By John German
Arrays of tiny shutters made at Sandia are serving much the same purpose as home window blinds — helping regulate interior temperatures — aboard one of three small experimental satellites launched into space March 22 as part of NASA’s ST5 mission.
The mission’s purpose is to demonstrate innovative technologies for a new generation of autonomous microsatellites. (See “NASA’s ST5 mission” on page 4.)
Satellite designers pay special attention to electronics temperatures. If circuit boards get too hot, they can fail. If batteries get too cold, they can degrade faster or perform intermittently.
Temperatures inside satellites can fluctuate to both extremes, heating up when in sunlight or cooling way down when in Earth’s shadow, for example. The heat generated by the electronics themselves can be trapped inside the satellite.
Larger satellites have sophisticated, and heftier, thermal control systems. Smaller ones, like the 25 kg (55 lbs) ST5 experimental microsatellites, each roughly the size of a wedding cake, require smaller, lighter-weight, and, ideally, lower-tech approaches.
In 2001 researchers from Johns Hopkins University’s Applied Physics Lab were attending a MEMS (microelectromechanical systems) short course at Sandia when the need for innovative microsatellite thermal control methods came up. The visitors were part of a Johns Hopkins team supporting the then-planned ST5 mission.
A collaboration was launched, and Sandia project lead Jim Allen (1769) and a team of Sandia MEMS designers worked with the Johns Hopkins researchers to design, using Sandia’s SUMMiT V™ technology, a MEMS device featuring a moving grillwork of shutters with slats that are
6 microns wide and 1,800 microns long. A human hair is about 100 microns thick.
The arrays of small shutters, moved back and forth by electrostatic actuators, expose either the gilded and highly reflective grillwork surface or a dark silicon substrate to maximize or minimize heat transfer through the satellite’s skin as needed.
The electrostatic actuators, themselves arrays of intermeshing, spring-loaded comb’s teeth pulled together by electrostatic attraction, are a proven micromotion staple also developed at Sandia.
Louvered satellite skin
Two of the three ST5 satellites have on their top and bottom decks 4-inch-square arrays of micro-louvers. A single array includes some 2,600 individual electrostatically driven devices. Each device — grillwork and actuator together — is approximately the size of the cross on this letter “t.”
Sandia’s Microelectronics Development Laboratory (MDL) fabricated and delivered to Johns Hopkins in October 2002 twelve louver-laden wafers for the ST5 satellites. Johns Hopkins performed the packaging, integration, and space-qualification testing.
Each array weighs just grams and consumes nanowatts of power when changing states, from open to closed or vice versa, and no power (only voltage) to maintain a position.
In all, Sandia has 90 square centimeters of louver-skin flying aboard two of the three microsats, which have been in an elliptical polar orbit 200 to 3,000 miles above the earth since March 22. The three-month experimental mission ended June 22, but as of Lab News press time the satellites continued to operate.
“The MEMS variable-emittance louvers have performed successfully during their three month mission,” says Ann Darrin, program manager at Johns Hopkins Applied Physics Lab. “This is the first time a fully space-qualified device of this type has ever been flown [in space], and the first to be flown on the outside of a satellite.”
Ten new tools
As a result of ST5, spacecraft designers have 10 new tools to work with, says Ray Taylor of NASA’s Science Mission Directorate, speaking of the 10 new technologies flown on the mission. “And tools that are not only smaller, lower power, and less expensive, but because of ST5 they will be proven in space,” he says. “Therefore, they can be used with a high degree of confidence in future missions.”
“I’m kind of in awe that these MEMS devices are in space,” says Jim. “It’s a pretty cool milestone for MEMS devices. I think it’s great that Sandia could be a part of it.”Other Sandians involved in the project included Sita Mani (5719), Ed Wyckoff (2132), Frank Loudermilk (1738), Dave Sandison (1749), and Jay Jakubczak (1710). Sandia’s Microelectronics Development Laboratory fabricated the delivered wafers. -- John German
Sen. Pete Domenici, R-N.M., Jemez Pueblo Gov. James Roger Madalena, and Sandia VP for Energy Security and Defense Technologies Les Shephard were among those present to dedicate a new Jemez Pueblo Municipal Water Filtration System July 5.
