Science and Technology News

Tuesday, November 30, 2010

GUCP Work Delayed by Rain to be Finished Today

At NASA's Kennedy Space Center in Florida, technicians plan to install reference dots on space shuttle Discovery's ground umbilical carrier plate, or GUCP, to monitor for movement during tanking. The work was expected to be completed yesterday, but was delayed by rain.

Discovery's launch is currently targeted for no earlier than Dec. 17, after shuttle managers determined more tests and analysis are needed.

The Program Requirements Control Board reviewed on Nov. 23 repairs and engineering evaluations associated with cracks on two 21-foot-long, U-shaped aluminum brackets, called stringers, on the shuttle's external tank. Managers decided the analysis and tests required to launch Discovery safely are not complete. The work will continue through this week.

The next status review by the PRCB will be Thursday, Dec. 2. If managers clear Discovery for launch on Dec. 17, the preferred time is about

From Earth to Mars

This view of grains from a sand dune near Christmas Lake, Ore., was taken by a test version of the Mars Hand Lens Imager (MAHLI) camera on Curiosity, NASA's Mars Science Laboratory, which is slated to launch in fall 2011. The image includes three manufactured spheres; each is a 2-millimeter-diameter (0.08-inch-diameter) ball bearing, placed to provide an independent measure of the image scale. Reflected in each sphere is the glow from the camera's four white LEDs (light-emitting diodes).

This image has a resolution of 15.4 microns per pixel, which is about twice as high as the camera resolution on Mars Rovers Spirit and Opportunity. The view covers an area about 1 inch, or 2.5 centimeters, across.

Geologists can examine an image like this for information about the composition of the sand. In this case, the largest white grains are pumice fragments and the dark black and gray grains are fragments of basalt. Nearly transparent, slightly yellow crystals are feldspars. The crystals and pumice were erupted by Mount Mazama in its terminal explosion about 7,700 years ago; the volcano is known today as Crater Lake.

Image Credit: NASA/JPL-Caltech/Malin Space Science Systems

Air Above Dead Sea Contains Very High Levels of Oxidized Mercury

In Hebrew, the Dead Sea is called Yam ha-Melah, the "sea of salt." Now measurements show that the sea's salt has profound effects on the chemistry of the air above its surface.

The atmosphere over the Dead Sea, researchers have found, is laden with oxidized mercury. Some of the highest levels of oxidized mercury ever observed outside the polar regions exist there.

The results appear in a paper published on-line November 28th in the journal Nature Geoscience.

In the research, funded by the National Science Foundation (NSF), scientist Daniel Obrist and colleagues at the Desert Research Institute in Reno, Nevada, and at Hebrew University in Israel measured several periods of extremely high atmospheric oxidized mercury.

Mercury exists in the atmosphere in an elemental and in an oxidized state. It's emitted by various natural and human processes, and can be converted in the atmosphere between these forms.

High levels of oxidized mercury are a concern, says Obrist, because this form is deposited quickly in the environment after its formation.

Atmospheric mercury deposition is the main way mercury, a potent neurotoxin, finds its way into global ecosystems.

After it's deposited, mercury can accumulate through the food chain where it may reach very high levels. "These levels are of major concern to humans," says Obrist, "especially in the consumption of mercury-laden fish."

Fish caught in oceans are the main source of mercury intake in the U.S. population.

Observations of high naturally-occurring oxidized mercury levels had been limited to the polar atmosphere. There, oxidized mercury is formed during a process called atmospheric mercury depletion events.

During mercury depletions, elemental mercury is converted to oxidized mercury, which is then readily deposited on surfaces.

These events may increase mercury loads to sensitive arctic environments by hundreds of tons of mercury each year.

Now, Obrist says, "we've found near-complete depletion of elemental mercury--and formation of some of the highest oxidized mercury levels ever seen--above the Dead Sea, a place where temperatures reach 45 degrees Celsius."

Such pronounced mercury depletion events were unexpected outside the frigid poles. High temperatures were thought to impede this chemical process.

"Elemental mercury is somewhat resistant to oxidation, so it's been difficult to explain levels of oxidized mercury measured in the atmosphere outside polar regions," says Alex Pszenny, director of NSF's Atmospheric Chemistry Program, which funded the research. "These new results provide an explanation."

The mechanisms involved in the conversion of mercury above the Dead Sea appear similar, however, to those in polar regions: both start with halogens.

Halogens, or halogen elements, are non-metal elements such as fluorine, chlorine, bromine and iodine.

Observations and modeling results indicate that at the Dead Sea, the conversion of elemental mercury is driven by bromine.

The new results show that bromine levels observed above oceans may be high enough to initiate mercury oxidation.

"We discovered that bromine can oxidize mercury in the mid-latitude atmosphere," says Obrist, "far from the poles. That points to an important role of bromine-induced mercury oxidation in mercury deposition over the world's oceans."

What goes into the ocean, he says, may eventually wind up in its fish. And in those who eat them.

Obrist's co-authors are Xavier Fain of the Desert Research Institute and Eran Tas, Mordechai Peleg, David Asaf and Menachem Luria of Hebrew University.

-NSF-

Analysis Continues on Discovery

At NASA's Kennedy Space Center in Florida, space shuttle Discovery was powered down for the weekend while analysis continued. Today, technicians will install reference dots on the ground umbilical carrier plate, or GUCP, to monitor for movement during tanking.

Discovery's launch is currently targeted for no earlier than Dec. 17 after shuttle managers determined more tests and analysis are needed.

The Program Requirements Control Board, or PRCB, reviewed on Nov. 23 repairs and engineering evaluations associated with cracks on two 21-foot-long, U-shaped aluminum brackets, called stringers, on the shuttle's external tank. Managers decided the analysis and tests required to launch Discovery safely are not complete. The work will continue through this week.

