The quest to find a second Earth–a potentially habitable planet that’s about the size of our home, but that lies in a distant solar system–has hit a snag. The Kepler space telescope was expected to be well on its way to detecting Earth-sized exoplanets by now, but an electronic glitch is slowing it down. The delays are caused by noisy amplifiers in the telescope’s electronics. The team is racing to fix the issue by changing the way data from the telescope is processed, but the delay could mean that ground-based observers now have the upper hand in the race to be the first to spot an Earth twin [Nature News].
Kepler, which was launched in March, uses the transit method to detect exoplanets; it’s watching a patch of 100,000 stars in hopes of detecting the brief dimming of a star’s light, which indicates that a planet has passed in front of the star. Kepler focuses light onto 42 light-detecting chips, called CCDs, each of which monitors stars in a different part of the telescope’s field of view. Each CCD is split into two for the purposes of sending data back to Earth, for a total of 84 data channels. Three of these channels are plagued by electronic noise that makes stars in their field of view appear to flicker – “like it’s changing its brightness at a rapid rate”, says Kepler chief scientist William Borucki [New Scientist]. That’s awkward, since the artificial flickers could obscure the real dimming that occurs during a planet’s transit.
The astronomers reportedly detected the problem during testing before Kepler’s launch, but they judged it riskier to dismantle the satellite at the last minute than to correct the glitch after launch. The noise affects only a small portion of the data, Borucki says, but the team has to fix the software — it would be “too cumbersome” to remove the bad data manually — so that it accounts for the noise automatically. He says that the fix should be in place by 2011 [Nature News].
Still, researchers say that the problem isn’t likely to delay the announcement of an Earth-like planet. For an exoplanet to be habitable to life as we know it, the planet would have to orbit its star at a distance that would keep it at a reasonable temperature and allow for liquid water. An Earth-like planet around a sun-like star would have an orbit roughly similar to Earth’s, and would take about a year to complete one circuit around its star. Astronomers feel the need to record three transits to confirm a planet’s existence–and in three years time, the noise-canceling software should be available. The delays would only affect habitable planets around smaller, cooler stars. The habitable zone for these stars is closer in, where planets could complete the necessary three orbits in about one Earth year. Without the glitch, this kind of planet could in principle be confirmed in 2010 [New Scientist].
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Image: Kepler / Ames Research Center