26 August 2003
Images, notes, and contact details appear below.
Astronomers hunt Martian water from Earth
As Mars makes its closest approach in almost 60,000 years, two Australian
astronomers have used the United Kingdom Infrared Telescope (UKIRT) in
Hawai`i to look for signs that the planet once had liquid water - and so may
have hosted life.
Dr. Jeremy Bailey of the Anglo-Australian Observatory and the Australian
Centre for Astrobiology (ACA) at Macquarie University in Sydney, and Sarah
Chamberlain, a PhD student at the ACA, have produced what is Bailey says is
"perhaps the sharpest image of Mars ever made from the ground."
But the real gold lies in the spectral data they obtained.
The scientists are applying the same remote-sensing technique that
geologists use to map minerals on the Earth's surface.
Minerals absorb some wavelengths from sunshine and reflect others. Each
mineral has its own 'spectral signature' - the set of wavelengths it
"We're looking particularly for the signatures of minerals, such as hydrated
clay minerals, that would indicate the past presence of liquid water," said
Similar prospecting by NASA's Mars Odyssey spacecraft has shown that there
is a vast amount of hydrogen below the surface of Mars. The consensus has
been that this is probably water ice.
But did Mars ever have liquid water? And if so, how much? It's still
NASA's Mars Global Surveyor has found sizeable deposits of a mineral called
crystalline (grey) hematite, which forms only in the presence of liquid
NASA's two Mars Exploration Rovers, due to land on the Martian surface in
January 2004, and the UK lander Beagle 2, due to land in December this year,
will also be looking for signs that Mars has had liquid water.
"While spacecraft can get up close, ground-based observations still have a
role, as they allow us to use larger and more powerful instruments," said
UKIRT, with a 3.8-m diameter aperture, is the world's largest telescope
devoted specifically to infrared observations.
UKIRT is funded by PPARC, the UK Particle Physics and Astronomy Research
Council. The Anglo-Australian Observatory is funded by the UK Government,
through PPARC, and the Australian Government.
UKIRT image of mars at infrared wavelengths. The dark markings resemble those seen at visible wavelengths, but the south
polar cap (at the bottom of the picture) is less prominent as its ice
absorbs at infrared wavelengths. The slight green colour around the polar
cap is a result of ice absorption.
The image was obtained with the UIST (UKIRT imager spectrometer) instrument
on the 3.8-m United Kingdom Infrared Telescope (UKIRT). It is a composite of
three narrowband-filter images at wavelengths of 1.57, 1.64 and 2.12
micrometres in the near infrared.
Observations: Jeremy Bailey (Anglo-Australian Observatory and Australian
Centre for Astrobiology, Macquarie University) and Sarah Chamberlain
(Australian Centre for Astrobiology, Macquarie University). Data processing:
Chris J. Davis, Joint Astronomy Centre, Hawai'i.
The United Kingdom Infrared Telescope. Credit: Nik Szymanek.
The United Kingdom Infrared Telescope at night with star trails. Credit: Nik Szymanek.
The world's largest telescope dedicated solely to infrared astronomy, the
3.8-metre UK Infrared Telescope (UKIRT) is sited near the summit of Mauna
Kea, Hawaii, at an altitude of 4194 meters above sea level. It is operated
by the Joint Astronomy Centre in Hilo, Hawaii, on behalf of the UK Particle
Physics and Astronomy Research Council.
The UKIRT Imager Spectrometer (UIST) was designed and built at the UK
Astronomy Technology Centre (UK ATC) in Edinburgh. It detects infrared light
at wavelengths between 1 and 5 microns with a 1024 x 1024 pixel Indium
Antimonide detector array. It can be used for imaging, spectroscopy,
integral field spectroscopy, and polarimetry. It cost just under UKP 3M to
build and was funded by the Particle Physics and Astronomy Research Council
Dr Jeremy Bailey
Associate Director, Australian Centre for Astrobiology, Macquarie University,
Australian Centre for Astrobiology, Macquarie University, Sydney,
Dr. Douglas Pierce-Price
Joint Astronomy Centre, Hilo, Hawai'i
Anglo-Australian Observatory, Sydney, Australia
tel +61-419-635-905 (intermittently during 26 Aug - 2 Sept.)
Macquarie University, Sydney, Australia
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