Proposal for Next Big Telescope Puzzles Some Astronomers

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

The small group had gathered here the American Museum ofNatural History in New York City to watch a live webcast from the NationalAcademy of Sciences in Washington, D.C. on the Astro2010Decadal Survey presented. The report designates the astronomy projectsdeemed most crucial for the next 10 years.

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

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

With an almost 5-foot (1.5-meter) mirror, the WFIRSTobservatory ranked first among other potential space-based projects and carriesa proposed launch date in 2020. The space telescope's large-scale imagingcapability would complement the targeted infrared observationsexpected from the $5-billion JamesWebb Space Telescope, which already represents a flagship NASA projectslated to launch in 2014.

That made scientific sense to the group of observers, exceptthat no one seemed to know the details behind WFIRST. According to theAstro2010 survey group, the new space telescope would settle fundamentalquestions about the nature of dark energy and search for exoplanets orbiting starsin the central bulge of the Milky Way.

In Hubble's footsteps

Both WFIRST and JWST are infrared space observatories. Someresearchers wondered why the report did not also choose a successorto the Hubble Space Telescope that could view the universe through opticalor ultraviolet light.

Yet Shara pointed out that astronomers and astrophysicistshave 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 madesense to wait for technology development to catch up for a next-gen optical/UVtelescope.

The choice of the $465-million LargeSynoptic Survey Telescope as a top priority for the ground-basedobservatory projects pleased Morgan May, an astrophysicist at BrookhavenNational 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. "Clearingthe ground [for the telescope] is nothing compared to coming in first for therecommendations."

The ground-based observatory would provide a steady streamof 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 10years to provide an unprecedented view of changes over time.

Gazing into the future

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

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

The report incorporated risks, costs and technical readinessfor the first time as the sixth decadal survey. Its long view also includedprojects considered in past decadal surveys, as well as those which mightmature for the future decadal survey.

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

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