The next status review by the PRCB will be Thursday, Dec. 2. If managers clear Discovery for launch on Dec. 17, the preferred time is about

Hurricane Season 2010: Tropical Cyclone 3S (Southern Indian Ocean)

NASA Sees Tropical Cyclone 3 Form in the Southern Indian Ocean

This infrared image of Tropical Cyclone 3's cold cloud tops (purple) was captured from NASA's Aqua satellite on Nov. 29 at (). The purple area indicates strong convection and cloud tops as cold as or colder than -63 Fahrenheit, indicating strong thunderstorms.
Credit: NASA/JPL, Ed Olsen NASA's Aqua satellite passed over the newly born third tropical cyclone of the Southern Indian Ocean season today and saw strong thunderstorms around its center of circulation.

An infrared image of Tropical Cyclone 3S's cold cloud tops was captured from the Atmospheric Infrared Sounder (AIRS) instrument that flies aboard NASA's Aqua satellite on Nov. 29 at (). The image showed strong convection and cloud tops as cold as or colder than -63 Fahrenheit, indicating strong thunderstorms.

Infrared satellite imagery also showed that the low level circulation center has consolidated (organized) and has improved convective banding (more organized bands of thunderstorms) this morning.

Tropical Cyclone 3S was located about 700 miles west of Cocos Island, near 11.9 South and 85.0 East. It was packing maximum sustained winds near 39 mph (35 knots) making it a weak tropical storm. It was moving west-southwest at 5 knots (6 mph). It's not threatening any land areas, but is kicking up 10-foot high seas.

The forecast calls for Tropical Cyclone 3S to intensify further, but then increased wind shear is expected to weaken it as it moves southeast. By Thursday, Tropical Cyclone 3S is expected to be located east of 90 East, so the forecast responsibility will fall under the Bureau of Meteorology in Australia.

Text Credit: Rob Gutro
NASA Goddard Space Flight Center, Greenbelt, MD

What's Up for December 2010?

What's Up for December? A lunar eclipse and a planetary trio grace the morning sky.

Hello and welcome! I'm Jane Houston Jones at NASA's Jet Propulsion Laboratory in Pasadena, California.

The earliest stargazers noticed star-like objects that changed position with respect to the stars. They also saw eclipses, like the lunar eclipse we get to see this month.

During an eclipse Earth’s shadow crosses the moon and the moon darkens. It may appear gray, brown or shades of red or orange, depending on how much dust is in our atmosphere.

This eclipse is best seen from North America. It occurs pre-dawn on the East Coast, in the middle of the night on the West Coast and the night before, in the late evening, in Alaska and Hawaii.

To get to the total eclipse, when the moon is fully within the Earth’s shadow, takes a little over an hour.

You won’t need a telescope to view the eclipse, but if you have one you’ll be able to see individual craters and other features as they pass in and out of shadow.

Venus is high and bright before dawn. It shrinks in size as the lit crescent widens to 50 percent by year end.

Mercury pops into the morning sky in late December. Look for it 10 degrees above the horizon just before sunrise.

On March 18, 2011, MESSENGER will become the first spacecraft to orbit Mercury.MESSENGER followed a path through the inner solar system, including one flyby of Earth, two flybys of Venus and three flybys of Mercury. This impressive journey is returning the first new spacecraft data from Mercury since NASA’s Mariner 10 mission 30 years ago.

Saturn is the third morning planet to watch this month. It won’t be visible in the early evening for a few more months, but why wait? The pretty rings are tilted open more than 10 degrees right now.

The Cassini spacecraft makes a flyby over the north pole of the moon Enceladus on the same night as the lunar eclipse. The fields and particles instruments will be trying to sniff anything that the moon might be emitting.

Learn more about this month’s Year of the Solar System resources at solarsystem.nasa.gov/yss

And you can learn all about NASA missions at www.nasa.gov

That’s all for this month. I’m Jane Houston Jones.

NASA Sets News Conference on Astrobiology Discovery

Dwayne Brown
Headquarters, Washington                               
 
Cathy Weselby
Ames Research Center, Moffett Field, Calif.

Science Journal Has Embargoed Details Until 2 p.m. EST On Dec. 2

WASHINGTON -- NASA will hold a news conference at on Thursday, Dec. 2, to discuss an astrobiology finding that will impact the search for evidence of extraterrestrial life. Astrobiology is the study of the origin, evolution, distribution and future of life in the universe.

The news conference will be held at the NASA Headquarters auditorium at 300 E St. SW, in Washington. It will be broadcast live on NASA Television and streamed on the agency's website at http://www.nasa.gov.

Participants are:
-Mary Voytek, director, Astrobiology Program, NASA Headquarters, Washington
-Felisa Wolfe-Simon, NASA astrobiology research fellow, U.S. Geological Survey, Menlo Park, Calif.
-Pamela Conrad, astrobiologist, NASA's Goddard Space Flight Center, Greenbelt, Md.
-Steven Benner, distinguished fellow, Foundation for Applied Molecular Evolution, Gainesville, Fla.
-James Elser, professor, Arizona State University, Tempe

Media representatives may attend the conference or ask questions by phone or from participating NASA locations. To obtain dial-in information, journalists must send their name, affiliation and telephone number to Steve Cole at stephen.e.cole@nasa.gov or call 202-358-0918 by Dec. 2.

For NASA TV streaming video and downlink information, visit http://www.nasa.gov/ntv.

For more information about NASA astrobiology activities, visit http://astrobiology.nasa.gov.

- end -

Dark Dune Fields of Proctor Crater, Mars

The dark rippled dunes of Mars' Proctor Crater likely formed more recently than the lighter rock forms they appear to cover, and are thought to slowly shift in response to pervasive winds. The dunes arise from a complex relationship between the sandy surface and high winds on Mars. Similar dunes were first seen in Proctor Crater by Mariner 9 more than 35 years ago.

This image was taken by HiRISE camera on board the Mars Reconnaissance Orbiter, currently in orbit around Mars.

