> Natalie Batalha                                         
> Tuesday, March 8, at 11:45 AM
> Kepler's Search for New Worlds

> Humanity's quest to learn about the existence of other worlds like our
> own has made a huge step forward with the launch of NASA's Kepler
> spacecraft in March 2009.  The mission is designed to survey a slice of
> the Milky Way Galaxy to identify planets orbiting other stars.  Kepler
> has the advantage that it can find planets as small as Earth in or near
> the habitable zone of each star.  It will help us determine if such
> planets are abundant in our galaxy.  Dr. Batalha will describe the
> techniques used by the Kepler team to identify Earth-size planets and
> share some of the mission discoveries to date.

> Natalie Batalha is a professor of physics and astronomy at San Jose
> State University in the heart of Silicon Valley, and the Deputy Science
> Team Lead for NASA's Kepler Mission. She holds a bachelor's in physics
> from the University of California, Berkeley, and a doctorate in
> astrophysics from UC Santa Cruz. After a post-doctoral fellowship in Rio
> de Janeiro, Brazil, Batalha became inspired by the growing number of
> planets being discovered around other stars (more than 500 such planets
> are currently known.) Eleven years later, she stands poised with the
> Kepler team to learn whether or not Earth-sized planets are abundant in
> our galaxy.

Natalie began her talk by explaining that before Kepler came along hunting for planets beyond the solar system was very difficult. It involved detecting the Doppler shift caused by the planet and its sun revolving around each other. Kepler was designed to take another approach. Because the atmosphere distorts light, it was necessary to put the new telescope beyond that. To meet all of their design goals they ended up with a telescope the size of a bus that weighs about as much as a car beyond earth orbit. The heart of the thing is a reflecting mirror more than a yard across, and a CCD array about a foot square with amazing resolution (96 million pixels).

She explained that the ultimate goal of the project is to find rocky planets where water is available in liquid form. To do this they start by looking for planets and then narrow the search from there. To detect planets they watch a star with great precision and look for the 1 part in 10,000 change in brightness when the planet goes from being a shadow crossing the sun to something on the other side of it. They make a list of the transitions for each star they are watching and then from the periodic nature of those make estimates of the period of the orbit and so forth.

Much thought went into picking the piece of the sky to look at, as well as how to look at it. After four years work the team picked a piece of the sky about as far across as your hand held at arms length. It's far enough from the axis of our solar system that sunlight doesn't drown out the stars. It's dense enough with stars that Kepler has a lot to examine, meaning about 150,000 stars that might have planets. Kepler first went on line from space and started downloading pictures on April 8th, 2009. Since then it has found hundreds of planet we didn't know about before. The most earth-like of them all is Kepler 10b, which is about 560 light years away.

Before Kepler we knew of about 500 planets, mostly Jupiter type biggies. Now the official list has 1235 entries. Many of them are smaller and rockier than the previously detected ones. Natalie Batalha said that 54 of them are likely to have water. She expects the list of planets to grow quickly over the next few years.

How many planets Kepler can add to our database depends on funding. Now that the satellite is up there, all of the funding for the mission amounts to about $20 million per year. The funding for the next three years is secure, but after that it depends on the winds in Washington. In about ten years time Kepler will have drifted far enough away from us that the info signal will become harder to read with our equipment. Also in that kind of time frame the engines that stabilize the craft are expected to run out of fuel. Until then it will continue to send us astronomical data at a rate of about 500 Gigabytes per month.

Tian Harter