NASA has opened the way for the signing of a $24.8 million contract between Cornell and the Jet Propulsion Laboratory for building an infrared spectrograph, a sophisticated instrument that will be sent into orbit to detect and analyze some of the most distant objects in the universe.

The contract announcement was made as NASA Administrator Daniel S. Goldin authorized the start of work on the Space Infrared Telescope Facility (SIRTF), an observatory that will be launched into orbit around the sun in 2001 to probe thousands of celestial objects in the infrared portion of the spectrum. Infrared detectors are sensitive to heat rather than visible light. Thus the SIRTF instruments will be able to "see" stars much younger than those visible to the orbiting Hubble Space Telescope.

The infrared spectrograph also will be able to detect heat-emitting stars that are obscured by fine interstellar dust, notes James Houck, Cornell professor of astronomy who is the principal investigator on the infrared spectrograph project.

Cornell will retain $5.6 million of the NASA funding for the management of the program, with $800,000 going to investigators at other universities. The bulk of the award, $17.3 million, will go to Ball Aerospace in Boulder, Colo., for the design and fabrication of the spectrograph. Boeing will receive $1.1 million to build the detector arrays.

Houck's connection with the program goes back to the late 1970s, when SIRTF was first proposed. In 1984 he led the team that submitted a design proposal. Since then, says Houck, the spectrograph has gone through "a huge number" of design changes as the budget for the orbiting space observatory was slashed from $2.5 billion to $450 million. As a result, the spectrograph has no moving parts, and it will be unable to analyze molecular gas in interstellar clouds, the seedbeds of star formation.

The spectrograph will be one of three infrared instruments on board the SIRTF observatory when it is fired 100,000 miles into space in December 2001 on a Delta 7920-H rocket from Cape Canaveral, Fla. The station will then follow the Earth in orbit around the sun, "rather like a duck following its mother," says Houck. After five years, though, the distance of the observatory from the Earth will be equal to one-third of the distance from the Earth to the sun. SIRTF will be equipped with advanced refrigeration equipment to keep the detectors cooled to within a few degrees of absolute zero.

About eight members of the Cornell astronomy department will be associated with the project during fabrication, growing to about 15 during the flight phase. At that time, a center will be established at Cornell to plan observations and analyze data over the five-year life of the infrared detectors.

This is the astronomy department's third contract with NASA to build and operate infrared detection equipment. It is also managing the program to develop and build an infrared camera that will be among the main instruments aboard an observatory to be installed on a Boeing 747-SP aircraft. And it is a member of the team developing the Wide Field Infrared Explorer, to be launched next year.