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Scientists are working on using cellulose to power microbial fuel cells, in which bacteria digest plant waste matter to create electricity directly.

These fuel cells could be used to charge batteries or power electrical devices.

Others are considering drawing power from microbes digesting human waste at wastewater treatment plants or manure from feedlot lagoons.

“Basically, we’re converting cellulose into a different energy source than ethanol,” said John Regan of Pennsylvania State University in University Park.

“It’s not more efficient right now, but if you look at what’s been done over the last decade, there has been about a five to six order-of-magnitude (100,000-1,000,000-fold) increase in power density,” he added.

Microorganisms generate electrons as they break down food sources for energy, but in most species the electrons are transferred to molecules inside the cell.

Microbial fuel cells rely on the ability of certain bacteria to transport electrons to the outside of the cell. If provided with electrodes in the right arrangement, the bacteria can dump their exterior electrons through a circuit, providing power.

But these “exoelectrogenic” microbes, as Regan calls them, cannot digest cellulose. So, the system relies on another type of bacteria to break the cellulose down into simple molecules that the electron dumpers can then use.

Regan found that wastewater, which contains a diverse community of microorganisms, could generate electricity from cellulose, too, though not as much. Adding extra cellulose-degraders to the wastewater sped up the process.

Regan envisions near-term applications that would not depend on cellulose, but rather would degrade the soup of compounds in wastewater.

“In waste treatment, the incoming product is free. It’s waste material, so you could use that electricity to run pumps or aerators,” he said.

Even if the wastewater couldn’t produce enough electricity to completely power the plant, it could at least reduce the plant’s utility bill.

One vehicle’s operative life is coming to a close, while the other’s is still in its formative stages. Their legacies will be inexorably linked: Without the space shuttle, delivery and assembly of the International Space Station’s (ISS) key components would have been difficult at best, and probably could not have happened.

And while the jury is still out as to whether history will deem the space station a success, the shuttle almost certainly will be remembered for its dramatic failures as much as the significant accomplishments its yeoman-like crews achieved since Columbia first flew in April 1981.

In the meantime, there is enough work to go around for both the shuttle and the ISS. Before the shuttle fleet is retired in 2010, their crews are scheduled to fly nine more missions to the station.

Five will involve installation of new equipment; two are more akin to space-borne teamster jobs, hauling supplies and parts.

Shortly thereafter, the Constellation program, with its Ares launch vehicle and Orion spacecraft, will be ready to take over the mission of carrying people into space for the next 30 to 40 years and expand the limits of the space frontier beyond low Earth orbit

The ISS, fully complete by then, will assume the shuttle’s role as an orbiting laboratory.

At that point, the space shuttle will be relegated to museums, where the first thoughts that will come to most visitors’ minds will no doubt involve the catastrophic losses of Challenger in January 1986 and Columbia in February 2003.

Such reactions may be overly simplistic, but they are understandable in the eyes of some who were close to the shuttle program.

“The shuttle is a remarkable technological achievement, but it is an equally remarkable policy mistake,” says John Logsdon, the chairman of the Space Policy Institute at The George Washington University in Washington and a former member of the NASA Advisory Council. He also served on the Columbia Accident Investigation Board.

The key error was the collective belief of the shuttle’s champions that “it could be a system that could operate inexpensively, routinely, and with a high level of safety,” Logsdon says. “It met none of those objectives.”

An “incredible ship”

Those shortcomings are recognized within NASA — hence the willingness throughout the agency to embrace Administrator Mike Griffin’s push toward Constellation as the next logical step toward the return to the Moon and the first trip to Mars.

The shuttle is an “incredible ship,” says Mike Hawes, program integration manager at NASA’s Space Operations Mission Directorate. “It launches like a rocket, flies like a satellite, lands like a plane, and has cargo capacity — particularly a return cargo capacity that’s huge.”

With the shuttle, NASA learned how to mechanize regular access to space, and came to terms with both the good and bad challenges of reusable spacecraft, Hawes says. Until scramjet and ramjet technology gets off the drawing boards and test bays and joins flight lines, the shuttle remains the only fully hypersonic vehicle ever to fly regularly and carry crews and payloads as well. The data on high-speed aerodynamics collected during shuttle missions will serve the designers and engineers of future ultrafast winged aircraft well, he said.

