Kepler's Exoplanet Hold The Hunt Until 2011

Just when the extra-solar planet hunt seemed to be going so well, NASA has announced that the orbital Earth-like exoplanet hunter will not be able to detect a world like our own until 2011 at the earliest.

The Kepler space telescope was launched in March and the hope is that in the small patch of sky (containing 100,000 stars) it is focussing in on, Earth-sized exoplanets orbiting within the "habitable zones" of their parent stars will be discovered. However, there's a problem: Kepler has noisy amplifiers.


Keep in mind that the sensitive equipment on board Kepler has been designed to detect the slightest change in brightness of a star as an exoplanet passes in front, thereby slightly dimming the starlight that is falling on Kepler's charge-coupled devices (CCDs). If you're looking at a star many light years away, you can expect this dip in brightness to be infinitesimally small.

The amplifiers in the space telescope's electronics are used to boost the signal from the CCDs. If there is any electronic noise between the light being received and the data being sent to Earth, the signal of transiting exoplanets may be lost in the fuzz. Unfortunately, three of these amplifiers are producing unacceptable levels of noise, prompting the Kepler team to evaluate their options.

The other amplifiers appear to be functioning well, but the noisy amplifiers really upset the balance. Ideally, if the instrument was on the ground, scientists could replace the amplifiers. But Kepler is in an Earth-trailing orbit (it orbits the sun at 1AU, following behind our planet), so there's no chance of an in-situ repair job.

To counteract this noise, scientists are working on a software solution. Although only a small portion of observations will be affected by the amplifier glitch, it would be too hard to remove the bad datasets when they are sent to mission control. Instead, the Kepler team must put the mission on hold until they devise a software solution that can automatically remove the noise soon after the data is received by the CCDs. The kicker is that the software isn't likely to be prepared until 2011.

Ouch.

So what can we do in the mean time? Actually, this Kepler glitch has presented an opportunity (and perhaps even an incentive) for other exoplanet hunting teams down here on the ground. Although Kepler can gain information about an exoplanet's size (the bigger the exoplanet, the more light it will block out), ground based observatories look out for a star's "wobble" to derive an exoplanet's mass (as the exoplanet orbits, it pulls the star slightly, producing a detectable shift in position). Looking out for an exoplent wobbling its parent star is known as the radial velocity measurement technique.

Astronomer Greg Laughlin from the University of California at Santa Cruz agrees that the delay for Kepler makes it "more likely that the first Earth-mass planet is going to go to the radial-velocity observers".

Although the Kepler news is frustrating, it doesn't mean the Earth-like exoplanet hunt is over, not by a long shot.