Capturing data on the most powerful and mysterious explosions in the universe is a bit like swatting at flies. The blasts, called gamma ray bursts, are usually too quick.
Astronomers need hours to swing their telescopes around to record the blasts, which typically last just seconds. And they're left with only a fading afterglow to examine.
But a team led by Neil Gehrels of the Goddard Space Flight Center in Greenbelt says an orbiting observatory it's proposed to NASA could provide a reliably fast response to gamma ray bursts and simultaneous observations in a variety of wavelengths.
Called Swift Gamma Ray Burst Explorer, the three-year, $135 million mission was one of five chosen Jan. 26 by the National Aeronautics and Space Administration to compete for final funding under NASA's Explorer series of space science missions.
An unrelated Maryland-based mission -- a $130 million Johns Hopkins University proposal to study the solar winds that cause displays of the northern and southern lights -- was also among the five finalists.
Chosen from 35 competitors, each of the five will receive $350,000 from NASA for feasibility studies. Two will be selected in September for NASA funding. The winning missions will be launched in 2003 and 2004.
Thankfully, the gamma ray bursts studied so far seem to occur in very distant galaxies. An eruption in our own Milky Way would turn night into day. And if it occurred on our side of our galaxy, scientists say, it could destroy Earth's protective ozone layer, or even blow the atmosphere away entirely.
To determine the bursts' origins -- and where and how often they might occur -- astronomers say they need more data on their locations, and they need to measure the flashes in a variety of wavelengths.
On Jan. 23, astronomers -- aided by a jury-rigged network of orbiting sensors, automated commands and robotic telescopes -- captured the first image of a gamma ray burst in progress -- just 22 seconds after it was detected. Most observers' responses to the same event took hours.
Goddard's Swift Gamma Ray Explorer could find such bursts reliably in 50 seconds, Gehrels said. And it would provide scientists with simultaneous data in visible, X-ray and gamma ray wavelengths.
The second Maryland mission under final consideration by NASA would be built and managed by Hopkins' Applied Physics Laboratory in Laurel and led by astrophysicist Barry H. Mauk.
"For every feature we see in the northern lights, there is a corresponding feature out in space causing that feature to happen," Mauk said. But scientists don't understand precisely how the two regions are connected.
APL's proposed Auroral Multiscale Midex mission would fly four identical satellites in close formation hundreds to several thousand miles above the Earth's poles. For 18 months, they would make a three-dimensional study of electric currents in the region and reveal their links to the shimmering auroral curtains below.
New knowledge might help improve forecasts of "space weather" -- magnetic and electrical forces streaming from the sun -- that can disrupt satellites, radio communications and electrical power grids.
Pub Date: 2/03/99