Nasa launches universe probe

It follows in the footsteps of the famous Hubble, Chandra and Compton observatories.

The Space Infrared Telescope Facility (SIRTF), as it is called, will detect infrared energy (heat) emitted from stars, galaxies and planets.

Astronomers will be able to study distant objects hidden by gas and dust that cannot be detected with visible light telescopes.

Young stars emerging from dusty galaxies that existed when the Universe was only about three billion years old are of particular interest.

The observatory has begun its journey into space on a Boeing Delta 2 rocket from Cape Canaveral, Florida, in the early hours of Monday.

Deeper, further
SIRTF is the largest, most sensitive, infrared telescope ever to be sent into space.

It will orbit for two to five years, drifting ever further into deep space.

UK astrophysicists will be among those making use of the observatory. They will survey the sky for infrared galaxies found up to 10 billion light years away.

"It allows us to look through dust," says Dr Sebastian Oliver of the Astronomy Centre at the University of Sussex. "This allows us to study objects that would otherwise be hidden."

Astronomers will be able to look back to a time when the Universe was a very violent place and many new stars were being born.

Michael Rowan-Robinson of Imperial College London says they will be able to look far deeper in the infrared than any previous survey.

"By looking back through almost 90% of the Universe's history, we shall be able to look back to a period when star formation was much more frequent than it is today," he says.

"This will enable us to trace the evolution of star formation from very early times."

New horizons
The launch of SIRFT marks the completion of Nasa's Great Observatories Program.

The Hubble Space Telescope, the Chandra X-ray Observatory and the Compton Gamma Ray Observatory study the Universe at other wavelengths.

Two are still in operation but Compton was taken out of commission in June 2000.

The European Space Agency is launching a larger infrared telescope - Herschel - in 2007.