- Hubble Captures Sparkling Jewel Box Star Cluster
- Humans, Shmumans: What Mars Needs Is an Armada of Robots and Blimps
- Birds Use Light, Not Magnetic Field, to Migrate
- Mysterious Clouds Form in Box of Beads
- Climate Change Caused Radical North Sea Change
- NASA Rocket Scientists Did ‘Frickin’ Fantastic’
- Doctors Kill Parasitic Worms By Poisoning the Bacteria in Their Innards
Posted: 29 Oct 2009 10:11 AM PDT
This stunning image of the Kappis Crucis Cluster, nicknamed the "Jewel Box," was one of the last gifts from a retiring camera on the Hubble Space Telescope.
Just before NASA brought the Wide Field Planetary Camera 2 back to Earth in mid-2009, it snapped this photo of the core of the NGC 4755 star cluster, the first comprehensive image of an open galactic cluster taken in multiple wavelengths. Using seven different filters, Hubble captured the Jewel Box cluster in far ultraviolet to near-infrared light. The different colors of the stars — from pale blue to bright ruby red — result from their differing intensities at various ultraviolet wavelengths.
Just bright enough to be seen from Earth with the naked eye, the Jewel Box was given its name by English astronomer John Herschel in the 1830's, who thought the sparkling blue and red stars resembled expensive jewelry. Like most open star clusters, the Jewel Box is made up of an array of sister stars, all formed from the same cloud of gas and dust with similar ages and chemical make-up. Located about 6,400 light-years away, near the Southern Cross in the constellation of Crux, the Jewel Box contains roughly 100 stars.
Besides Hubble, two other telescopes have also recently captured new images of the Jewel Box. A wide-field photo taken by the 2.2-meter telescope at the European Southern Observatory's La Silla observatory in Chile shows the multi-colored cluster surrounded by thousands of neighboring stars. A close-up from ESO's Very Large Telescope captures the stars in detail and ranks as one of the best images of the Jewel Box ever taken from the ground. Both images can be seen in the composite photo below.
Image 1: NASA/ESA and Jesús Maíz Apellániz/Instituto de Astrofísica de Andalucía, Spain. Image 2: ESO, NASA/ESA, Digitized Sky Survey 2 and Jesús Maíz Apellániz/Instituto de Astrofísica de Andalucía, Spain.
Posted: 29 Oct 2009 09:50 AM PDT
Airships may be the key component in a new robotic system for exploring the celestial bodies most likely to harbor life like Mars and Jupiter's moon, Titan.
The dirigibles would provide regional observations and autonomous command for ground-based vehicles, while maintaining contact with orbiters.
It'd be a new role for airships, which were the wonder of the aerial world in the days before airplanes (and rockets and space shuttles).
"The balloon or airship has a lot of advantages: It's buoyant, so it keeps its altitude and you do not need to invest energy to keep it afloat," said Wolfgang Fink, who led the work at Cal Tech's Visual and Autonomous Exploration Systems Research Laboratory, before accepting an appointment at the University of Arizona. "It has a lot of advantages, especially in places like Titan, which has a dense atmosphere that's perfect for an airship."
Current robotic exploration missions are limited. Orbiting telescopes like the Mars Reconnaissance Orbiter provide low-resolution views of vast swaths of a celestial body while rovers and landers provide detailed observations of a tiny region. Fink argues that we'll need teams of robots to do any serious exploration looking for interesting features that might tip us off to the presence of life or geological activity.
And on planets with atmospheres, airships are the ideal middle layer for "tier-scalable reconnaissance," a vision Fink has spelled out in a series of papers over the past several years.
To test how teams of autonomous robots working together could explore an area, Fink's team built a miniature lab version of the system, as seen in the image above. At just 4 feet by 5 feet, it's not exactly the surface of Mars, but it allowed the team to test out a piece of software that picks out anomalous objects in a landscape, the Automatic Global Feature Analyzer.
The software doesn't try to place what it reads in images into known categories. Instead, it looks for the odd stuff out — the Waldo — within a series of images.
"If you do not know what you will encounter, you have to embrace the unknown," Fink said.
With the miniature lab tests complete, Fink plans to take his show on the road, probably to the Arizona desert. Over a large geographic region, they'll float an airship with on-board camera and release rovers controlled by the feature analyzer software.
