After a series of delays, NASA's Wide-field Infrared Survey Explorer (WISE) began its mission Monday morning, rocketing toward orbit at 9:09 A.M. (Eastern Standard Time). WISE's launch from Vandenberg Air Force Base in California was initially delayed because of a scheduling conflict with a satellite launch on the east coast, then twice pushed back due to an anomaly in a steering engine on its booster rocket.
WISE is an infrared astronomy platform charged with mapping the entire sky from a polar orbit around Earth. Following a monthlong checkout, the satellite is designed to spend nine months surveying the sky in the infrared wavelengths that are largely blocked by the planet's atmosphere and hence inaccessible to ground-based observers. Among the tasks WISE may accomplish on orbit are cataloguing dim, failed stars known as brown dwarfs, some of which may lie closer to the sun than the nearest presently known stellar neighbors; giving sky watchers a better idea of the threat presented by near-Earth asteroids; and singling out interesting targets both near and far for larger telescopes to study in greater detail.
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NASA Infrared Surveyor
Geo Engineering Combats Climate Change
COPENHAGEN—The controversy at this climate summit revolves around two simple issues: Who cuts? Who pays? Of course, climate change does not distinguish between a ton of carbon dioxide emitted from cutting down a peat forest in Indonesia versus a ton emitted as a result of burning coal in Germany. Therefore, a relatively new term is beginning to stir some controversy here in the Danish capital outside the direct negotations: geoengineering.
That's in part because the "Conference of Parties" negotiations have taken so long. After 17 years, the basic issues remain to be addressed, and overall emissions have grown since 2000—the year enshrined in the United Nations Framework Convention on Climate Change treaty as the peak year of greenhouse gas emissions for the developed world (the U.S. signed this agreement). With little hope of reducing emissions in the near term—some scientists, such as geochemist Wally Broecker of Columbia University think we'll be lucky to stop at concentrations of 550 parts per million in the atmosphere—more radical solutions are on offer: artificial, eternal volcanoes; using saltwater mist to increase cloud cover; even flotillas of mirrors in space.
"Geoengineering is plan B," says oceanographer John Shepherd of the U.K's Royal Society of plans to deliberately tinker with the planet's climate. "It's not to be adopted unless absolutely necessary."
After all, "geoengineering is technically possible," Shepherd adds. But "in most cases, it's still on the backs of envelopes and there are very many things to be concerned about, like environmental impacts."
It's not just environmental impacts from filling the skies with sulfur dioxide to mimic the cooling impact of a massive volcanic eruption, like Mount Pinatubo in 1991, among other plans on offer. "This will have vast human rights implications, on self-determination, on the right to food," says Diana Bronson, program manager at the ETC Group. "We're talking about technologies that would modify the entire planet."
And though building a sulfur dioxide smokestack to the stratosphere is an expensive proposition, there are simpler and cheaper ways to accomplish these ends, including dumping such particles from a helicopter. "It would take 10 Howitzers firing a shell a minute a year to get sulfates into the atmosphere," says Jason Blackstock, an analyst at the International Institute for Applied Systems Analysis. "Fifty to eighty countries in the world are capable of this."
Already, Russian scientist Yuri Izrael has begun to experiment and the Chinese routinely seed clouds to produce rain or snow. The Indians and Germans have conducted scientific testing of dumping iron in the ocean to attempt to promote algae growth and thus carbon sequestration.
"We aren't going back to the climate we had before," says Jane Long, associate director for energy and environment at Lawrence Livermore National Laboratory. "We are going to be managing the environment, not just the climate but also hydrology, soils. We have to learn how to do that."
Of course, there are geoengineering options that are not as dangerous, such as mechanical devices to suck CO2 out of the air. Physicist Klaus Lackner of Columbia University and others are working on such devices and believe they could be accomplished for $300 per metric ton of CO2 removed. And others advocate restoring organic carbon to the soil in the form of so-called biochar (charcoal), which could sequester as much as 900 megatonnes of carbon over the next several decades.
But still questions of governance remain. For example, who will determine the appropriate level for CO2 concentrations in the atmosphere? Freezing Russians or sweltering island states? Who will control the global thermostat?
"Reducing emissions should remain the top priority for the foreseeable future," Shepherd says, "but serious research is needed rather than enthusiasts working in their spare time." Perhaps control of the world's climate shouldn't be trusted to basement tinkerers or scientists.