Image Credit: NASA/JPL-Caltech/University of Arizona

Monday, November 29, 2010

Three NSF-Funded Scientists among Recipients of $3 Million Kavli Prize

Among the latest winners of the Kavli Prize are three scientists who have received NSF funding over the past several years. The Kavli Prize is awarded each year by the Kavli Foundation to scientists "whose discoveries have dramatically expanded human understanding in the fields of astrophysics, nanoscience and neuroscience;" prizes are presented to researchers in each of these three disciplines. Among the eight recipients for 2010 were the three NSF-funded scientists:  Nadrian C. Seeman of New York University; Roger Angel of the University of Arizona, Tucson; and Jerry Nelson of the University of California, Santa Cruz.

Seeman is a co-recipient of the nanoscience prize, which was jointly awarded to Donald Eigler of IBM's Almaden Research Center, San Jose, Calif.  Nelson and Angel are co-recipients of the astrophysics prize, which was jointly awarded to Ray Wilson, formerly of Imperial College London and the European Southern Observatory.

Recipients each received a scroll and a gold medal, and a total of $3,000,000 was divided among the three fields recognized with the prize, so that each recipient received his share of $1,000,000.  Recipients were chosen by three prize committees of distinguished scientists that were recommended by the Chinese Academy of Sciences, the French Academy of Sciences, the Max Planck Society, the U.S. National Academy of Sciences and the Royal Society.

The Kavli Prize was initiated by and named in honor of Fred Kavli, a Norwegian-American physicist, entrepreneur and philanthropist, and is a partnership of the Norwegian Academy of Science and Letters, the Kavli Foundation and the Norwegian Ministry of Education and Research.  The award recipients were announced on June 3, 2010 in Oslo, Norway, by the President of the Norwegian Academy of Science and Letters, Nils Christian Stenseth, and transmitted live to the World Science Festival, which spanned June 2-6 in New York City.

Nadrian Seeman

Seeman invented DNA nanotechnology, which uses DNA as a building block of more complex structures and devices. He was awarded a Kavli for his design of devices that may lead to new materials and systems billionths of a meter in size.

"The idea is to use the information contained in branched DNA or similar polymers to control the structure of matter as tightly as possible," said Seeman. 

Seeman explores how to use DNA information to create self-assembled three-dimensional synthetic DNA structures. Ultimately, living organisms could be utilized to create raw materials for new nanoscale circuits, sensors and medical devices.

"Our target is to use our ability to control the structure of DNA to organize other molecular species," said Seeman. "Thus, the original motivating goal of the work was to organize biological macromolecules so that their structures could be established using crystallography, with the DNA as a scaffold for target molecules."

Seeman also explained how his research can be applied to technology. "We and others are organizing other species for nanoelectronics purposes," said Seeman. In nanoelectronics, electronic devices are built from components approximately the size of single molecules. Structural DNA nanotechnology will allow for smaller and more complex products.

When asked what inspired his field of study, Seeman replied, "I was a crystallographer who could crystallize nothing. It was very frustrating. When I had the idea to use DNA sticky ends to organize DNA molecules, it felt like the synthesis of everything I knew about. There was no way I could not pursue it."

"Ultimately, the history of the human species can be written as the history of our materials," said Seeman. I am hoping that DNA nanotechnology will improve our control through yet another significant increment."

Roger Angel

Roger Angel develops methods to build optical telescopes and was awarded the Kavli for his unique process and methods in creating large primary mirrors

Angel is the founder of the University of Arizona's Steward Observatory Mirror Lab, the largest facility in the world for the manufacturing of astronomical mirrors, which produces lightweight, honeycombed mirrors 1.8 to 8.4 meters in diameter. His Lab produced two 8.4-meter mirrors for the international Large Binocular Telescope, the largest single optical telescope in the world, located in Arizona, as well as four 6.5-meter mirrors including for the Multi-Mirror Telescope, also in Arizona, and the two Magellan Telescopes in Chile.

Currently, the Mirror Lab is completing two 8.4-meter mirrors, one for the Large Synoptic Survey Telescope (LSST), ranked by the National Academy of Sciences as the top priority for ground-based astronomy in the next decade, and the other as the first of seven for the Giant Magellan Telescope.

To construct the mirrors, Angel has developed a unique process that melts 10 to 20 tons of borosilicate glass into a single substrate that has an internal honeycombed structure. The gaps hexagonal voids reduce the weight and thermal inertia of the structure, providing the stiffness and lack of thermal gradients needed for the best possible image quality in large ground-based telescopes. The disk-like mirrors are ground and polished and tested using laser technology and coated with aluminum, ready for use in the telescope with a minimum of operational overhead.

Angel explained that telescopes contribute knowledge to the "origin of our universe and how it works."  Large telescopes provide both the light grasp needed to observe the light from the waves that originated billions of years ago when galaxies were formed, providing insight to the conditions during the big bang, and the very sharp and high contrast images needed to study planets of nearby stars. As well as the big primary mirrors, Angel has developed very thin, flexible, smaller mirrors used to remove the atmospheric blurring that would otherwise prevent exo-planet imaging.

According to Angel, one of the benefits from astronomy is a better understanding of our own planet and the effects of greenhouse gases and global warming. "Stars will be here forever, but our own planet is under threat," explained Angel, who plans to use his technology to create what he describes as "energy telescopes designed to take light from the sun and turn it into solar electricity, at a price that doesn't have to be subsidized."

Jerry Nelson

Nelson explores the use of segmented optics to build the large-diameter telescopes. He was awarded a Kavli for developing and showing how such a system of segments could be combined to form a large-diameter mirror. He provided the concept and design for the segmented mirrors used in the twin Keck telescopes on Mauna Kea, Hawaii, the largest optical/infrared telescopes in the world.

Nelson's Keck telescope mirror design consists of 36 individual hexagonal mirrors that are combined to form a 10-meter diameter telescope mirror. The key features of his design, according to Nelson, "include the development of an effective way to polish and manufacture the mirror segments, a simple way to support the segments against gravity and an active control system to keep the mirror segments in near perfect alignment in the face of gravity, thermal and temporary disturbances."

Using the Keck telescopes, scientists have made a variety of significant astronomical findings ranging from discovering new planets to identifying the source of gamma ray bursts.

