Picturing a universe that's out of sight (Forwarded)

Office of News and Public Affairs
Harvard University
Cambridge, Massachusetts

December 11, 2003

Picturing a universe that's out of sight

Satellite sees through space clouds

By William J. Cromie, Harvard News Office,

Heart pounding, nerves strung tight, Giovanni Fazio fixed his eyes on the rocket
about to be launched. Sitting on top of it was his whole life's work, a camera
that could look beyond the visible universe to see planets, stars, and galaxies
being born.

"There's 20 years of my work sitting on top of a huge piece of dynamite about to
be lighted," he recalls thinking. "Will the rocket take it into space or will it
go up in smoke? My family was with me and I was very nervous."

Packed in a hi-tech thermos bottle on the rocket sat IRAC, IRS, and MIPS,
cameras and spectrographs that see heat (infrared radiation) rather than visible
light. As you read this, new stars and, possibly, planets are forming behind
black curtains of dust and gas in our galaxy. These births are attended by
bursts of infrared radiation that are visible to the instruments when the
cameras are cooled to near 450 degrees below zero Fahrenheit.

Other cosmic mysteries veiled from our eyes will become clearer as a result of
the infrared waves they emit. They include brown dwarfs, ultraluminous infrared
galaxies, and things that happened as long ago as 12 billion years. Brown dwarfs
are bigger and warmer than planets but smaller and colder than stars. These
hidden bodies are thought to make up part of the so-called dark matter that far
exceeds the volume of visible matter in our universe. Ultraluminous galaxies are
probably galaxies in collision, their intensely hot fires fueled by black holes
and bursts of star formation. Other infrared radiation shows objects as they
existed near the beginning of the universe. Due to the expansions of the
universe, their light has been stretched or shifted to infrared wavelengths
during its long journey to our telescopes. This, in effect, allows astronomers
to look far back in time.

Fazio, a senior physicist at the Harvard-Smithsonian Center for Astrophysics,
directed the design and construction of IRAC, an infrared array camera that
captures unseen waves just longer than visible red light. MIPS, the multiband
imaging photometer, "sees" longer infrared wavelengths. IRS, an infrared
spectrometer, breaks up this radiation in ways that allow astronomers to see
which atoms and molecules are responsible for the unseen chemistry in space.

The three instruments sit at the focus or "eyepiece" of a 34-inch-diameter
telescope mounted in a spacecraft called the Space Infrared Telescope Facility,
or SIRTF for short. It's the largest and most sensitive infrared observatory
ever lofted into space.

Into the wild, cold yonder

Fazio and his colleagues have been sending telescopes above Earth's atmosphere,
which blocks most incoming infrared rays, since the 1970s. Then he used large
balloons bloated with helium gas to lift the instruments to altitudes of
hundreds of miles. In the 1980s, his team launched an infrared telescope aboard
the Space Shuttle, but it didn't work well. Finally, last Aug. 25, he waited for
the ignition of a Delta rocket, with extra boosters strapped to it, to blast his
life's ambition into an orbit around the sun.

The boosters ignited, flames roared from the Delta's tail, and the telescope
began its ascent.

"I never get tired of balloon or rocket launches no matter how many I see,"
Fazio says. "The SIRTF launch was not as explosive as a Space Shuttle liftoff,
but when it's your launch, it makes a difference."

To the cheers and squeals of the crowd the rocket got smaller and smaller until
all there was to see was a trail of smoke. Controllers on the ground then
maneuvered it into a solar orbit where astronomers hope it will stay for as long
as five or six years. SIRTF will stay in Earth's shadow as it circles the sun,
but it will get further and further behind our planet as time passes. In
mid-December, it is about 2.5 million miles away. After five years, that
distance will increase to about 50 million miles.

It's frigid out there, and SIRTF instruments need that intense cold to see well.
Heat from Earth, sun, and the spacecraft itself must be chilled away. In
addition to the iciness of space, the instruments sit in an oversized thermos, a
dewar of liquid helium that keeps temperatures near minus 450 degrees
Fahrenheit, cold enough to slow molecules almost to a standstill. The useful
life of the telescope and the instruments looking through it will be determined
by how long the helium lasts.

Be clever or quit

If you look directly at the Orion constellation on a dark night, you see a
peppering of bright and dim stars. But peer at the same scene through an
infrared telescope, and you see something totally different. The famous
constellation explodes into a vast celestial tapestry of glowing dust lit up by
newborn stars.

When Fazio saw the universe this way in images sent back from gigantic balloons
that rose above Palestine, Texas, in the 1970s, he dedicated himself to the task
of seeing clearer and farther by infrared light. "Our equipment was very
primitive then, but we made many discoveries about star formation in our Milky
Way galaxy," he recalls.

In the 1980s, when space shuttles began carrying scientific experiments into
orbit, he saw these craft as an ideal way to put more sensitive infrared
telescopes higher into space. After finally getting a telescope aboard a
shuttle, Fazio concluded that this was not the right way to go. Just as water
vapor and dust in the atmosphere block infrared light from reaching ground
telescopes, moisture and particles around the spaceship ruined the view. "It was
too wet and dirty," he says with frustration.

Fazio and his team started to design and build an independent, unmanned
observatory that functioned on its own like the Hubble Space Telescope. They
calculated it would cost $1.5 billion. Caught in a budget crunch, the National
Aeronautics and Space Administration told the team they would have to do it for
$450 million.

"That was a real challenge," Fazio admits. "But we learned that when you are
forced to either be clever or quit, it's amazing what you can do."

It took the team almost 10 years to develop the infrared detectors they would
need to assemble the finest such telescope ever built. "I have no regrets about
that," Fazio says. "Even with all the delays we encountered, the technology we
developed still remains among the best available."

These detectors may give us the first detailed view of how stars and planets are
born in our galaxy and how galaxies formed in the early universe. "I can't
promise that we'll see new planets in the Milky Way," Fazio admits, "but you
never know."

Such infrared cameras have also been finding plenty of employment on the ground.
Firefighters use them to search for people in smoke-filled spaces. They allow
police and security officers to see what is going on in total darkness. They
enable engineers to study heat stresses in airplanes, revealing areas where
special maintenance may be needed. In Iraq, infrared cameras mounted on their
helmets give soldiers eyes in the night, and let them find dangers in tunnels
and dark rooms. In the future, infrared sensors might allow doctors to detect
cancer tumors by the abnormal heat they give off.

Meanwhile, the best-ever infrared images of the universe have started coming
down from space. "They are so spectacular, they are worth the 20 years of
heartbreaks," Fazio says. "I feel like a kid in a toy store. It's a science
wonderland."

[NOTE: Images supporting this article are available at
http://www.news.harvard.edu/gazette/...satellite.html ]