Transporting the space shuttle from the assembly building to the launch pad is quite a heavy task.
The three-million-pound shuttle sits on an eight-million-pound mobile launch platform (MLP) and is carried by a six-million-pound crawler. The crawler transports the vehicle and platform four miles from the Vehicle Assembly Building at Kennedy Space Center in Florida to the launch pad.
Moving the shuttle that distance, which normally takes five to six hours at 0.9 mph, had been considered a relatively low-stress process during most of the life of the shuttle system. As the equipment ages, however, more emphasis is being given to understanding how the rollout may fatigue the transport system.
NASA contacted Sandia to assist with a series of tests to help understand the fatigue caused by vibrations during the rollout. Overall, the tests are part of NASA's return-to-flight mission, with first flight scheduled between May 15 and June 3.
Sandia helped NASA design the test and instrumentation to measure the dynamic vibration environment of the rollout. Sandia is also providing additional support to NASA by computing the input forces that the crawler applies to the MLP, which are being used by Boeing and NASA to compute the fatigue life for critical shuttle components.
T om Carne (9124) has assisted with a series of tests beginning in November 2003 to develop the data necessary to understand the environment and the response of the space shuttle vehicle during rollout.
"NASA requested Sandia to assist them in this project because of our expertise in planning and conducting structural dynamic tests on very large structures," Tom says, adding that the Solid Mechanics/Structural Dynamics Group has done numerous structural analysis projects on large structures including the I-40 Rio Grande bridge, numerous large wind turbines up to 110 meters tall, and the Armored Tractor with SafeGuards Transporter. One of the group's main missions is analysis and testing of the shock and vibration requirements for weapons.
Rollout data analysis
Data were collected for rollouts of the MLP-only and the MLP with the two solid rocket boosters, at five different speeds ranging from 0.5 to 0.9 mph. For the tests more than 100 accelerometers were placed on the MLP, crawler, and solid rocket boosters. A data acquisition system installed inside the MLP for the road test measured and recorded the accelerations. The data were analyzed so that the character of the rollout environment is understood and can be analytically imposed on the shuttle using a finite element model to predict fatigue damage to critical components. Even though these stresses are much lower than those seen during the launch, the five- to six-hour duration of the transport and the low-frequency content in this environment could cause fatigue in components within the orbiter.
Tom says the rollout analysis team determined that there are two families of forcing harmonics caused by the crawler drive train that excite the MLP as a function of crawler speed, in addition to the random inputs induced by the road bed. Fortunately, he, says the harmonic forcing frequencies can be adjusted by merely changing the drive speed of the crawler, moving the inputs to less damaging frequencies.
Forcing function analysis
The team used a Sandia-developed algorithm, the Sum of Weighted Accelerations Technique (SWAT), to estimate the applied forces. Tom says the SWAT results were very beneficial in choosing a new rollout speed that will extend the fatigue life of the shuttle components that were affected by rollout.
The SWAT-generated input forces have subsequently been used as the force input for NASA's NASTRAN structural analysis of the MLP, emulating the test conditions. The correlation between the rollout-measured data and the predictions from the NASTRAN analysis has engendered confidence in both the SWAT computed forces and the NASTRAN model of the MLP and solid rocket boosters.
"We are able to help NASA and Boeing by providing force input to their computer models to predict fatigue life," says Tom.
The analyses showed that modifying the speed of the crawler would reduce the fatigue stresses of the critical shuttle components. They showed through analysis that merely reducing the speed from 0.9 mph to 0.8 mph would significantly reduce the vibrations in the shuttle by shifting the impact frequency of the crawler treads. The shuttle's vibration response can be much reduced when the driving frequencies are shifted away from its own resonant natural frequencies.
Space shuttle Discovery is scheduled to roll over to the VAB this week for STS-114, the space shuttle's return-to-flight mission. Tom will again be on-site at Kennedy Space Center to help analyze and interpret the rollout vibration data from this return-to-flight mission. -- Michael Padilla
By Neal Singer
To investigate tumors, pathologists currently rely on labor-intensive microscopic examination using century-old cell-staining methods that take days to complete and may give false readings.
A lightning-fast laser technique -- its development led by Sandia's Paul Gourley (8331) -- has provided laboratory demonstrations of accurate, realtime, high-throughput identification of liver tumor cells at their earliest stages, and without invasive chemical reagents.
Paul released the information on March 21 at the American Physical Society meeting in Los Angeles.
The technique passes a laser beam through human cells pumped from a flask through tiny microchannels. The beam creates flashes of light when it encounters mitochondria, which act as focusing lenses to create conditions necessary for lasing. These changes, registered by a receptor, instantly identify cancer-modified mitochondria in cells gone wrong.
Mitochondria are known as the power pack of cells, energizing them like batteries do flashlight bulbs.
"There are hundreds of mitochondria, sometimes thousands, in a cell," Paul says. "To see them in the old way requires a time-consuming process like fluorescent tagging or a chemical reagent. We've found we can see them immediately by light alone."
The techniques could be critical to advancing early detection, diagnosis, and treatment of disease.
More technically put, "To rapidly assess the health of a single mammalian cell," Paul says, "the key discovery was the elucidation of biophotonic differences in normal and cancer cells by using intracellular mitochondria as biomarkers for disease. This technique holds promise for detecting cancer at a very early stage and could nearly eliminate delays in diagnosis and treatment."
The technique is effective because "it measures changes in the cell architecture, especially those arising from alterations in protein density, cytoskeleton shape, and distribution of mitochondria -- changes that occur when a cell becomes cancerous," says Paul.
