PITTSBURGH Astrophysicist gets grant to explore 'dark energy'

Scientists think dark energy is accelerating the expansion of the universe.
PITTSBURGH (AP) -- Carnegie Mellon University wants to develop a small spacecraft equipped with seven X-ray telescopes that would be used by NASA to map the universe and so-called "dark energy," a force that scientists theorize is causing the universe to expand at an accelerated rate.
Carnegie Mellon astrophysicist Richard Griffiths received $450,000 from NASA to develop the Dark Universe Observatory to be launched in 2007. Griffiths has five months to develop a plan for the project, which is one of five NASA is considering for its Small Explorer missions program.
NASA will give two of the five programs the go-ahead next summer.
Griffiths said the mission is important because scientists don't know how dark energy behaves -- "because we don't know what it is."
Scientists say the universe has been expanding since the Big Bang, the event that most physicists believe marked the beginning of the universe.
Scientists' beliefs
Scientists previously debated whether gravity would slow that expansion or whether the universe would continue to grow. Based on measurements of the distances between exploding stars, many scientists now believe the expansion of the universe is speeding up. Dark energy is the term given to the as-yet-unknown force that scientists believe is causing that acceleration.
The Carnegie Mellon spacecraft would use the telescopes to create a three-dimensional "map" of the universe by plotting the positions of some 10,000 clusters of galaxies. The measurements of those clusters would, in effect, provide an independent measurement of dark energy.
Griffiths said the telescopes might also provide insight into how fast the clusters form, which could possibly be used to learn more about the nature of dark energy.
The project would likely cost about $153 million, Griffiths said, although NASA likely would only pay $132 million. The rest of the money would come from Germany's Max Planck Institute for Extraterrestrial Physics, which designed the kind of X-ray telescope that will be used aboard the spacecraft.
NASA began the Explorer program in 1992 to provide scientists frequent access to physics- and astronomy-related issues.
Other Explorer missions under consideration for approval next summer are being developed at NASA's Goddard Space Flight Center in Greenbelt, Md.; the Southwest Research Institute in San Antonio, Texas; the California Institute of Technology; and the University of Colorado.