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Fire Technology Milestone

In the 1940s, research indicated that fire caused about 10,000 deaths annually in the United States and property losses exceeded $700 million.

SwRI staff saw a need -- both for individuals and industries -- and founded its Department of Fire Technology to research, test, and quantify fire and its hazards. Fifty years later, the department has grown into one of the world's largest organizations dedicated to fire research and testing.

SwRI offers multidisciplinary fire and explosion research and testing services, including consultation, listing and labeling, third-party sampling and inspection, and development of engineering and scientific solutions. The Institute serves government and commercial clients in the construction, transportation, chemical and petrochemical, nuclear, and telecommunications industries.

"We have developed one of the leading laboratories in the world for studying fire," says Alex Wenzel, director of the Department of Fire Technology. "Unlike other organizations, the Institute can draw from a variety of specialties and technical capabilities in other disciplines, from one location."

Fire technology projects have ranged from the development of a fire extinguisher for NASA following the Apollo I fire in 1967, to a study of the flammability characteristics of mobile homes in the 1970s, to the development of a jet fire facility used to simulate the intense jet fires that threaten offshore drilling rigs in the 1990s.

The SwRI Department of Fire Technology is accredited by the National Evaluation Service, Inc., and is ISO/IEC Guide 25 compliant. The Institute is certified as a qualified testing laboratory and a third-party quality assurance and inspection agency. SwRI has also been designated a Nationally Recognized Testing Laboratory by the Occupational Safety and Health Administration. Government agencies such as the U.S. Coast Guard, General Services Administration, Federal Aviation Administration, Department of Housing and Urban Development, and Nuclear Regulatory Commission have recognized the department.

Internationally, SwRI is recognized by Lloyd's Register of Shipping, Det Norske Veritas, the American Bureau of Shipping, the Standards Council of Canada, and the Explosives and Dangerous Goods Division of the Occupational Safety and Health Service of New Zealand.

Contact Wenzel at (210) 522-2311 or awenzel@swri.org.

Particle Detector Validated

SwRI scientists have successfully performed the initial validation of the ion and electron spectrometer (IES), developed for the Rosetta comet orbiter mission of the European Space Agency (ESA).

The instrument was built with extreme miniaturization of its electronic systems and was fabricated from magnesium to achieve a total mass of only 1,040 grams. Despite its small size, IES was shown in laboratory tests to achieve a sensitivity comparable to that of instruments weighing five times more.

"The miniaturization of these instruments adds up to a considerable savings in cost, mass, volume, and power," says Dr. James L. Burch, vice president of the SwRI Instrumentation and Space Research Division and IES principal investigator. "We're pleased that the system worked flawlessly."

The engineering qualification model was operated under space environment conditions with all measured parameters meeting or exceeding design specifications, including its inherently high angle and energy resolution of 5 degrees and 4 percent, respectively.

The instrument will simultaneously measure the flux of electrons and ions surrounding Comet Wirtanen over an energy range extending from the lower limits of detectability, near 1 electron volt, up to 22,000 electron volts. It uses a novel, electrostatic scanning technique to view particles from directions encompassing 70 percent of the celestial sphere. The instrument will be delivered to ESA in early 2000. Development was sponsored by the Jet Propulsion Laboratory in Pasadena, California.

During the mission, the Rosetta orbiter will use remote-sensing instruments to map and examine the surface of Comet Wirtanen. Other instruments, including IES, will analyze the dust and gases that emanate from the surface as it is warmed by the sun. The Rosetta mission will be one of the most thorough investigations of a comet ever attempted.

With its low mass and a power input of less than 2 watts, the IES instrument is suitable for a variety of interplanetary and Earth-orbiting satellite missions requiring extreme limits on mass, volume, and power. Contact Burch at (210) 522-2526 or jburch@swri.org.

Pluto's Family

SwRI planetary astronomers suggest that some Kuiper Belt objects may be leftover shards from the giant collision that created the Pluto-Charon system.

Pluto-Charon is the only known double planet in the solar system, orbiting about 40 times as far away from the sun as Earth. It is embedded in the Kuiper Belt of planetesimals, comets, and miniature icy worlds that surround our planetary system in a thick disk. The Kuiper Belt is a larger and more populous, icy-rich analog to its better known cousin, the Asteroid Belt of rocky debris orbiting between Mars and Jupiter.

Astronomers have suspected for more than a decade that Pluto and its 1,200 kilometer-wide satellite, Charon, formed as a pair during a giant collision in the ancient past between proto-Pluto and another Kuiper Belt object (KBO). Evidence for this collision includes the orbital configuration, the relative masses, and the angular momentum of the Pluto-Charon system.

Now, SwRI astronomers Dr. Alan Stern, Dr. Robin Canup, and Dr. Daniel Durda have found clues that some KBOs in neighboring orbits to Pluto may, in fact, be debris created in the Pluto-Charon forming event.

The evidence found by the SwRI team linking some KBOs called "Plutinos" to Pluto-Charon comes in three forms. First, there is a close orbital similarity between some KBOs and Pluto that is consistent with the expected distribution of debris from the Pluto-Charon formation event. Second, the colors of Pluto and some KBOs and Charon and other KBOs suggest similar surface compositions. Third, the apparent size distribution of the objects that suggest themselves as potential shards of the Pluto-Charon forming collision is similar to both laboratory results from studies of catastrophic collisions and asteroid belt families known to result from collisions.

