The Earth really unique in its ability to support life? Right now, that’s a $300 million question. When NASA’s Kepler Mission launches in 2007, we may find the answer.
Started more than a decade ago, the Kepler Mission (www.kepler.arc.nasa.gov/index.html) is the first program to search for Earth-sized planets. What’s more, it will look for planets that, based on their orbits, are capable of supporting life.
Named in honor of 16th-century German mathematician and astronomer Johannes Kepler, the project bears his name primarily because Kepler proved that planets travel in an ellipse (not a circle) around the sun. The name is also appropriate because Kepler’s laws of optics are still used in telescopes.
The Kepler Mission will look at the "habitable zone" of stars, where planets maintain orbits a sufficient distance from their star so that they remain relatively temperate and, therefore, may contain water.
The key to this mission is the telescope. When the telescope is launched it will be the largest Schmidt telescope to orbit the sun with a .95-meter (a little over 3 feet) optical corrector and a 1.4-meter mirror to simultaneously observe over 100 square degrees, said William Borucki, principal investigator for the Kepler Project at NASA’s Ames Research Center. Tim Kelly, senior program manager for the Kepler Project at Ball Aerospace & Technologies, pointed out that we shouldn’t call it a telescope. "When we talk about telescopes, we have this mental image that it takes pictures of stars." Kepler won’t take pictures. Kepler, more precisely, is a photometer. It will measure the brightness of approximately 100,000 stars.
A transit occurs when a planet crosses the line of sight between its parent star (in Earth’s case, the sun) and the observer. With each transit, some of the light from the star is blocked. Kepler will measure that dimming; readings on periodic flickers will be used to determine the planets’ sizes and orbits. When that information is combined with the known energy output of a star, the likelihood of liquid water on the planet can be deduced.
Launching in ‘07
Still in the design phase, the Kepler project will come together in pieces over the next few years. Optics specialists at Brashear, in Pittsburgh, are designing and fabricating Kepler’s primary mirror, about 1.5 meters (4.9 feet) in diameter, and a special lens about 1 meter in diameter. Meanwhile, Kelly’s team in Boulder, Colorado, is building the photometer (which includes about 1,000 pieces, not counting washers, nuts, and bolts) and the spacecraft.
Borucki said about 60 people at NASA and Ball Aerospace & Technologies are currently at work on the project, most of them involved in telescope operation and designing and building communications and ground control systems. Before Kepler’s launch, the size of the team will double, according to Borucki. After it is launched, a crew of about 30 will be assigned to operate the telescope and analyze the resulting data.
Borucki’s team will begin to interpret the data sent back from the Kepler Mission within a few months of launch. "Within six to twelve months, we’ll know if there are other ‘Earths,’" Borucki told us. "Three to four years after the start of the mission, we’ll be able to see if they are in the habitable zone.
"If we find out we’re the only Earth, there can never be a Star Trek," Borucki cautioned. There simply wouldn’t be anyone to visit. "On the other hand, we might find many [other habitable planets]." Borucki won’t guess about the mission’s possible finds, but other experts speculate we might find more than 50 Earth-like planets.
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