It’s a moment University of Washington astronomy professor Donald Brownlee has been awaiting for nearly two decades. If all goes as planned, that moment will arrive Saturday afternoon when a Boeing Delta II rocket, with “University of Washington” emblazoned on the side, sends a desk-sized spacecraft on a seven-year journey to rendezvous with a comet.
Stardust is scheduled to launch from Cape Canaveral, Fla., at 1:07 p.m. PST, and UWTV will provide live coverage. The mission, selected in 1995 by NASA as part of its Discovery series, aims to capture particles from comet Wild 2 (pronounced Vilt 2) and return them to Earth for analysis in laboratories at the UW, NASA and around the world. There’s much to be learned, Brownlee said.
“People have long suspected that comets played a role in the origin of life. No one really knows this because no one knows how life began. But we do know that comets are the most carbon-rich materials in the solar system, and we know they’re full of organic compounds and they fall on the Earth all the time. Even now we have tens of thousands of tons of comet particles landing on the Earth every year,” he said.
Even though microscopic comet particles blanket open spaces such as parks and football stadiums every year, those particles don’t tell the same story as ones collected from a comet such as Wild 2, Brownlee said. That’s because Wild 2 only recently started orbiting close enough to the sun to make the mission feasible, so there hasn’t been time enough for the sun’s heat to destroy the characteristics of particles that have been preserved in a cryogenic deep freeze of space for billions of year.
In 1980, Brownlee and NASA first considered a mission to capture comet particles. In that case, the target would have been Halley’s comet, but the idea proved unworkable. Various technological advances and a bit of celestial luck changed that. Before 1974, Wild 2 traveled outside the orbit of Jupiter. But a close encounter with Jupiter that year altered the comet’s trajectory, bringing it close enough to make Stardust possible. The spacecraft’s encounter with the comet in early 2004 will take place just outside the orbit of Mars, 242 million miles from Earth on the other side of the sun.
The mission is the first since Apollo 17 in 1972 to return extraterrestrial samples to Earth, and it is the first to bring back samples from beyond the orbit of the moon. Scientists will study the returned comet particles in the hope of understanding how life evolved on Earth. The planet probably was formed without water and without carbon or nitrogen, the building blocks of life. “The building blocks of life have long been thought to have come from further out in the solar system, out further away from the sun, and these would be materials from asteroids and comets,” Brownlee said.
Stardust will have journeyed 3.1 billion miles before it parachutes into the Utah desert in early 2006. During its encounter with Wild 2, a tennis-racquet shaped collector, sheathed with a wispy substance called aerogel, will be extended to collect comet grains when the spacecraft is within 100 miles of the comet’s icy core. A high-power antenna will transmit close-up pictures, and sensitive equipment will gather data about the comet.
The mission is a collaboration of the UW, NASA, NASA’s Jet Propulsion Laboratory at the California Institute of Technology in Pasadena, Calif., and Lockheed Martin Astronautics in Denver. Other key members of the team are The Boeing Co., Germany’s Max-Planck-Institut f?raterrestrische Physik, the NASA Ames Research Center and the University of Chicago.
Brownlee expects information gathered by Stardust to shed light on how the solar system and the universe evolved. The mission also could have implications on astrobiology, the search for life beyond Earth. The UW this fall will begin the first doctoral program in astrobiology to train people to look for life on other celestial bodies, such as Mars and Europa, a moon of Jupiter.
“From the astrobiology standpoint, we’re interested in what kind of organic materials actually exist and how much there is and whether this played a role (in the formation of life),” Brownlee said. “Now this may be an impossible problem. We can study astrobiology and we can investigate how life might have formed, but no one was there taking notes when life formed.
“You have things … before there was life and things after there was life but the real records aren’t there,” he said. “But by insight on this, you can at least look at what the starting materials were. So that’s what Stardust is going to do, look at the starting materials, what was around in the solar system before life existed on Earth.”
The name “Stardust” seemed appropriate because of the nature of the project and the fact that people can relate to that name, Brownlee said. A recent radio interview ended with a few bars of the song “Woodstock” by Joni Mitchell, which includes the lyrics: “We are stardust, we are golden, we are 2 billion-year-old carbon.” That’s an appropriate thought, Brownlee said.
“Comets are a vehicle that brings organic materials to the Earth. Many of the carbon atoms in our bodies were in comets early in the history of the solar system. So one of the bylines of the Stardust mission is that we are stardust. Our bodies are actually made of stardust.”
Science aside, there’s a hint of romanticism about this mission. That’s why, come Saturday, it won’t be “Woodstock” but instead the soft strains of Hoagy Carmichael’s “Stardust” drifting through the launch area.
Additional information is available at http://stardust.jpl.nasa.gov or at http://www.washington.edu/newsroom/stardust/stardust.html