Comet-Smasher to Hunt Alien Worlds

Deming and his colleagues have begun using Deep Impact's larger telescope for follow-up studies of some of these so-called transiting planets.

First, they measure the combined light of a star and the known orbiting planet. As the planet passes behind the star, Deep Impact makes another measurement of just the starlight. Subtracting the light from the star from the combined readings leaves researchers with measurements of just the planet.

"We can analyze this light to discover what the atmospheres of these planets are like," Deming said.

Observations of the giant transiting planet HAT-P-4 began Jan. 22, but a problem aiming the telescope caused the star to move out the field of view about 20 percent of the time, Deming said in the project's blog. The problem was resolved, and by this week, Deep Impact had made thousands of observations.

"Ongoing efforts to improve the calibration of the data will allow sensitivity to small planets that we hope to discover," Deming added.

Scientists plan to calibrate Deep Impact's findings by looking at a planet they know well: Earth. Observing the home planet in visible and infrared light will give scientists a better idea of what an alien Earth looks like in Deep Impact's eyes.

Related Links:

Irene Klotz's blog: Space Diary

More on Deep Impact's new mission

NASA's Deep Impact page

How Stuff Works: Planet-Hunting