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Lab News -- October 23, 2009

October 23, 2009

LabNews 10/23/2009PDF 3 Mb)

Oct. 9 meteor event adds to understanding of atmospheric phenomena

By Bill Murphy

 

You probably didn’t see it, but a couple of instruments in the Sandia-established Sentinel network did. What they saw — and you likely missed — was a marvelous nighttime light show.

In the early morning hours of Oct. 9 — at around 2 a.m. MDT — a meteor came streaking into the atmosphere over the western US. Its trail, an unusually bright and persistent slash across the dark sky, was picked up by at least two Sentinel skywatch systems, one at Sandia and one maintained by serious amateur astronomer Tom Ashcraft near Lamy, N.M.

The meteor, visually striking enough to generate local media interest, came out of the northwest sky and — according to early estimates by Sandia astrophysicist Dale Jackson (5737) — likely impacted somewhere in the rough country south and east of Glorieta, N.M. Dale says that as he and colleague Dick Spalding (5730) refine and analyze the data collected that night, they’ll get a better handle on the size and trajectory of the meteor and may even be able to pinpoint the impact location with some precision.

Using a Google Maps application written specifically for the purpose in the summer of 2008 by student intern Leandra Boucheron (1344 now; 5737 last year), Dale and Dick plotted the meteor’s flight path as seen from the Sandia instrument and from Tom Ashcraft’s instrument in Lamy. With those two frames of reference, they used the software to generate a Google Map overlay showing the initial estimate of the meteor track.

Dick is in the process of polling other members of the Sentinel network to find out if any other systems detected the meteor that night. As with GPS data, the more different frames of reference they have to work with, the more accurately Dick and Dale can refine the trajectory and impact point.

Despite a media-published estimate that the Oct. 9 meteor might be as large as a small car, Dick and Dale think it’s likely it was about the size of a beach ball — big enough to make a pretty impressive streak across the sky, but not that unusual. Dick, who’s been watching the skies for a long time as part his work at Sandia, says that about once a year there’s a meteor event in the Albuquerque skies on the scale of the one seen on Oct. 9.

Space junk or meteor?

Was it maybe not a meteor at all, but space junk?

Dale and Dick can rule that out with confidence. For one thing, the object was traveling too fast: Space junk — most of which is coming out of low Earth orbit — enters the atmosphere at roughly 17,000 miles per hour. A meteor enters the atmosphere at speeds of 25,000 mph or higher.

Also, as the Oct. 9 object swept across the sky in its downward arc, it displayed a flaring phenomenon characteristic of meteors and not seen in space junk reentries.

The flaring happened in rapid pulses; it’s quite evident in video of the event and shows up as strikingly obvious spikes in a light curve plot of the meteor’s transit of the sky.

The flares interest Dale and Dick because the mechanism that causes the phenomenon is not well understood. Conventional theory would hold that the flares are caused by a thermodynamic process — the heating and ablation of meteor material. (That’s how heat shields worked on the Mercury/ Gemini/Apollo spacecraft.) But the flares recorded on Oct. 9 happened way too fast to be the result of a heating process, says Dick.

“There’s some other emission mechanism at work here,” he asserts.

Dick subscribes to an idea proposed in a paper published last year by Czech researchers: The flaring detected in meteors is contended to be an electrical phenomenon. According to their theory, as a meteor enters the outer edges of the atmosphere it encounters triboelectric charging, which builds up and discharges over and over again very rapidly. The discharges can be substantial — those are the flares you see in the recordings, Dick says.

Dale, the astrophysicist, agrees that conventional explanations for the flaring phenomenon don’t cut it.

“I challenge anyone to reproduce the curve we see here, demonstrating these effects, using the standard [thermodynamic] model,” Dale says.

Understanding the flare-causing mechanism is of more than academic interest. First, Dale notes, a better understanding is needed to ensure safe spacecraft reentry. While the flaring phenomenon and its electrical implications hasn’t specifically been associated with spacecraft, it would be the unwise scientist or engineer who would dismiss the concern out of hand.

