Los Alamos software key to new Swift satellite mission (Forwarded)

News and Public Affairs
Los Alamos National Laboratory

Contact:
Nancy Ambrosiano, , (505) 667-0471

Nov. 16, 2004

04-091

Los Alamos software key to new Swift satellite mission

LOS ALAMOS, N.M. -- "Swift," a new NASA satellite, will head for the heavens
Nov. 17, designed to detect gamma-ray bursts and whip around to catch them in
the act. And the trigger software that makes the flying observatory smart enough
to do this comes from the Space Science team at the Los Alamos National Laboratory.

Gamma-ray bursts, first discovered by Los Alamos in the course of nuclear
nonproliferation data analysis, occur randomly throughout the universe. They are
the most powerful explosions known to mankind, exceeded only by the Big Bang.
Swift's Burst Alert Telescope will detect and locate about two bursts a week and
relay their positions to the ground in less than 15 seconds.

By studying the bursts, scientists have the opportunity to illuminate some of
the earliest mysteries of the universe. "We believe Swift is capable of
observing gamma-ray bursts right back through time to the very first stars that
ever formed after the Big Bang," said lead Los Alamos project scientist Ed
Fenimore, a Laboratory Fellow.

The main mission objectives for Swift are to determine what makes gamma-ray
bursts tick, and perhaps more importantly, determine how the burst evolves and
interacts with the surroundings: The burst's afterglow is the only place in the
universe where something 10 times the size of the Earth is moving 0.9999 the
speed of light.

The component with which Los Alamos is most intimately involved is the Burst
Alert Telescope (BAT), hardware built and developed by Goddard Space Flight
Center, under the direction of Neal Gehrels. The Los Alamos role was in
developing the BAT's onboard scientific software that, as Fenimore says,
"basically tells Swift when to point, and where to point."

The onboard "trigger" software scans the data from the BAT and determines when a
gamma-ray burst is in progress. "Although human eyes on the ground can easily do
this, doing it blindly on the satellite is quite difficult," Fenimore said. "In
fact, in past gamma-ray burst experiments, it has been common that nine out of
10 triggers are false alarms. False alarms would be disastrous since Swift will
actually slew itself around to try to observe the false source." Swift turns in
space within 70 to 100 seconds to view the fading event.

The GRBs location information from Swift will also be broadcast to waiting
robotic telescopes on the ground. Among them is the Los Alamos RAPTOR telescope,
which can point anywhere within 6 seconds and capture the burst while it is
still happening.

The critical second piece of the Los Alamos effort is the software to locate the
gamma-ray burst so that the satellite knows exactly which direction it should
orient its other telescopes. The BAT uses an imaging technique pioneered by Los
Alamos called coded-aperture imaging, and most recently used by Los Alamos
aboard the High Energy Transient Explorer (HETE) satellite.

In the imaging equipment aboard Swift, 54,000 pinholes in a panel of lead the
size of a full sheet of plywood produce an "image," actually thousands of
overlapping images (approximately 30,000 of them). The Los Alamos software must
unscramble those overlapping images and make one stronger, brighter picture from
which the precise location of the gamma-ray burst can be found, while
eliminating known sources and statistical variations.

David Palmer, a Los Alamos astrophysicist with a special expertise in
coded-aperture imaging and clever algorithms, is the key person for virtually
all of the scientific software on BAT, some 30,000 lines of code. For the
software to handle the required tasks takes a vast amount of computer code, with
hundreds of interacting components. "It was thanks to his grasp of the whole
picture in all its complexity that Palmer was able to develop this scientific
package," Fenimore said, "Palmer probably did the work of 20 people on this
project."

To prepare for the ongoing software work during the craft's two-year life,
Fenimore and his team have developed complex simulations at Los Alamos to
recreate the BAT instrument's likely behavior and experiences in space. The
simulator allows the team to practice responding to potential issues that may
require tuning of the software. The software was designed with "lots of knobs"
as Fenimore phrases it, to allow the team to continuously tweak software. A
special challenge for Palmer has been the relative age of the computer aboard
the craft: it is a 25 MHz computer, 100 times slower than the computers most
people have at home.

The Swift observatory is scheduled for launch at 12:09 p.m., EST Wednesday, Nov.
17, with a one-hour launch window. The satellite is aboard a Boeing Delta II
rocket, launching from Cape Canaveral Air Force Station (CCAFS), Fla.

Swift is part of NASA's medium explorer (MIDEX) program. The hardware was
developed by an international team from the United States, the United Kingdom
and Italy, with additional scientific involvement in France, Japan, Germany,
Denmark, Spain and South Africa.

Los Alamos National Laboratory is operated by the University of California for
the National Nuclear Security Administration (NNSA) of the U.S. Department of
Energy and works in partnership with NNSA's Sandia and Lawrence Livermore
national laboratories to support NNSA in its mission.

Los Alamos develops and applies science and technology to ensure the safety and
reliability of the U.S. nuclear deterrent; reduce the threat of weapons of mass
destruction, proliferation and terrorism; and solve national problems in
defense, energy, environment and infrastructure.

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