As NASA gets to work on the Constellation Program

Using Satellites to Pinpoint and Predict Pollution

The European Space Agency is expanding its satellite data network to better track air pollution on a global
As NASA gets to work on the Constellation Program—the space agency's next not-so-small-step for mankind that hopes to put U.S. astronauts back on the moon by 2020—the European Space Agency (ESA) has set its sights on learning more about our own planet. Toward that end the agency this month, at its Tropospheric Emission Monitoring Internet Service (TEMIS) conference in Italy, touted its ability to provide free atmospheric and environmental data to help nations assess air pollution problems.

ESA's TEMIS delivers data in what the agency calls "near-real time" and also provides long-term forecasts based on tropospheric trace gas concentrations, aerosols and ultraviolet (UV) radiation. TEMIS gathers information from its own satellites and also has agreements with NASA and the Darmstadt, Germany–based European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) to make their data available on its Web site. This data includes info from the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite and the Global Ozone Monitoring Experiment (GOME-2) instrument on the MetOp satellite, which was developed by EUMETSAT and ESA to provide a closer view of the atmosphere from low Earth orbit.

ESA plans to expand TEMIS to monitor the transboundary and hemispheric movement of air pollution. The OMI and GOME-2 instruments are spectrometers, which can pinpoint different trace gases in wavelength ranges, providing a measure of Earth's entire atmosphere in a single day.

"Key users of this data are environmental agencies [that] have to report on things like greenhouse gases," says Claus Zehner, an ESA Earth observation application engineer, noting that the European Union (E.U.) continues to keep tabs on air quality over its member nations. By law, they have to report each year on the status of the air quality in their countries, he adds. The E.U. is now considering changing its European Air Quality monitoring laws to mandate the use of satellite data.

Among the most important info ESA has provided is data on levels of nitrogen dioxide (NO2) in the atmosphere. NO2, a known pollutant, has been linked to respiratory ills and environmental destroyers such climate change and acid rain. Researchers have identified major NO2 hot spots and industrial culprits, thanks to ESA data gathered between 1996 and 2006.

ESA data has traditionally been used by environmental protection agencies in European Community countries, but its use is spreading. Researchers at Harvard University, for example, used Aura's OMI data to analyze changes in air quality achieved by limiting traffic in Beijing during a China–Africa summit held there last year. In an attempt to ease travel congestion, Beijing officials reduced traffic flow by 30 percent during the conference, barring some 800,000 of its 2.82-million strong fleet of private vehicles from traveling within city limits.

TEMIS enabled Harvard researchers to obtain accurate, independent measurements of NO2 in the city air at that time. By comparing the satellite observations with measurements from the ground, along with a global chemical transport model, they learned that the atmospheric models failed to accurately reflect a dramatic 40 percent drop in nitrogen dioxide levels in Beijing's air during the traffic restriction, says Yuxuan Wang, a Harvard lecturer and research assistant specializing in atmospheric chemistry.
"Without the TEMIS data, I would say that it would be impossible to do" the Beijing emissions study, Wang says. Chinese scientists were able to provide some data, she says, but it didn't come close to the details captured by the satellites. Wang and her colleagues continue to use ESA data to study regional NO2 emission distribution as well as gauge the amount of nitric oxide (NO) plus nitrogen dioxide (collectively known as NOX) present in the air.

ESA data has also been used to study patterns of gaseous pollutant emissions throughout India and to assess the prevalence of disease related to air pollution in New Zealand.

Zehner says that the agency plans to build and launch at least five "sentinel" satellites to monitor not only trace gases that indicate pollution in the atmosphere, but also the surface temperature of the oceans, the movement of ice and the shifting of land masses. The first three are expected to launch by 2012; the remaining two are tentatively scheduled to be sent into orbit by 2015, he says.

ESA's goal is to provide reliable information that can be used to advocate and establish policies designed to improve the environment, Zehner says, adding, "We are offering the first steps needed for monitoring greenhouse gases and other environmental areas."