"Astronomy is unique in its focus on understanding the universe in which we live, and allowing us to appreciate our place in this universe," explained Nelson. "Because of this very role, astronomy is immensely popular with all people, and this knowledge is vitally important to us all."

Currently, Nelson is the project scientist for the Thirty Meter Telescope Project (TMT), which is designed to be even larger than the 10-meter diameter Keck telescopes.

"Building apparatus for experiments is, to me, endlessly challenging, both because of the learning experiences and the puzzles that one needs to solve to successfully build things," explained Nelson. "The opportunity to explore the complexities of constructing giant telescopes was a great treat and has kept me occupied and entertained for many years."

-- Ellen Ferrante, National Science Foundation

Getting a Tighter Grip on Cell Division

The dance of cell division is carefully choreographed and has little room for error. Paired genetic information is lined up in the middle of the cell in the form of chromosomes. The chromosomes must then be carefully pulled apart so that the resulting daughter cells each have an identical copy of the mother cell's DNA.

The molecular machinery that shepherds and literally pulls the chromosomes apart consists of paired microtubules radiating from opposite poles of the dividing cell and an enormous, but precise, molecular complex called a kinetochore. This 'gentle giant' grabs onto a single special locus on the chromosome known as the centromere.

Paradoxically, the more tension on the microtubule, the tighter the grip of the kinetochore--analogous to the clever mechanism of a Chinese finger trap that grips a finger tighter, the more you try to pull it off. In fact, the proper amount of tension may be a clue to the cell that all is proceeding according to plan. In the absence of tension, the cell is alerted to damage or mutation such as cancer and will frequently self-destruct.

In another feat of molecular acrobatics and precision, as the microtubule draws the captured chromosome towards the pole, it is actually shortening by losing tubulin subunits. To make things a little more complicated, it is disassembling at the very point where the kintechore attaches. In other words: imagine pulling yourself up on a rope, but as you progress upwards, the end of the rope is disappearing right from under where you were last gripping it. This is what this deft mechanism is accomplishing. Because the kinetochore has many points of contact (like a sleeve, or like that very same Chinese handcuff) it is good at not letting go of the microtubule even as it disassembles away.

At 100 nanometers across, the kinetochore is a true behemoth. One of the most complicated functional molecules in the cell is a ribosome, but that only measures 25 nanometers across by comparison.

This perspective of molecular size and complexity should highlight what a true achievement it is that Bungo Akiyoshi (of the Fred Hutchinson Cancer Research Center, Seattle) and colleagues are reporting isolating the kinetochore outside of the cell and having it perform the same tasks in vitro that it is seen to undertake in vivo. They report their findings in the November 25 issue of Nature. The research was, in part, supported by a grant from the National Science Foundation.

Sue Biggins, who participated in the research, says "Purifying this molecule out of the cell is as exciting today, as seeing the ribosome was back over 50 years ago!"

-NSF-

Discovery Powered Down, Analysis Continue

At NASA's Kennedy Space Center in Florida, space shuttle Discovery is powered down for the weekend while analysis continue. Discovery's launch is currently targeted for no earlier than Dec. 17, after shuttle managers determined more tests and analysis are needed.

The Program Requirements Control Board reviewed on Wednesday repairs and engineering evaluations associated with cracks on two 21-foot-long, U-shaped aluminum brackets, called stringers, on the shuttle's external tank. Managers decided the analysis and tests required to launch Discovery safely are not complete. The work will continue through next week.

The next status review by the PRCB will be Thursday, Dec. 2. If managers clear Discovery for launch on Dec. 17, the preferred time is about

The Water Dance

Water (H2O) is a unique molecule that holds amazing properties. Scientists have a good grasp of the structure and chemistry of individual molecules of water. But understanding how large numbers of these molecules move and interact--within bulk liquid water, or at the interface between water and air--is much more complicated.

Theoretical chemist James Skinner, at the University of Wisconsin in Madison, has been researching water for over a decade.  According to Skinner, understanding the dance of water molecules is key to understanding how all of life works.

"We now appreciate that it is virtually impossible to grasp almost anything at the molecular level about biology, without understanding how water molecules interact with biomolecules within cells," said Skinner, who is supported by a grant from the National Science Foundation (NSF) Division of Chemistry. "This includes fundamental processes like protein folding, photosynthesis and the biology of vision."

But how do scientists search out the secrets of water's choreography? Skinner, along with three other scientists--Krzysztof Szalewicz, professor of physics and astronomy at the University of Delaware; Martin Gruebele and his research team at the University of Illinois; and Geraldine Richmond and her team at the University of Oregon--use different approaches to get at water's unique movements and interactions.

Making molecular movies

Skinner and his research group at the University of Wisconsin are analyzing and interpreting the results of experiments that use infrared light to probe the motions of molecules in liquid water.

The vibrations between oxygen and hydrogen atoms within a molecule absorb infrared light. By varying the frequency of the light and measuring how much is absorbed at each frequency, the researchers record a graph called an "absorption spectrum." More modern techniques use ultrashort pulses of infrared laser light.

"Data from these experiments contain information about local molecular environments," Skinner said. "But this information is often hard to extract. We use first principles calculations, molecular dynamics simulations, statistical mechanics, and basically any theoretical approach that will enable us to further our understanding."

One method in particular, molecular dynamics simulation, allows the researchers to "see" water molecules in action.

Like designing the computer graphics for a movie, they start with an initial configuration of the molecules and then advance it forward in time, frame by frame. To do this, the team created a model of the potential energy for a large collection of water molecules in terms of interactions between groups of two or three molecules.

"We can show the trajectories (in time) of all the atoms in a system," Skinner said."The simulations--and hence the movies--always involve approximations (for example, using classical mechanics instead of quantum mechanics for motion of the atomic nuclei)." Even so, the simulations have proved to be quite accurate.

Up next for Skinner's team, is a study of the ways biomolecules such as peptides, proteins, nucleic acids, and membrane lipids, dissolve in water. "Experiments, coupled with new theoretical and computational techniques, will surely shed new light on the critical problem of water dynamics around biomolecules, and its effect on how they function," he said.

