Kepler Mission Could Detect Exomoons 64
Lord Northern writes "According to several news sources, NASA's Kepler mission is said to be able to detect habitable moons orbiting planets in other star systems. Kepler is a space telescope designed to detect exoplanets. Its mission will have it orbiting the Sun for 3.5 years, after which we'll be able to tell if any of our neighboring stars actually have planetary systems around them. However, apparently we will be able to detect not only exoplanets, but also exomoons orbiting those exoplanets. The Kepler team came to that conclusion after running a computer simulation which found that the telescope was sensitive enough to detect the gravitational pull of an orbiting moon (PDF). This means that the data expected by the end of the mission is going to be very rich, and it is said that moons as small as 0.2 times the mass of earth could be detected. Further details about the Kepler mission are available from NASA."
Correction for the summary (Score:5, Informative)
The summary makes one error, suggesting that Kepler is capable of detecting the gravitational 'wobble' caused by a moon. Rather, Kepler, or any system of similar sensitivity, is able to detect the transit of a moon, and recognize it as being distinct from that of the parent planet.
Understandable mistake, since all of the early exo-planet detections were made using the 'wobble' method (detecting the Doppler shift corresponding with a stars motion due to a heavy, close planet). However, the transit method, which measures small dips in the brightness as the planet passes in front of its parent star is far more sensitive, though more difficult to use due to noise constraints.
Basically, imagine if you were looking at our sun from another star system, and Jupiter stood out clearly as a dip in the light curve, reappearing every 8 or 9 years(?). With this, something like Io or Europa would show up as a smaller periodic variation overlaid on that larger dip. Only noise levels are standing in the way of detecting it, and apparently they think Kepler can handle it.