Sandia demonstrated the coagulation filtration method of removing arsenic from drinking water as part of the dedication ceremony at Jemez Pueblo’s new water treatment facility. Sandia engineer Bill Holub (6118) explained that coagulation filtration was chosen from about 20 other types of filtration systems based on the chemical makeup of Jemez’ water.
This is the fourth arsenic-removal demonstration site in New Mexico that Sandia has established as part of a consortium made up of Sandia, the AWWA Research Foundation (AwwaRF), and WERC, a consortium for environmental education and technology development. The other arsenic-removal demonstration plants are located in Socorro, Anthony (Desert Sands), and Rio Rancho. A fifth is planned for a site in Oklahoma.
Project manager Richard Kottenstette (6118) says each of the four demonstration sites uses different arsenic-removal technologies. The coagulation-assisted filtration method being tested at Jemez Pueblo removes suspended and dissolved solids from the water. The method is currently being used in projects in El Paso and Paradise Hills (near Albuquerque). The pilot testing at Jemez Pueblo presents an opportunity to assess a small-scale test in a unique water quality environment, he says.
Domenici secured funding for the arsenic-removal test project through DOE as chairman of the Senate Energy and Water Development Appropriations Subcommittee.
This January, the arsenic standard for drinking water in the US was lowered from 50 to 10 parts per billion. These changes were intended to safeguard consumers from exposure to large quantities of arsenic.
During the dedication, Domenici said that many rural communities in New Mexico have arsenic levels that will now fail to meet the new water quality standards for arsenic.
Many smaller communities affected by the new standard have only a single source for fresh water and may be forced to install and maintain costly water treatment facilities. Part of the research underway includes evaluating costs associated with installation and maintenance of the various technologies.
The senator expressed concern that the new arsenic level restrictions could represent “a serious hardship” to smaller communities in many areas across the American Southwest, including Texas, Idaho, New Mexico, and large parts of Utah.
Jemez Pueblo’s water previously had slightly higher arsenic levels than allowed under a recently changed clean water law. Arsenic, manganese, and iron in Pueblo water has resulted in poor-tasting, rust-colored water that stained clothing and tasted unpleasant. These troubles bothered those in the community for years, Madalena said.
Worldwide, in areas that have been contaminated with arsenic through pollution and where naturally occurring levels of arsenic are high, arsenic contamination affects the water supply of millions of people.
Those sponsoring the project hope that the technologies being evaluated at the project’s many sites can someday be refined and adapted for use in low-cost applications in areas all over the world. -- Stephanie Holinka
In West Texas, New Mexico, and other places around the world, wind turbines are used to generate electricity. But how can engineers determine their efficiency and health?
Sandia’s Wind Energy Technology Dept. 6214 has developed a device, the Accurate Time Linked data Acquisition System (ATLAS II), which answers that question and can provide all of the information necessary to the understand how well a machine is performing.
Housed in an environmentally protected aluminum box, ATLAS II is capable of sampling a large number of signals at once to characterize the inflow, the operational state, and the structural response of a wind turbine.
The ATLAS II has several key attributes that make it particularly attractive for wind turbine deployment. It is small and highly reliable, can operate continuously, uses off-the-shelf components, and has lightning protection on all channels.
“The system provides us with sufficient data to help us understand how our turbine blade designs perform in real-world conditions, allowing us to improve on the original design and our design codes,” says Jose Zayas (6214), the project lead who has been working on ATLAS II since its inception in 1999.
Last year the ATLAS II team completed a proj-ect with GE Energy and the National Renewable Energy Laboratory (NREL) to monitor the performance of a GE wind turbine in a Great Plains site located about 30 miles south of Lamar, Colo., and will soon start a new monitoring work-for- others (WFO) project with Texas Tech University.
