Telescope Launches to Scout for High-Energy Action

NASA launched a telescope today that will scour the skies for the most intense and violent phenomena in the universe.

The next-generation gamma ray telescope will track high energy radiation. These photons of light are so jacked with power they register not by bouncing off a mirror but by blasting into bits of matter and antimatter.

It is the job of GLAST -- the Gamma Ray Large Area Telescope -- to sort through the particles and figure out where they came from. The observatory, which weighs nearly 5 tons, launched aboard an unmanned Delta rocket at 12:05 a.m. ET today from Cape Canaveral Air Force Station in Florida.

"Throughout all of human existence, there's been a shared experience of looking up at the night sky at the stars ... but it's only very recently that we have come to understand that all that light is only secondary byproducts of high-energy physical properties," said Steve Ritz, the lead scientist for GLAST from NASA's Goddard Space Flight Center in Greenbelt, Md.

It has been eight years since NASA's Compton Gamma Ray Observatory fell from space after a productive and eye-opening mission to study the gamma ray bursts.

Putting telescopes in orbit, beyond the filter of Earth's atmosphere, has opened new windows for exploring the universe.

"What we see when we look in other parts of the electromagnetic spectrum is very different than what we see with our natural eyesight," Ritz said. "GLAST is giving us a chance to peak behind the curtain or under the hood to see how things are working."

Gamma radiation is light's most energetic form, millions to hundreds of billions of times more powerful than visible light. The energies are so high that Albert Einstein's famous E=mc2 equation, which captures the relationship between matter and energy, provides the framework for designing how the telescope works.

Gamma rays, which are pure energy, slam into a layer of tungsten in the detector and split into pairs of subatomic particles, an electron and its antimatter partner, a positron. Layers of silicon can then trace the direction of the incoming gamma rays. Another detector, called a calorimeter, absorbs and measures the particles' energy.

Many more particles besides gamma rays will bombard GLAST's detectors, so the telescope wears what engineers call a "hat" to sort out cosmic ray hits and other unwanted visitors.

The Gamma Ray Universe

It's a huge effort, one that NASA is spending close to $700 million to mount, but the scientific payoffs have the potential to rewire our understanding of the universe. For starters, there is GLAST's range.

The telescope's two instruments can detect such a broad span of gamma radiation that if it were a piano it would cover 23 octaves, Ritz said.

That's important because gamma rays are tied to a wide variety of phenomena including neutron stars, black holes and dark matter. An instrument on the predecessor Compton Telescope mapped 271 gamma ray targets, 171 of which have not been unidentified. Another device found bursts of gamma rays coming from all over the sky.

"We've seen just the tip of the iceberg," Ritz said.

With its wide-angle view of the universe, GLAST is designed to survey the whole sky every three hours. It also will cover a range of radiation never before studied and reveal bizarre physics triggered by immense gravity, powerful magnetism and supercharged electrical fields that cannot be replicated on Earth.

"We're really at a unique time in the history of science and astronomy that we can study the cosmos across the electromagnetic spectrum for the first time," said John Morse, director of NASA's astrophysics division at the agency's Washington, D.C. headquarters.

"Every time you push the boundaries and do something an order of magnitude better than you've done before, you always wind up with new discoveries," he said.

The observatory is expected to last five years, but scientists are hoping for a mission twice as long. There is no shortage of targets.

Gamma rays are emitted from objects throughout the universe, as near as the sun and moon and as far away as the beginning of time.

Scientists also may learn about dark matter, which is a generic term for explaining the missing mass needed to account for the expansion of the universe.

"Many people suspect there are clues to the nature of dark matter in gamma rays," Ritz said. "We'd love to understand much more about it."

Other areas of study include:

*Neutron stars, which are created in the cores of massive stars. These objects are so dense with matter that a billion tons of neutron star material would only fill a tablespoon. The magnetic fields these entities create are huge.

*Supermassive black holes, which are believed to reside in most, if not all, galaxies. Though these objects, which emit no light, cannot be studied directly, they have a powerful impact on their surroundings, generating jets, for example, that are blown completely out of the host galaxies. Scientists do not know how this is possible.

*Active galactic nuclei, which are galaxies with extraordinarily luminous cores that are powered by black holes containing millions or even billions of times more material than our sun.

*Gamma ray bursts, which are the brightest gamma ray phenomena known, outshining all other sources of gamma rays combined. In seconds, a single burst can radiate more energy than the sun has and will produce over its 10-billion year lifetime.

*The speed of light, which may or may not be uniform in a vacuum. Einstein's special theory of relativity states that electromagnetic radiation should travel at the same speed, which is 186,282.4 miles per second. However, some attempts to mesh this theory with quantum mechanics have an alternative theory that predicts extremely high-energy gamma rays could travel at a slightly different speed than other forms of light due to tiny turbulences when matter and antimatter particles form and annihilate. Some physicists suggest these fluctuations also produce tiny black holes, which may boost or slow the speed of very high energy gamma rays.

"With such a huge leap in capability," said Ritz, "I'm expecting the most important science we're going to do is not on anybody's list."