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Lab News --March 26, 2010

March 26, 2010

LabNews03/26/2010PDF (2.6 Mb)

MTI: Ten years after entering orbit, satellite continues to serve

By Darrick Hurst

For engineers and scientists at Sandia, the evening of Friday, March 12, marked a proud moment in exceptional service to the nation. Hundreds of miles above the Earth, the Multispectral Thermal Imager satellite reached its 10th anniversary of service as it completed its 55,000th orbit — far exceeding both its intended maximum life and its potential applications in the process.

MTI imagery of Popocatépetl volcano in Mexico reveals subsurface hot spots and maps magma channels, while other thermal bands provide information on the effects of escaping gases. The goal is to improve computer simulations needed to model volcanic activity and environmental impacts. The study of volcanoes is important because they represent one of the most active features of landscape generation and can pose a threat to humans and the environment.

“The MTI satellite project is a terrific example of how NNSA and the Department of Energy leverage the best science and engineering in the world to advance nonproliferation efforts and promote national security,” NNSA Administrator Thomas D’Agostino says. “The multilaboratory team has consistently demonstrated the critical role our national laboratories play in tackling the most challenging problems facing our nation and the world.”

NNSA sponsored the MTI satellite project as a trilab effort to develop and evaluate advanced space-based technology for nonproliferation treaty monitoring and other national security and civilian applications. The project was carried out by DOE’s Savannah River National Laboratory and NNSA’s Los Alamos and Sandia laboratories. Sandia served as the lead lab, responsible for systems engineering, integration, testing, launch support, and on-orbit operations.

“This has been an exhilarating program to be a part of,” says Randy Bell, director of the Office of Nuclear Detonation Detection and former MTI program manager. “[The MTI program] achieved many firsts in satellite engineering and remote sensing science. The program relied on a small, experienced, dedicated core team that ensured there was great technical and programmatic communication across all subsystems and science elements.”

Originally only intended for a one- to three-year mission, the MTI satellite was designed to provide highly accurate radiometry with good spatial resolution in 15 spectral bands and to measure ground temperatures from space with accuracies in the realm of one Kelvin.

For a PDF version of this file with more images generated by MTI satalitte data, click the photo at left.
Analysts armed with advanced computer simulation codes and expertise could then employ these precision radiometric and thermal imaging capabilities to research and explore phenomenology associated with nuclear proliferation. The temperature data collected by the MTI satellite is important because heat is a characteristic that is difficult to hide and serves as a strong indicator of a facility’s function and throughput — producing power or nuclear weapons material.

“After reaching the DOE program’s three-year goal, the asset was still functional and providing us with important data but was without a primary sponsor,” says Brian Post (5764), current project lead for the MTI satellite. “By leveraging many small funding sources between existing and new proj- ects, we were able to continue supporting minimized operations for the MTI for a period of time until we could secure new overall sponsorship for the project.”

Overcoming obstacles

 After completing the initial nonproliferation mission, the scientists, engineers, and technicians supporting the MTI began to use the satellite in new mission roles, and were obliged to deal with a multitude of unexpected or unplanned issues to keep the system mission capable. 

“Having gone well beyond its one-year mission, several anomalies arose over the following years that threatened to end the mission,” Brian says. “The inertial reference unit failed, the onboard calibration capability was lost, the focal plane array was damaged when the sun unexpectedly entered the telescope’s field of view, the MTI’s long-term orbit plane drifted beyond its design limit, and the satellite experienced battery failures and other power and control problems. Each time, the outstanding project team was able to mitigate these issues and keep the satellite operating and functional.”

Through their innovations, the operations team and the system’s original designers at Sandia and Ball Aerospace not only succeeded in nursing the MTI back to life, but they also made design improvements to the MTI that enhanced the system capabilities and imaging capacity.

“The data and research results that have come from the MTI project in the more than 10 years it has operated more than justify the satellite as a worthwhile investment,” Brian says. “I truly believe we are lucky as a nation to have the MTI and to have kept it going as a resource. The value of this asset and technology is shown not just in the original mission we completed, but also in the multitude of other projects and programs that the MTI either initiated or contributed to directly.”