The shuttle also performed well when called upon to support missions to build the space station, Hawes says, providing a platform for extravehicular activity as well as deployment for space arms and other complicated assemblies.

“But we learned it was a very expensive machine to operate, care and feed,” Hawes says. “And another thing — because of its long life cycle and small numbers — the total production run of orbiters being five — there are unique challenges in maintaining an industrial base.”

The shuttle’s unmet aspirations can be traced to the unrealistic conglomeration of functions it was supposed to perform from the beginning, says Howard E. McCurdy, a professor of public affairs at American University in Washington and author of white papers that outline how NASA could operate more efficiently.

“It’s important to keep in mind the huge controversy, going back to the 1950s, whether a spacecraft should have wings,” says McCurdy. “Should it have a ballistic shape? We go back and forth on that.”

Fixed-wing advocates prevailed, McCurdy says, convincing decision- makers that “the X-15 plus reusability equals one-tenth of the cost” of reaching space. Future generations of shuttles were supposed to do the job even better, he says, recalling former NASA Administrator Daniel S. Goldin’s hopes of someday deploying shuttles back and forth from space with the reliability of combat fighter aircraft.

Further complicating matters, McCurdy says, “The project was in a perpetual state of redesign — not just by the engineers, but by the people who were providing the money.” Engineers were “driven crazy,” he says, by the responses they would receive from contractors, field engineers, even political types, who had the audacity to come back with submissions of drawings with their own ideas of what the craft should look like.

“As they say on Capitol Hill, it [was] the only train in the station. It involved large amounts of money, infrequent new starts. Everybody gets involved,” McCurdy says.

At that point, projects like the shuttle take on the characteristics of any big undertaking. Because so many people have so many different objectives, it became unwieldy and hard to manage.

“The same thing was true with the space station in the beginning,” McCurdy says. While some supporters wanted the ISS to carry hangars for satellites, others wanted space telescopes. The two are mutually exclusive, he says; you cannot have a space telescope on one end of a platform and somebody banging on some piece of hardware in a satellite bay on the other end.

That collective mentality is “one of the reasons why we spent tens of billions of dollars on the space station but got nothing but a bunch of Power Point presentations,” McCurdy says.

A city in space

Now, as the ISS takes shape, it is emerging as a significant milestone in the history of cooperative ventures among nations.

The space station’s scientific missions, from the U.S. standpoint, chiefly surround resolving issues related to survival in space. Until we learn how to reduce bone mass loss and mitigate the potentially deadly effects of long-term exposure to radiation, there will be no manned missions to Mars.

“But we can talk about science all we want, but really, international relations are the most important thing,” says Roger D. Launius, the curator of the National Air and Space Museum and former chief historian at NASA. “That 16 nations [came] together to build the thing peacefully is a very significant development. It never happened in past human history, and quite frankly this may be the end of it, [given] the strife in the world and new strains between us and Russia.”

The collaboration may appear touchy-feely to laypersons, but to engineers and scientists it is anything but. Construction and deployment of Canada’s shuttle arm, the European space laboratory and the Japanese science missions meant that the task at hand became “truly multilateral,” says Hawes.

Adding the entry of Russia into the mix in the early 1990s led to appropriate increases in potential complications to the matrix. U.S. and Russian teams had to learn to communicate in each other’s language of program management and engineering.

“We learned there is no one formula to doing [international] partnerships,” Hawes says. “What do you mean when you’re talking about ‘verification?’ How do you test for structural strength? We found as we integrated the Russians that some [methods] are similar and some are different. Once we got past the language issue, we were able to build hardware that works once it gets into space, without ever seeing its physical counterpart on the ground.”

The science, Hawes believes, will sort itself out after the ISS expands to a six-person crew, up from the present three.

“We’ll have much larger capacity to do science both in terms of increased test subjects in which the crew is part of our experiment, and also the crew time to apply to a broader range of experiments,” Hawes says.

A space probe is headed for a second swing past Mercury to pick up a gravitational boost and eventually become the first spacecraft to orbit the closest planet to our sun.

