When the mission was planned, astronomers assumed that natural variations in the light detected by Kepler would be much as variations in our sun’s light. But Kepler taught them something new. On average, starlight appeared to vary twice as much as sunlight. “Kepler is rewriting the textbooks,” Gilliland says. That was an important scientific finding but an ominous turn for the mission.

Last June Gilliland reported at an American Astronomical Society meeting in Boston that the unanticipated variation in starlight means Kepler has to make more observations to 
complete the survey of its little patch of sky. It can still do what it is supposed to do, but it needs more time. The Kepler team estimates that the telescope will now need about eight years to complete what was originally planned to be a 3.5-year mission.

The annual cost to salvage the mission would be relatively small—$17 to $20 million, about what NASA spent on a new toilet for the International Space Station. NASA’s failure to grant Kepler an extension would be a little like deciding to stop maintaining your car. You would save money in the short term, but in the end you would lose everything.

This possibility comes atop NASA’s recent cancellation of follow-up missions aimed at revealing more about the worlds Kepler has found. One space telescope, called the Terrestrial Planet Finder (TPF), was put on hold in 2007. It was designed to look at the atmospheres of exoplanets for characteristic signs of life—water vapor, methane (made by bacteria), and oxygen (made by plant photosynthesis). If tpf found those things, “it would be hard to explain what it could be other than life,” says Wesley Traub, chief scientist in NASA’s Exoplanet Exploration Program.

Part of the responsibility for mothballing TPF lies with exoplanet hunters themselves, who split over three competing versions of the spacecraft. “So now we have nothing,” says Geoff Marcy, a pioneering exoplanet hunter and a member of the Kepler team. “How is this possible?” He says that TPF would have been astronomy’s equivalent of the Human Genome Project—a groundbreaking effort that would have transformed the field.

The other potential Kepler successor, the Space Interferometry Mission, or SIM, was canceled in 2010 after NASA had already spent $600 million on it. The National Research Council, which reviews astronomy projects and sets priorities every 10 years, did not recommend SIM, so it was dropped from NASA’s list. Traub called the cancellation “the most humiliating, embarrassing thing I’ve ever seen in my life.”

Like every government agency, NASA faces sharp cutbacks as part of the larger effort to tame the federal deficit; this was underscored in July, when the House Appropriations Committee stripped funding for the high-priority (and over-budget) James Webb Space Telescope. The budget the Senate proposed in September would restore the money, but it has yet to be finalized.

Still, it is hard to understand why Kepler and the other exoplanet missions were not given the highest priority. These spacecraft were designed to answer one of the most important questions in the universe: Are we alone? Barring a direct voyage to other stars, such missions are the closest we will ever come to finding out.

NASA is perilously close to abandoning Kepler, 
the space telescope that 
has revealed a bounty 
of exoplanets and the 
intoxicating possibility of life on other worlds.

NASA will decide whether to extend Kepler’s lifetime this spring, when a scientific review committee from outside the agency evaluates competing missions and makes recommendations. NASA spokesman Trent Perrotto said respective project managers “have the challenge of making the strongest possible scientific case for continued operations.” NASA will fund the most promising projects from what is expected to be a fairly small budget.

Last fall, exoplanet specialists met in the Grand Tetons in Wyoming to pool their latest findings and spread the word about the urgency of extending Kepler. “It would be darn depressing if we don’t get an extended mission,” says Roger Hunter, Kepler’s project manager. “You have to take a step sometime to determine if there’s life in the galaxy beyond the solar system. Kepler is a major step.” If NASA fails to act, Kepler will be turned off in November. Finding a real-life Tatooine is intoxicating, but so much more can still be done, and soon, if NASA can just find the money and the will.

Will humans ever drop in to shake hands with whomever or whatever might live on one of Kepler’s planets? Batalha’s answer is startling. “Absolutely,” she says without hesitation. “I have no question. Once we have these destinations sighted in our telescopes, imagine how that will change our drive to get there.” Perhaps she is right. And even if we don’t find alien life out there, watching crimson and orange suns descend at twilight might be satisfaction enough.

TOP NEW PLANETS

Kepler-10b  The smallest known planet outside our solar system, it is just 1.4 times as wide as Earth and is as dense as solid iron. Despite its Earthlike size, a 2,800-degree Fahrenheit surface rules out the possibility of life.

Kepler-11  In this miniature version of our solar system, announced in February, five of the six planets circle their star more closely than Mercury orbits the sun.

Kepler-16b Tattooine is real, sort of. This Saturn-size world orbits a pair of stars that would offer golden double sunsets, but also eccentric weather: The planet’s temperatures would fluctuate wildly as it and the two stars move about their orbits.

HD 85512b  In September European astronomers announced the discovery of 50 new planets, including one of the most Earthlike ones yet: HD 85512b, a rocky world just 3.6 times as massive as our own and mild enough to have liquid water.

LkCa 15B  Scientists got their first look at the birth of a planet in October. Astronomers used the Keck telescopes in Hawaii to image a disk of debris surrounding a young star and found a Jupiter-size planet still forming within.

— Andrew Grant