Kepler Arrives At Launch Pad

Feb 20, 2009
By Michael Mecham



Kepler, NASA's wide-field, planet-hunting orbiting observatory, was moved to Pad 17 at the Cape Canaveral Air Force Station Feb. 19 in preparation for a March 5 liftoff on a United Launch Alliance Delta II booster.

High winds prevented mounting the 2,320-pound spacecraft, which is due for a 10:48 p.m. EDT launch.

Launch will be into a solar orbit trailing Earth by about 9 million miles, from which it will take a "planetary census" by staring at a field of 100,000 target stars in the Cygnus-Lyra region of the Milky Way.

"Kepler is a critical component in NASA's broader efforts to ultimately find and study planets where Earth-like conditions may be present," NASA Astrophysics Division Director Jon Morse said Feb. 19.

The spacecraft's telescope is the largest and most sensitive of its kind yet launched.

With a 1.4-meter (4.6-foot) primary mirror and 0.95 meter aperture, it will scan the widest patch of the sky yet recorded from space.

Its camera uses 42 charge-coupled devices (CCDs) with a combined 95 megapixels to detect the small shifts in light - astronomers call them "winks" - caused when a planet transits in front of a distant star. The telescope is about 30,000 times more sensitive than the Hubble Space Telescope, whose comparable instrument uses just 4 CCDs.

Improved instruments have allowed ground-based observatories to begin deducing the presence of planets outside the solar system, known as exoplanets, since 1995. But most have been gas giants like Neptune and Jupiter.

Only a few appear closer to Earth's size and none of them have been in a "habitable" orbit from their host star that would allow liquid water and, thus, the possibility of life.

Kepler is expected to find all kinds of exoplanets, but its prized find will be terrestrial planets in habitable zones.

The $591 million mission has a nominal 3.5-year duration, but could be extended to six years.

Artist's concept of Kepler: NASA