The GE Energy/NREL/Sandia collaboration involved testing a 1.5-megawatt, 80-meter tall turbine with a rotor diameter of 70.6 meters. GE Energy is the largest wind turbine manufacturer in the US and sells them to developers such as Florida Power & Light all over the world. Wind plant operators sell the electricity to utilities such as the Public Service Company of New Mexico.
The GE turbine was equipped with four ATLAS II units, collecting a total of 67 measurements, including 12 to characterize the inflow, eight to characterize the operational state of the turbine, and 24 to characterize the structural response.
The system collected data continuously for 24 hours a day, seven days a week. The four units were placed at various locations on the turbine, and a GPS time stamp was used to maintain synchronization between the units. (See a schematic of the field deployment at right.) All data streams from the different units were merged into a single data stream at the base of the turbine where the ATLAS II software compressed the data and stored them onto a local computer.
Data collection efforts began on Sept. 14, 2004, and ended Jan. 19, 2005. During that time, more than 17,000 data records were collected, for a total of 285 Gb of data.
Because the turbine was located at a remote site, the data were transmitted to NREL via a satellite link and later transmitted to Sandia. In places where there is access to the Internet, the data can be monitored in real time over the web.
The Texas Tech project will start in August with an environmental monitoring box being placed on a 200-meter meteorological tower at a test site near the campus in Lubbock.
The university is expected to eventually erect a utility-size wind turbine. The ATLAS II will be used to collect data from the machine.
Sandia also is planning three experiments, using the ATLAS II to monitor the performance of three advanced blade designs on a test turbine it operates in conjunction with the US Department of Agriculture’s research station in Bushland, Tex. -- Chris Burroughs
By Neal Singer
What better arrangement when building a new house than for the architect to consult with the tenants?
In a remarkable paper in the July 21 issue of Science, a team of researchers from Sandia and the University of New Mexico under the leadership of Sandia Fellow Jeff Brinker demonstrated that common yeast cells (as well as bacterial and some mammalian cells) customize the construction of nanocompartments built for them.
These nanocompartments — imagine a kind of tiny apartment house — form when single cells are added to a visually clear, aqueous solution of silica and phospholipids, and the slurry is then dried on a surface. (Phospholipids are molecules that make up cell membranes.)
Ordinarily, the drying of lipid-silica solutions produces an ordered porous nanostructure by a process known as molecular self-assembly (see Lab News, most recently April 30, 2004). This can be visualized as a kind of tract housing.
In the current experiments, however, the construction process is altered by the live yeast or bacteria.
During drying, the cells actively organize lipids into a sort of multilayered cell membrane that not only serves as an interface between the cell and the surrounding silica nanostructure, but acts as a template for the silica.
This improved architecture seamlessly retains water, needed by the cell to stay alive. Further, by eliminating stresses ordinarily caused by drying, the nanostructure forms without fine-line cracks. These improvements help maintain the functionality of the cell and the accessibility of its surface.
“Cheap, tiny, and very lightweight sensors of chemical or biological agents could be made from long-lived cells that require no upkeep, yet sense and then communicate effectively with each other and their external environment,” says former UNM graduate student Helen Baca, lead author on the paper and advised by Brinker .
By comparison the more common practice of merely “trapping cells in gels” leads to stress, cracks, and rapid cell death upon drying.
Already launched on the space shuttle
The incorporated cells of the Brinker group are self-sustaining — they do not need external buffers and even survive being placed in a vacuum.
To study their use as cell-based sensors for extreme environments, samples of the yeast- and bacteria-containing nanostructures were launched on the just-completed mission of the US space shuttle Discovery. It will remain on the space station as part of a US Air Force experiment to determine their longevity when exposed to the extreme stresses of the radiation and vacuum of outer space.
Of the NASA mission, Jeff says, “Ordinarily, under such extreme conditions, the cells would turn into raisins. But, because of the remarkable coherency of the cell-lipid-silica interface and the ability of the lipid-silica nanostructure to serve as a reservoir for water, no cracking or shrinkage is observed. The cells are maintained in the necessary fluidic environment.”
