By Mike Janes
When the Advanced Simulation and Computing (ASC) program was established by the DOE in 1995, the end result was a shift in emphasis from test-based confidence in the nation’s nuclear arsenal to simulation-based confidence.
But the ASC program — which is now an NNSA program — and the computer modeling capability at its core are now providing a new, no less vital service: developing a scientific basis for aviation security explosive detection requirements. The findings are expected to lead to revisions to the Transportation Security Administration’s certification standards.
“Today, under ASC, computer simulation capabilities are routinely developed to analyze and predict the performance, safety, and reliability of nuclear weapons and to certify their functionality,” says Sandia’s Jim Phelan (6418), who leads the tri-lab effort. “We’re now able to leverage that capability and apply it to the important problem of damage from explosives aboard aircraft.”
The current requirements for screening checked baggage for explosives at airports were established in 1993 following the Pan Am Flight 103 bombing in 1988. The requirements, however, were based on forensic assessments of historic incidents and actual explosive tests with retired aircraft. Such assessments, says Jim, offer incomplete and limited knowledge of factors that must be considered when trying to mitigate the threat of onboard explosions.
“Today, we have a much better understanding of the range of explosives threats, such as liquid explosives and homemade bombs,” says Jim. “But what we have not had is a more detailed understanding of the differing explosive power from potential threat materials and the impact on the aircraft structure. That’s where computational modeling comes in.”
Leveraging the high-performance computing capability DOE has developed over the past decade, Sandia and its partners — Lawrence Livermore National Laboratory and Los Alamos National Laboratory — now have access to lightning-fast supercomputers, parallel computing software, and visualization features currently used to support the nation’s nuclear weapons complex.
“ASC tools are very applicable to solving the aviation onboard explosion problem,” says Jim. Computational modeling, he says, offers a scientific basis for the breadth of explosive threats that cannot be derived by the empirical tests historically conducted.
“Those kinds of tests have to be done, because they are the ground truth for actual aircraft explosions,” Jim says. But such tests alone, he adds, can’t adequately examine the multitude of factors that must be considered, including explosives and aircraft types, threat quantity, onboard locations, flight conditions, and other physical details that factor into managing the risks from aviation terrorism.
“You absolutely must do modeling to assess where the threshold is before performing a test,” he says.
The tri-lab team’s first order of business when taking on this challenge last year was to “scope” the problem and determine how ASC tools could best go about tackling it. In December, a briefing that included several sample simulation results was delivered to TSA, which then asked the team to reproduce a series of historic experimental tests and determine whether modeling could, indeed, produce valid results. Another briefing, in June, confirmed the modeling capability.
Computational modeling, says Jim, offers several advantages above and beyond the obvious avoidance of aircraft destruction for experimental purposes. Hydrodynamic blast models, which are supported by decades of explosive science measurement and analysis, accurately determine the high pressures caused by detonations. Finite element structural models, which represent the structural components of an aircraft’s airframe, can show the tearing, bending, and breaking of the airframe components.
The tri-lab team is working with a major aircraft manufacturer to use detailed structural information on one of the aircraft in today’s fleet, information that is subsequently used in the computational models. By this fall, the team will provide TSA with a report on the vulnerability to a common fleet aircraft, and revisions to the certification standards are expected to commence shortly thereafter.
Jim emphasizes that the project has been a team effort, with contributions from Dennis Roach (6416) and the Aircraft Airworthiness project; Ken Smith (6418) from Contraband Detection Dept; Jeff Gruda (1524), Kenneth Gwinn (1524), Jonathan Rath (1524), Tim Shelton (1524) and Marlin Kipp (1431) from the Advanced Simulation and Computing program; and Jerry Stofleth (5434) and the Explosives Applications Department.-- Mike Janes
Sandia’s Red Storm supercomputer helped the US Navy figure out how to shoot down an errant satellite in February.
The satellite failed shortly after its launch in 2006 and by early this year its orbit was deteriorating to the point where it was about to reenter the Earth’s atmosphere. The satellite posed a potential safety hazard due to the frozen hydrazine propellant on board. The Navy shot down the satellite Feb. 20, 2008. The work had been classified until last week.
For about two months preceding the event, the Sandia team ran Red Storm simulations to assess and plan the complex mission. Researchers used all of Red Storm’s 26,569 processors to perform simulations that allowed the team to predict various details and possibilities. The information contributed to the decision to proceed, and helped DoD plan and execute the shot, as well as conduct analysis after the satellite was brought down.
