NASA mission searching for planets similar to Earth

February 5, 2009 12:35 am

The first stage of the Delta 2 launch vehicle that will carry the Kepler spacecraft into orbit waits for the installation of the final solid rocket boosters.

WITHOUT a doubt, one of the most exciting discoveries in astronomy over the past few decades has been the fact that planets are orbiting stars beyond the solar system. Both astronomers and the public have been excited by the fact that planetary systems exist beyond our own.

As of Feb. 1, 2009, some 336 planets have been discovered orbiting distant stars, according to the PlanetQuest Web site planetquest.jpl.nasa.gov. These extrasolar planets, as they're called, are gas giants similar to the planet Jupiter, so the search is on for planets resembling the size and mass of Earth.

Extrasolar planets are very difficult to detect visually because they are small and hidden by the blinding glare of the stars they orbit. However, extrasolar planets have been discovered by using indirect methods such as observing a star's "wobble," caused by the gravitational tug exerted by an orbiting planet or by measuring the drop in a star's brightness as a planet passes in front of the star. The latter technique is called the transit method. From our earthly perspective, planetary transits happen in our solar system when Mercury and Venus pass in front of the sun on rare occasions.

Enter a new NASA mission named Kepler. Set for launch in March, it will be the first of several missions to find Earth-size planets. It consists of a spacecraft and an instrument called a photometer, which is a very sensitive telescope and light detector.

Kepler will concentrate on finding Earth-size planets orbiting distant stars using the transit method. The mission has an expected lifetime of four to possibly six years and will "stare" at 100,000 stars similar to our own sun located in the constellations Cygnus and Lyra.

Kepler's 95-megapixel detectors will allow the spacecraft to uncover possible extrasolar planets with unprecedented accuracy as it continuously gazes at the same part of the sky during its four-year mission. Kepler will concentrate on finding these planets in and around a star's habitable zone, the areas where planets may harbor water and atmospheres conducive to life.

Imagine the possibilities if Kepler finds that several Earth-like planets are scattered throughout our Milky Way Galaxy. If Earth-size planets are found to be commonplace around sun-like stars, it will certainly be a remarkable discovery and open a new chapter in astronomy and science. If Kepler uncovers no Earth-like planets, that discovery too will be significant as we realize how unique and fragile life is in our neighborhood of the Milky Way.

Regardless of what Kepler finds, one thing is certain: As telescopes, computers and light-detector technologies are improved, our discoveries will become more exciting in the upcoming years. Kepler is the first phase of what undoubtedly will become a very exciting chapter in the search for planets and life beyond our own solar system's boundaries.

February Skies

Venus still reigns over the western evening sky after sunset. The thin crescent moon joins Venus during the evening of the 27th.

Saturn becomes a prime-time planet this month as it is well-placed in the southeastern sky a few hours after sunset. The moon will be to the right of Saturn during the evening of the 10th.

Jupiter reappears in the early morning sky close to the southeastern horizon late in the month. Use the moon to find Jupiter during the morning of the 22nd, when the moon will lie to the upper right of Jupiter.

David Abbou of Stafford County conducts public outreach on astronomy and the space program as a NASA JPL Solar System Ambassador. He is a member of the Rappahannock Astronomy Club. Contact him at david.abbou@ verizon.net.