After a flawless launch early today, the European Space Agency's Rosetta spacecraft is finally on its way to study the history of the solar system. If all goes according to plan, the $1 billion probe will intercept a comet in 10 years and lower a small lander to its icy surface.
Just as the probe's namesake Rosetta Stone helped archaeologists translate Egyptian hieroglyphs, researchers hope the ambitious mission will help them decipher the early history of our solar system. Comets are small, frozen remnants of the birth of the planets; they are thought to have delivered most of the water to the young Earth, as well as the organic building blocks of life. Rosetta marks the first attempt to make a soft landing on a comet. If successful, the lander would study the comet's chemical and structural composition and drill beneath its surface, while the Rosetta orbiter will monitor how the gas and dust production of the comet changes as it closes in on the sun.
Originally, Rosetta was scheduled to lift off a year ago. But the launch was delayed over concerns about the safety of the Ariane 5 rockets slated to launch the craft (ScienceNOW, 14 January 2003). After missing a narrow launch window, scientists had to chose a new target for Rosetta--the comet Churyumov-Gerasimenko. The snags continued last week, when the launch was postponed twice--first because of the weather, and then because of a problem with the rocket's insulating foam. Now technicians are confident the mission is on track. "Landing on a snowball is quite a challenge," says Berndt Feuerbacher, a project manager with the German Aerospace Centre in Cologne, "but it's much simpler than landing on Mars."
Rosetta scientists are more worried by the prospect of waiting 10 years before data becomes available. "Most of us will be retired by the time Rosetta reaches its target, and the scientists who will work on the data are still in high school," says Angioletta Coradini of the Italian Institute for Interplanetary Physics in Rome. Still, she says, it's worth the wait. "We'll be studying a new world that is evolving right before our eyes."