UK Astronomers Look Forward To Looking Back (SIRTF)

Royal Astronomical Society Press Notice
London, U.K.

Issued by Peter Bond, RAS Press Officer

tel: +44 (0)1483-268672fax: +44 (0)1483-274047

CONTACTS

Professor Michael Rowan-Robinson
Astrophysics Group
Blackett Laboratory
Imperial College
Prince Consort Road
London SW7 2BW
Tel: +44 (0)207-594-7530 or (0)208-444-0170 until 21 August.
Mobile +44 (0)781-793-9950
E-mail:

Dr. Sebastian Oliver
Astronomy Centre
University of Sussex
Falmer
Brighton BN1 9QJ
Tel: +44 (0)1273-67-8852 or (0)1273-697829
Mobile: +44 (0)797-101-9161
E-mail:

University of Sussex press contacts:
Jacqui Bealing or Peter Simmons
Tel: 01273 678888
Fax: 01273 877456
E-mail: or

Date: 18 August 2003

PN03-33

UK ASTRONOMERS LOOK FORWARD TO LOOKING BACK

When NASA launches its Space Infrared Telescope Facility (SIRTF) -- the agency's
fourth 'Great Observatory' -- later this week, astronomers around the world will
be looking forward to using one of the most powerful time machines ever built.

Among those anticipating the opportunity to look back billions of years to an
era when the universe was in its youth are Professor Michael Rowan-Robinson
(Imperial College London) and Dr. Sebastian Oliver (University of Sussex), who
will be participating in the international SIRTF Wide-area InfraRed
Extragalactic (SWIRE) survey.

Taking advantage of SIRTF's ability to detect infrared radiation (heat) from the
coolest objects in the universe, the SWIRE team will study galaxies located up
to 10 billion light years away where infant stars are beginning to emerge from
the dust clouds in which they were born.

Over a period of nine months, the SWIRE survey will observe seven areas of the
sky covering a total of 65 square degrees -- equivalent to the area taken up by
360 full moons. These areas have been carefully selected because they are
exceptionally transparent due to an absence of Galactic dust.

Using all 7 SIRTF wavebands (3.6, 4.5, 5.8, 8, 24, 70 and 160 microns), SWIRE is
expected to detect more than 1 million infrared galaxies, many of them dusty,
star-forming galaxies that existed when the universe was only about three
billion years old.

"We shall be studying star-forming galaxies and quasars at high redshifts,
looking far deeper in the infrared than any previous survey," said Professor
Rowan-Robinson, Deputy Principal Investigator for the SWIRE programme.

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

"This is the most exciting and the most important project I have ever been
involved with," said Sebastian Oliver, a SWIRE Co-Investigator. "Our infrared
survey will be combined with studies by ground-based telescopes (such as the UK
Infrared Telescope in Hawaii) and by orbiting observatories, such as the Hubble
Space Telescope, Chandra and XMM-Newton, that study the universe at other
wavelengths."

"The SWIRE survey will provide our first glimpse of many distant galaxies," he
added.

"Long ago, galaxies were much closer together, and we think that colliding
galaxies triggered periods of rapid star birth and quasar activity. We expect to
see thousands of colliding galaxies in the ancient universe, and this will help
us to explain how galaxies grew and evolved."

NOTES FOR EDITORS

The SWIRE team is led by Dr. Carol Lonsdale at the Infrared Processing and
Analysis Center, California Institute of Technology.

SWIRE is the largest of the 6 major 'Legacy' observational programmes being
undertaken with SIRTF. These projects utilise a total of 3160 hours of SIRTF
observing time, primarily in the first year of the mission, and integrate
substantial ancillary data from ground-based observatories and other space-borne
telescopes.

A Boeing Delta 2 rocket carrying SIRTF is currently scheduled for launch from
Cape Canaveral, Florida on August 23 at 05:37 GMT (06:37 BST).

SIRTF is the fourth and last of NASA's Great Observatories. Two of these, the
Hubble Space Telescope and the Chandra X-ray Observatory are currently
operational. The Compton Gamma Ray Observatory re-entered Earth's atmosphere on
4 June 2000.

Originally intended as a $2 billion observatory that would be launched by the
space shuttle, SIRTF has suffered prolonged delays as the result of downsizing
and redesign of the spacecraft.

The new observatory is still the largest, most sensitive infrared space
observatory ever built, although its mirror is 'only' 85 cm (33 inches) in
diameter, much smaller than the Hubble Space Telescope or modern ground-based
telescopes. It carries three cryogenically cooled instruments incorporating
state-of-the-art infrared detectors.

The telescope will be cooled to a temperature of -268 C (only 5.2 C above
absolute zero) by a tank containing 360 litres of liquid helium.

SIRTF is expected to operate for at least two-and-a-half years, with a goal of
five years. Some of its detectors will be able to operate even after the supply
of helium runs out.

Following launch, the spacecraft will drift slowly away from our planet into
deep space, receding from us at a rate of about 9 million miles per year. By
following this remote, Earth-trailing orbit, heat 'pollution' from the Earth and
Moon will be reduced. Observations will also be made easier because the Earth
will not be blocking the view and there will be no periods in the planet's shadow.

The mission is a cornerstone of NASA's Origins Programme, which seeks to answer
the questions "Where did we come from? Are we alone?"

Observing at infrared wavelengths between 3 and 180 microns, SIRTF will be able
to study the coolest objects in the universe and probe the dense dust clouds
that block visible light. The four main areas of study will be:

* Brown dwarfs (small, failed stars) and giant gas planets around other stars.
* The discovery and study of debris disks around nearby stars.
* Ultraluminous infrared galaxies and quasars
* The early universe -- when and how the first stars and galaxies formed.

UK astronomers are currently helping to develop a much larger infrared
telescope, known as Herschel, which will be launched by the European Space
Agency in 2007.

Infrared radiation was discovered in 1800 by the German-born British astronomer,
William Herschel.

FURTHER INFORMATION

* SIRTF home page
http://sirtf.caltech.edu/
* Imperial College London
http://astro.ic.ac.uk/
* Sussex University
http://astronomy.sussex.ac.uk/
* ESA Herschel mission
http://sci.esa.int/herschel
* ESA brochure 'The Infrared Universe'
http://www.spacetelescope.org/about/#readmore