The work helped planners decide at what altitude to hit the satellite, how to hit it to minimize the spread of debris, including its hazardous fuel, and the best way to make sure the satellite was destroyed with a single shot.
Bill Guyton, director of Center 5400, says the team was called upon because of its years of experience in missile defense intercept simulations of reentry vehicles.
Daniel Kelly, manager of Lethality and Threat Dept. 5417, led the team of six staff members who were called upon to perform hundreds of impact simulations in a matter of days and weeks to answer critical technical questions affecting early decisions to go forward with the operation.
“We were contacted on Jan. 11, 2008, by the Missile Defense Agency and asked to deliver in nine days the required ‘hit point’ for high probability of success,” says Daniel. “The team put in a lot of long days, and with help from resources across the laboratory, provided results for several pivotal deadlines during the buildup to the operation.”
The team also supported operation day at Schriever AFB, Colo., to assist in the real-time assessment of the event where decisions were made that a second intercept shot was not required.
“Our team did a great job in providing the simulation data necessary to complete this important mission,” said NNSA Administrator Thomas D’Agostino. “This is a great example of the ways that the nation’s investment in nuclear deterrence can be more broadly employed for national security.” — Michael Padilla
They worked for almost seven years in secret.
Most people did not know that the work in Ray Goehner’s (1822) materials characterization department was contributing important information to the FBI’s investigation of letters containing Bacillus anthracis, the spores that cause the disease anthrax. The spores were mailed in the fall of 2001 to several news media offices and to two US senators. Five people were killed.
Sandia’s work demonstrated to the FBI that the form of B. anthracis contained in those letters was not a weaponized form, a form of the bacteria prepared to disperse more readily. The possibility of a weaponized form was of great concern to investigators, says Joseph Michael (1822), the principal investigator for the project. This information was crucial in ruling out state-sponsored terrorism.
In the fall of 2001, the FBI considered how best to investigate the anthrax letters. The agency convened two blue ribbon exploratory panels, and Sandia’s name came up during both panels for its expertise in electron and ion microscopies and microanalysis over the range of length scales from millimeters down to nanometers. The first spore material from the letters arrived at Sandia in February 2002.
The team worked under an Intelligence Work for Others (IWFO) contract with the FBI. Sandia faced some uncertainty in working on this type of project. Researchers signed nondisclosure agreements and agreed to make themselves available to government agencies on short notice when called to give information.
Joseph, transmission electron microscopy (TEM) lab owner Paul Kotula (1822), and a team of roughly a dozen others examined more than 200 samples in those six and a half years. The samples analyzed at Sandia were confirmed to be nonviable prior to arriving at the Labs. They received samples from the letter delivered to the New York Post, to former Sen. Tom Daschle (D-S.D.), and to Sen. Patrick Leahy (D-Vt.). The samples looked different, in part because of how they were prepared, which made examination initially difficult.
When B. anthracis spores are weaponized, the spores are coated with silica nanoparticles that look almost like lint under the microscope. The “lint” makes the particles “bouncier” and less likely to clump and fall to the ground. That makes the spores more respirable and able to do more damage, says Joe. Weaponization of the spores would be an indicator of state-sponsored terrorism.
“Initially, scanning electron microscopy [SEM] conducted at another laboratory showed high silicon and oxygen signals that led that lab to conclude that the spores were a weaponized form,” says Paul. “The possible misinterpretation of the SEM results arose because microanalysis in the SEM is not a surface-sensitive tool,” says Paul. “Because a spore body can be 1.5 to 2 microns wide by 1 micron long, a SEM cannot localize the elemental signal from whole spore bodies.”
Using more sensitive transmission electron microscopy, Joe and Paul’s research indicated that the silica in the spore samples was not added artificially, but was incorporated as a natural part of the spore formation process. “The spores we examined,” Paul says, “lacked that fuzzy outer coating that would indicate that they’d been weaponized.”
Sandia’s work was the first to actually link the spore material in the New York Post, the Daschle, and the Leahy letters. The elemental signatures and the locations of these signatures, while not indicating intentional weaponization, did show that the spores were indistinguishable and therefore likely came from the same source. That conclusion was corroborated a few years later by the DNA studies.
The materials characterization lab serves as a materials analysis resource for a diverse collection of projects. The lab plays an important role in stockpile surveillance, supporting Sandia’s nuclear weapons mission.
Joe was recently released from his nondisclosure agreement and flown to Washington, D.C., to participate in news conferences at FBI headquarters along with several members of research teams who’d been asked to examine other aspects of the anthrax case.
The FBI was pleased with Sandia’s work, says Joe. — Stephanie Holinka