International Exoplanet Telescope Could Follow Kepler, Astronomer Tells Lawmakers

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WASHINGTON — An astronomy professor quizzed by the House Science Committee about how NASA should probe the universe for signs of life said the agency could collaborate on an international telescope to perform detailed observations of faraway, Earth-like planets discovered by the Kepler Space Telescope.

To really scrutinize the so-called exoplanets discovered by Kepler, “we need to go to a direct imaging mission in space, and there’s no plan on the books for that,” Massachusetts Institute of Technology astrophysicist Sara Seager told the House Science Committee during a Dec. 3 hearing. 

Seager, a 2013 MacArthur Foundation “genius grant” winner, has worked extensively on characterization of exoplanets seen by observatories including Kepler, a now-hobbled astrophysics mission that on Dec. 4 was cleared by NASA to compete with other, healthier spacecraft for extended mission funding in a review slated for March.

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Seager offered her suggestion in response to a question from House Science Committee Chairman Lamar Smith (R-Texas), who wanted to know about astrobiology concepts that might be ready to start scanning for signs of alien life in the next five to 10 years.

When asked by Rep. Eddie Bernice Johnson (Texas), the committee’s top Democrat, about potential international contributions to such a project, Seager said the cash-strapped U.S. space agency would probably need to rely on other countries to build and launch the observatory.

That, Seager said, is because the right telescope for the task requires an untested, experimental piece of hardware known as a Starshade to get a closer look at the exoplanets discovered by Kepler. An adjustable, free-floating, flower-shaped Starshade would allow a nearby telescope to see a faraway planet by blocking light from the world’s host-star — light that otherwise would hide the potentially habitable planet from view.

“We may see a scenario in a very budget-constrained environment where here in the United States, we build the Starshade … but we get the telescope and launch from international partners,” Seager said. “That’s a way we accomplish this in the near term.”

Near-term, in this case, means five to 10 years from now. By that time, NASA’s Astrophysics Division, which along with the Planetary Science Division is one of two parts of the agency’s Science Mission Directorate concerned with the search for alien life, plans to have launched its $8.8 billion James Webb Space Telescope (JWST) and moved on to its next big project.

The post-JWST project NASA Astrophysics is actually studying does not much resemble Seager’s hypothetical observatory, although it might include an instrument called a coronagraph designed to detect more exoplanets.

On Dec. 3, a day before the House Science Committee’s hearing, Paul Hertz, head of NASA’s Astrophysics Division, described the agency’s latest concept for the Wide Field Infrared Survey Telescope (WFIRST) — a mission designed to fulfill science objectives the astrophysics community identified in 2010 as top priority after JWST.

The WFIRST concept NASA is now studying would utilize one of the two unflown spy telescopes the agency got from the National Reconnaissance Office in 2012. Each of those has a 2.4-meter-diameter primary mirror that, NASA determined, would be an acceptable building block for the visible and near-infrared observations the science community wants WFIRST to make. 

Hertz said NASA has asked the National Research Council (NRC) to study whether the 2.4-meter WFIRST concept meets the science objectives laid out in the council’s 2010 astrophysics decadal survey, which set out the community’s top science priorities from 2012 to 2021. The review should be finished around March, Hertz told the NASA Advisory Council’s Science Committee, which met at NASA headquarters here Dec. 3 and Dec. 4.

Even with the NRC’s blessing NASA would make no decision about the WFIRST first mission until early 2016 at the earliest, according to a slide Hertz showed the NASA Advisory Council Dec. 3. In any case, there is no money in the astrophysics budget to start the WFIRST mission until after JWST, scheduled to launch in 2018, is out of the pipeline.

 

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