Proposal for Next Big Telescope Puzzles Some Astronomers

NEW YORK — Some astrophysicists were a bit puzzled by the choice of a $1.6 billion infrared space telescope as the top priority for the next decade of astronomy, even if they mostly agreed with other projects laid out in an influential report released Friday.

The small group had gathered here the American Museum of Natural History in New York City to watch a live webcast from the National Academy of Sciences in Washington, D.C. on the Astro2010 Decadal Survey presented. The report designates the astronomy projects deemed most crucial for the next 10 years.

"I don't think there were losers," said Michael Shara, an astrophysicist at Columbia University in New York. "I think the entire community really won, and won big time."

The report's big ticket item was the Wide-Field Infrared Survey Telescope.

With an almost 5-foot (1.5-meter) mirror, the WFIRST observatory ranked first among other potential space-based projects and carries a proposed launch date in 2020. The space telescope's large-scale imaging capability would complement the targeted infrared observations expected from the $5-billion James Webb Space Telescope, which already represents a flagship NASA project slated to launch in 2014.

That made scientific sense to the group of observers, except that no one seemed to know the details behind WFIRST. According to the Astro2010 survey group, the new space telescope would settle fundamental questions about the nature of dark energy and search for exoplanets orbiting stars in the central bulge of the Milky Way.

In Hubble's footsteps

Both WFIRST and JWST are infrared space observatories. Some researchers wondered why the report did not also choose a successor to the Hubble Space Telescope that could view the universe through optical or ultraviolet light.

Yet Shara pointed out that astronomers and astrophysicists have had a "phenomenal UV telescope, i.e. Hubble, for the last 20 years, and we're getting it for another five [years]." He added that it made sense to wait for technology development to catch up for a next-gen optical/UV telescope.

The choice of the $465-million Large Synoptic Survey Telescope as a top priority for the ground-based observatory projects pleased Morgan May, an astrophysicist at Brookhaven National Laboratory in Upton, NY.

His group has a lead role on developing sensors for LSST, which would use optical eyes to gaze at the heavens from its site in Chile.

"I think it's wonderful," May said. "Clearing the ground [for the telescope] is nothing compared to coming in first for the recommendations."

The ground-based observatory would provide a steady stream of snapshots showcasing the night sky through an almost 28-foot (8.4-meter) aperture. LSST is scheduled to scan each region of the sky 1,000 times over 10 years to provide an unprecedented view of changes over time.

Gazing into the future

A big uncertainty still hangs over the funding for all the priorities listed in the report. But Shara seemed confident that the report's committee had already made the hard, realistic choices when considering the future budgets of NASA, the National Science Foundation and the Department of Energy.

"The reason I think this process has worked so well is that it was driven by the science first, but also by the economics, by the harsh realities, by what is ready, by what has a real chance of succeeding," Shara explained. "So there was a great deal of reality in all of this."

The report incorporated risks, costs and technical readiness for the first time as the sixth decadal survey. Its long view also included projects considered in past decadal surveys, as well as those which might mature for the future decadal survey.

"From new worlds to new physics, the coming decade of discovery leverages not only our current space observatories — such as the Hubble, Spitzer, Chandra and Fermi space telescopes — but also our planned facilities — especially those from previous decadal surveys, the James Webb Space Telescope and the Stratospheric Observatory for Infrared Astronomy (SOFIA)," said NASA officials in a statement.

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