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Greener Way of Getting Electricity From Natural Gas
A new type of natural-gas electric power plant proposed by MIT researchers could provide electricity with zero carbon dioxide emissions to the atmosphere, at costs comparable to or less than conventional natural-gas plants, and even to coal-burning plants. But that can only come about if and when a price is set on the emission of carbon dioxide and other greenhouse gases — a step the U.S. Congress and other governments are considering as a way to halt climate change.
postdoctoral associate Thomas Adams and Paul I. Barton, the Lammot du Pont Professor of Chemical Engineering, propose a system that uses solid-oxide fuel cells, which can produce power from fuel without burning it. The system would not require any new technology, but would rather combine existing components, or ones that are already well under development, in a novel configuration (for which they have applied for a patent). The system would also have the advantage of running on natural gas, a relatively plentiful fuel source — proven global reserves of natural gas are expected to last about 60 years at current consumption rates — that is considered more environmentally friendly than coal or oil. (Present natural-gas power plants produce an average of 1,135 pounds of carbon dioxide for every megawatt-hour of electricity produced — half to one-third the emissions from coal plants, depending on the type of coal.)
Natural gas already accounts for 22 percent of all U.S. electricity production, and that percentage is likely to rise in coming years if carbon prices are put into effect. For these and other reasons, a system that can produce electricity from natural gas at a competitive price with zero greenhouse gas emissions could prove to be an attractive alternative to conventional power plants that use fossil fuels.
The system proposed by Adams and Barton would not emit into the air any carbon dioxide or other gases believed responsible for global warming, but would instead produce a stream of mostly pure carbon dioxide. This stream could be harnessed and stored underground relatively easily, a process known as carbon capture and sequestration (CCS). One additional advantage of the proposed system is that, unlike a conventional natural gas plant with CCS that would consume significant amounts of water, the fuel-cell based system actually produces clean water that could easily be treated to provide potable water as a side benefit, Adams says.
Although no full-scale plants using such systems have yet been built, the basic principles have been demonstrated in a number of smaller units including a 250-kilowatt plant, and prototype megawatt-scale plants are planned for completion around 2012. Actual utility-scale power plants would likely be on the order of 500 megawatts, Adams says. And because fuel cells, unlike conventional turbine-based generators, are inherently modular, once the system has been proved at small size it can easily be scaled up. “You don’t need one large unit,” Adams explains. “You can do hundreds or thousands of small ones, run in parallel.”
Adams says practical application of such systems is “not very far away at all,” and could probably be ready for commercialization within a few years. “This is near-horizon technology,” he says.
Costs and benefits
Adams and Barton, with funding from the BP-MIT Conversion Research Program, used computer simulations to analyze the relative costs and performance of this system versus other existing or proposed generating systems, including natural gas or coal-powered systems incorporating carbon capture technologies.
Combined-cycle natural gas plants — the most efficient type of fossil-fuel power plants in use today — could be retrofitted with a carbon-capture system to reduce the output of greenhouse gases by 90 percent. But the MIT researchers’ study found that their proposed system could eliminate virtually 100 percent of these emissions, at a comparable cost for the electricity produced, and with even a higher efficiency (in terms of the amount of electricity produced from a given amount of fuel). Jack Brouwer, associate director of the National Fuel Cell Research Center at the University of California, Irvine, says that the high efficiency and the carbon separation capabilities of solid-oxide fuel cell technology “are indeed impressive.”
Absent any price for carbon emissions, Adams says, when it comes to generating electricity “the cheapest fuel will always be pulverized coal.” But as soon as there is some form of carbon pricing — which attempts to take into account the true price exacted on the environment by greenhouse gas emissions — “ours is the lowest price option,” he says, as long as the pricing is more than about $15 per metric ton of emitted carbon dioxide. Such a pricing mechanism would be put in place, for example, by the Waxman-Markey “American Clean Energy and Security Act” that was passed by the U.S. House of Representatives in July, through its “cap and trade” provisions. (A corresponding bill has not yet reached the floor of the U.S. Senate.) If the program becomes law, the actual price per ton of carbon would vary, being determined through the free market.
CCS is considered the only practical way of meeting reduced emissions targets under a cap-and-trade program, because alternatives to the use of fossil fuels are not far enough advanced to be able to quickly replace them at reasonable cost. CCS involves separating out the carbon dioxide from other gases in the plant’s exhaust, and then injecting them into deep geological formations (for example, in depleted oil wells) to keep them from going into the atmosphere. Most approaches to capturing the carbon dioxide emissions from a fossil-fuel power plant require the use of a chemical solvent that absorbs the carbon dioxide from a mixture of gases — a process that is inherently inefficient and adds significantly to the cost of the power produced. Adams and Barton’s system eliminates this inefficient separation step.
One of the critiques most often leveled against proposals for fuel-cell power plants is that the technology has high initial costs compared to conventional combustion technologies. But the new study found that once carbon pricing is in effect, even if the cost of fuel cells remains more than double that targeted by the U.S. Department of Energy for 2010, the solid-oxide fuel cell system would be the cheapest option available in terms of lifecycle costs of electricity produced, even though the up-front capital costs could be three to four times greater than for natural gas or coal combustion systems.
In fact, the system’s predicted efficiency is so high that it beats the lifecycle cost of a combined-cycle natural gas plant, even without carbon pricing. And the study shows that a very low level of carbon tax, on the order of $5 to $10 per ton, would make this technology cheaper than coal plants, which are currently the lowest cost option for electricity generation.