Scientists expect to get more than 1,200 pictures when NASA’s MESSENGER spacecraft zips past Mercury early Monday, which would help reveal most of planet’s remaining unmapped terrain. The flyby should also provide a gravity assist that will prepare MESSENGER to enter orbit around Mercury in March 2011.

“For needles with smaller and smaller eyes, this team is getting better and better,” said Sean Solomon, MESSENGER’s principal investigator at the Carnegie Institution of Washington, during a Wednesday teleconference. He described the maneuvers as a “threading exercise” requiring the highest precision.

MESSENGER, short for the bulky name MErcury Surface, Space ENvironment, GEochemistry, and Ranging, should pass 125 miles (200 km) above Mercury, or roughly the same as the separation distance during a first flyby on Jan. 14. Its cameras and instruments will cover 30 percent of the planet surface, including never-before-seen areas on the western side of the planet opposite to the first flyby’s coverage.

No spacecraft has caught such close looks at the planet since NASA’s Mariner 10 probe, which zipped by Mercury three times in 1974 and 1975.

The earlier Mariner probe managed to map just 45 percent of the planet’s surface during its three flybys, while MESSENGER scoped out half of the planet’s uncharted surface during its first flyby.

However, MESSENGER still needs to perform an intricate dance with Mercury before it can turn full-time photographer. Each flyby requires precise earlier adjustments to the spacecraft’s course that normally use up precious onboard propellant.

Mission planners skirted this issue and saved up more propellant for the spacecraft’s later mission by taking advantage of the solar wind.

“MESSENGER is first interplanetary mission to use solar sailing as a means to control its trajectory,” said Daniel O’Shaughnessy, the lead MESSENGER navigator at Johns Hopkins University Applied Physics Laboratory in Laurel, Md. He added that they achieved accuracy within a third of a mile (1 km) using “only the subtle push of sunlight and without a single drop of propellant in over six months.”

The spacecraft will begin its 15,000 mph (24,140 kph) flyby in the early morning hours of U.S. EDT on Monday, Oct. 6. Its team will occasionally lose contact as MESSENGER turns this way and that to take pictures and compile seven large image mosaics of the planet surface. The closest approach during the roughly 30-hour encounter is set for about 4:45 a.m. EDT (0845 GMT).

A 17-minute power outage will occur as MESSENGER passes into Mercury’s shadow, requiring the spacecraft to rely on internal batteries instead of its solar panels.

The first MESSENGER flyby found evidence that volcanoes and not impacts had created Mercury’s flat, smooth plains. It also showed that Mercury’s magnetic field is elongated like a tear drop, with the solar wind pushing against the side closest to the sun and pressing it close to the surface.

MESSENGER approaches its upcoming flyby as an experienced planetary hopper, having revisited Earth once and swung by Venus twice since its August 2004 launch. A third flyby of Mercury is also scheduled for Sept. 2009, before the spacecraft enters orbit in 2011.

NASA extended the mission of the busy Phoenix lander Monday, saying it will operate the lander until it dies in the cold and dark of the Martian winter.

It is already snowing there, above the equivalent of the Arctic circle on Mars, the researchers said.

The explorer found evidence that the dust on the surface of Mars resembles seawater in its chemical makeup, adding to evidence that liquid water that once may have supported life flowed on the planet’s surface.

The Phoenix lander already has operated far longer than expected when it was dropped onto the Martian surface in May, and its controllers said they would squeeze every drop of life they could out of the solar-powered lander.

“We are literally trying to make hay as the sun shines,” Barry Goldstein, Phoenix project manager at the Jet Propulsion Laboratory in Pasadena, California, told reporters.

Scheduled to last just 90 Martian days, known as sols, the lander has already operated for more than 120.

But soon the sun will dip below the horizon until next April. Already the lander is getting less power, after a summer of light-filled days that resemble the months of daylight enjoyed at the Earth’s poles in the summer.

Mars weatherman Jim Whiteway of York University in Toronto, Canada, said the lander has seen snow, frost and clouds forming as the atmosphere cools, although the snow is vaporizing before reaching the ground.

“Nothing like this view has ever been seen on Mars,” Whiteway said. “We’ll be looking for signs that the snow may even reach the ground.”