Serving science beyond nonproliferation

NNSA made the MTI system available to other users for government-sponsored research in the national interest after the satellite had completed its initial goals. As it turned out, the 15 spectral bands that the MTI science team had selected to address the program’s nonproliferation mission also provide valuable data to scientists who study a vast array of geophysical and other environmental phenomena, with applications never envisioned by the MTI developers. In addition to numerous defense-related applications, the more than 100 members of the MTI users group have employed the satellite’s imagery for research in such diverse areas as volcanology, glaciology, entomology, climatology, and the study of the moon.

“An important goal for us was to make our data available to the community,” Brian says. “And not just provide that data, but provide it in a format that researchers can understand, use, and manipulate in their work.”

The MTI’s data and imaging capabilities have proven useful to researchers studying the health of glacier ice, as well as the character of the permanent or seasonal ice pack in the Arctic or Antarctic, which can give climate scientists information they need to refine global climate models. The MTI has also provided useful data to researchers who study clouds in an effort to understand their effect on global warming. In addition to the direct scientific contributions of the MTI data, images have also been used as a resource for algorithm and signal processing technique developments.

Continuing to serve into the future

With sponsorship secured for the foreseeable future of the MTI satellite, the project team eagerly looks forward to years of continued work supporting research and development interests.
“Based on our latest predictions, the satellite still has many years of life left on orbit prior to re-entry,” Brian says. “We look forward to continuing our work contributing to and enabling our nation’s research and technology development. Particularly with the full lifespan of the satellite in mind, this has been a fantastic government investment and an incredibly successful project.”

The MTI project was the collaborative work of more than 500 Sandians from across 36 centers and more than 100 departments at Sandia, and more than a thousand others across all the program’s participants.

“The outstanding results of the MTI program are the product of a lot of hard work and attention to detail from a lot of people,” says Brian Brock (5735), original project manager for the MTI. “The satellite was designed with such a radiometric accuracy and precision that LANL and the National Institute of Standards and Technology had to develop new standards to calibrate it. When the MTI launched, there simply was nothing like it and it is still a unique asset. It was truly a world-class product from a world-class team.”

 “This program clearly demonstrated that it’s the quality of the people that matter most in the quality of the outcome,” Bell says. “Throughout all phases of the program from initial planning, design, development, launch, and operations, there was a careful balance between rigorous engineering to ensure reliability and exploratory science to push the limits of performance.”

“I owe a debt of gratitude to both our incredibly capable project team and also to the original subject matter experts who, although not actively working on the project, never cease to come to our aid when needed,” says Brian Post.

Other participants in the MTI satellite project include the Air Force Research Laboratory, National Institute of Standards and Technology, Ball Aerospace, Santa Barbara Research Center, Hughes Danbury Optical Systems, TRW, more than 40 other commercial and academic institutions in 16 states, and a users group with experimenters representing more than 50 government organizations. -- Darrick Hurst

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Breaking the logjam: Improving data download from space

By Neal Singer

Sandia-developed satellite systems have increased their sensing capabilities dramatically in recent years, but the bandwidth available for these payloads to transmit data to Earth has essentially remained constant, creating a kind of data logjam.

The Sandia solution has been to prereduce the large data stream by developing processing architectures that increase satellite onboard computing capabilities. Then, only the most useful information would be transmitted to Earth.

ASTRONAUTS deploy passive experiment containers (PECs), including MISSE-7, during an EVA outside the International Space Station. (NASA photo)

See also: A space-based polymer mirror that can be reshaped on the fly

But questions as to how well the latest in computing electronics would fare in the harsh environment of outer space, where high-energy particles might collide with a transistor and change the value of an individual calculation, remained unresolved.

Now, preliminary results of a Sandia experiment in progress on the International Space Station are providing insights into the effects of high-energy radiation on these computing electronics, enabling appropriate mitigation of these potentially crippling effects in future Sandia designs.
“We’re getting true on-orbit data from a space environment,” says Dave Bullington (2664), Sandia’s lead engineer on the experiment taking place in low Earth orbit.

