For the past three years, there's been only one NASA-owned device in hunting for Earth-like planets. The Kepler mission has allowed scientists to look at 170,000 stars. It has been responsible for changing our outlook about planets and planetary systems throughout the galaxy.
At SETIcon II last month, a science and sci-fi gathering in Santa Clara, Calif., Kepler scientists and SETI astronomers said that the search for alien life relies on Kepler's discoveries, and that citizen science can help keep the increasingly rare industry of planet hunting alive.
Kepler and SETI
At the SETI Institute, which faces the perennial problem of overcoming a lack of funding, Kepler has been a boon to the search for planets capable of supporting life.
"What Kepler is telling us about habitable planets that we didn't know beforehand is info that bears directly on the search for life," says Geoff Marcy, an astronomer at UC Berkeley and a co-investigator on the Kepler project. So far, he says, Kepler has discovered about 3000 planets, and about three-quarters of those are between the size of Earth and two to three times that of Earth. "What are these planets? We have some very good clues," he says. "We have been able to measure the density of 15 or so. They are nearly one gram per cubic centimeter. That's the density of water." And water is the first and most important indicator of the possibility of life.
"When you look up at the night sky at the stars your naked eye can see, what you know is that a vast majority of those stars have these remarkable planets," Marcy says. "There must be large amounts of water . . . and water is the key solvent of biochemical reactions. I think what Kepler has discovered is it's very likely these water worlds are a predominant type of planet in the universe and can certainly serve as the petri dishes for life as we know it."
Seth Shostak, senior astronomer at the SETI Institute, says Kepler's data has helped SETI scientists sharpen their methods in the search for life. Without Kepler, they'd still be looking at the entire sky. With Kepler, they have a host of new exoplanets to study—and they know a lot more about the makeup of alien solar systems.
"The trump card in all this is the result that planets are very commonplace. Before 1995, we didn't know that," Shostak says. "Essentially all stars have planets. The number of planets around stars is in the order of a trillion. That's very good news for SETI."
Kepler and You
Although the Kepler scientists have made major breakthroughs in the discovery of Earth-like planets, they face the same good problem to have that many modern scientists confront: too much data to handle.
As a result, the Kepler mission has been slowly making its findings available to the public, and the astronomers believe there's a good possibility they've missed some discoveries. But in October, NASA will turn the problem over to us. It plans to drop all the firewalls on the collected data, giving the public access to the entire archive.
"Kepler is changing. It's not a young mission where we're nervous about the data," says Martin Still, director of the Kepler Guest Observer Office. "We have much more confidence in pushing this stuff into the public arena as early as possible. Anybody can go to this archive and find their very own planet. Kepler's gonna be more about putting together samples of planets. The job of getting excited about finding individual planets is probably more [the public's] domain now than it is ours."
Citizen scientists have already begun taking on the job of planet hunting. In another panel at SETIcon about harnessing the power of the public, Yale University astronomer Debra Ann Fischer said her Kepler-based project, planethunters.org, "has exceeded our expectations for how successful the project might be." Citizen scientists have already completed the equivalent of 200 years of 24/7 research. So far, it has amounted to four papers (co-authored by at-home planet hunters) about planet detection and assessment techniques. "It's that kind of power that's enabled the detection of things that slipped through the pipeline before," Fischer says.
This is the result the Kepler folks are hoping for. Once the entire database is available, armchair astronomers could help the Kepler mission perfect its own tactics. "We hope you attack big data with lots of technologies we've never heard of," Kepler instrument scientist and physicist Douglas Caldwell says. "We know [our software] misses things and there are things in our data that it's not tuned to do well with."
Still says: "This isn't just stamp collecting. Our pipeline is designed to find as many planets as possible over a very large statistical example. Our goal is to understand what is missed. The job that you guys will hopefully do over the next few years is not only great for community science, but it is critical to the success of the Kepler mission."