In addition to boosting biomedical research, Skinner believes that understanding the dance of water is also crucial to climate science. "To model the chemical and physical processes in the atmosphere one needs to understand reactivity of aerosol particles, which is often controlled by water dynamics at the surface of the aerosols," he said.

First principles findings

Krzysztof Szalewicz , professor of physics and astronomy at the University of Delaware, uses the ab initio, or "first principles," approach to researching water molecules in motion.

With support from NSF's Quantum Calculations Program in the Division of Chemistry, Szalewicz and his team start with what is known about each type of atom within the molecule--in this case hydrogen and oxygen. Then they plug that information into the Schrödinger wave equation.

"By solving Schrödinger's equation, we can predict the properties of lighter atoms and molecules almost exactly," Szalewicz said. Physicist Erwin Schrödinger developed his Nobel Prize-winning equation in 1926 as a way to explain the wave-like nature of particles at the nanometer (billionth of a meter) scale. His equation is central to the theory of quantum mechanics.

Once Szalewicz's team solved the equation for individual water molecules, they used the results to create a model of two molecules interacting. Then they increased the number of molecules to three. By combining several of these models, the team was able to simulate a large number of molecules interacting in bulk liquid water.

"We can model water very accurately and we did systems as large as 40 atoms fairly accurately," Szalewicz said.  "However, that is about the limit at the present time."

Following the first principles method, Szalewicz and his team used no data from lab experiments to develop their model. "So-called empirical approaches use experimental data to adjust their predictions," he said. "Thus, if experimental data are wrong, the predictions will be wrong."

But in this case, the model's predictions were gratifying. "The agreement of our predictions with experiment for water was excellent," he said.

"If you look at the whole range of properties, our predictions are better than any published ones, even including results obtained by empirical approaches," Szalewicz said. "Because liquid water is a rather complicated system despite the simplicity of water molecule itself, this was a demanding test for our approach."

Movers and shapers

Meanwhile, Martin Gruebele and his research team at the University of Illinois, sponsored by NSF's Division of Molecular and Cellular Biosciences, follow a different method. The team uses pulses of terahertz (THz) radiation, which falls between infrared and microwave radiation on the electromagnetic spectrum, to directly measure the movements of water molecules around proteins. Because water molecules consist of a single oxygen atom and two hydrogen atoms, they are dwarfed by the complex, folded protein molecules, made up of hundreds or thousands of individual atoms.

"Proteins influence the dynamics of up to thousands of water molecules surrounding them out to a distance comparable to the size of the protein," Gruebele said.

These affected molecules form a thick "solvation shell" around the unwieldy protein. In the process, the two-way interaction between water and protein causes hydrogen bonds and other weak bonds in the molecules to change and rearrange.

Good vibrations

To measure just how far this influence stretches, Gruebele's group flashes laser light pulses in the THz range through a mixed sample of protein and water. When this radiation hits a molecule, if its wavelength matches the natural vibration frequency of the atomic bonds that join the molecule together, it absorbs that energy. This extra energy causes the bonds between atoms to vibrate with regular, repetitive motions.

"Pulsed THz light oscillates about once every picosecond (one-trillionth of a second)," Gruebele said. And since water molecules and proteins both vibrate on a similar time scale, they can absorb light with wavelengths in that range.

In order to "see" what is taking place inside the molecules, the researchers used a spectroscope to measure the specific wavelengths absorbed.But in the process, they discovered something totally unexpected.

"We knew that dry protein powder absorbs less THz light than water does," Gruebele explained. "So we expected that adding protein powder to water would decrease the amount of light absorbed."  But instead it increased, as long as protein concentrations remained low.

"We concluded that this happens because the solvation shell actually absorbs more light than bulk water, which more than makes up for the smaller absorption of light by the protein," Gruebele said.

"As you add more protein molecules, the solvation shells around each one begin to overlap and the absorption stops increasing," he added. "This actually allows you to measure the size of the shells: We found they are almost three nanometers (three billionths of a meter) in diameter. This is small in human terms, but gigantic in terms of the size of a water molecule."

In addition to this THz absorption spectrum method, Gruebele's team used three other measurement techniques to illuminate different aspects of the protein folding process. 

"The combination of these four techniques shows that water adopts a "folded" structure and dynamics very early during the protein folding process," he explained. "Thus, water is an early driver and an integral part of that process."

In their next phase of research, Gruebele and his team will look at how water molecules mediate the binding of two biologically active molecules, such as two proteins, or a drug and a protein.

"Eventually, this would give us a much better estimate of how strongly drugs bind and why they are specific," he said. "Such information would save a great deal of live animal testing, and reduce the cost of pharmaceutical screening in the search for drugs."

Surface surprises

Another NSF-funded research effort, headed by Geraldine Richmond and her team at the University of Oregon, is probing the interactions between surface water molecules and atmospheric gases.

"I've always been fascinated by water--the way it flows, how it controls our body temperature and the temperature on this planet, how things can float on it," said Richmond.

"And the surface of water to me is the most fascinating," she said. "It plays such an important role in our environment and our bodies." Richmond and her group are supported by an award from NSF's Electrochemistry and Surface Chemistry Program.

"We want to understand how environmentally important gases such as sulfur dioxide (SO2) and carbon dioxide (CO2) interact with water surfaces," Richmond said. "We know a lot about how such gases behave once they are in water, but not much at all about what happens when they first make contact."

Richmond's team was surprised to find that SO2 tends to hang out at the surface before submerging, whereas CO2 dives right in.

"This is the first time that anyone has ever measured, with this level of molecular detail, a gas-surface complex at the surface of liquid water," she said. "We are now investigating a whole series of important environmental gases, ions and solutes at the water surface."

The group is also looking at the differences between surface chemistry and chemistry in bulk water. "What we do is to try to understand the underlying principles behind the chemistry that occurs in the atmosphere," Richmond said.