NASA’s “Materials on the International Space Station Experiment” (MISSE) program, under the direction of the Naval Research Laboratory (NRL), provides opportunities for low-risk, quick and inexpensive flight tests of materials and equipment in space aboard the International Space Station (ISS), says NRL lead Robert Walters.

Passive experiment containers hold multiple experiments

MISSE provides suitcase-like containers called passive experiment containers (PECs) to hold multiple experiments. These are mounted by astronauts on the exterior of the ISS, thus exposing the experiments to the rigors of space.

The seventh in an ongoing series of MISSE flight opportunities, MISSE-7 for the first time offered researchers power and data connections provided by the ISS from which to run actively powered experiments.

On Nov. 16, 2009, the space shuttle launched carrying the MISSE-7 equipment and on Nov. 23, astronauts manually deployed these containers on the exterior of the ISS. Sandia has been receiving data from this research payload ever since.

At the heart of these new computing architectures are powerful yet flexible computing chips, configurable to support different missions. These chips are called reconfigurable field-programmable gate arrays (FPGAs).

Reconfigurable field-programmable gate arrays

Since these FPGAs are reconfigurable rather than limited to a predefined architecture, their circuits can be overwritten, somewhat the way a read-write compact disk has more possible uses than a read-only disk. This makes prototyping easier and also permits changing missions on satellites previously designed for other purposes. Because new generations of FPGAs available from commercial suppliers may not have been fully tested for reliable performance in space, Sandia engineers help validate device performance in a relevant environment before the devices are integrated into high-consequence operational systems.

Sandia, in a partnership with Xilinx, designed the SEU Xilinx-Sandia Experiment (SEUXSE) for this opportunity to fly on MISSE-7. (SEUs — single event upsets — refer to electronic changes caused by collisions with a single subatomic particle.)

SEUXSE contains a fourth-generation space qualified FPGA (Virtex 4) and a fifth-generation commercial or non-space qualified FPGA (Virtex 5) from Xilinx. Converting the ISS power to levels compatible with the Virtex devices are Sandia-designed power converters known as point-of-load (POL) converters.

Sandia engineer Brandon Witcher (5762) provided the POL design for SEUXSE — the first time these efficient, high-quality power converters have been used in space.

Special algorithms were developed and programmed into both of these Virtex FPGAs to detect and report upset events while the FPGAs were running typical satellite data-processing tasks.
Dave notes that each Virtex contains two traditional processors in addition to several other circuits designed to capture upset performance data relating to each circuit type. “We’re validating models with four computers inside these chips and sending back data messages every few minutes.”

With the data collected from this platform, researchers in future Sandia programs will know exactly how these FPGAs and POL converters perform in the space environment and how to design mitigation approaches into these processing routines to account for upsets encountered in space.


A second experiment called SEUXSE II, featuring even more recent computing components, has already been prepared to lift off on a future shuttle flight as part of MISSE-8.
For SEUXSE II, Sandia researchers replaced the commercial version of the Virtex 5 from Xilinx with an early release version of the space-qualified Virtex 5.

“Fortunately,” says SEUXSE researcher Jeff Kalb (2664), “the new Virtex 5 from Xilinx had a compatible footprint to the previous Virtex 5 and we could leverage the hardware that was designed for MISSE-7.”

Sandia researchers were also able to expand on the algorithms designed for MISSE-7 to provide even more insight to the space environment on MISSE-8.

SEUXSE II was delivered to NRL on Feb. 1, 2010, and MISSE-8 is expected to launch on the Space Shuttle in July 2010. When it is deployed on the ISS, it will replace the MISSE-7 PEC, which will be returned to Earth on the shuttle, allowing Sandia researchers to analyze SEUXSE hardware after it has been on orbit.

Sandia is the first to put these versions of the Virtex technology into orbit, Jeff says. These FPGAs and POL converters likely will become the heart of future processing architectures for Sandia’s DOE/NNSA customers. “The point is for us to get early on-orbit information on how these devices function in space.”

The mechanical design of SEUXSE and SEUXSE II was achieved by Dennis Clingan (2617), experienced in designing packages for NASA programs where astronaut safety is paramount.

