Rocket Raised For NASA Planet Hunt

A Delta 2 rocket that will launch a NASA planet-hunter is being raised at Cape Canaveral Air Force Station this week as the agency mounts a campaign to launch the spacecraft next spring.

The 12-story United Launch Alliance rocket and its payload -- NASA's Kepler spacecraft -- are tentatively slated to blast off March 5 from Launch Complex 17B.

The $500 million Kepler mission is aimed at surveying part of the Milky Way galaxy in an effort to uncover evidence of Earth-like planets orbiting stars in habitable zones. Scientists hope to determine how many of the billions of stars in the galaxy host such planets.

Built by Ball Aerospace & Technologies Corp. of Boulder, Colo., the spacecraft will use a powerful photometer to continuously measure the brightness of 100,000 stars, searching for planets that cross in front of them.

A planet transiting in front of its parent star will block a small fraction of the star's light. Kepler will detect this change in brightness and use it to determine the planet's size and orbital period.

Scientists have discovered 322 planets circling other stars; most are gas giants the size of Jupiter or larger. Kepler will be the first spacecraft capable of detecting much smaller, Earth-like planets in zones where conditions would be conducive to hosting life.

The Kepler spacecraft will be launched into an Earth-trailing solar orbit by the Delta 2 rocket, the first stage of which was erected earlier this week at Launch Complex 17B. Nine strap-on solid rocket boosters were attached to the stage, which is powered by an RS-27A LOX-Kerosene engine.

The second stage of the rocket, with its Aerojet AJ-10 hypergolic engine, is scheduled to be erected in early December. The spacecraft passed thermal vacuum tests at Ball Aerospace chambers in September and is being prepared for shipment to Cape Canaveral.

The tests exposed the spacecraft to the extreme temperatures and vacuum conditions it will encounter in space. The idea was to make certain the spacecraft and its sensitive detectors and electronics will operate properly during a 3.5-year mission.

Read more about the Kepler mission here: Kepler Mission.

ABOUT THE IMAGES: Click to enlarge and save the images. Then click the enlarged images for even bigger views. The top image shows a United Launch Alliance Delta 2 rocket being erected at Launch Complex 17B at Cape Canaveral Air Force Station. Note the strap-on solid rocket boosters poised for mating the the first stage of the vehicle. Photo credit: NASA/Jim Grossmann. The second shows Ball Aerospace engineers checking out the spacecraft after thermal vacuum chamber in Boulder, Colo. Photo credit: Ball Aerospace.