With the Herschel/Planck telescopes now on their way — the successful launch took place at 1312 UTC from the European Space Agency’s launch pad at Kourou, and the two spacecraft are now on separate trajectories — we can take a breather to reflect on what a busy time it’s been of late for space telescopes. The ongoing Hubble repairs are a fascinating story in and of themselves, but we’ve also got Kepler to think about as its hunt for Earth-like planets around other stars now gets underway.
Shaking out the instrumentation has taken some time, but the Kepler operations team slowed the pace of communications about a week ago to eighteen hours per day, a number that will drop to six as science observations now proceed. For the balance of the mission, according to JPL project manager Jim Fanson, communications will occur only twice per week as Kepler sends home precious data.
“Now the fun begins,” said William Borucki, Kepler science principal investigator at NASA’s Ames Research Center, Moffett Field, Calif. “We are all really excited to start sorting through the data and discovering the planets.”
Expect the first discoveries to be gas giants close to their stars, easiest to spot and confirm using Kepler’s transit methods. Then things get even more interesting. This is a mission that should be able to find terrestrial worlds in the ultimate sense; i.e., planets that not only approximate ours in size but are also roughly at the distance required for liquid water to exist at the surface. We still call that distance the ‘habitable zone’ even though it’s becoming clear, as witness the case around Jupiter, that tidal forces can provide immense energies that could extend a different kind of habitable zone much farther from its star. And then there’s Enceladus…
Given my own predilection for small, red stars and the chances for life around them, I’ll be fascinated to see what we learn about the number of potentially life-bearing planets around M-dwarfs. Remember that these account for something like 70 percent of the stars in our galaxy. Kepler’s take on this after completion of its three and a half-year mission should give us some sense whether such planets are commonplace, or whether we’re more likely to find life around G- and K-class stars more similar to our own Sun.
As to Kepler itself, having read Alan Boss’ book The Crowded Universe (Basic Books, 2009) recently, I’m still amazed that the mission ever got into space. The agonizing politics of funding top-end science have put the brakes on such powerful options as the Space Interferometry Mission (now shrunken to SIM Lite) and the Terrestrial Planet Finder. How Kepler made its way through the maze of review panels and budget cuts to get on the launch pad makes for absorbing reading, but not nearly as absorbing as what we may find in its final report.