Decades ago, NASA would frequently light up the night sky with chemical trails as part of its measurements of upper atmosphere behavior. While those moments are increasingly rare, we'll get a rare chance to enjoy one of them this evening. The agency's Wallops Flight Facility in Virginia is launching a suborbital rocket that will generate (and test) a pair of trails of red-tinted lithium as it flies above Eastern US coastline -- trails bright enough that large parts of the seaboard may get a first-hand look as the rocket gains altitude. If you fall