"One would think that if a cell became nonfunctional, it would become disorganized. In cancer, however, that's not the case. A cancer cell is like an insurgent terrorist with a very well-defined agenda. It rearranges the cytoskeleton. It's no longer a cooperative agent in a collection of cells but becomes malicious, tries to get outside the area, and hijacks the respiratory machinery of a cell."
The biocavity laser
It is these changes -- a kind of beefing-up of the criminal forces -- that Paul's device, called a biocavity laser, detects.
A nano-thin layering of gallium aluminum arsenide combinations send up numerous tiny beams from a small cross-sectional generating area. These beams are reinforced or thwarted by the position and density of the mitochondria.
"The pictures we get from normal and cancer cells are very different," says Paul. "Mitochondria conspire to cluster around the nucleus and work together to supply energy to the healthy, functioning cell. In contrast, the mitochondria in the cancer cell sit all over, isolated and balled up in a quiescent, nonfunctioning state. Apparently, the rapidly growing cancer cells derive energy from an alternative source such as free glucose in the cell."
Working with UCSD
Fortunately, a mitochondrion is nearly the same size as the light wavelength of about 800 nanometers, a frequency otherwise little absorbed by the body. Because of this close match, the laser is exquisitely sensitive to subtle changes in mitochondria size and effects of clustering. To date, the research team has found that 90 to 95 percent of light scatter generated is from optical properties of mitochondria.
According to Bob Naviaux, professor at the School of Medicine at the University of California at San Diego and co-director of its Mitochondrial and Metabolic Disease Center, "What's attractive about this novel optical method for identifying cancer cells is that it's a very rapid and general method that potentially can be applied to cancer cells from solid tumors as well as hematological malignancies like leukemia."
A project proposal has been filed with Sandia to support collaborative work between the unique research capabilities of UCSD and Sandia. "There are 300 different cell types in the human body and different mitochondria for each different shape and arrangements," says Naviaux. "We want a library of spectra from different cell types and their cancers."
Aiding stem cell research
Of further interest is that the biocavity laser may be applied not only to identifying the spectra associated with cancer cells but also those associated with stem cells, and how these optical signals change as they differentiate into nerve, muscle, and other tissues. "At present, there's no rapid method for identifying the transitional states [of a stem cell] with the functional cell type it eventually becomes. That process is a mysterious sequence of metabolic and genetic changes." There are, he says, metabolic similarities between stem cells and cancer cells, and researchers would like to clearly identify the differences.
"Stem cells are therapeutic," says Naviaux. "How are their spectra distinct from cancer?"
A difficulty still ahead is viewing cancer cells in fluids taken directly from the body, rather than isolated by type in a flask. The cells should be distinguishable from other floating material by their responsiveness to particular wavelengths. -- Neal Singer
Fourteen Egyptian engineers, physicists, and chemists are spending eight weeks at Sandia this spring learning the intricacies of safely handling sealed radioactive sources. This training program is part of a larger project to greatly improve the cradle-to-grave management of sealed radioactive sources in Egypt.
Sealed sources are radioactive materials typically encapsulated in small metal vials or containers. They can be used for a variety of purposes -- medical for eradicating cancers and industrial for anything from sterilizing surgical instruments to detecting erosion inside pipes.
"Of the 14 Egyptian students, only five had prior education and/or background in radiation protection," says John Cochran (4163), project manager of the Integrated Management Program for Radioactive Sealed Sources (IMPRSS) in Egypt. "We are giving them a condensed version of the training Sandia's Radiological Control Technicians receive."
The special training the 14 Egyptians are receiving is tied directly to an incident in 2000 when an Egyptian farmer living in a rural area outside Cairo discovered a small shiny piece of metal on the ground. Thinking it unusual, he took it home to show his family. Five weeks later the man and his son were dead, and several other family members were seriously ill.
After much investigation, which even involved temporarily quarantining an Egyptian village, it was determined that the cause of death and illness was radiation exposure. The man had found a sealed source that came from a pipeline inspection instrument. It was accidentally left at the site.
The incident set off a national uproar that resulted in the government of Egypt wanting to greatly improve the country's infrastructure to safely manage sealed radioactive sources.
Starting in 1994, Sandia hosted several Egyptians in the US on fellowships, and Sandia's capabilities were known by the Egyptian Atomic Energy Authority (EAEA). After the incident the EAEA contacted Sandia to help the country develop a program that would help protect the people of Egypt by improving the safety of cradle-to-grave management of sealed sources.
Sandia and the EAEA submitted a joint proposal to the US Agency for International Development in Cairo for funding.
"Three years went by between making the pitch and getting the money in the door. We were persistent," John says.
They then put together a program that covered the full life cycle of sealed source management, including tracking, awareness, security, regulatory reform, recovery, conditioning, storage, recycling, disposal, and the ability to respond to an emergency involving a sealed source.
Before training the 14 Egyptian engineers, chemists, and physicists, Sandia presented three-day classes in Egypt on sealed source management for members of the EAEA and the Egyptian Ministry of Health and another for users, like hospital personnel.
Brian Thomson of Behavior-Based Safety and Training Dept. 6342, who developed the eight-week program, says the curriculum is customized for the Egyptians' needs. The program involves six weeks of lecture and hands-on training in a mock radiological area, one week of training on teletherapy devices (devices used for medical purposes such as cancer treatment), and one week of radiological emergency training and exercises.
Upon their return to Egypt, the 14 students will share their new knowledge of how to safely handle sealed sources with their colleagues. -- Chris Burroughs