Astronomy Picture of the Day

Explanation: This carrot shaped track is actually little more than 5 hundredths of an inch long. It is the trail of a meteroid through aerogel exposed to space by the shuttle launched EURECA (European Recoverable Carrier) spacecraft. The meteoroid itself, about a thousandth of an inch in diameter, is visible where it came to rest, just beyond the tip of the carrot (far right). Chemical analyses of interplanetary dust particles similar to this one suggest that some of them may be bits of comets and represent samples of material from the early stages of the formation of the Solar System. NASA's Stardust mission, planned for launch in 1999, will attempt to directly collect dust from the tail of a comet and return it to Earth -- the first non-lunar sample return mission ever! In addition to peering into the chemistry and history of the solar system, the composition of cometary dust has important implications for the possibility of past life on Mars.