The cell-architected nanostructure is, he says, “an amazing way to preserve a cell.”
The cells already have emerged still viable after examination in electron microscopes and after X-ray exposure in Argonne’s Advance Photon Source, where the accelerating voltage ranges from one to 20 keV, says Jeff.
Genetic modification done cheap
More interestingly, the entrapped cells easily absorb other nanocomponents inserted at the cellular interface. Because of this, the cell can internalize new DNA (introduced as a plasmid), providing an efficient form of genetic modification of cells without the usual procedures of heat shock or cumbersome puncturing procedures (electroporation) that could result in cell death. Thus, the yeast can be modified to glow fluorescent green when it contacts a harmful chemical or biotoxin.
Because such nanostructures are cheap, extremely light and small, and easy to make, they could conceivably be attached to insects and their emanations read remotely by beams from unmanned aircraft.
The method also makes it easier to prepare individual cells for laboratory investigation under microscopes. “Normally, to visually examine a cell, researchers use time-consuming fixation or solvent extraction techniques,” says Jeff. “We can spin-coat a cell in seconds, pop the cell into an electron microscope, and it doesn’t shrink when air is evacuated from the microscope chamber.” The cell can be immediately imaged, says Jeff.
“Spin-coating” refers to deposition of the cell suspension slurry on a spinning substrate until dry.
From their comfortable “home,” the empowered cells can also direct their own landscaping. They can organize metallic nanocrystals added at the cell surface. These may enhance the sensitivity of Raman spectroscopy for monitoring the onset of infection or the course of therapy. The cells also localize proteins at the cellular interface.
A model for persistent infections
Assistant Professor Graham Timmins of UNM’s College of Pharmacy notes that the encapsulated cells’ unusual longevity may serve as a model for persistent infections such as tuberculosis, which have a long latency period.
TB bacteria can remain dormant in vivo for 30-50 years and then re-activate to cause disease. Currently the state of the dormant bacterium is not understood. Timmins and Brinker are discussing further experiments to validate the model.
Finally, building the cells into a coating with a high enough density might elicit from them a defensive, multicellular signal of an unpleasant nature that discourages unwanted biofilm formation on the coated surface — important for avoiding infections that could be carried by implants and catheters.
“This is not the end of the story, but the beginning,” says Jeff. “No one else has created these symbiotic materials and observed these effects. It’s a totally new area.”
The cell’s ability to sense and respond to its environment is what forms these unique nano-structures, says Jeff. During spin-drying, the cells react to the increasing concentrations of materials in the developing silica nanostructure by expelling water and developing a gradient in the local pH. This in turn influences lipid organization, the form of the silica nanostructure, the decrease in developed stress, and ultimately the living conditions of the ensconced cellular tenants.
The work was initially funded by Sandia’s Laboratory Directed Research and Development (LDRD) office, then by DOE’s Basic Energy Sciences group for its fundamental implications, and then (through UNM) by the Department of Defense (Air Force) for its practical possibilities.
Along with Helen Baca, the lead researcher, current graduate students Carlee Ashley and Eric Carnes have made significant contributions. Others contributing are Deanna Lopez, Jeb Flemming (1716), Darren Dunphy (1851), Seema Sigh, Zhu Chen,
Nanguo Liu, Hongyou Fan (1851), Gabriel Lopez, Susan Brozik (1714), and Margaret Werner-Washburn. Flemming, Dunphy, Fan, and Brozik are Sandians; Liu is from LANL; other participants are from UNM. Brinker, in addition to his position at Sandia, is a professor of chemical engineering at UNM.
-- Neal Singer
By Julie Hall
Sandia researchers and their collaborators have won two R&D 100 awards, which are presented annually by R&D Magazine in recognition of the 100 most technologically significant products introduced into the marketplace over the past year.