Buoyed by the success of its first spacewalk, China on Sunday set its sights on launching a space lab in 2011 and establishing a space station in 2020.

China aims to set up a space station in 2020 and before that it will launch a “simple” space lab in 2011, Wang Zhaoyao, a spokesman of the country’s manned space programme told reporters here.

The station will be manned, Wang said Zhaoyao at a press conference following the successful return of the country’s third manned mission Shenzhou-7 after a 68-hour voyage during which a Chinese astronaut performed the country’s first space walk.

China will also test the orbiter docking technology after the Shenzhou-7 mission, he was quoted as saying by the official Xinhua news agency.

Meanwhile, Chinese Premier Wen Jiabao said it is the Chinese people’s persistent aspiration to develop the manned spaceflight technologies for the peaceful exploration and use of the outer space.

“The successful mission marked a milestone and great leap forward of China’s space technology development as China became the third country capable of spacewalk,” Wen said.

Wen congratulated the three astronauts and space scientists, saying that “it is a new important success in our nation’s space technology field, and the country and the people will always treasure up your historical achievements.”

The great success will also play a significant role for the development of the country’s economy, technology and national defence, as well as for the promotion of national solidarity in the country’s modernisation drive, he said.

The World Wildlife Fund on Thursday criticised the release of four poachers who admitted to killing 18 rhinos in Zimbabwe, saying such lax law enforcement is unravelling conservation progress.

“The lack of enforcement and increased poaching pressure in Zimbabwe now threaten to reverse the excellent trends in rhino populations of recent years,” said Susan Lieberman, director of WWF’s species programme.

Rhino poaching is growing throughout Zimbabwe, with around 70 rhinos killed since 2000 in the Lowveld Conservancies — where most of the nation’s rhinos are found, WWF said.

In 2008 alone, about 20 rhinos were shot in the Lowveld, while “prior to 2000, for a period of seven years, there was no rhino poaching wahtsoever,” said Raoul du Toit, Lowveld rhino conservation project manager.

WWF said poachers are killing rhinos in snares and shooting them for their horns.

While some poachers from neighbouring Zambia have been arrested and convicted, no Zimbabwean poacher has been convicted.

“The few Zimbabwean poachers arrested, have subsequently been released on bail, and then absconded or have evaded prosecution in the courts,” WWF said.

In the case of the four Zimbabweans who admitted to killing 18 rhinos, they were “granted bail, freed and immediately absconded.”

Zimbabwe is home to 300 white rhinos and 500 black rhinos, which are more endangered. Worldwide, there are currently around 14,500 white rhinos and nearly 4,000 black rhinos, added WWF.

Ever wondered why a song sounds sexy sometimes and annoying at other times? Well, a study on songbirds has shed new light on this question, showing that a change in hormone levels may affect the way we perceive social cues.

Emory University’s Donna Maney, who used white-throated sparrows for the study, says that the changes in hormone levels affect the perception by altering a system of brain nuclei, common to all vertebrates, called the ’social behaviour network.’

“Social behaviours such as courtship, parenting and aggression depend primarily on two factors: a social signal to trigger the behaviour, and a hormonal milieu that facilitates or permits it,” said the study leader.

“Our results demonstrate a possible neural mechanism by which hormones may alter the processing of these signals and affect social decision-making,” she added.

During the study, the research group treated female white-throated sparrows with estrogen, to mimic the levels seen during the breeding season, and compared them with females that had low, non-breeding levels of estrogen.

The birds listened to recordings of either male white-throated sparrow song (a courtship signal that should command the attention of breeding females) or synthetic beeps (which should be pretty boring for all the females).

The researchers then used a marker of new protein synthesis to map and quantify the activity in the social behaviour network that was induced specifically by song.

Across most of the network, song-specific neural responses were higher in the “breeding” females than the “non-breeding” ones. But the effects of estrogen were not identical in every region.

“If every node in the network just responded more in the presence of estrogen, then we’d conclude that estrogen acts as an on-off switch,” Maney said.

“But what we’re seeing is more complicated than that. Some activity goes up with estrogen, and some goes down. We are seeing how estrogen changes the big picture as the brain processes social information,” she added.

The findings suggest that the perceived meaning of a stimulus may be related to the activity in the entire social behaviour network, rather than a single region of the brain.

