# Caltech, Cornell announce new $2-million study for building giant submillimeter telescope PASADENA, Calif.—The California Institute of Technology and Cornell University are in the planning stages for a new 25-meter telescope to be built in Chile. The submillimeter telescope will cost an estimated$60 million and will be nearly two times larger in diameter than the largest submillimeter telescope currently in existence.

The first step of the plan, which is being announced today jointly by Caltech and Cornell, commits the two institutions to a \$2-million study, says Jonas Zmuidzinas, a physics professor at Caltech who is leading the Institute's part of the collaboration. The telescope is projected for a 2012 completion date on a high site in the Atacama Desert of northern Chile, and will significantly ramp up Caltech's research in submillimeter astronomy.

Scientists from Cornell, Caltech, and Caltech's Jet Propulsion Laboratory (JPL) will be participating in the telescope study, including Caltech faculty members Andrew Blain, Sunil Golwala, Andrew Lange, Tom Phillips, Anthony Readhead, Anneila Sargent, and others.

"We are very much looking forward to working with our Cornell colleagues on this project," says Zmuidzinas.

At Cornell, the participants will include professors Riccardo Giovanelli, Terry Herter, Gordon Stacey, and Bob Brown.

Submillimeter wavelength astronomy allows the study of a number of astrophysical phenomena that do not emit much visible or infrared light. The new telescope will observe stars and planets forming from swirling disks of gas and dust, will make measurements to determine the composition of the molecular clouds from which the stars are born, and could even discover large numbers of galaxies undergoing huge bursts of star formation in the very distant universe.

Also, the 25-meter telescope could be used to study the origin of large-scale structure in the universe.

"So far, we have gotten just a small taste of what there is to learn at submillimeter wavelengths," says Zmuidzinas. "This telescope will be a huge step forward for the field."

The new telescope is poised to take advantage of the rapid development of sensitive superconducting detectors, an area in which Zmuidzinas and his Caltech/JPL colleagues have been making important contributions. The new superconducting detectors enable large submillimeter cameras to be built, which will produce very sensitive panoramic images of the submillimeter sky.

The 25-meter telescope is a natural progression in Caltech and JPL's longstanding interest in submillimeter astronomy. Caltech already operates the Caltech Submillimeter Observatory (CSO), a 10.4-meter telescope constructed and operated with funding from the National Science Foundation, with Tom Phillips serving as director. The telescope is fitted with sensitive submillimeter detectors and cameras, many of which were developed in collaboration with JPL, making it ideal for seeking out and observing the diffuse gases and their constituent molecules, crucial to understanding star formation.

The advantages of the new telescope will be fourfold. First, due to the larger size of its mirror and its more accurate surface, the 25-meter telscope should provide six to 12 times the light-gathering ability of the CSO, depending on the exact wavelength. Second, the larger diameter and better surface will result in much sharper images of the sky. Third, the large new cameras will provide huge advantages over those currently available.

Finally, the 16,500-foot elevation of the Atacama Desert will provide an especially dry sky for maximum effectiveness. Submillimeter wavelengths (as short as two-tenths of a millimeter) are strongly absorbed by the water vapor in the atmosphere. For maximum effectiveness, a submillimeter telescope must be located at a very high, very dry altitude--the higher the better--or best of all, in space.

However, while the idea of a large (10-meter) submillimeter telescope in space is being considered by NASA and JPL, it is still more than a decade away. Meanwhile, existing space telescopes such as the Hubble and the Spitzer work at shorter wavelengths, in the visible and infrared, respectively.

In 2007, the European Space Agency plans to launch the 3.5-meter Herschel Space Observatory, which will be the first general-purpose submillimeter observatory in space. NASA is participating in this project, and scientists at JPL and Caltech are providing detectors and components for the science instruments.

"It is a very exciting time for submillimeter astronomy," says Zmuidzinas. "We are making rapid progress on all fronts--in detectors, instruments, and new facilities--and this is leading to important scientific discoveries."

Written by Robert Tindol

Caltech Media Relations