Stardust memories
ENGLISH GETS its word comet from the Greek word for long-haired. On Jan. 15, a NASA spacecraft that had sailed through the long hair of a comet sent back to Earth a canister with dust from that fly-by. Last week scientists opened the container and, to their joy, found thousands of dust samples that will provide clues to the formation of the solar system. The probe, the first to bring extraterrestrial material back to Earth from outside the orbit of the moon, vividly demonstrates the scientific value of robotic projects that do not bear the risk and expense of manned missions.
Moving in space beyond the planets, the ice and dust that make up comets are hieroglyphs of an event -- the solar system's birth --that occurred 4.5 billion years ago. The Stardust spacecraft also gathered interstellar particles during its flight, which began seven years ago. Comparing those particles with the ones collected while approaching within 149 miles of the comet named Wild 2 should be particularly interesting to researchers. The comet, by the way, owes its name to a Swiss scientist, not to any unpredictable behavior on its part.
On Thursday, NASA launched its New Horizons spacecraft -- also unmanned -- on a journey of 9 1/2 years to the solar system's most distant planet, Pluto. New Horizons will be the first probe into the Kuiper Belt of rocky, icy objects orbiting the sun. It, too, should provide information about material that possibly harbors some of the elements instrumental in the original formation of life.
Both Stardust and New Horizons have survived cost-cutting at NASA necessitated by its new mandate from President Bush to plan manned flights first to the moon and then to Mars.
Another project, the Deep Space Climate Observatory, has fallen victim to what NASA calls ''competing priorities." The observatory was to have been located at the gravity-neutral point between the Earth and the sun, about 1 million miles from Earth. From that vantage, it could have monitored this planet's energy balance, proving or disproving the theory of those who contend that natural variations in the sun's output of energy are causing global warming, not the emissions of greenhouse gases by industry and vehicles.
It is regrettable that finances will keep scientists from getting this, and other, information from the observatory. But in the meantime, the comet dust will be a gold mine to other scientists. Lead Stardust investigator Donald Brownlee of the University of Washington, in Seattle, said he was pleased in particular by the size of the particles. As many as a dozen, he said, could be ''larger than human-hair size." Dust that is wider than a hair will tell us much about the long hair of Wild 2 and the birth of our world. 