisse of the Deep Impact team, copper was chosen because its density put a lot of mass into a small package, its relative softness reduced bounce at impact, and […]

    By Science News
  2. Planetary Science

    A Grand Slam

    A 372-kilogram copper projectile released from NASA's Deep Impact spacecraft successfully slammed into Comet Tempel 1 on July 4, producing some heavenly fireworks.

    By Ron Cowen
  3. Math

    Air Transport Central

    The world's air transportation network resembles the Internet.

    By Ivars Peterson
  4. Health & Medicine

    Epilepsy surgery stands test of time

    Brain surgery for people with severe epilepsy keeps many of these patients free of seizures for decades.