SETI public: Kepler's mission to find other Earths

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http://www.floridatoday.com/news/space/stories/2003b/122503other.htm

Dec 24, 2003

Space telescope on mission to find other Earth-like planets

By John Kelly
FLORIDA TODAY

MOUNTAIN VIEW, Calif. -- Bill Borucki knew he was right, and he's a patient man.

Turned down for funding not once, not twice, but four times in the 1990s, Borucki did not quit trying to prove he has figured out a way to find and count other Earths in the universe.
NASA finally bankrolled Borucki's mission. If it works, the Kepler space telescope could give us the best answer yet to the nagging question, "Is there life out there?"
"We want to know whether or not planets such as Earth are common around other stars," said Jill Tarter, one member of the science team working with Borucki on the project.
"We had to fight for years to get that approved," said Tarter, the SETI Institute researcher who was the basis for the Jodie Foster character in the movie "Contact." "There was a lot of criticism saying we couldn't do it technologically. We can do it. It's going to be very illuminating."
Illumination, in fact, is the central theme of the Kepler mission. The spacecraft is basically a light meter, albeit a very complicated one.
NASA plans to launch the ship from Cape Canaveral in 2007. It will orbit the sun, following roughly the same path as Earth. After its eye opens in space, the telescope will spend four years staring at the same 100,000 stars.
Kepler will measure light from those stars, noting when the light dims and by how much. If a star repeatedly dims by the same amount in a regular pattern, such as four times in four years, that could indicate an orbiting planet.
The rest of the job is math. The star's normal brightness will tell Borucki's team how big it is. The amount the star's light is dimmed will tell the scientists how large the orbiting planet is. The length of time from one pass to the next will tell them how far the planet is from the star.
Borucki's team will look for planets about the size of Earth in what's called the "habitable zone." That means the planets must be orbiting the star at a distance that would make them warm enough to support the existence of large amounts of liquid water.
"If we find Earths are frequent and if we find they're frequent in the habitable zones, then there's probably a lot of life out there," said Borucki, a senior research scientist at NASA's Ames Research Center near San Francisco. "If on the other hand Earths are very rare, the opposite is probably true. That is to say life is rare because there simply aren't planets for life to live on.
"If there are no other Earths, there will never be a 'Star Trek' because there's no place to go," he said.
Kepler will not end the debate about whether there are other Earths out there.
First, the mission's findings must be followed up by more sophisticated spacecraft that will have to determine the chemical makeup of planets spotted by Kepler and Earth telescopes. It might take another decade or two to get that kind of technology launched into space. By then, Borucki said Kepler will have done the homework necessary to tell more sophisticated future telescopes where to look -- or perhaps whether it's even worth it to look.
"First you've got to find out if there is something there to have chemistry," Borucki said.
The other big issue is the science of planet-hunting is tricky. There are a variety of methods used to try to spot planets circling distant stars, with mixed success.
"There's a long history of people claiming to have found planets and then they find out later that, 'Oops. No we haven't,' " said Steve Benner, a University of Florida researcher who serves on a National Academies of Science committee that regularly reviews NASA's work.
That's because there is no perfect way to try to identify and characterize objects so far away. It's hard enough to study the planets in the outer edge of our own solar system. Kepler's biggest challenge could be its vantage point. To see stars dim as planets pass by, the spacecraft will have to be looking at the star from exactly the right angle.
"It's a thin sheet of paper and you've got to be looking at the edge of that sheet of paper." Benner said. "What if you don't see any? What conclusion are you going to draw? If you don't see anything, you're really not going to know."
If Kepler does spot a dozen or so Earth-like planets, Benner and Borucki said the implication could be that hundreds or even thousands of them exist. If so, it could change the way people think about Earthlings' place in the universe. The public's reaction could be key because it could prompt increased funding for this kind of research.
"We are not short of ideas on ways to identify and characterize planets," said Mark Wyatt of the United Kingdom Technology Centre's Royal Observatory, who is seeking extrasolar planets with Earth-based telescopes and has published journal articles identifying some candidates. "We need the resources to implement those ideas."

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