MetOp-A takes up service


EUMETSAT has just reported that Europe entered a new era of meteorology and climatology when MetOp-A, Europe’s first polar-orbiting meteorological satellite, was on 15 May 2007 officially declared operational after only six months of commissioning.

The first scientific data were received as early as two days after the end of the Launch and Early-Orbit Phase. Now the full data flow from its instruments is available to users on an operational basis, offering unprecedented accuracy and resolution of different variables such as temperature and humidity, wind speed, ozone and measurements of trace gases such as carbon dioxide, nitrous oxide and methane.
Through its instruments, which sound the atmosphere throughout its depth, MetOp-A gathers essential global information, day and night about the atmosphere, land and ocean surfaces. MetOp-A data will significantly improve weather forecasting e.g. by direct assimilation into Numerical Weather Prediction Models that compute forecasts ranging from a few hours to up to 10 days ahead.

Researchers discover a way to briefly store data acoustically to alleviate traffic bottlenecks

New Way to Help Networks Handle Ever-Heavier Data Loads

As demand for streaming video over the Web, voice over Internet protocol (VoIP) calling services and other forms of Internet-based multimedia communication skyrockets, content creators and consumers are counting on fiber-optic networks to handle these increasing loads quickly and efficiently. One way to ensure this happens is to enhance the ability of such networks, which transmit data over glass or plastic threads, to capture and retain data even for very brief intervals.

Toward that end, a team of researchers from Duke University and University of Rochester's Institute of Optics recently reported in Science that it successfully transferred encoded information from a laser beam to sound waves and back to light waves, a breakthrough that could speed development of faster optical communication networks. Swapping data between optics and acoustics allows it to be stored in pockets of acoustic vibration created when laser beams interact along a short strand of optical fiber.

The research is significant, because it addresses how memory can be created for optical pulses. "The primary thrust is investigating slow light via stimulated Brillouin scattering, where we slow down a pulse as it propagates through an optical fiber," says study co-author Daniel Gauthier, chairman of Duke's department of physics. Brillouin scattering occurs when light traveling through a medium, such as glass, changes its path as it encounters varying densities.

The main goal of the research is to pave the way for better fiber-optic communication systems, which today consist of fiber placed underground and linked by routers. The typical way to send data over an optical network is to break it up into chunks called packets. When a packet comes into a router, its address information is read. The problem with routers is that they each contain a single switch that can only process one packet at a time. As a result, some packets are dropped unless others coming in are buffered (saved) or can wait until it is their turn to be routed. "If you drop the packet, you reduce the throughput of the entire network," Gauthier says. "If you buffer, then the packets are processed one after the other."

As greater demands are placed on telecommunication infrastructures, "it's important to start to investigate parallel technologies," he adds.

Gauthier and his colleagues discovered that when two laser beams of slightly different frequencies are pointed at one another along a piece of glass fiber, they create acoustic vibrations called phonons. When co-author Zhaoming Zhu, Gauthier's postdoctoral research associate, encoded information onto one of these beams, the data could be imprinted on these newly created phonons and retained for 12 billionths of a second, long enough to be transferred back to light again by shining a third laser through the fiber.

"When thinking about how to store light in optical fibers," Zhu says, "we realized that we can convert optical information to acoustic vibration, something that hasn't been done before."

The researchers are seeking ways to create longer storage times and reduce the peak power of the laser beam needed for retaining and reading out the information, a process that will take years before a commercial version of the technology is available.

"There is still a great need for developing new strategies for optimizing the flow of information over the Internet," says Robert Boyd, a professor of optics and physics at the Institute of Optics and a research co-author. "If two data packets arrive at a switch at the same time, you need to store one until the other packet clears the switch, maybe 100 nanoseconds later. Our technique is aimed at … building buffers for high-speed telecommunications."

During the first phase of the project—which is part of the Defense Advanced Research Projects Agency's (DARPA) Defense Sciences Office slow-light program—Zhu says he learned that pulses could be stored and read out at a later time. The second phase was the actual experiment in which data pulses were stored (as acoustic waves in an optical fiber) and retrieved after a certain period of time.