Testing materials in the harsh space environment
MISSE-7 is also flying the Sandia Passive ISS Research Experiments (SPIRE). These tests passively expose a variety of materials and devices to the harsh space environment.  Upon return to ground, they will be tested to determine if degradation has occurred due to synergistic factors such as ionizing radiation, UV exposure, thermal cycling, micrometeorite impacts and vacuum effects.   Radiation-shielding structural composites (Dave Calkins, 1833 and Gayle Thayer, 5711), doped laser fibers (former Sandian Dahv Kliner), pure tin finished parts (Ed Binasiewicz, 5761), MEMs latching impact sensors (Mike Baker, 1749), and GaAs photodiodes (Alan Hsu, 5719) are some of the 15 Sandia passive experiments that together are SPIRE.

Sandia, through the support of the NA-22 Space Nuclear Detonation Detection (SNDD) Program office, developed SEUXSE and SPIRE in an 18-month period for a cost that was one-fifth of other comparable experiments. SEUXSE II was then delivered in one-third the time and cost of the original SEUXSE.

Additional help was given by Gayle Thayer (5711), who is the principle investigator and primary interface with NRL; Tracie Durbin (1513), who provided thermal analysis; Ethan Blansett (5735) who provided space radiation environment modeling and upset rate predictions; Mythi To (5337), who provided SEUXSE hardware design support; Dave Heine (2664) Jonathan Donaldson (2664), Chris Wojahn (5337), Dave Lee (2664), and Jim Daniels (5337), who developed the algorithms and provided test support for SEUXSE; and Org. 5761, which provided fabrication support.

A space-based polymer mirror that can be reshaped on the fly

In March 2008, Sandia researchers sent space-grade polymers to the International Space Station to see whether the inexpensive lightweight material, with its easily changeable shape, could replace expensive orbiting telescopic mirrors made of polished glass or beryllium.

“A conventional telescope mirror takes 18 months to two and a half years to manufacture,” program manager Jeff Martin (2617) says. “You have to order it exactly and you can’t change it. It’s the long tent pole in a satellite system.

“But a polymer mirror with a controllable shape opens up space missions that couldn’t otherwise exist. Apply a voltage to its piezoelectric-coated surface and it changes curvature to create the surface you want.”

The work envisioned controlled changes in curvature similar to the more expensive technique called adaptive optics, which changes the alignment of submirrors to alter the overall shape of a telescope’s mirror by hundreds of nanometers.

 “But a polymer mirror’s shape can be altered by hundreds of micrometers,” points out Sandia principal investigator Mat Celina (1821), “and in a continuous fashion.” A polymeric mirror would also be far less expensive.

To monitor degradation of materials sensitive to the strong UV and atomic oxygen found in the harsh environment of low Earth orbit, Mat’s team secured Sandia’s place in the
MISSE-6 program, the first time the Labs was so involved.

NASA’s Materials on the International Space Station Experiment (MISSE) program, under the direction of the Naval Research Laboratory, provides opportunities to researchers for low-risk, quick, and inexpensive flight tests of materials and equipment in space aboard the International Space Station (ISS).

Sandia researchers equipped their experiment with solid-state data loggers to record declining function over time.

These experiments, designed by Mat, Tim Dargaville, and Gary Jones (all 1821) were the first of their kind to activate piezoelectric materials and record their responsiveness during cumulative space exposure. They were also the first active MISSE experiment. “We also exposed passive samples for comparison,” says Mat.

The process applied voltage to a bimetallic strip to make its tip go up and down. The extent of motion was recorded.

“Over time, that amplitude should get smaller and smaller,” says Jeff. “Of course, if these materials were phenomenal, there would be no

How phenomenal is still an open question. The experiment, expected to be in space for six months, was there for a year and a half because the Columbia shuttle disaster delayed subsequent launches. The materials returned to Earth in September 2009, and were returned to Sandia researchers for analysis in November. Piecing together the results could take as long as a year.

The plastic material is a polyvinylidene fluoride (PVDF) copolymer, a material that can be produced in large plastic sheets. Big rolls are available at Lowe’s, Jeff says. “An extra processing step makes it shrink or grow when you apply a voltage. We invented a new flavor to get the best advantages in a space environment.”

