Galaxy Quest

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With data retrieved from a revolutionary new telescope, a University of Miami cosmologist and other researchers have discovered previously unidentified ’starburst’ galaxies that could help unlock some of the secrets of the cosmos.

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At the launch site: The BLAST gondola is driven to the high-altitude balloon that will take the telescope 120,000 feet into the sky.

The star-gazing parties staged by the local university were a popular draw for many of the residents living in the town of La Crosse, Wisconsin.

One of them was a kid named Joshua Gundersen, an eighth-grader who was fascinated by physics and the stars.

Star man: Physics professor Joshua Gundersen helped develop an innovative new telescope that has identified several ‘starburst’ galaxies that lie five to ten billion light years from Earth.

“I remember attending planetarium shows and writing a paper about cosmology,” Gundersen recalls, noting that his interest in the subject was kindled by the Carl Sagan book Cosmos.

Back then, Gundersen probably never imagined he’d grow up one day to build a device that is helping to solve some of the secrets of the cosmos.

Now a University of Miami physicist and cosmologist, Gundersen is part of an international research team that built an innovative new telescope and launched it to the edge of the atmosphere, where it discovered previously unidentified dust-obscured, star-forming galaxies that could help illuminate the origins of the universe.

“We weren’t the first to discover them,” Gundersen says.

But with the BLAST telescope (Balloon-borne Large-Aperture Sub-millimeter Telescope) he helped design and invent, Gundersen and colleagues have identified a lot more of them.

Baloon Flight
During an 11-day flight in 2006, the telescope, while tethered to a balloon 120,000 feet above Antarctica, took measurements in three different submillimeter wavelengths of the far reaches of space. The data revealed close to a thousand of these “starburst” galaxies that lie five to ten billion light years from Earth, produce stars at an incredible rate, and hide about half of the starlight in the cosmos.


At the launch site: The BLAST gondola is driven to the high-altitude balloon that will take the telescope 120,000 feet into the sky. Photo courtesy of Mark Halpern.
“By going to balloon altitudes, we got a nice, crystal-clear picture of these things,” Gundersen says.

According to Mark Devlin, a professor of astronomy and astrophysics at the University of Pennsylvania and the project’s principal investigator, “We measured everything–from thousands of small clouds in our own galaxy undergoing star formation to galaxies in the universe when it was only a quarter of its present age.”

Most of the galaxies in the universe have been detected at optical wavelengths visible to the naked eye. The “starburst” galaxies identified by Gundersen and his colleagues, however, are a new class of galaxies, enshrouded by dust that absorbs most their starlight and then re-emits it at far-infrared wavelengths.

“It is these far-infrared and submillimeter wavelengths that we’re able to detect with BLAST,” Gundersen explains.

The rich data, released only recently after two years of extensive analysis, are being combined with information from other NASA observatories like the Spitzer space telescope and the Chandra X-ray, helping astronomers and cosmologists to better understand the evolutionary history of these “starburst” galaxies and how they may be associated with larger-scale structures in the universe.

Funded by NASA, the National Science Foundation, the Canadian Space Agency, and other organizations, the BLAST study will also help to answer questions about the development of other galaxies and the earliest stages of star formation of our own Milky Way.

Baby Picture
“BLAST has given us a unique picture into both of these processes,” Gundersen explains. “The light we’re getting from these submillimeter galaxies is from a time when they were first forming. In a sense, it’s like getting a baby picture.”

Data recovered from the telescope’s 2006 Antarctica mission have been published in the journal Nature. “But we’ve only scratched the surface,” Gundersen notes, saying that information gleaned from the flight will generate another 15 to 20 articles.

One significant finding not reported in the recent Nature article: the discovery of a population of cold clouds of gas and dust that represents the earliest stages of star formation. “It’s kind of amazing to think that these blobs of matter, which are about 30 degrees above absolute zero, will eventually turn into something that’s millions of degrees,” Gundersen says.

Up, up and away: Tethered to a balloon, the BLAST telescope soars to its eventual altitude of 120,000 feet.
The birth of his second son prevented Gundersen from making the Antarctica trip three years ago, when the high-altitude balloon carrying BLAST was launched.

Graduate student Nick Thomas went instead, spending seven weeks at the McMurdo scientific research station in Antarctica, where he helped assemble the device and worked on some of its electronic systems. Gundersen kept abreast of the mission’s progress via e-mails and telephone calls.

While the telescope’s flight into the outer reaches of the atmosphere went off without a hitch, it was the return trip that nearly proved disastrous.

Finding a Needle in a Haystack
After 11 days aloft, the telescope and the critical information it carried were almost lost forever. The telescope was dragged several miles across the Antarctica ice shelf by its parachute, which failed to separate from the device upon landing, as it was supposed to do. As a result, pieces of the container that housed the critical hard disk of data broke off and were scattered in all directions.

“That was pretty scary,” Gundersen said. “We could access only a very small fraction of the data during the flight. To retrieve the rest, we had to recover the hard disk. It was like finding a needle in a haystack.”

Luckily, the telescope, which is about the size of a Ford Explorer, was located.

The hard disk survived, but other parts of the telescope were damaged beyond repair. The telescope’s primary mirror will soon be shipped to Miami, where Gundersen and his team of researchers hope to conduct more optical testing with the instrument.

For now it’s back to the construction yard. A second BLAST is being built, and scientists hope to send it up from Antarctica some time next year. Gundersen plans to be there.

Paving the Way for Herschel
He is pleased that his work on BLAST has helped pave the wave for one of the European Space Agency’s most ambitious missions to study the cosmos.

The Herschel telescope, which will launch into orbit next Thursday from a space center in French Guiana, will peer into the dustiest and earliest stages of planet, star, and galaxy growth, using the same detector system that flew aboard BLAST.

“The idea with BLAST was that we could test a new detector system on a much cheaper, faster platform, namely a balloon payload,” Gundersen says. “By doing so, we were able to scoop a lot of the science from this multibillion dollar program. Herschel has an identical detector system to BLAST, along with two other important instruments that we didn’t have. It will do a lot more than what BLAST did.

“But we achieved some of the important goals first.”


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