March 15, 2004
A spectacular new image showcases the Hubble
Space Telescope's unique capabilities
By Tim Stephens
The unveiling last week of the Hubble Ultra Deep Field, a spectacular
new set of images from the Hubble Space Telescope, brought mixed emotions
to UCSC astronomers who are trying to save the orbiting telescope from
a premature end.
A close-up snapshot of galaxies in the Hubble Ultra Deep Field
reveals the drama of galactic life. Three galaxies just below
center are enmeshed in battle, their shapes distorted by the brutal
encounter. These oddball galaxies chronicle a period when the
universe was younger and more chaotic. Order and structure were
just beginning to emerge. The smallest, reddest galaxies may be
among the most distant known, existing when the cosmos was 800
million years old. Photo: NASA, ESA,
S. Beckwith (STScI), and the HUDF Team
While the Ultra Deep Field offers astronomers the deepest, most detailed
view ever of the distant universe, it also underscores the unique capabilities
that will be lost if the Hubble is allowed to die.
Congress is currently reviewing a NASA decision announced in January
to cancel a planned servicing mission to the Hubble that would have
extended its life past the end of the decade.
Astronomers at UCSC and elsewhere have been outspoken in their support
for the Hubble.
"The Hubble Space Telescope is the most successful telescope ever
built and continues to be the centerpiece of worldwide astronomical
research," said Sandra Faber, University Professor of astronomy
and astrophysics. "Furthermore, Hubble is entering a new and even
more productive phase in which bigger cameras enable it to map larger
regions of the sky, storing away data on millions of stars and galaxies
as a precious resource for future generations."
The Ultra Deep Field (UDF) is a deeper, more detailed version of the
iconic Hubble Deep Field images obtained in 1995 and 1998. The UDF was
acquired with a more powerful camera than the original deep field images,
and more telescope time was devoted to it, enabling Hubble to capture
light from the faintest and most distant objects ever observed. The
results give scientists a view back to a time when the universe was
just 5 percent of its present age, about 700 million years after the
"These results demonstrate how incredibly powerful the Hubble
is. It is exploring some of the most interesting and important science
questions of our day, and without it we won't be able to do these kinds
of studies," said Garth Illingworth, professor of astronomy and
astrophysics at UCSC.
Illingworth is deputy leader of the science team for the Advanced Camera
for Surveys (ACS), one of two Hubble cameras used to obtain the UDF.
He also helped plan the use of the Near Infrared Camera and Multi-Object
Spectrometer (NICMOS) to image the same field. The combination of the
two cameras--the ACS detecting optical wavelengths (visible light) and
NICMOS detecting infrared wavelengths--gives astronomers a wealth of
"Combining these images, we should be able to look back to within
several hundred million years from the Big Bang and see if we can find
galaxies in the earliest stages of their evolution," Illingworth
The ACS was installed on Hubble in 2002, and a new cooling system for
NICMOS was installed during the same servicing mission. Additional instrument
upgrades were planned for the servicing mission that is now slated for
Only the Hubble Space Telescope can provide the extremely high resolution
and wide field of view needed to obtain images like the UDF. Ground-based
telescopes can obtain high-resolution images using adaptive optics technology,
but adaptive optics works only over a tiny field of view, and it works
only at much longer wavelengths of light, said Claire Max, professor
of astronomy and astrophysics and deputy director of the Center for
Adaptive Optics at UCSC.
"Using adaptive optics on the ground is like looking through a
soda straw compared to Hubble's wide-angle lens," Max said.
Data from Hubble are used to guide the work astronomers do at ground-based
observatories around the world, Illingworth said.
"When it comes to understanding galaxies--how they formed and
evolved into galaxies like our own Milky Way--Hubble is at the center
of a web, a large network of telescopes," he said. "Astronomers
use the big telescopes on the ground to further explore objects detected
Hubble provides exquisitely detailed images of distant galaxies, showing
their size and brightness and what kinds of stars they hold. Large ground-based
telescopes, such as the Keck Telescopes, are needed to perform the spectroscopic
analysis that can tell astronomers exactly how far away a galaxy is
and other important properties. But without wide-field surveys like
the UDF, astronomers wouldn't know where to point their giant ground-based
telescopes to find those faint galaxies.
"It's an amazingly complementary activity. We can do so much more
by using both together than we could ever do using ground-based telescopes
alone," Illingworth said.
The original Hubble Deep Field image contained hundreds of tiny flecks
and blobs of light that further analysis proved to be distant galaxies
in the early stages of their evolution. But as deep as that image was,
many of the most distant galaxies were extremely faint, and some were
barely detectable. The UDF, with its higher resolution and wider field
of view, is expected to reveal more distant objects in greater detail
than astronomers have ever seen.
"I expect the UDF to be as important as the original Hubble Deep
Field has been in opening up new opportunities to study new objects,
as well as objects we know about but don't yet understand," Illingworth
Additional details and images of the Hubble Ultra Deep Field are available
This illustration places the "look-back time" of the
Hubble Ultra Deep Field in the context of the history of the universe.
Illustration: NASA and A. Field ( STScI )
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