The work is funded by Sandia’s Laboratory Directed Research and Development office. -- Neal Singer

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How graphene grows

By Patti Koning

Big things often come in small — or in this case, thin — packages. Graphene, a single-atom-thick planar sheet of carbon atoms, is considered by many to be the next, big thing in nanoelectronics, the material that might keep Moore’s law in existence.

 Graphene came into vogue about five years ago when two Manchester University scientists, Andre Geim and Kostya Novoselov, extracted it from bulk graphite. Graphene is chemically simple but physically strong and highly conductive. Electrons move through it at 1/300th the speed of light, significantly faster than through silicon. Scientists are excited by its potential for improved solar cells, LCD displays, touch screens, and other technologies.

Sandia researchers Elena Starodub, Kevin McCarty (far left) and Norm Bartelt (far right) around the Low Energy Electron Microscope used to study graphene growth. (Photo by Randy Wong) (Click on image to enlarge)

Norm Bartelt, Elena Starodub, and Kevin McCarty (all 8656) have been studying the formation of graphene for the past three years. This is no small task; graphene grows at extremely high temperatures, so its formation cannot be imaged using standard microscopy methods.

“There was a realization that you can do more with this material,” explains Norm. “We want to understand how it forms. With that knowledge, you can control growth to make better-performing materials.”

Recently, the team had a double breakthrough. They developed a method to image graphene in the earliest stages of formation and then they saw something very unexpected. It takes clusters of five carbon atoms to add area to a growing graphene sheet, an observation that greatly surprised Norm, a theoretical physicist.

“The rate at which carbon atoms attach should be proportional to the number of carbon atoms present,” he explains. “I’ve spent 20 years developing theories to explain how thin films grow, and none has behaved like this. We discovered that carbon atoms go through a complicated contortion before attaching to a graphene sheet.” To convince Norm, Elena repeated her measurements more than once, looking for an error that could explain the unexpected result.

Kevin developed the use of electron reflectivity to measure the number of carbon atoms on the surface. “I tried out the method on simpler systems, metal films growing on metal, and thought that it might work with graphene growth,” he says. “We found that the reflectivity is sensitive to minuscule amounts of carbon on the substrate surface.”

With practice, Kevin was able to image the growth of graphene while measuring the concentration of the carbon atoms floating around the surface — in a sort of pre-graphene configuration.
 “Once Kevin had learned how to measure very small concentrations of atoms attached to the surface, we then found this bizarre behavior of graphene growth, which was like nothing any of us had seen before,” says Norm. “We used information from the images that is usually ignored.”

Elena has been perfecting the technique of growing individual graphene crystals to continue studying how they develop. By closely monitoring the concentration of carbon, she can make what Norm describes as “tremendously large, perfect crystals.” This has led to more discoveries about the different phases of graphene on specific surfaces; for example, on the metal iridium the graphene crystals grow in four different orientations.

Peter Feibelman (1130) is doing first-principles calculations of the atomic structure of carbon and graphene on metal surfaces to help the team get a better sense of what is behind its behavior as it nucleates and grows. “Our method does not have atomic resolution, so we are guessing about where individual carbon atoms are,” says Norm. “With his first-principles calculations, Peter can develop hypotheses to test against our measurements."

Peter’s contribution both validates and enhances the experimental work. “It gives us a much more complete description,” says Kevin. “We can then make statements about the behavior of individual carbon atoms.”

The project has generated six papers over the past 18 months, published in the New Journal of Physics, Physical Review B, and Carbon. The two articles in the New Journal of Physics were featured on the publisher’s “Select” website while the second paper in Physical Review B, “Graphene Growth by Metal Etching on Ru(0001),” was an editor’s selection.

The technique development began under a Laboratory Directed Research and Development (LDRD) project. The research is currently supported by the Office of Basic Energy Sciences and by an LDRD project to enable graphene nanoelectronics. “Using the knowledge developed through this research, graphene with extremely low defect densities is being grown and tested,” explains Kevin. “This is important because the material’s superb electronic and mechanical properties are only realized in samples of high crystalline quality.” -- Patti Koning

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