"We really want to demonstrate that methods for storing optical information are much broader than people thought," Gauthier says. "In the current telecommunication systems, you turn the optical signal into an electronic signal and store it in RAM. The optical data pulses are then regenerated by using the electrical signals to turn on and off an auxiliary laser source. But this process generates heat. The faster this is done, the more heat is generated."

For this to work in the real world, the scientists say the communication fibers must be made of a material that provides an acoustic time frame long enough to allow the information to move from optical to sound, then return to optical. One option, Gauthier says, is to work with a new type of glass made from a chalcogenide, which has good semiconductor properties and contains one or more elements from the periodic table's chalcogenide group, also known as the "oxygen family," which includes oxygen, sulfur, selenium and tellurium.

Another option that researchers are exploring is to run the laser beams through a hollow optical fiber filled with gas (such as xenon), which would allow them to use a less powerful laser to induce longer lasting sound waves in the gas. This could potentially create a sound wave 50 times longer and allow the lasers used to be 100 times less powerful—and less energy intensive—thereby delivering more data more quickly at a lower cost.

New Video VoIP Software, Webcams End That Pixelated Feeling

Skype and Logitech team up to deliver video voice over Internet protocol calls that look more like TV than home videos

Thanks to the rapid-fire growth of broadband network connectivity, video voice over Internet protocol (VoIP) services now give callers around the world the ability to gab away for no more than the cost of their monthly Internet service provider fee. Until now, though, the video capabilities have been little more than a novelty that tempts callers with grainy images of their friends and family that lack the ability to capture their movement with any fluidity.

But that could change as early as next month when Luxembourg–based Skype, a division of online auctioneer eBay, is set to unveil the latest version of its software, which is tuned to work with a new lineup of "high-quality video" Web cameras from Fremont, Calif.–based Logitech. The companies gave a preview Tuesday of what's to come at a New York City press conference, where they demonstrated their software and hardware working together to produce video VoIP that looks more like watching TV than grainy home movies.

This is no small feat, as the laundry list of requirements indicates. What do you need to take advantage of this latest offering? Skype 3.6 (coming in early to mid November), any of three new Logitech Web cameras introduced Tuesday, the latest version of Logitech's Web camera drivers, a bandwidth connection of at least 380 Kbps (kilobits per second) and a PC with at least one gigabyte of RAM and a dual-core, 2.0 GHz (gigahertz) or faster processor running Windows XP or Vista. The result will be a sharp video image resolution of 640 by 480 pixels at up to 30 fps (frames per second), up from Skype's previous capacity of 320 by 240–pixel resolution at no more than 15 fps.

The goal, the companies say, is to alleviate some of the frustrations that video VoIP users must contend with, in particular the choppy, pixilated images of loved ones that freeze and jump during VoIP conversations. The upgrades in software and camera equipment are designed to "make people feel like they're together during a conversation," even if they are separated by hundreds of miles, Don Albert, vice president and general manager of Skype North America said at the press conference.

Added Gina Clark, vice president and general manager of Logitech's Internet Communications business unit: "Our goal is to make lifelike video calls.''

Have an Apple? Sorry. You'll have to stay on the sidelines—at least for awhile. Albert said there was currently no plan to release a Mac version of Skype 3.6, but Logitech's Clark said she would be interested in exploring the new cameras' performance on Macs, even though most Macs now come with embedded Web cameras.

All three of Logitech's new Web cameras offer a glass lens made by Oberkochen, Germany–based optical lens maker Carl Zeiss. (Most Web cameras come with plastic lenses, but more expensive glass lenses produce higher quality images.) The cameras also include an autofocus feature that resolves images in less than three seconds and can handle close-ups up to about four inches (10 centimeters) from the lens. The price tag for the new Web cameras: $100 and up.

Skype, which earlier this week introduced a 3G Internet phone with built-in software, says that 25 percent of its 246 million users worldwide use their VoIP technology to make video calls to other Skype users. Although Skype has offered VoIP since 2003, it has offered video calls for only about two years. Interest in video VoIP is expected to grow, but it will only go as far as broadband connectivity can permeate. Logitech estimates that half of U.S. households currently have access to broadband.