New space telescope will watch powerful cosmic blasts
BY JUSTIN RAY
Posted: September 23, 2004
An agile gamma-ray observatory with a focus on the most intense explosions in the cosmos -- cataclysmic blasts occurring every day throughout the universe that seemingly foreshadow the creation of black holes -- will be launched into space October 26.
While circling Earth at an altitude of 375 miles, NASA's Swift spacecraft will detect and study the brilliant bursts of gamma-rays, which erupt in random points across the sky without warning. Swift's scientific data will determine a burst's distance and brightness, plus provide insight into the blast's locale and surroundings to offer clues about what ignites these events.
Gamma-ray bursts last between a few milliseconds and a few minutes and never appear in the same spot again. They emit more than one hundred billion times the energy than the Sun does in an entire year. A lingering afterglow -- a phenomenon discovered just seven years ago -- can last hours or weeks in X-ray and optical light and radio waves, but strangely not all bursts have an afterglow.
Astrophysicists have two competing ideas to explain the origin of gamma-ray bursts and both are linked to black holes. The death of massive stars in extraordinary explosions, called hypernovae, that result in the birth of black holes and two neutron stars orbiting each other that eventually collide and create a black hole are scenarios that would produce such violent releases of gamma-rays.
Project leaders hope the $250 million mission will explain why some bursts are significantly shorter than others, why some lack an afterglow and answer the fundamental question of what triggers a burst. Swift could discover there are different types of gamma-ray bursts, proving more than one of the theories put forth by astronomers.
The Swift spacecraft gets its name from the nimble bird because the satellite can swiftly turn to catch a burst and afterglow on the fly.
The observatory's Burst Alert Telescope, which can see a sixth of the entire sky at one time, will detect and locate the flashes. That positioning information allows the satellite to reorient itself within moments to point the onboard X-ray Telescope and the Ultraviolet/Optical Telescope to conduct a thorough examination of the afterglow, perhaps even the burst itself if the blast lasts long enough.
"Swift is an awe-inspiring mission -- tracking down what are the fastest and most powerful events in the universe," said professor Alan Wells from the University of Leicester, the U.K. lead investigator for Swift's X-ray telescope.
Some bursts may occur in the first generation of stars, scientists believe, and Swift should either prove or squash this theory. By peering billions of years into the past, Swift's research will help study the early universe, too, and potentially offer clues to the rate of black hole creation.
"Some bursts likely originate from the farthest reaches, and hence earliest epoch, of the universe," said Swift mission director John Nousek, professor of astronomy and astrophysics at Penn State. "They act like beacons shining through everything along their paths, including the gas between and within galaxies along the line of sight."
The two-year Swift mission aims to observe more than 200 bursts. This is one of NASA's medium-class Explorer missions and includes partners in the U.K. and Italy.
The Burst Alert Telescope was built by NASA's Goddard Space Flight Center; the X-ray Telescope was made by Penn State University, the University of Leicester and Italy's Osservatorio Astronomico di Brera; and the Ultraviolet/Optical Telescope was built by Penn State and the U.K.'s Mullard Space Science Laboratory. Spectrum Astro built Swift's structure.
The Boeing-built Delta 2 rocket to carry NASA's Swift spacecraft high above Earth will begin to take shape on Cape Canaveral's launch pad 17A today.
The Delta 2 rocket is scheduled for launch October 26 during a 60-minute window opening at 1:00 p.m. EDT (1700 GMT).
The mission was delayed from its original launch date of October 7 in the wake of Hurricane Frances. The storm postponed on-pad assembly of the Delta 2, which was supposed to start September 1.
The Swift spacecraft was returned to the protective confines of its shipping container to ride out the storm at the Hangar AE satellite processing room on Cape Canaveral Air Force Station. Swift was removed from the container last Thursday. The craft will undergo final testing and preps before heading to the launch pad in mid-October.