Los Alamos National Laboratory
CONTACT:
Jim Danneskiold, (505) 667-1640 / [email protected]
Kathy DeLucas (505) 665-9201 / [email protected]
LOS ALAMOS READY FOR AUG. 28 LAUNCH OF SATELLITE TO STUDY NON-PROLIFERATION, LIGHTNING
LOS ALAMOS, N. M., Aug. 22, 1997 -- All systems are go for the Aug. 28 launch of Los Alamos National Laboratory's FORTE satellite, which will test new ways of spotting secret nuclear weapons tests, teach scientists more about lightning and prove the merits of its revolutionary, all-composite structure.
An Air Force Pegasus-XL rocket is scheduled to blast FORTE into orbit 500 miles above Earth around 8 a.m., PDT. FORTE and the Pegasus first will hitch a ride to 40,000 feet on an L-1011 aircraft from Vandenberg Air Force Base in California.
FORTE, which stands for Fast On-orbit Recording of Transient Events, is a lightweight satellite designed as a test bed for technology to monitor compliance with arms control treaties. FORTE's instruments will detect, record and analyze bursts of radio energy arising from near Earth's surface. A joint project of the Department of Energy's Los Alamos and Sandia national laboratories, the satellite also will gather data on the physics of lightning and the ionosphere, the electrically conducting region of the atmosphere from about 50 to 600 miles above Earth.
But FORTE itself, rather than the instruments it carries, is the big news.
Weighing just 90 pounds, FORTE is the first all-composite spacecraft, its framework made entirely of graphite-reinforced epoxy. The new process developed for building FORTE by Los Alamos and a San Diego company, Composite Optics Inc., is child's play: the satellite snaps together like a model aircraft.
"The all-composite structure gives FORTE a big performance advantage," said project leader Steve Knox of Los Alamos' Nonproliferation and International Security Division. "Because the structure is so light, we can put an extra 50 pounds of payload into orbit, compared to a satellite of the same size built with conventional materials."
The seven-foot-tall satellite carries three decks with aluminum honeycomb cores and composite facing to support the onboard instruments.
FORTE includes a radio frequency sensor system with three broad-bandwidth receivers covering the range of 30-300 Megahertz, which includes commercial and UHF television, amateur and FM radio and aircraft navigation and communication bands. The improved detection technology that is undergoing testing on FORTE is the first step; scientists eventually hope to develop and launch an autonomous radio frequency detection system that performs reliably in the electromagnetically noisy environment of near-Earth space.
FORTE receives radio frequency signals via a novel, 35-foot-long antenna that has two arrays set at right angles to each other to help researchers learn how the ionosphere affects the propagation of radio frequency signals. The antenna, which is coiled up inside the satellite like a Slinky toy, will be unfurled after FORTE reaches orbit.
The satellite also carries a Sandia-designed wide-field optical imager that can locate lighting flashes and pinpoint global lightning distribution to a six-mile resolution. Such data will aid scientists studying global climate effects, where the lightning flash rate within a thunderstorm can be related to the precipitation rate. The associated radio frequency emission data can help explain the atmospheric breakdown mechanisms that lead to lightning discharges.
Sandia scientists also designed a device that suppresses television and radio signals that could confuse the radio frequency instruments and developed the power and communication subsystems.
FORTE should make major contributions to ionospheric and lightning physics research by combining its space-based optical and radio frequency data with data from ground-based geophysics experiments. The radio frequency receivers also will measure horizontal electron density gradients, of fundamental importance to ionospheric physics.
The third major instrument on FORTE is an event classifier, a set of adaptive processors that can distinguish lightning from man-made electromagnetic signals, a key to future nonproliferation satellites.
After four years of exhaustive preparations, it should take FORTE about 10 minutes from the time the L-1011 drops the Pegasus-XL rocket until the satellite reaches orbit, Knox said.
"The rocket takes about five seconds to ignite after it drops at 40,000 feet. Those probably will be the longest five seconds of my life," Knox said.
Stage one burns for 72 seconds, then the second stage burns for about the same length of time and the fairing that covers FORTE separates. For five to eight minutes, the satellite will coast along an upward parabolic arc, followed by a short third-stage rocket burn to insert FORTE into orbit. The FORTE ground crew should know immediately whether it reached the right orbit.
About 90 minutes later, a ground station in Alaska should get a health report on the little satellite's battery charging, electrical current, attitude control and other key systems that indicate FORTE's health after its short ride into space.
The satellite was mated to the rocket on Aug. 15, and the protective fairing covered it up on Aug. 20. The rocket is scheduled for mating to the aircraft on Tuesday.
"Everything's been going very smoothly, both with the space vehicle and with the rocket," Knox said Thursday. "We haven't run into anything major that has caused us to worry."
The graphite-epoxy composite of which FORTE is made has been used in commercial aircraft components and elsewhere, but not for a complete satellite structure. The surprisingly simple assembly method developed by Los Alamos and Composite Optics is two-thirds faster and 60 percent less expensive than other methods. Flat laminates of the composite are nested and precut using a high-pressure water jet. The precut parts, many of which are modular and interchangeable, are easily assembled by a built-in self- fixturing technique similar to the mortise-and-tenon joints used by woodworkers, which ensures accurate placement and fit when the pieces are joined with a conventional structural adhesive.
Composite structures have zero thermal growth, in contrast to aluminum structures that expand and shrink as temperatures fluctuate. The method can be used for a wide variety of structures, such as precision optical reflectors, receivers for telecommunications and other frameworks.
The fiberglass antenna, designed by Los Alamos and fabricated by Astro Aerospace of Santa Barbara, Calif., is stowed in a foot-long canister. After FORTE reaches orbit, the two receiving arrays extend like wire-thin arms from the central boom as it's unfurled. A set of torque rods that push against Earth's magnetic field will keep the antenna aimed toward Earth.
FORTE has been through a rigorous series of tests, including a February test at Los Alamos of the solar power cells that cover nearly all of its exterior panels; several environmental, stress and "shake" tests at Los Alamos and thermal testing in vacuum at Sandia to ensure the satellite can withstand the rigors of launch and spaceflight; and recent mission simulations at Vandenberg. This week, crews tested hardware and software for the rocket's inertial navigation system that will home in on FORTE's circular orbit.
A satellite ground station at Sandia in Albuquerque and an operations center at Los Alamos will combine to control the satellite and receive data from it.
FORTE is the second satellite built by Los Alamos. The first one, ALEXIS, was launched in 1993 and still operates, well past its one-year projected lifetime. ALEXIS carries X-ray telescopes and a radio signal detection experiment. The detection experiment, known as Blackbeard, provides a less sophisticated version of FORTE's ability to correlate lightning-induced radio frequency pulses with flashes of light.
Los Alamos National Laboratory is operated by the University of California for the U.S. Department of Energy.
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