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Robots of Nature
To a robot designer like Sangbae Kim, the animal kingdom is full of inspiration.
"I always look at animals and ask why they are the way they are," says Kim, an assistant professor of mechanical engineering at MIT. "As an engineer, looking at them and speculating is fascinating."
While a graduate student at Stanford,
Kim drew inspiration from the gecko to build a climbing robot, and he is now designing a running robot that mimics the movements of a cheetah. Such agile, fast-moving robots could perform military surveillance and search-and-rescue missions deemed too dangerous for humans to undertake.
His Biomimetic Robotics Lab is one of several at MIT pursuing biologically inspired engineering. A team of mechanical engineers has built robotic fish, and materials scientists have designed moisture-collecting materials that mimic a beetle's shell.
Evolution has produced finely tuned adaptations over millions of years, so it only makes sense to turn to nature for design ideas. However, while Kim seeks inspiration in nature, he's not trying to produce exact robotic copies of a particular animal. Such copying would be difficult to achieve and not necessarily the most effective design strategy.
"There are millions of things that animals have to adapt for, and it is almost impossible to compare evolution to our engineering/mathematical optimization process," says Kim. "And you have to be careful about copying other features that may not be related to the particular function you want to achieve. Therefore, extracting scientific principle is extremely important for designers like me."
Stickybot
When Kim and his colleagues at Stanford set out to build a climbing robot, at first they figured they needed to make the robot's feet sticky. However, they soon realized that very sticky feet can't detach very easily.
Their approach shifted dramatically with the 2006 discovery, by Lewis and Clark College biologist Kellar Autumn, that geckos use a phenomenon called directional adhesion to stick to walls.
"The gecko gave us a completely new perspective. Stickiness does not necessarily come from chemical composition; it can come from mechanical properties and geometry," says Kim. "The geometry enables strange phenomena such as directional adhesion, which sticks in only one direction."
The pads of a gecko's feet are covered with a forest of tiny hairs called setae, some of which are one-twentieth the width of a human hair. The setae, in turn, branch into hundreds of tiny smaller hairs called spatulae, which are about one-thousandth the width of a human hair. These hairs cling to surfaces using tiny molecular interactions known as van der Waals forces. Collectively, the forces are strong enough to support the gecko's weight as it scrambles up a vertical surface.
To demonstrate, Kim rummages around in a desk drawer in his office and pulls out a small rectangle of the gecko-inspired adhesive material, which resembles a tiny patch of blue Astroturf. A compact disc gently held against the horizontal surface attaches securely in one direction and then easily detaches in the opposite direction.
The adhesive is covered with hairs made of rubber silicone, which are thicker than those on a gecko's paw (about four times thicker than a human hair). Because thicker hairs require smoother surfaces for adhesion, Stickybot can only climb extremely smooth surfaces like glass.
Kim and his colleagues, led by Stanford professor Mark Cutkosky, first demonstrated Stickybot in 2006, and Time magazine named it one of that year's best inventions. The paper describing the robot also won the 2008 Best Paper Award for the IEEE Transactions on Robotics.
Potential applications for the stickybot technology include exterior repair of underwater oil pipelines and window washing. Kim also plans to start designing climbing equipment for humans using the directional adhesion technology.
Need for speed
Kim, who arrived at MIT as an assistant professor in June, is now turning his attention to a speedier robot, inspired by the cheetah. Four graduate students have just begun working on the cheetah project, and within the next two years Kim hopes to have a prototype that can run 35 miles per hour.
Though his design incorporates principles from a variety of running animals, including horses and dogs, Kim zeroed in on the cheetah because of its special adaptations for speed. One feature he plans to mimic is the flexibility of the cheetah's backbone, which gives extra speed or force to its running motion.
To demonstrate how extra joints can add force and speed, Kim leans back in his chair and mimics throwing a baseball, in slow motion — first the shoulder, then the elbow, then the wrist bend. The force imparted by each of those joints adds up, allowing a pitcher to throw a faster pitch. In the same way, the joints of the cheetah's leg — hip, knee and ankle — are aided by the extra speed generated by its bending backbone, which is much more flexible than that of other running mammals.
Kim and his students plan to start building and testing prototypes within the next 18 months, after using a computer model to calculate the optimal limb length and weight, gait and torque of the hip and knee joints.
He expects that the biggest challenge will be getting enough power out of the motor to furnish the desired speed. To that end, he plans to build the robot out of lightweight carbon fiber-foam composite, so less power is needed to propel it.
Another difficult problem is coordinating the control of three joints in four legs. Those 12 joints each have to move in concert with the others, and they need to be able to react smoothly to disturbances in the gait, such as tripping over a rock, and regain balance.
Kim believes his robots could be a significant improvement over current wheeled robots used for scouting and search and rescue, which are efficient but slow. "It's going to be very exciting to see how fast we can go and how rough a terrain we can navigate."
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