On Saturday, the National Aeronautics and Space Administration is to launch a probe meant to capture interplanetary and interstellar dust in some of its rawest and purest forms, including many thousands of grains from a comet. After a seven-year trek, the craft is to return the samples to Earth, the first ever from beyond the Moon. Appropriately enough, the mission is dubbed Stardust. It's the building block of planets and human bodies. The urge to investigate is driven by more than curiosity.
Earth sits in a cosmic shooting gallery, surrounded by speeding blocks of ice and rock.
Today, scientists are seeking to learn more about comets and other clumps of star dust in case earthlings might one day want to divert one of the intruders, which can threaten more ruin than all the world's nuclear arsenals combined. Most intriguing of all, scientists hope a harvest of Stardust data will yield clues to the origin of life on Earth, and perhaps elsewhere. A rain of cosmic and cometary material is widely thought to have brought early Earth not only water but the carbon-rich molecules necessary for life. Indeed, some scientists believe the speeding mountains of dirty ice known as comets may themselves support primitive life. While highly speculative, such thinking has been bolstered ever so slightly in recent years by the discovery of earthly microbes dwelling in all manner of extreme environments from hot springs to polar ices.