Tanzania RPCV Eli Rykoff installs small, automated telescope in Turkey and Namibia
Catching those gamma rays
U-M scientists are key players in far-flung telescope project
Thursday, 15, 2004
BY ANNE RUETER
News Staff Reporter
If one of the universe's most powerful explosions occurs, Carl Akerlof and Eli Rykoff are ready. They recently returned from a craggy peak in Turkey, where they made the final adjustments on a small, automated telescope. It's now ready to catch flashes of light that accompany gamma ray bursts - mysterious, massive events in galaxies far beyond the Milky Way, so fleeting they're over before large, advanced telescopes can respond and observe them.
Akerlof, a University of Michigan astrophysicist, and Rykoff, a U-M physics Ph.D. student, are key players in a space project that's the antithesis of big science. Back in his U-M campus office, Akerlof starts to explain the challenge for this low-budget venture: "You're trying to learn about something happening 10 billion light years away" - "and you have 30 seconds to do it," Rykoff finishes with a grin.
The telescope at Bakirlitepe, Turkey, completes a set of four telescopes designed to track and analyze gamma ray bursts. Akerlof has been a guiding force behind the Robotic Optical Transient Search Experiment, a multi-institution collaboration to place these modest telescopes strategically around the globe.
At a total cost of $2 million to $3 million, ROTSE has been a minuscule item in NASA's budget - a fact Akerlof is proud of. The team contracted with a New Mexico water-tower manufacturer to make the white steel chamber that shelters the telescope. A retiree in the amateur astronomy market built the telescope mount.
The other telescopes are located at Los Alamos, N.M.; Coonabarabran, Australia; and Mt. Gamsberg, Namibia. Besides the U-M, other participants are Los Alamos National Laboratory, Lawrence Livermore National Laboratory, the University of New South Wales in Australia and the Max Planck Institute for Nuclear Physics in Germany.
Now that the Turkey telescope is operating, the team can boast on its T-shirts, "The sun never rises on the ROTSE empire." Scientists chose the four sites so that around the clock, at least one is observing dark skies.
Bursts increasingly intrigue scientists
When certain rapidly rotating super-bright stars explode, they emit bright, very brief flashes of gamma rays. Gamma rays are very high-energy waves, sometimes described as the tsunami of all the types of radiation found in the electromagnetic spectrum. They're outside the realm of visible light.
Scientists first discovered gamma ray bursts in 1973. They learned more about them using large telescopes to observe their afterglow. Some appeared to occur during supernova events, in which huge stars self-destruct. Gamma rays from the bursts do not penetrate Earth's atmosphere, but satellites in space can detect them.
The challenge Akerlof and others took on was to build inexpensive Earth-based optical telescopes with a wide field of view that can react promptly to the satellite data. Light, also given off during the distant explosion, guides the small telescopes to the source of the gamma rays, while the intense explosion is happening, so it can gather valuable data.
All four telescopes are located at or near national observatories. But to install them, team members still had to rough it.
The Namibia telescope is 200 kilometers down a dirt road. It had to be raised to a high perch to keep snakes out. Rykoff had contended with Africa's legendary snakes before as a Peace Corps volunteer in Tanzania. "They didn't cease to be scary," he says.
The Turkey telescope, perched on a rocky peak, posed the most challenges. Snow made the road impassible in January, when Akerlof originally planned the installation.
Why the bursts fascinate
Scientists like Akerlof want to observe gamma ray bursts in process to learn more about what actually causes them.
"The intriguing thing about them is, they are such prodigious sources of energy," Akerlof says. A 1999 gamma ray burst was the most luminous object ever recorded - for 10 seconds. "We'd like to understand the energetics: How do they work?"
Another attraction: "(Gamma ray bursts) illuminate a very early time in the universe," he says. Measurements of distant supernovae also reveal much about early star formation, but some gamma ray bursts could provide data from even earlier times, Akerlof says. Gamma ray bursts occur in only a small subset of supernova events. For a gamma ray burst to occur, a star has to have a larger mass than most supernovas we measure today, he says.
Telescopes are like first responders
The four ROTSE telescopes are humble but nimble. They're automated units, programmed to scan the skies as soon as the satellite signals that a gamma ray burst has occurred. Thanks to the Internet, scientists on the ground can get the coordinates seconds after the satellite detects a gamma ray burst. Akerlof and Rykoff are looking forward to the launch this fall of SWIFT, a new NASA satellite that is faster and has more capabilities than the HETE-2 satellite that currently activates the telescopes.
Once SWIFT detects a burst, it will be able to turn toward it in 60 seconds. That's still a bit slower than ROTSE.
"In six seconds we can be on target," says Rykoff. "For that first minute we will be the only ones on it." Gamma ray bursts typically last only 30 seconds. The afterglow can last days or weeks.
When any of the four telescopes gets a satellite signal via the Internet, "We get paged," says Rykoff, pointing to the pager on his belt. So far, the pagers have gone off about 20 times.
Computers in the U-M Randall Building track what's going on at the telescopes. The ROTSE team at U-M also includes physics professor Tim McKay and post-doctoral researcher Don Smith.
A decade ago, Akerlof met a lot of resistance in the scientific community when he pushed the idea for the telescopes. The message he often heard was "no use trying, you'll never see anything."
But then in January 1999, an earlier ROTSE telescope caught the first optical evidence of a huge gamma ray burst as it was happening. The accomplishment made the cover of the prestigious journal Nature. A framed copy hangs on his office wall.
After that, funding for the four telescopes followed easily.
The four telescopes detect other fleeting events in space besides gamma ray bursts, which SWIFT is expected to detect at a rate of two or three a week. The telescopes also monitor active galactic nuclei and study variable stars.
It's time for the gamma ray burst effort to pay off, but no big burst events have happened since all four telescopes have been up and running. Now, says Rykoff ruefully, "there's four times as much to go wrong."
Turkish scientists get 30 percent of the telescope time.
"We wanted them to have a self-interest in maintaining it," Akerlof says. Most of the time, experts there will be able to handle technical problems with the instrument.
Reporter Anne Rueter can be reached at (734) 994-6759 or arueter@annarbornews.com
© 2004 Ann Arbor News. Used with permission
