NASA launches last of the 'Great Observatories'
CAPE CANAVERAL, Florida (CNN) -- After two decades of development and delays, NASA early Monday launched a powerful infrared telescope to peer into the deepest reaches of space.
The Space Infrared Telescope Facility (SIRTF) -- the fourth in NASA's Great Observatories series of astronomical spacecraft -- lifted off at 1:35 a.m. EDT.
Others in the series are the Hubble Space Telescope, launched by the space shuttle in 1990; the Gamma Ray Observatory, launched in 1991; and the Chandra X-Ray Observatory, launched in 1999.
Each of the Great Observatories observes different colors of light that cannot be viewed from the Earth's surface, and each serves a different function.
Scientist Anne Kinney explained that on deep surveys Hubble Space Telescope scientists try to find the "reddest" objects which indicates the greatest distance.
"With SIRTF you'll be able to fill in that population of most distant objects," Kinney said.
"Meanwhile you look at the same field with the Chandra X-Ray observatory and you see a little beacon that says black hole here -- it points out where all of the black holes are in the field. You're testing very different types of physics, very different things -- a lot of synergy."
SIRTF holds the record for one of the most delayed spacecraft and the one which has gone through the most changes.
When planned in 1983 it was scheduled for launch in 1990 as a science instrument flying inside the space shuttle's cargo bay on relatively short two-week missions.
Then it evolved into a free-flying spacecraft to be serviced by the space shuttle like the Hubble Space Telescope.
Later it evolved into a smaller spacecraft without any capability to be serviced by the shuttle and the size was reduced to save money.
Unlike most astronomical spacecraft SIRTF will not be orbiting the Earth. Instead, it will be put into orbit around the sun.
"SIRTF will be following the Earth around the sun, kind of like a faithful puppy dog," astronomer Michael Werner said. The solar orbit increases the lifetime of the spacecraft.
SIRTF will gradually lag further and further away from the Earth until it's too far to be detected. But in about six decades the Earth will "catch up" with SIRTF, like a race car lapping another race car.
SIRTF observes in the infrared light band and its scientists joke that SIRTF looks at the "cold, the dark, and the dirty."
At longer infrared wavelengths SIRTF will look at clouds of dust between stars. At shorter infrared wavelengths SIRTF will be able to see through the clouds, similar to how fog lamps can view objects further away than normal headlamps.
"That's a very powerful combination which is made possible by the broad wavelength coverage we have," Werner said.
Astronomers have compared using different wavelength telescopes to the different musical instruments in an orchestra. While each instrument produces good music by itself the combination of the different instruments produces a far richer, more detailed sound.
SIRTF's detectors are incredibly sensitive. If you could put a common household television remote control in deep space SIRTF could detect it at a distance of 25,000 miles.
Many of SIRTF's scientists have been working on the project for parts of three decades. One astronomer noted that they should have realized the project was jinxed when NASA's announcement of opportunity in 1983 was released on a Friday the 13th.
To detect incredibly faint objects at the edge of the universe SIRTF's cameras are bathed in liquid Helium just a couple of degrees above absolute zero. The spacecraft has 95 gallons (360 liters) of Helium, enough to last about five and a half years.
The first science images will come down about two months after launch after the spacecraft is checked out. The SIRTF project cost taxpayers about $1.19 billion.
-- Journalist Philip Chien contributed to this report.