Also, adds Dick, it’s important that the nation’s skywatchers understand what they see when they see it. When you see a pattern of unusual flaring behavior in the sky — whether you’re seeing it from a space-based or ground-based platform — it’s critical to understand what’s causing it. Is it that triboelectric phenomenon associated with meteor activity? Or is it a rogue test of a nuclear device?

Understanding the difference is vitally important, Dick says.

The real issue, says Dale, is that there isn’t a lot of data available about atmospheric phenomena similar to this.

“There just aren’t a lot of resources invested in monitoring the atmosphere,” he says.

What is the Sentinel network?

The Sentinel network was conceived of about a decade ago by Sandia senior engineer Dick Spalding (5730) and colleague George Alder (ret.). It was established specifically to record transient light events such as the Oct. 9 meteor. It’s designed to monitor the skies more or less automatically, with little need for hands-on maintenance.

Today, there are nearly 100 Sentinel systems deployed in 11 US states and five Canadian provinces; there’s even an outlier system in Ireland. They are mostly maintained by knowledgeable and dedicated amateur volunteers. (Astronomy is one area of science where amateurs still make valued, important, and frequent contributions to the body of knowledge.)

A Sentinel system consists of a small, inexpensive black-and-white video camera equipped with a fisheye lens, with digitized video fed to a PC. The camera sees the entire sky and any time a light event occurs that meets certain software-defined characteristics, the camera starts recording whatever is in the video. Thus, whenever a bright light event happens — like the Oct. 9 meteor event over Albuquerque — the Sentinel system captures a precise video record of it. -- Bill Murphy

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Boeing, Caltrans, other industry partners join with Sandia on new mobile lighting application

By Mike Janes

What started out as a modest idea from Boeing to develop a fuel cell-powered mobile lighting system has attracted the attention of everyone from Hollywood to the California Department of Transportation (Caltrans). And Sandia is happily sitting square in the middle.

Mobile lighting refers to small, portable lighting systems used primarily by highway construction crews, airport maintenance personnel, and even film crews. Boeing, says Sandia project lead Lennie Klebanoff (8367), is embracing alternative energy options; the company approached him last year about getting fuel cell technology into airport ground support equipment, which includes lighting systems.

Traditionally, mobile lighting units are powered by diesel fuel generators that produce CO2, NOx (nitrogen oxides produced during combustion), and soot, making them less than ideal for the environment. In addition, diesel units are noisy, which creates a safety hazard when construction personnel are distracted and can’t hear oncoming traffic. A fuel cell running on pure hydrogen, on the other hand, is both very quiet and a zero-emission electric power source.

Lennie estimates that each deployed fuel cell-based mobile light would avoid the burning of nearly 900 gallons of diesel fuel per year and eliminate NOx and soot emissions. If the hydrogen used is generated from nonfossil fuel sources, then each mobile light unit would also reduce CO2 emissions by about nine metric tons per year.

Two separate designs

Sandia has adopted a two-pronged (alpha and beta) approach to the project. First, along with a number of external partners who are contributing time and in-kind resources, Lennie’s team is overseeing the production of the alpha mobile lighting unit that is expected to debut at an upcoming meeting of the American Association of State Highway and Transportation Officials (AASHTO). The alpha unit, while separate from the more advanced beta design that Sandia recently completed for Boeing, came about due to the enthusiasm of several industry partners and their desire to see a system built sooner rather than later.

The alpha system consists of advanced power-saving Light Emitting Plasma™ technology (contributed by Luxim, Lumenworks, and Stray Light), two high-pressure hydrogen tanks (purchased by Sandia), a trailer to transport the equipment (provided by Multiquip), and a fuel cell (provided and installed by Altergy Systems). Multiquip and Altergy are assembling the overall unit, while Sandia has consulted on its design and formulated the alpha unit technical plan for the team.

“The beauty of this project is that it ties together the manufacturers [Multiquip, Altergy Systems, Luxim, Lumenworks, and Stray Light] with Sandia and the end users [Caltrans, San Francisco International Airport, or SFO] in one collaboration, hopefully reducing commercialization barriers that so often hinder the widespread use of new technology,” says Lennie. The end goal of the project, he adds, is to get fuel cell technology into more widespread commercial use, particularly in general construction and aviation maintenance applications.