Future research will be required to prove this new hypothesis, dubbed "Pluto's Family." If borne out by future tests, it would constitute the first discovery of a genetically related, parent-daughter family of objects in the Kuiper Belt. Further, because the KBO region surrounding Pluto has been known for some time to be delivering comets to Earth's vicinity, the new work suggests that a small, but nonetheless important, fraction of the comets observed by astronomers may actually consist of samples of Pluto and Charon.

Defense Honor

SwRI received the Department of Defense (DOD) James S. Cogswell Outstanding Industrial Security Achievement Award in 1999.

The award recognizes outstanding industry participation in the National Industrial Security Program. Administered by the Defense Security Service, the annual award was established in 1966 and was later named after Cogswell, the first chief of DOD's Office of Industrial Security. Fewer than one-half percent of eligible defense contractors have been recipients. SwRI previously received the award in 1992.

"This is a great honor for the Institute and for all staff members involved in our security program," says Security Manager George Stevenson.

SwRI has been a government contractor since its establishment in 1947. Each year, half of the more than 1,000 major contracts under way at the Institute are for the federal government.

Freitas, Winter elected Fellows

Dr. Christopher J. Freitas, a principal engineer in the SwRI Mechanical and Materials Engineering Division, and Dr. Dean C. Winter, director of SwRI's Bioengineering Department, have been elected Fellows of the American Society of Mechanical Engineers (ASME).

Freitas' work has spanned a broad range, from hydraulic pipeline transient analysis to three-dimensional, time-dependent simulations of complex turbulent flow behavior to fluid-structure interaction. He has led research and development into high-performance parallel computing for workstation clusters and massively parallel processor machines.

Freitas has served ASME in many functions, including chairman of the Fluids Engineering Division, chairman of the Coordinating Group on Computational Fluid Dynamics, National Technical Planning Committee member, and associate editor of the Journal of Fluids Engineering.

At SwRI, Winter has directed and performed experimental studies on problems involving fluid mechanics of the respiratory system and has been responsible for the development of several medical devices related to cardiovascular and respiratory systems.

He has been active in ASME for more than 20 years and is on the ASME Biofluidmechanics Committee. He has organized numerous scientific sessions for ASME meetings in the areas of respiratory and cardiovascular fluid mechanics. He also served as co-chairman of the 1988 International Conference on Mechanics in Medicine and Biology.

Contact Freitas at (210) 522-2137 or cfreitas@swri.org and Winter at (210) 522-2681 or dwinter@swri.org.

Lunar Tilt

The mysterious tilt of the moon's orbit is probably a natural consequence of the moon's formation from a giant collision with early Earth, according to a new study by scientists at SwRI.

The moon's orbit can be traced backwards in time to reveal that when the moon formed near the Earth, its orbit was inclined by approximately 10 degrees relative to the Earth's equator. Most other planetary satellites in the solar system have orbital inclinations smaller than 1 or 2 degrees. The cause of the moon's large orbital tilt has long been a mystery.

"The inclination problem had been one of the last remaining obstacles for the impact hypothesis of moon formation," says Institute Scientist Dr. William R. Ward. The widely favored "giant impact theory" proposes that a Mars-sized body collided with Earth 4.5 billion years ago, creating a hot disk of debris from which the moon accumulated. Previous models of the moon's formation from such a disk predict that the lunar orbit should have been nearly aligned with the Earth's equator, with only about a 1 degree tilt.

The new theory, published in the February 17 issue of Nature, proposes that the moon acquired its large tilt soon after it formed because of a gravitational interaction with debris left over from the impact event. Modeling results presented in the paper, authored by Ward and SwRI planetary scientist Dr. Robin M. Canup, show that the moon could have acquired its 10 degree tilt as a consequence of the moon-forming impact.

To yield a lunar-sized moon, the giant impact must place about two lunar masses of material into an Earth-orbiting disk, according to Canup. In the model, debris particles in the inner regions of such a disk are prevented from coalescing by Earth's gravity, which tends to pull objects apart. Instead, the moon rapidly coalesces at the outer edge of the debris disk, at a distance of about 14,000 miles from the Earth. "The newly formed moon would have likely co-existed for some time with an inner disk of gas and debris left over from the impact," says Canup.

After the moon coalesced, its gravity would generate waves in the inner disk. The gravitational interaction of the moon with these waves would, in turn, modify the lunar orbit. The waves are launched at certain locations in the disk where the motions of disk particles are in resonance with the motion of the moon.

The waves generated at one such resonance -- where the orbital period of the moon is approximately three times that of the disk particles -- are called "bending waves," which corrugate the surface of the disk. The gravitational attraction between the moon and these rippled waves in the disk then acts to amplify the tilt of the moon's orbit.

Ward and Canup's model simulated the interaction of the moon and the inner debris disk, assuming that the moon formed in an orbit with only a 1 degree tilt. They found that the interaction of the moon with the bending waves it generates in such a disk can amplify the lunar inclination to values as high as 15 degrees before the disk dissipates. The required tilt of about 10 degrees can be achieved if the disk contained at least 25 to 50 percent of a lunar mass and persisted from decades to as long as a century. These values are consistent with those predicted by other models of the impact event.

"This theory explains the moon's anomalous orbital tilt as a natural consequence of its formation from a giant impact event," says Ward. "Rather than producing conflicting evidence, the lunar inclination may now represent an additional corroboration of the impact event," agrees Canup.

Contact Ward at (303) 546-6351 or ward@boulder.swri.edu.

Published in the Spring 2000 issue of Technology Today®, published by Southwest Research Institute. For more information, contact Maria Stothoff.

Spring 2000 Technology Today
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