"For example, nitric acid accumulates in aerosols and clouds," she explained. "Since a lot of the reactions that happen in the atmosphere occur on the surface of aerosol particles that contain these strong acids, we wanted to understand if nitric acid continues to act as a strong acid when it sits at the surface of the aerosol."

Because aerosol interactions are so complex, the scientists simplified their study to focus on how individual molecules of nitric acid behave at the surface of a solution of nitric acid in water.

"What we find is quite remarkable," Richmond said. "When nitric acid sits at the surface of water, it acts as a weak acid -- not a strong one. This comes from the fact that at the surface, it is surrounded by fewer water molecules. Consequently it doesn't dissociate, or get pulled apart, and therefore is far less reactive there than inside the bulk liquid."

Mixing oil and water

Richmond's teamw is also fascinated by interactions between oil and water. "Normally people think that oil and water don't mix; but there is a weak attraction between them," she said. "That leads to some interesting consequences."

Richmond describes the human body as "one big oil/water interface, with water continually flowing past oily membranes," for example ions transporting through cell walls.

"We find at this oil-water interface, water is highly oriented and creates conditions that can facilitate some of the most important chemistry in our bodies," Richmond said.

"Related to this we try then to understand how the unique properties of the junction between water and oil influences the adsorption of surfactants such as soaps, dispersants and polymers." 

Why is this important? "Everything from mayonnaise to oil-spill dispersants relies on surfactants such as these adsorbing at the interface and in some cases, working to keep the oil and water separated," she explained.

"Our laboratory work provides unique insights into the molecular properties of the interface but this information is somewhat two-dimensional," Richmond said. "There are missing pieces."

To fill in the three-dimensional picture, the scientists count on computer simulations. But there is a downside. "Often you don't know how realistic the results are and whether the models you are using in your simulations are correct," she pointed out.

"However, in our case we can check their accuracy by seeing how close the computer results match our experimental results," Richmond added. "Then we dig into the calculations to see what kind of molecular interactions gave us that match. So they really work hand-in-hand to give us a robust three dimensional picture of what is happening at the surface of water."

-- Holly Bigelow Martin

Sunday, November 28, 2010

Mammals Grew 1,000 Times Larger After the Demise of the Dinosaurs

NSF enabled the assembly of an international, interdisciplinary team that was the first to quantitatively document body size patterns over the past 100 million years

Researchers have demonstrated that the extinction of dinosaurs some 65 million years ago paved the way for mammals to get bigger, about a thousand times larger than they had been when dinosaurs roamed the earth. The study, released today in the journal Science, is the first to quantitatively document the patterns of body size of mammals after the existence of dinosaurs.

The research, funded by a National Science Foundation (NSF) Research Coordination Network (RCN) grant, led by Principal Investigator Felisa Smith of the University of New Mexico, brought together an international team of paleontologists, evolutionary biologists and macroecologists from universities throughout the United States and around the world.

RCN grants began in NSF's Directorate for Biological Sciences to encourage and foster communications and collaborations among scientists with common goals and interests. Groups of investigators are supported to communicate and coordinate their research efforts across disciplinary, organizational, institutional and geographical boundaries. The proposed networking activities each focus on a theme: a broad research question, a specific group of organisms, or particular technologies or approaches. Innovative ideas for implementing novel networking strategies to promote research coordination and collaboration that enable new research directions or advancement of a field are especially encouraged. What results are diverse, multi-disciplinary research teams that harness and synthesize different insights and data to achieve new, exciting discoveries.

"The findings on mammal size detailed in Science are evidence of the value of coordination networks, and of their success in bringing together scientists who have not worked together in the past," said NSF Program Manager Saran Twombly. "Smith's group had combined data in a new synthesis to advance our understanding of the evolution of body size."

Based on the success of research funded by RCN grants in NSF's Directorate for Biological Sciences, the program has been replicated in other directorates and offices throughout the foundation, including the directorates for Mathematical & Physical Sciences; Geosciences; Education & Human Resources and Social, Behavioral and Economic Sciences; as well as the offices of Polar Programs, International Science and Engineering, and Cyberinfrastructure.

For more detail about this discovery, read the University of New Mexico's press release.

-NSF-

Friday, November 26, 2010

Rings Around a Crescent

A crescent Saturn appears nestled within encircling rings in this Cassini spacecraft image. Clouds swirl through the atmosphere of the planet and a barely visible Prometheus orbits between the planet's main rings and its the thin F ring. Saturn's moon Prometheus appears as a speck above the rings near the middle of the image.

This view looks toward the southern, unilluminated side of the rings from about 3 degrees below the ringplane.

The image was taken with the Cassini spacecraft's wide-angle camera on Sept. 14, 2010, and was obtained at a distance of approximately 1.6 million miles, or 2.6 million kilometers, from Saturn and at a sun-Saturn-spacecraft, or phase, angle of 100 degrees.

Image Credit: NASA/JPL/Space Science Institute

Inspections Complete on Repaired Tank Stringers

Teams have completed final inspections on the stringer repair work on space shuttle Discovery's external fuel tank at NASA's Kennedy Space Center in Florida. The environmental enclosure, built to support foaming operations, was removed. Flight Crew Systems middeck stow operations are under way.

The Space Shuttle Program will review the analysis and repairs that are required to safely launch shuttle Discovery on its STS-133 mission at a special Program Requirements Control Board session Wednesday. Pending a successful review of the flight rationale at that meeting, a Launch Status Briefing would be held with senior NASA management on Monday, Nov. 29 at Kennedy.

Kennedy's “Call-to-Stations” to begin the launch countdown will be no earlier than Nov. 30, supporting a first launch attempt no earlier than Dec. 3 at about 2:52 a.m. EST.

Soyuz Landing Caps Space Station's First Decade of Expeditions

Stephanie Schierholz
Headquarters, Washington
 
Kelly Humphries
Johnson Space Center, Houston
 
WASHINGTON -- Expedition 25 Commander Doug Wheelock and Flight Engineers Shannon Walker and Fyodor Yurchikhin safely landed their Soyuz spacecraft on the Kazakhstan steppe Thursday, wrapping up a five-month stay aboard the International Space Station.

