Infrared Telescope Lifts Off

Categories: Cosmic Evolution

In the early morning hours of Monday, August 25th [1:35 AM EDT], NASA successfully launched its fourth and final element in the NASA family of Great Observatories. Today’s launch was the infrared telescope called SIRTF.

Flying eastward over the Atlantic Ocean, the new observatory entered an Earth-trailing orbit –the first of its kind– at about 43 minutes after launch. Five minutes later, the spacecraft separated from the Delta’s second and final stage. At about 2:39 a.m. Eastern Daylight Time (11:39 p.m. Pacific Daylight Time, Aug. 24), about 64 minutes after take-off, the NASA Deep Space Network station in Canberra, Australia received the first data from the spacecraft.

"All systems are operating smoothly, and we couldn’t be more delighted," said David Gallagher, project manager for the mission at NASA’s Jet Propulsion Laboratory, Pasadena, Calif.

In the early morning of August 25, 2003, NASA launched the Space Infrared Telescope Facility (SIRTF) the fourth and final element in NASA’s family of Great Observatories.
Credit: Ball Aerospace & Technologies Corp., 2003

"We are aware of the risks associated with SIRTF and discuss them constantly," says Michael Werner, project scientist for the telescope, who was at Cape Canaveral when SIRTF blasted off into space on its Delta 2 rocket. "We will all breathe a huge sigh of relief when we get our first telemetry back an hour after launch, reporting that we have the sun on the solar panels and that everything is behaving nominally."

NASA’s Space Infrared Telescope Facility (SIRTF) is a new platform for exploring the universe using infrared light. Astronomers find the infrared to be a valuable tool as it opens an important window into otherwise hidden regions of the universe. Research into the origin and composition of planets hinges on infrared observations which can reveal the composition of objects within our solar system as well as detect the material that may be forming worlds around other stars. Likewise in the infrared astronomers can study stars throughout their lives, from the earliest stages of formation in the hearts of dust clouds to their final years as they sputter and die. On larger scales, astronomers can probe distant galaxies individually or collectively, expanding our picture of the universe as a whole.

"A major area for SIRTF contributions to astrobiology will be in the spectroscopic study of carbon-bearing molecules and solids in the interstellar medium and in circumstellar shells," says Werner, project scientist for SIRTF. "Data from these programs will become available eight months after launch."

SIRTF was first proposed in 1979, but formal approval to start the project was not granted until 1996. Advances in technology over the years helped improve the overall design of the observatory. The original launch date was December 2001, but this was pushed back due to problems with computer hardware and software.

The scientific potential of SIRTF is rooted in four basic physical principles that define the importance of infrared investigations for studying astrophysical problems. The infrared region is the part of the electromagnetic spectrum stretching from about 1 micron (near-infrared) to 200 microns (far-infrared). Note that the human eye is sensitive to light between the wavelengths of 0.4 and 0.7 microns.

Reveal cool states of matter

Solid bodies in space — ranging in size from sub-micron-sized interstellar dust grains to giant planets — have temperatures spanning the range from 3 to 1500 Kelvin (K). Most of the energy radiated by objects in this temperature range lies in the infrared. Infrared observations are therefore of particular importance in studying low-temperature environments such as dusty interstellar clouds where stars are forming and the icy surfaces of planetary satellites and asteroids.

View from SIRTF rocket cam at lift-off
Credit: NASA


Explore the hidden Universe

Cosmic dust grains effectively obscure parts of the visible Universe and block our view of many critical astronomical environments. This dust becomes transparent in the near-infrared, where observers can probe optically invisible regions such as the center of our Milky Way Galaxy (and other galaxies) and dense clouds where stars and planets may be forming. For many objects including dust-embedded stars, active galactic nuclei, and even entire galaxies — the visible radiation absorbed by the dust and re-radiated in the infrared accounts for virtually the entire luminosity.

Delta Heavy Lift, SIRTF on pad.
Credit: NASA


Access to many spectral features

Emission and absorption bands of virtually all molecules and solids lie in the infrared, where they can be used to probe conditions in relatively cool celestial environments. Many atoms and ions have spectral features in the infrared which can be used for diagnostic studies of stellar atmospheres and interstellar gas, exploring regions which are too cool or too dust-enshrouded to be reached with optical observations.

Probe the early life of the cosmos

The cosmic redshift that results from the general expansion of the Universe inexorably shifts energy to longer wavelengths in an amount proportional to the object’s distance.

SIRTF Command Center
Credit: NASA

Because of the finite speed of light, objects at high redshifts are observed as they appeared when the Universe and the objects were much younger. As a result of the expansion of the Universe, most of the optical and ultraviolet radiation emitted from stars, galaxies, and quasars since the beginning of time now lies in the infrared. How and when the first objects in the Universe formed will be learned in large part from infrared observations.

What’s Next

SIRTF will get a new name after it is launched. NASA held a contest to re-name the telescope, and over 7,000 people submitted suggestions. The spacecraft’s new name will be revealed at a press conference four months after launch. The first SIRTF images will be available at that time, as well.

SIRTF is the last of the "Great Observatories" that NASA first proposed in the 1970s. Each observatory examines the heavens in a different electromagnetic spectrum. Because they are space borne telescopes, orbiting above the distorting atmosphere of the Earth, they are able to gain unprecedented views of the universe. The most famous is the Hubble Space Telescope, the visible light telescope, and it is expected to operate until 2010. The Compton Observatory, launched in 1991, examined gamma rays until its mission ended in 1999. The Chandra Observatory, launched in 1999, examines X-rays and is scheduled to operate through 2004.

SIRTF has a 2.5-year mission, although it could be extended to 5 years. Because SIRTF will lag a little further behind the Earth as time goes by, after 5 years SIRTF will be about 50 million miles away.

Related Web Pages

Magellan Telescope Project
Infrared Camera MIRAC3/BLINC (Harvard)
Space Infrared Telescope Facility Science Center (Caltech)
University of Arizona Astronomy (M. Meyer)
Infrared Space Observatory (ESA)
Planetary Embryos Hatch