“The same neural mechanism may be operating in humans. In women, preferences for male faces, voices, body odours and behaviour change over the course of the menstrual cycle as estrogen levels rise and fall. Our work with these songbirds shows a possible neural basis for those changes,” Maney said.

The study will be published in the Nov. 10 edition of the Journal of Comparative Neurology.

A former NASA scientist has used radio waves to transmit solar power a distance of 92 miles (148 km) between two Hawaiian islands, an achievement that he says proves the technology exists to beam solar power from satellites back to Earth.

John C. Mankins demonstrated the solar power transmission for the Discovery Channel, which paid for the four month experiment and will broadcast the results Friday at 9 p.m. EDT. His vision is to transmit solar power collected by orbiting satellites as large as 1,102 pounds (500 kg) to lake-sized receiver stations on Earth.

Mankins, who worked at NASA for 25 years and managed the agency’s space-based solar program before it was disbanded, transmitted 20 watts of power between the two islands in May. The receivers, however, were so small that less than one one-thousandth of a percent of the power was received, Mankins said.

The experiment cost about $1 million, and Mankins said larger arrays could be constructed with more money.

Each of the nine solar panels used was built to transmit about 20 watts of power, but the transmission was scaled back to two watts per panel in order to obtain U.S. Federal Aviation Administration approval for the test.

Despite the miniscule reception on the receiving end, Mankins said the ground-based test proved it is possible to transmit solar power through the atmosphere.

“The test was in no way fully successful,” he said. “I think it showed it is possible to transmit solar power quickly and affordably.”

The Discovery Channel will highlight the solar power beaming experiment Friday, Sept. 12 in “Discovery Project Earth: Orbital Power Plant.” ?Check local listings.

The tireless tongue already controls taste and speech, helps kiss and swallow and fights germs. Now scientists hope to add one more ability to the mouthy muscle, and turn it into a computer control pad.

Georgia Tech researchers believe a magnetic, tongue-powered system could transform a disabled person’s mouth into a virtual computer, teeth into a keyboard — and tongue into the key that manipulates it all.

“You could have full control over your environment by just being able to move your tongue,” said Maysam Ghovanloo, a Georgia Tech assistant professor who leads the team’s research.

The group’s Tongue Drive System turns the tongue into a joystick of sorts, allowing the disabled to manipulate wheelchairs, manage home appliances and control computers. The work still has a ways to go — one potential user called the design “grotesque” — but early tests are encouraging.

The system is far from the first that seeks a new way to control electronics through facial movements. But disabled advocates have particularly high hopes that the tongue could prove the most effective.

“This could give you an almost infinite number of switches and options for communication,” said Mike Jones, a vice president of research and technology at the Shepherd Center, an Atlanta rehabilitation hospital. “It’s easy, and somebody could learn an entirely different language.”

That’s quite a contrast to the handful of methods already available to the hundreds of thousands of Americans who are disabled from the neck down.

The “sip and puff” technique, which lets people issue commands by inhaling and exhaling into a tube, is among the most popular. But it offers users only four different commands, limiting their options.

Control systems that use sophisticated pads to measure neck and head movements are also widespread, but using the hardware can be tiring, and frustrating on smaller electronics like computers.

And while newer innovations that track eye movement are promising, they can be costly, slow and susceptible to mixed signals.

The tongue, though, is a more flexible, sensitive and tireless option. And like other facial muscles, its functions tend to be spared in accidents that can paralyze most of the rest of the body, because the tongue is attached to the brain, not the spinal cord.

The tongue’s promise has long enticed scientists. In the 1960s, research work focused on turning the tongue into a primitive lens by attaching electrodes to the tissue. More recent studies have connected a camera that activates tongue electrodes in the shape of an object, helping blind people sense images.

A Palo Alto, Calif.-based company, newAbilities Systems Inc., has already designed a nine-button keypad placed on the roof of the mouth to control electronics.

Ghovanloo’s work, however, centers on creating a virtual keyboard instead of a physical one. He does that through a magnet about 3 millimeters wide that’s placed under the tip of the tongue.