Russian cosmonaut Yurchikhin, the Soyuz commander, was at the controls of the spacecraft as it undocked at from the station's Rassvet module. The trio landed at ( on Nov. 26 local time) at a site northeast of the town of Arkalyk.

Working in frigid temperatures, Russian recovery teams were on hand to help the crew exit the Soyuz vehicle and re-adjust to gravity. Yurchikhin will return to the Gagarin Cosmonaut Training Center in Star City, outside of Moscow, while Wheelock and Walker will fly directly home to Houston.

The trio launched aboard the Soyuz TMA-19 spacecraft from the Baikonur Cosmodrome in Kazakhstan on June 15. As members of the Expedition 24 and 25 crews, they spent 163 days in space, 161 of them aboard the station, and celebrated the 10th anniversary of continuous human life, work and research by international crews aboard the station on Nov. 2.

During their mission, the Expedition 24 and 25 crew members worked on more than 120 microgravity experiments in human research; biology and biotechnology; physical and materials sciences; technology development; and Earth and space sciences.

The astronauts also responded to an emergency shutdown of half of the station's external cooling system and supported three unplanned spacewalks by Wheelock and Expedition 24 Flight Engineer Tracy Caldwell Dyson to replace the faulty pump module that caused the shutdown. Their efforts restored the station's critical cooling system to full function.

Yurchikhin has logged 371 total days in space, Wheelock 178 days and Walker 163 days.

The station is occupied by Expedition 26 Commander Scott Kelly and Flight Engineers Alexander Kaleri and Oleg Skripochka of the Russian Federal Space Agency. A new trio of Expedition 26 flight engineers, NASA astronaut Catherine Coleman, Russian cosmonaut Dmitry Kondratyev and Paolo Nespoli of the European Space Agency, will launch from the Baikonur Cosmodrome on Dec. 15. They will dock with the station and join its crew on Dec. 17.

To send holiday greetings to the crew and get more information about the space station, visit http://www.nasa.gov/station.

Wheelock and Kelly both post updates about their missions to their Twitter pages at http://www.twitter.com/Astro_Wheels and http://www.twitter.com/StationCDRKelly.

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Expedition 25 Landing

The Soyuz TMA-19 spacecraft with Expedition 25 Commander Doug Wheelock and Flight Engineers Shannon Walker and Fyodor Yurchikhin touches down near the town of Arkalyk, Kazakhstan on Friday, Nov. 26, 2010. Russian Cosmonaut Yurchikhin and NASA Astronauts Wheelock and Walker, are returning from six months onboard the International Space Station where they served as members of the Expedition 24 and 25 crews.

Photo Credit: NASA/Bill Ingalls

Thursday, November 25, 2010

NASA Invites Public to Send Holiday Greetings to Station and Watch Message from Space

Stephanie Schierholz
Headquarters, Washington
 
James Hartsfield
Johnson Space Center, Houston
 
HOUSTON -- For many Americans, the Thanksgiving holiday is about journeys that bring families and friends together. This Thanksgiving, half of the International Space Station crew will return home to Earth. The crew has recorded a holiday greeting that is airing on NASA Television and available on the NASA website.

The public also is invited to send holiday greetings to the astronauts, cosmonauts and scientists aboard the space station via the NASA website. To send a personalized message to the crew, visit http://www.nasa.gov/externalflash/postcard.

Expedition 25 Commander Doug Wheelock and Flight Engineers Shannon Walker and Fyodor Yurchikhin are scheduled to leave the station aboard a Soyuz spacecraft Thursday, Nov. 25, at about and land in Kazakhstan at Remaining aboard are Expedition 26 crew members Commander Scott Kelly and Flight Engineers Alexander Kaleri and Oleg Skripochka.

For more information about the Expedition 25 and 26 mission and crew, visit http://www.nasa.gov/station.

For NASA TV streaming video, schedules and downlink information, visit http://www.nasa.gov/ntv.

Wheelock and Kelly both post updates about their missions to their Twitter pages at http://www.twitter.com/Astro_Wheels and http://www.twitter.com/StationCDRKelly.

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Wednesday, November 24, 2010

NASA Study Finds Earth's Lakes Are Warming

Steve Cole
Headquarters, Washington     
 
Alan Buis
Jet Propulsion Laboratory, Pasadena, Calif.

WASHINGTON -- In the first comprehensive global survey of temperature trends in major lakes, NASA researchers determined Earth's largest lakes have warmed during the past 25 years in response to climate change.

Researchers Philipp Schneider and Simon Hook of NASA's Jet Propulsion Laboratory in Pasadena, Calif., used satellite data to measure the surface temperatures of 167 large lakes worldwide.

They reported an average warming rate of 0.81 degrees Fahrenheit per decade, with some lakes warming as much as 1.8 degrees Fahrenheit per decade. The warming trend was global, and the greatest increases were in the mid- to high-latitudes of the Northern Hemisphere.

"Our analysis provides a new, independent data source for assessing the impact of climate change over land around the world," said Schneider, lead author of the study published this week in the journal Geophysical Research Letters. "The results have implications for lake ecosystems, which can be adversely affected by even small water temperature changes."

Small changes in water temperature can result in algal blooms that can make a lake toxic to fish or result in the introduction of non-native species that change the lake's natural ecosystem.

Scientists have long used air temperature measurements taken near Earth's surface to compute warming trends. More recently, scientists have supplemented these measurements with thermal infrared satellite data that can be used to provide a comprehensive, accurate view of how surface temperatures are changing worldwide.

The NASA researchers used thermal infrared imagery from National Oceanic and Atmospheric Administration and European Space Agency satellites. They focused on summer temperatures (July-September in the Northern Hemisphere and January-March in the Southern Hemisphere) because of the difficulty in collecting data in seasons when lakes are ice-covered and/or often hidden by clouds. Only nighttime data were used in the study

The bodies studied were selected from a global database of lakes and wetlands based on size (typically at least 193 square miles or larger) or other unique characteristics of scientific merit. The selected lakes also had to have large surface areas located away from shorelines, so land influences did not interfere with the measurements. Satellite lake data were collected from the point farthest from any shoreline.