Sandia winners include:
“I congratulate the researchers who have won these awards, which highlight the power and promise of DOE’s investments in science and technology,” Energy Secretary Samuel W. Bodman said. “Through the efforts of dedicated and innovative scientists and engineers at our national laboratories, DOE is helping to enhance our nation’s energy, economic, and national security.”
Compute Process Allocator (CPA)
The CPA’s principal application is to maximize throughput on massively parallel supercomputers by managing how processors are assigned to particular computing jobs given a stream of computing tasks submitted to a job queue. The CPA assigns each job to a set of processors, which are exclusively dedicated to the job until completion. The CPA obtains maximum throughput by choosing processors for a job that are physically near each other, minimizing communication and bandwidth inefficiencies.
In experiments at Sandia, the optimized node allocation strategy employed by CPA increased throughput by 23 percent, in effect processing five jobs in the time it normally took to process four.
The CPA is scalable to tens of thousands of processors and is currently being used on supercomputers at Sandia (Red Storm), Oak Ridge National Laboratory, the US Army’s Engineer Research and Development Center Major Shared Resource Center, Pittsburgh Supercomputing Center, and the Swiss Scientific Computing Center.
Solid-state fluoride ion batteries have a high energy density while being inherently safe. The battery consists of nontoxic fluoride, and all three battery components of the HTSS10V — anode, cathode, and ionic conductor — are solid, making it the best and safest choice for high-temperature activities such as oil and gas drilling, currently its primary application. Traditional lithium batteries are at risk of exploding or leaking chemicals under high-temperature uses. Solid-state battery technology offers the largest temperature range — room temperature to 500° C — of any battery technology.
Other advantages of solid-state batteries are:
Researchers are currently working on a rechargeable version for laptop computers.
Limited production of the batteries began in 2005 at Russia’s VNIIEF Institute. Under a joint program with Sandia and General Atomics, the batteries will be produced in Sarov, Russia, and in San Diego, Calif., for high-end oil and gas drilling uses. -- Julie Hall
By Nancy Garcia
NECIS (the Nanoscience, Engineering, and Computation Institute at Sandia, pronounced “nexus”) is a new institute that focuses on research activities that integrate nanoscale physical and biological sciences with computational science.
“NECIS recognizes and coordinates leading-edge, innovative experiments,” says principal investigator Jean Lee (8759), “with new approaches in computational science and materials modeling to tackle fundamental challenges in nanosystems modeling and simulation.”
This produces efficient development and validation of “disruptive” nanotechnologies. (A disruptive technology, rather than being an incremental advance, overturns an existing, dominant one.) In collaboration with key university partners, NECIS research projects are designed to inspire and expedite breakthroughs in nanotechnology that support DOE strategic areas such as energy, science, and defense.
Because many US universities do not offer programs that combine experiments with computation, and fewer American students are pursuing careers in science and engineering, NECIS aims to bridge these gaps by providing top US students research opportunities that bring together nanoscale experiments with advanced modeling, simulation, and computation.
NECIS serves as an incubator for nurturing new trends and trendsetters that will drive technical innovation in emerging fields such as nano-engineering and advanced computing to improve national security and enhance US technological competitiveness.
Along with Jean, NECIS is led by co-principal investigators Jonathan Zimmerman (8776) and Scott Collis (1414). In this inaugural year, NECIS has close to 50 interns participating in its summer program who are roughly equally distributed between Sandia’s California and New Mexico sites.
NECIS is aiming to grow in future years to include more interns and more research activities, and to become part of Sandia’s response to the American Competitiveness Initiative, announced in President Bush’s 2006 State of the Union address. The initiative foresees increasing research spending in DOE’s Office of Science and the National Science Foundation.
NECIS is the 11th educational institute at Sandia and is a crosscutting effort with three other Sandia institutes (the Sandia Institute for Nanoscale Engineering and Science, the Engineering Sciences Summer Institute, and the Computer Science Research Institute). All the institutes offer research opportunities for a range of applicants, primarily upper-division undergraduate students through PhD-level students.