Kepler Mission: Search for Extraterrestrial Planets

For many years the curiosity of exploring different planets with Earth-like characteristics has intrigued many scientists and astronomers. Every new discovery of a planet or star far beyond our own solar system has raised some baffling questions such as:

Are there other plants, orbiting other stars having characteristics similar to Earth?

Or,

Is Earth the only habitable planet in the universe?

Or,

Are there any chances of an extraterrestrial contact?

The third possibility may be a far-fetched one, but for the first two, scientists are confident in finding a concrete answer. Well, NASA has always been in the forefront to discover new and interesting facts about the solar system, the Milky Way and far-off galaxies. With the Kepler Mission, it will certainly shed light on extra-terrestrial planets or Earth-size planets that orbit around stars like our sun.

The Kepler Mission, which is named after Johannes Kepler, who is known for his laws of planetary motion, is planned for launch in April 2009. Being NASA’s tenth Discovery mission, it is designed to explore the structure and diversity of planetary systems in our galaxy and will emphasize more the detection of Earth-size planets. For four years it will monitor 100,000 stars similar to our sun and if it detects any planets, which can be determined to be in a habitable zone about the star, the possibility of life in the universe cannot be negated. But if the results are inconclusive, it may mean we are alone in the galaxy.

The scientific objective of the mission is to explore the planetary systems, their structures and range. The main focus will be to detect and characterize Earth-size planets by surveying beyond our solar system. The survey will help to detect hundreds of large and terrestrial planets in or near the “habitable zone” of a star. The “habitable zone” is defined by scientists as “the distance from a star where liquid water can exist on a planet's surface”.

The Six Important goals of the Kepler Mission

The following are the six important objectives or goals explained in brief (Courtesy: NASA's Kepler Mission Website):

1. Determine the frequency of terrestrial and larger planets in or near the habitable zone of a wide variety of spectral types of the stars.

2. Estimate the number of planets and their orbital distribution in the multiple-star system.

3. Find out the range of sizes and shapes of the orbits of these planets

4. Determine the range of orbit size, mass, brightness and density of short-period giant planets.

5. Ascertain the properties of those stars that harbor planetary systems. Properties that are to be determined include the luminosity class, spectral type, the rate at which the star rotates, surface brightness and stellar activity.

6. Identifying additional members of each discovered planetary system using complementary techniques.

The final results derived from these objectives will help scientists to understand more about the planetary formation, its frequency (i.e. the frequency of formation), general characteristics of stars with terrestrial planets and structure of individual planetary systems.

The estimated mass of the spacecraft is 1,039 kilograms (about 2,290 lb). The photometer mounted on the spacecraft is a device that measures the brightness of light. It has a 0.95-meter aperture and a 105 square degrees (about a 12 degree diameter) FOV (field-of-view). With a 37-inch (95 cm) diameter lens, the photometer will function like a giant camcorder and measure the brightness of 100,000 stars continuously and simultaneously. With the help of sensors, the photometer will record the “transit” of planets across the faces of the star (A “transit” occurs when a planet moves in front of a star and the star gets dimmer for hours, indicating that a planet has passed by). This will provide the raw data, which will help scientists to determine the planet’s size and the orbital period.

The photometer is made up of just one “instrument”. This “instrument” is actually an array of 42 Charge Coupled Devices (CCDs), each measuring 50x25 mm. Each CCD has 2200x1024 pixels. CCDs are not only used to take pictures but also are deliberately defocused to 10 arc seconds to improve the photometric precision.

Our past experience says that planets much smaller than Jupiter cannot be detected. But the need to conduct a search for small or terrestrial planets is considered important to detect Earth-like or habitable planets. The Kepler mission is designed to detect such planets and may be it will prove that we are not alone in this universe. Keep your fingers crossed!

http://kepler.nasa.gov/about/

http://kepler.nasa.gov/sci/design/spacecraft.html

http://discovery.nasa.gov/kepler.html

http://en.wikipedia.org/wiki/Kepler_Mission

http://kepler.nasa.gov/media/art.html

http://kepler.nasa.gov/sci/design/spacecraft.html