Lennie also points out that the project marks the first time Sandia has worked hand-in-hand with Caltrans, a significant development as Sandia/California has identified transportation energy as a key mission area and hopes to partner with Caltrans again in the future.

Other partners fall into place

Sandia initially completed a project for Boeing that examined the use of fuel cells for aircraft emergency power, Lennie says. Boeing was happy enough with the work, he says, that he was then contacted by its Phantom Work division (the main R&D arm of the company). This time, Boeing asked if Sandia would be interested in exploring the viability and applicability of fuel cells for ground support equipment. That discussion quickly led to the idea of developing a fuel cell mobile light for aviation ground support.

The project broadened considerably when Lennie gave a talk at the California Hydrogen Business Council in Sacramento. That talk led to concrete interest from Golden State Energy and the California Fuel Cell Partnership (CAFCP). Golden State Energy has since been instrumental in making connections with a fuel cell supplier (Altergy Systems) as well as a leading manufacturer of construction equipment (Multiquip Inc.), while CAFCP helped link Sandia with SFO, which would now like to deploy a unit.

After Lennie briefed Caltrans Director Randy Iwasaki on the idea, Iwasaki directed his Division of Research and Innovation (DRI) to get involved. Not surprisingly, Caltrans has proven to be an enthusiastic and highly engaged partner in the deployment of the Alpha unit, which will be field-tested in Caltrans maintenance projects near Los Angeles. “Caltrans and all the other project partners have been amazing,” says Lennie.

In addition to Caltrans, Altergy Systems, Luxim, Lumenworks, Stray Light, CAFCP, Golden State Energy, Boeing, and Multiquip, the project has attracted the interest of SFO, a longtime partner with Sandia on various homeland security projects. SFO would like to test the system for use in nighttime runway repair work, as well as in its terminal renovation activities. Unlike diesel systems, the fuel cell-powered mobile light can be used indoors.

Boeing design to use metal hydride storage

“Caltrans wanted us to get the alpha version in front of their highway transportation peers immediately, and our unit will be in operation and actually illuminating the new electric cars being featured at the AASHTO meeting,” says Lennie. “It will give all of us good feedback on how interested potential customers are in the technology, and also allow us to get an initial assessment of how the technology performs, particularly the plasma lighting.”

The plasma lights contributed by Luxim and Lumenworks, he says, use half the power of traditional LED lighting.

Boeing funded Sandia primarily to develop the beta design, a more sophisticated, technically ambitious unit that uses metal hydride storage tanks designed by Ovonic Hydrogen Solutions. These tanks store 12 kilograms of hydrogen, and thus offer some 90 hours of operating time (compared to the 30-40 hours offered by the alpha unit). Sandia’s engineers designed the overall beta system and solved the thermal management issues that surround metal hydride storage, including coupling waste fuel cell heat to the hydride bed.

Metal hydride storage is also appealing since it removes many of the safety concerns found with having high pressure on the alpha unit (whose tanks hold hydrogen at 5,000 psi, compared to 250 psi with the metal hydride tank system). These are all important considerations for commercialization, Lennie says.

The system’s beta version, says Lennie, was designed by an engineering team led by Terry Johnson (8365) and Celia Song, a summer student from Cornell University, and George Sartor (8365). Sal Birtola (8350) and Ben Chao from Ovonic Hydrogen Solutions made important contributions to the system design, while management support from Jay Keller (8367) was also key to the project. Song presented the design to Boeing in mid-August.

Lennie says other funding sources are being sought so that the beta system can be built and both versions of the system can then be tested and compared on equal terms. The team would also like to use the field-test data to perform quantitative analyses of the emissions reductions and increased energy efficiency afforded by the technology. Ultimately, he says, it will be the manufacturers that decide which system is most attractive for commercial purposes.

Since 2002, Sandia has enjoyed an umbrella CRADA with Boeing that has resulted in more than 20 technical projects between the two organizations. -- Mike Janes

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