02-06-09

Technicians prepare the Kepler Mission's photometer for its scheduled launch from Cape Canaveral on March 5. The instrument will point at a field of about 170,000 stars and look for any variations in brightness. The variations can signal planets crossing in front of their stars and can help astronomers study stars and their interiors. NASA photo.

Iowa State astronomer to study stars with data from NASA's Kepler mission

AMES, Iowa -- NASA's Kepler Mission will be the first attempt to look for earth-like planets in our part of the Milky Way. It will also be the first chance for astronomers such as Steve Kawaler to get a much closer look at the stars they study.

Kawaler, an Iowa State University professor of physics and astronomy, plans to celebrate the new research program by witnessing the mission's launch in early March (the National Aeronautics and Space Administration says the mission is currently scheduled to launch on March 5) at Cape Canaveral Air Force Station in Florida.

The mission has a lot for astronomers to get excited about.

Looking for planets that could support life was "the stuff that got me interested in astronomy when I was a kid," Kawaler said.

And he said the mission's space telescope will do a lot to advance his research of stars and their interiors.

"We've been doing this work the hard way -- from the earth, which is a spinning platform," Kawaler said.

To overcome the Earth's rotation, a research collaboration called the Whole Earth Telescope was established in 1986 to coordinate star observations and share data. Kawaler, who has served as director of the project, said even a whole-earth collaboration has significant limits.

Weather can get in the way of observations and data collection. No two telescopes are exactly the same and so produce subtly different data sets. Ground measurements can't be as precise as measurements from space. And funding hasn't been available to do observations for more than a few weeks at a time.

"Kepler will do this the right way," Kawaler said. "Kepler will give us a huge amount of data. About 170,000 stars will be observed every half hour, continuously, for three and a half years or more."

The Kepler Mission will launch a CCD photometer (the equivalent of a 95 megapixel camera) into space. The instrument will use an aperture that's nearly one meter in diameter to collect data about the Cygnus-Lyra region of the galaxy. Its primary job is to find any variations in the brightness of the stars within its view.

Tiny dips in brightness can signal a planet passing in front of its star. Scientists at NASA's Ames Research Center in California will lead a team studying those planetary transits. Data from the transits can reveal the planet's size, orbit and temperature. That will allow researchers to find earth-sized planets that orbit within the habitable zone of their stars.

Another team of researchers -- the Kepler Asteroseismic Science Consortium -- will use the same data to study the internal structure of stars. The consortium is led by Jorgen Christensen-Dalsgaard and Hans Kjeldsen of Aarhus University in Aarhus, Denmark, and Kawaler serves on the project's 12-member steering committee.

The consortium will study how the spheres of gas that make up stars oscillate and change brightness. Studies of those star quakes can answer questions about the interior properties of stars such as their density, temperature and composition. It's similar to how geologists study earthquakes to learn about the Earth's interior.

Consortium scientists will also use the data to measure the exact sizes of stars with earth-like planets.

The scientists should begin seeing new data about 90 days after Kepler's launch.

Kawaler is looking forward to seeing where the new information takes researchers.

"Fifteen years ago we knew of one planetary system," he said. "Now we know of 300-plus, but only one Earth. This is our chance to find dozens of other Earths."

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