Kepler Honored, Not Mourned: Even without Telescope, Scientists Will Hunt Planets

Article excerpt

When scientists at the Harvard-Smithsonian Center for Astrophysics scheduled a conference called "Exoplanets in the Post-Kepler Era" for May 2013, they figured that era would still be several years off when the meeting happened. But after May's malfunction of a crucial piece of equipment on NASA's planet-hunting Kepler space telescope, the gathering of more than 100 astronomers in Cambridge, Mass., proved all too timely.

As astronomers presented new planetary measurements and observation techniques, Kepler engineers in California were strategizing about how to remotely repair one of two broken reaction wheels that precisely point the telescope. They planned to beam commands up to the $600-million telescope, but admit that a fix is a long shot.

Kepler is shut down and probably out of service for good (SN Online: 5/15/13). But its discoveries have revolutionized scientists' understanding of planets beyond the solar system and are steering the course of existing and future missions. Though astronomers would have liked to have gotten a few more years out of the instrument, it already has planet hunters more confident than ever that they will detect an Earthlike world with the ingredients and conditions for life.

"This is still an upbeat, exciting field," says David Latham, a Harvard-Smithsonian astronomer and member of the Kepler team. "Kepler contributed enormously, and now we're excited to go on to the next steps."

Kepler has become so synonymous with exoplanets that it can be hard to remember the state of the science before the telescope launched. When a Delta II rocket carried Kepler into space on March 6, 2009, astronomers knew that the galaxy contained at least 350 exoplanets, nearly all of them the size of Jupiter or larger.

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After four years detecting the shadows of stars' orbiting worlds, Kepler has added nearly 3,000 planets to that census. And because of Kepler, astronomers are convinced that the Milky Way contains hundreds of billions of planets, roughly one for every star, with at least 17 billion of them Earth-sized.

Those numbers boosted the case for funding NASA's next exoplanet-hunting mission, the Transiting Exoplanet Survey Satellite, which is scheduled for a 2017 launch. Whereas Kepler has fixed its gaze on distant stars, TESS will focus on nearby stars so that powerful instruments like the upcoming James Webb Space Telescope will be able to probe the atmospheres of planets that TESS discovers. Kepler's planet haul has TESS scientists optimistic that their modest $200-million telescope, while less sensitive than Kepler, will nonetheless uncover plenty of planets in our neighborhood, including a handful of Earth-sized worlds.

Kepler has also exposed an intriguing new class of potentially habitable planets larger than the Earth-sized realms astronomers have traditionally targeted. Kepler's database includes nearly 700 worlds that are between 25 and 100 percent larger in diameter than Earth. …