The magnet’s movement is tracked by sensors on the side of each cheek, which sends data to a receiver atop a rather bulky set of headgear. It is then processed by software that converts the movement into commands for a wheelchair or other electronics.

After turning the system on, users are asked to establish six commands: Left, right, forward, backward, single-click and double-click. A graduate student who tested the technology was cruising the lab at will in a wheelchair, tongue firmly in cheek.

It’s an impressive display, and Ghovanloo said he hopes he could one day add dozens more commands that turn teeth into keyboards and cheeks into computer consoles. For example, “Left-up could be turning lights on, right-down could be turning off the TV,” Ghovanloo said.

Early tests involving Georgia Tech students are encouraging, and the team’s work has already attracted a $120,000 grant from the National Science Foundation and $150,000 from the Christopher and Dana Reeve Foundation.

But plenty of challenges await. Researchers must pare down the bulky headgear, which looks like a prop from a 1980s movie, into a dental retainer. The team also must improve the software, tinker with the size of the magnet and boost the wireless battery’s charge.

Above all, they must find a way to keep costs in between the “sip and puff” systems, which can cost hundreds of dollars, to more sophisticated eye-tracking systems, which cost thousands.

Still, the research encourages Justin Cochran, a 26-year-old college student who watched a recent test.

The design certainly needs improvements. “It’s in its infancy and quite grotesque,” he said. But Cochran said its potential for almost limitless control options makes him want to shelve his “sip and puff” wheelchair.

“You could control not just your chair, your TV, your computer, but your entire life,” he said. “And it’s all one system.”

The Cassini probe has pinpointed exact locations where icy jets erupt from Saturn’s icy moon Enceladus.

New carefully targeted pictures reveal details of the prominent south polar “tiger stripe” fractures from which the jets emerge. The images show the fractures are about 980 feet (300 meters) deep, with V-shaped inner walls. The outer flanks of some of the fractures show extensive deposits of fine material. Finely fractured terrain littered with blocks of ice the size of small houses surround the fractures.

“This is the mother lode for us,” said Carolyn Porco, Cassini imaging team leader at the Space Science Institute, Boulder, Colo. “A place that may ultimately reveal just exactly what kind of environment — habitable or not — we have within this tortured little moon.”

One highly anticipated result of the flyby was finding the location within the fractures from which the jets blast icy particles, water vapor and trace organics into space. Scientists are now studying the nature and intensity of this process on Enceladus, and its effects on surrounding terrain. This information, coupled with observations by Cassini’s other instruments, may answer the question of whether reservoirs of liquid water exist beneath the surface.

The high-resolution images were acquired during an Aug. 11, 2008, flyby of Enceladus, as Cassini sped past the icy moon at 40,000 miles per hour (64,000 kilometers per hour). A special technique, dubbed “skeet shooting” by the imaging team, was developed to cancel out the high speed of the moon relative to Cassini and obtain the ultra-sharp views.

“The challenge is equivalent to trying to capture a sharp, unsmeared picture of a distant roadside billboard with a telephoto lens out the window of a speeding car.” said Paul Helfenstein, Cassini imaging team associate at Cornell University, Ithaca, NY., who developed and used the skeet-shoot technique to design the image sequence.

Helfenstein said that from Cassini’s point of view, “Enceladus was streaking across the sky so quickly that the spacecraft had no hope of tracking any feature on its surface. Our best option was to point the spacecraft far ahead of Enceladus, spin the spacecraft and camera as fast as possible in the direction of Enceladus’ predicted path, and let Enceladus overtake us at a time when we could match its motion across the sky, snapping images along the way.”

The combination of high-resolution snapshots and broader images showing the whole region is critical for understanding what may be powering the activity on Enceladus.

The images show extensive fallout of icy particles along some of the fractures, and even in areas between two jet sources. Scientists suggest that once warm vapor rises from underground to the cold surface through narrow channels, the icy particles may condense and seal off an active vent. New jets may then appear elsewhere along the same fracture.

“For the first time, we are beginning to understand how freshly erupted surface deposits differ from older deposits,” Helfenstein said. ”Over geologic time, the eruptions have clearly moved up and down the lengths of the tiger stripes.”

Cassini flew through an icy plume from Enceladus earlier this year, and detected organic molecules similar to those found in comets.