UA Steward Observatory team to deliver far-infrared camera for SIRTF

Lori Stiles
March 29, 2000

George H. Rieke, 520-621-2832,
Erick T. Young, 520-621-4119,

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TUCSON, Ariz. - Astronomers looking at the very cold, far-infrared universe have barely glimpsed what's there.

They've had to make do with imaging systems that survey the cosmos a few pixel points of light at a time. And they've had to grab opportunities to observe from space or high in the atmosphere, where the cosmic far infrared photons are visible.

Things will change dramatically with the launch of the Space Infrared Telescope Facility (SIRTF) in December 2001.

SIRTF will fly three science instruments in orbit around the sun for perhaps as long as five years - as long as the liquid helium lasts to keep the imaging systems cooled to near absolute zero.

One of the instruments, from the University of Arizona, will use the first true imaging arrays at far-infrared wavelengths. It will detect far-infrared objects 100 times fainter than have ever been seen before.

Where pioneering far-infrared surveys of the 1980s - 1990s saw nearly empty sky, SIRTF will get views packed with infrared-bright objects, said University of Arizona astronomer George H. Rieke.

Rieke is principal investigator for the Multiband Imaging Photometer for SIRTF (MIPS), the science instrument for the far infrared. The MIPS is a highly sensitive camera that will take images of the coolest objects in space, objects at temperatures between about minus 430 and minus 300 degrees Fahrenheit.

Next Monday, April 3, Rieke and his entire UA Steward Observatory team will be at Ball Aerospace in Boulder, Colo., to demonstrate that their instrument meets NASA's requirements. They will hand over the instrument officially a few weeks later.

Then MIPS will be mounted in a helium dewar (a kind of sophisticated thermos bottle), cooled to 1.5 degrees Kelvin, (or minus 457 Fahrenheit, just above absolute zero), mounted with the dewar in the telescope and tested. The completed telescope with instruments gets shipped next year to Lockheed-Martin in Sunnyvale, Calif., where it will be installed in the spacecraft and further tested. The full SIRTF observatory will travel a few months before launch to the NASA Kennedy Space Center at Cape Canaveral, Fla.

The Harvard-Smithsonian Center for Astrophysics (CfA) and Cornell University are on a similar schedule for the other two SIRTF science instruments. CfA has developed the Infrared Array Camera and Cornell University has developed the Infrared Spectograph.

Rieke's group began work on their camera in 1984, when SIRTF was envisioned as a $2 billion mission. The SIRTF design was overhauled in 1994 to cut mission costs to under a half billion dollars. The UA team contracted to build MIPS for $23.7 million. Advances in infrared detectors allowed SIRTF to retain much of its power despite the huge budget cut.

UA astronomer Erick T. Young, deputy principal investigator for MIPS, led the Steward Observatory team that designed and built the first far-infrared detector arrays for their part of the SIRTF mission. The arrays will enable MIPS to see far-infrared objects never seen before.

"Such images will show us infrared-bright galaxies to the edge of the known Universe, maybe even farther than any galaxies we have discovered so far," Rieke said.

"And we can look around nearby sun-like stars for planetary debris systems with emissions as wimpy as our own solar system emission.

"In fact, we've shown that MIPS, looking back from any close star, could detect the finely divided material we expect lies out in the Kuiper Belt," he added. The Kuiper Belt is the system of small, faint and very cold objects recently found beyond the orbits of Neptune and Pluto.

But the real breakthroughs are up to the astronomical community, which will get 80 percent of SIRTF observing time, Rieke emphasized. The SIRTF Science Center at the California Institute of Technology will issue a first call for observing proposals a month from now.

"With such an advance in capability, we expect that discoveries will be made well beyond our currently imagined ones," Rieke said.


The UA camera on SIRTF contains three super-cooled detector systems that operate at different wavelengths.

One array, supplied by Boeing North America, operates at 24 microns, 50 times the wavelength of visible light. (A micron is one-thousandth of a millimeter.)

Another far-infrared array, built at Steward Observatory, is sensitive to radiation at 70 microns. It contains 1,024 detectors, 100 times larger than previous arrays operating in space at this wavelength. Each detector has about 30 times the sensitivity of those in the earlier arrays.

A third array, also built at Steward Observatory, operates at 160 microns, which is about 300 times the wavelength of visible light. There are 10 times as many detectors -- each 10 times more sensitive -- as in any previous array operated in space at this wavelength.

All objects above the coldest possible temperature, absolute zero, or minus 459 degrees Fahrenheit, emit infrared radiation, or heat. Helium is used to chill the MIPS arrays to just 2 degrees Fahrenheit above absolute zero to avoid blinding the arrays with heat from SIRTF itself.


Eric Arens, University of California, Berkeley
Charles Beichman, California Institute of Technology
Steven Gaelema, Black Forest Engineering
T.Nicholas Gautier, Jet Propulsion Laboratory
Eugene Haller, Lawrence Berkeley National Laboratory
Charles Lada, Harvard Smithsonian Astrophysical Observatory
Frank Low, University of Arizona
Jeremy Mould, Mount Stromlo & Siding Spring Observatory
Gerry Neugebauer, California Institute of Technology
Paul Richards, University of California, Berkeley
Marcia Rieke, University of Arizona
Peter Strittmatter, University of Arizona
Michael Werner, Jet Propulsion Laboratory


Jeff Beeman - Detectors and Stimulators
Michael Bradley-Focal Plane Construction
Jim Cadien - Detector Testing
Cindy Davidson - Process Engineer
Jim Davis - Focal Plane Construction
Chad Engelbracht - Instrument Scientist
Kimberly Ennico - Instrument Science
Karl Gordon - Instrument Science
Dean Hines - Scientist-At-Large
Todd Horne - Research Specialist
Doug Kelly - Instrument Science
Dak Knight - Focal Plane Construction
Mary McCormick - Administrative Support
Tom McMahon - Systems Engineer
George Rieke - Principal Investigator
Gil Rivlis - Software, Computers, and Miscellaneous
Raz Quillen Rivlis - Destructive Test Consultant
Rick Schnurr - Stressed Ge:Ga Array Lead
John Stansberry - Instrument Science
Patsy Van Buren - Administrative Support
Debbie Wilson - Program Manager
Greg Winters - Focal Plane Engineer
Erick Young - Deputy Principal Investigator


Jet Propulsion Laboratory
SIRTF Science Center, California Institute of Technology
Ball Aerospace and Technologies Corp.
Lockheed Martin Missiles and Space
Smithsonian Astrophysical Observatory
NASA-Goddard Space Flight Center
Cornell University
University of Arizona


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