(Kepler probe awaiting launch. NASA photo)
At 8:48 p.m. Friday, a space probe unlike any other is scheduled to launch from Cape Canaveral aboard a Delta II rocket: the $600 million Kepler mission, which will search for Earthlike planets in places where life as we know it may be possible.
A NASA briefing notes, “The Kepler Mission, NASA Discovery mission #10, is specifically designed to survey our region of the Milky Way galaxy to discover hundreds of Earth-size and smaller planets in or near the habitable zone and determine the fraction of the hundreds of billions of stars in our galaxy that might have such planets.”
The habitable zone is the area around a star where conditions may support life. It’s also called the Goldilocks Zone because it’s not too hot and not too cold. There, liquid water could exist on a planet’s surface without freezing solid or boiling off into space. The zone’s size would vary as the star’s energy output does; a NASA diagram shows the habitable zone around the sun starting midway between the orbits of Venus and Earth and extending out to just reach part of Mars’ orbit.
A NASA video released Feb. 27 features statements from a host of NASA experts concerning Kepler. Jim Fanson, Kepler Project Manager at the Jet Propulsion Laboratory, Pasadena, was quoted as saying the project is NASA’s first probe “capable of finding Earth-like planets orbiting other stars in the galaxy in a region around the star we call the habitable zone.”
Natalie Batalha, professor of astronomy and physics at San Jose State University, added that Kepler will answer the question, are Earthlike planets rare or common in our galaxy?
Don’t look for Kepler sending back detailed views of a planet sailing around its star. The images will cover a vast swatch of stars in a field about 15 degrees in diameter. A fist at arm’s length is ten degrees.
When a planet crosses in front of a star, the star’s light will dim, and this may be detected the probe’s 37-inch-diameter telescope. The amount and frequency of dimming will allow scientists to estimate the planet’s size and distance from the star. For three and a half years, the Kepler telescope will stare at the same region and track any changes in the brightness of the thousands of stars.
The probe’s CCD camera has 96 million pixels and “very little noise so we can find very small planets,” said Bill Borucki, principal investigator for the Kepler Project.
Kepler will slowly drift away from Earth and begin to orbit the sun. It was study as many as 170,000 sun-like stars in the Cygnus-Lyra section of our galaxy – stars that have been selected as most suitable for planets. “Finally, we expect to end with somewhere between a few hundred and a few thousand signals that are really planets around the stars that we’re looking at,” added Kepler’s telescope and CCD array are so sensitive, added Nick Gaultier, Kepler project scientist.
Jim Fanson, Kepler Project manager at the Jet Propulsion Laboratory, Pasadena, said in a separate press release THAT Kepler’s telescope and CCD array are so sensitive if the probe were to look down at a town on Earth, it “would be able to detect the dimming of a porch light as someone passed in front.”
The release, dated Feb. 19, puts the project in a nutshell: “It is expected to find hundreds of planets the size of Earth and larger at various distances from their stars. If Earth-size planets are common in the habitable zone, Kepler could find dozens; if those planets are rare, Kepler might find none.”
(Diagram of Kepler spacecraft. NASA art)