The largest and most consistent area of warming was northern Europe. The warming trend was slightly weaker in southeastern Europe, around the Black and Caspian seas and Kazakhstan. The trends increased slightly farther east in Siberia, Mongolia and northern China.

In North America, trends were slightly higher in the southwest United States than in the Great Lakes region. Warming was weaker in the tropics and in the mid-latitudes of the Southern Hemisphere. The results were consistent with the expected changes associated with global warming.

The satellite temperature trends largely agreed with trends measured by nine buoys in the Great Lakes, Earth's largest group of freshwater lakes in terms of total surface area and volume.

The lake temperature trends were also in agreement with independent surface air temperature data from NASA's Goddard Institute for Space Studies in New York. In certain regions, such as the Great Lakes and northern Europe, water bodies appear to be warming more quickly than surrounding air temperature.

For more information about NASA and agency programs, visit http://www.nasa.gov.

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Harrat Khaybar

Harrat Khaybar, Saudi Arabia lies in the western half of the Arabian peninsula and contains not only large expanses of sand and gravel, but also extensive lava fields known as haraat (harrat for a named field). According to scientists, the volcanic field was formed by eruptions along a long north-south linear vent system over the past 5 million years; the most recent recorded eruption took place between 600-700 A.D.

The presence of tuff cones -- formed by eruption of lava in the presence of water together with other volcanic features indicative of water -- in the Harrat Khaybar suggest that the local climate was much wetter during some periods of volcanic activity. Today, however, the regional climate is hyperarid -- little to no yearly precipitation -- leading to an almost total lack of vegetation.

The image was taken by the Expedition 16 crew aboard the Inernational Space Station in March 2008.

Image Credit: NASA

Glowing Squid

Shining Symbiosis: Bobtail squid and their bacteria buddies

In deep ocean waters, it's sometimes difficult to hide from predators. That's why so many sea creatures have evolved extraordinary methods of disguise.

Cephalopods, such as octopus, squid and cuttlefish, are big on camouflage, by day or night. In fact, the Hawaiian bobtail squid has several means of stealthy self- preservation.

"During the day, if they are disturbed from the sand, they will come out, sit on the surface with a sand coat on them, trying to be invisible," says Margaret McFall-Ngai, professor of medical microbiology and immunology at the University of Wisconsin-Madison. "And, if that doesn’t work, they will eject ink. They themselves turn completely white, as transparent as they can be, and leave behind that blob of ink in the same size as they are."

With support from the National Science Foundation (NSF), McFall-Ngai and her team study another bobtail squid camouflage scheme; one that glows in the dark!

This small nocturnal animal has a mutually beneficial relationship with bacteria called Vibrio fischeri that live on the squid's underside. The bacteria allow the squid to produce light, which then allows the squid to escape from things that might want to eat it. "The squid emit ventral luminescence that is often very, very close to the quality of light coming from the moon and stars at night," explains McFall-Ngai.

So, for fish looking up from below for something to eat, the squid are camouflaged against the moon or the starlight because they don't cast a shadow.

"It's like a 'Klingon' cloaking device," she notes.

But the Vibrio fischeri don't stay in the squid continuously. Every day, in response to the light cue of dawn, the squid vents 90 percent of the bacteria back into the seawater. "And then, while it's sitting quiescent in the sand, the bacteria grow up in the crypt so that when [the squid] comes out in the evening, it will have a full complement of luminous Vibrio fischeri," says McFall-Ngai.

The key to the symbiotic relationship of the squid and bacteria is a "light organ."

"The light organ has remarkable morphological and anatomical similarities to the eye. It has a lens, an iris analog and reflective tissue," she explains.

Shortly after the squid eggs hatch, the juveniles "invite" the helpful bacteria inside.

Graduate research assistant Elizabeth Heath-Heckman does microscopic studies of juvenile squid, just a few days old. "There are some structures that are specific to a baby light organ, as opposed to an adult light organ," she says. "The juveniles have protrusions, called appendages that help to direct seawater, bringing bacteria to the light organ."

"The bacteria live inside the squid, but they don't live inside the squid's cells," continues Heath-Heckman. "So you have this sort of cave, this kind of nest that the squid makes for the bacteria."

So, what do the bacteria get out of this relationship? "Any time bacteria are in an environment where they can gain nutrients, and increase their population, it's a good place to be," explains McFall-Ngai.

This successful counter-illumination, anti-predatory strategy could lead to several applications for human benefit.

Materials science experts in the U.S. Air Force are studying possible improvements in camouflage through the reflective qualities of the squid-bacteria symbiosis. Scientists also want to know more about how the two species communicate.

"So at the very basic level, we're asking how animal cells talk to bacterial cells: what is the common language, and what is conserved over evolutionary history in that conversation?" continues McFall-Ngai, who also is trying to determine what kind of signal the baby squid use to initially attract the "good" bacteria. "How in the world does the animal know that this is a beneficial symbiont, and not a pathogen?" That's another aspect of the study that could help with human physiology and medicine.

Bobtail squid only live as long as a year, but there are healthy populations of them where McFall-Ngai and her colleagues collect the animals in Kaneohe Bay, off the Hawaiian island of Oahu. McFall-Ngai also says it's a fascinating animal to study.

"They really are beautiful animals. They are also a good size, not too big, not too small. At one point, someone said to me, 'study something the size of your thumb', and that's exactly the size that they are, but they really are exquisite," she adds.

And--brainy!

"They are relatives of the octopus, really smart animals. They are very likely smarter than fish, very large brains for body size," she notes.

As for the research in general, McFall-Ngai says she feels really lucky to be a scientist. "I think it has to be a gift for any scientist, to find yourself going through a career, a long career, and always being excited about what the next question is, and what the students are finding."

Miles O'Brien, Science Nation Correspondent
Marsha Walton, Science Nation Producer