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University of Iowa News Release


Aug. 26, 2009

NASA selects UI researchers to participate in x-ray telescope mission

NASA recently selected a group of University of Iowa researchers to be part of a team that will use an x-ray telescope aboard a satellite to explore the distortion of space by spinning black holes and the creation of intense magnetic fields around dead stars.

Called the Gravity and Extreme Magnetism Small Explorer (GEMS) satellite, the project is coordinated by NASA's Goddard Space Flight Center in Greenbelt, Md. Although the satellite isn't scheduled for launch until 2014, the seven UI researchers have been hard at work for about one year, according to Phil Kaaret, leader of the UI GEMS researchers and professor in the College of Liberal Arts and Sciences Department of Physics and Astronomy.

"The satellite will measure the polarization of X-rays coming from black holes and other exotic objects such as neutron stars and supernova remnants," Kaaret said. "At Iowa, we will calibrate the X-ray detectors, contribute to the science planning and analysis, and Iowa students are building a detector that may extend the energy coverage to lower energies."

In contrast to visible light, the measurement of polarized X-rays is a rarely used, but productive investigative tool. "Polarization is the best tool to directly see how black holes warp space-time," Kaaret said.

"Just as polarized sun glasses cut down on glare, seeing polarized X-rays will reveal details about black holes that are obscured even with the best existing telescopes," Kaaret said.

Although astronomers have observed thousands of X-ray sources, only one outside of the solar system, the Crab Nebula, has been measured in polarized X-rays. The GEMS satellite will be 100 times more sensitive to polarization than previous X-ray detectors and, as a result, will be able to detect emissions from ultra-dense neutron stars, stellar-mass black holes, and the ultra-massive black holes at the centers of distant galaxies.

In addition to Kaaret, the Iowa group consists of physics graduate students Zachary Prieskorn and Ryan Allured, physics undergraduate students Mark Gorski and Alicia Maxwell, electrical and computer engineering undergraduate student Harrison Harnisch, and mechanical engineering undergraduate student Phillip Deierling.

Along with Iowa, other universities participating in the mission include: MIT, Johns Hopkins University, Cornell University, Rice University, the University of Oulu (Finland), North Carolina State University and Washington University. NASA has capped mission costs, excluding the launch vehicle, at $105 million, and the UI portion of that funding will be determined at a later date.

STORY SOURCE: University of Iowa News Services, 300 Plaza Centre One, Suite 371, Iowa City, Iowa 52242-2500

CONTACTS: Research: Philip Kaaret, Department of Physics and Astronomy, 319-335-1985, 319-594-0073 (cell),; Media: Gary Galluzzo, University News Services, 319-384-0009,