"For initial test purposes, we could put a Coke can and see if the science algorithms will flag these anomalies," Fink said, "And then, once they are flagged, generate the navigation commands that are issued from the airships to the ground."
They plan to try the Coke can test in the next year. As time goes on, they will try more difficult terrains out because ultimately, it's the extreme areas of other planets that could prove the most interesting. By keeping the ground units cheap, they can also have more of them, allowing the missions to take greater risks.
"Mountain ranges, canyons, cliffs, those are the locations where interesting stuff might happen," Fink said. "You need to be able to get into those high risk areas to get a nice and interesting science return. You might lose some of these agents you deploy, but because they are simplified, you can deploy more of them and still afford to lose some of them."
The entire system — satellite, airships, and ground rovers — could be ready to go in the next decade, which would be long before NASA could actually use it.
Image: 1. NASA/JPL. 2. Wolfgang Fink. 3. The invasion of Normandy, U.S. Coast Guard Collection.
Posted: 28 Oct 2009 03:31 PM PDT
A cell in the eye may be worth two in the beak, at least when it comes to a migratory bird's magnetic compass. In European robins, a visual center in the brain and light-sensing cells in the eye — not magnetic sensing cells in the beak — allow the songbirds to sense which direction is north and migrate correctly, a new study finds. The study, appearing Oct. 29 in Nature, may improve conservation efforts for migratory birds.
"This is really fascinating science," says biophysicist Klaus Schultenof the University of Illinois at Urbana-Champaign, who was one of the first to suggest that migrating birds can sense magnetic fields.
Researchers have known that built-in biological compasses tell migrating birds which way to fly, but the details of how birds detect magnetic fields has been unclear.
"This is basically the sixth sense of biology, but no one knows how it works," says study co-author Henrik Mouritsenof the University of Oldenburg in Germany. "The magnetic sense is by far the least-understood sense in the natural world."
Some researchers had proposed that iron-based receptors in cells found in the upper beaks of some migratory birds sense the magnetic field and send that information along a nerve to the brain. Other scientists favor the hypothesis that light-sensing cells in birds' eyes sense the magnetic field and send the information along a different route to a light-processing part of the brain called cluster N.
Special proteins called cryptochromes in the birds' eyes may mediate this light-dependent magnetic sensing, Mouritsen says. Light hitting the proteins produces a pair of free radicals, highly reactive molecules with unpaired electrons. These electrons have a property called spin which may be sensitive to Earth's magnetic field. Signals from the free radicals may then move to nerve cells in cluster N, ultimately telling the birds where north is.
To find the location that houses the magnetic compass, Mouritsen and his colleagues caught 36 migratory European robins and made sure that the birds could all orient correctly under natural and induced magnetic fields. Next, the researchers performed surgeries on the birds to deactivate one of the two systems. The team either severed the nerve that connects the beak cells to the brain, or damaged the brain cells in cluster N that receive light signals from cells in the eye.
Birds with the severed beak-to-brain nerve — called the trigeminal nerve — still oriented perfectly, Mouritsen says. "No information from those iron crystals could get to the brain, but the birds oriented just as well," he says, suggesting that the beak cells are not important for orientation.
On the other hand, birds with damaged cluster N regions could no longer sense and orient to magnetic fields. These robins failed to pick up both the Earth's natural magnetic field and the artificial fields created by the researchers.
The new study "nicely confirms that the trigeminal nerve is not involved in this direction sensing," says John Phillips, a neuro-ecologist at Virginia Tech in Blacksburg. "This is an important advance in what we know about these systems."
Mouritsen thinks the cells in the beak might play a different role in magnetic sensing, such as picking up minor changes in the strength of the magnetic field along a north-south axis, he says.
Understanding more about how birds navigate and sense the environment may have important conservation implications, Mouritsen says. Migratory birds that humans have relocated often fly back to the original migratory grounds. But if researchers can figure out how the birds navigate, conservationists may be able to trick the birds into staying where it's safe.
Posted: 28 Oct 2009 12:00 PM PDT
With nothing more than beads in a glass box, physicists have revealed yet another mysterious property of granular solids, now recognized by scientists as a unique state of matter, like solids or gases.
When the box was filled to the brim and rotated, the beads moved in patterns known from convection clouds — another system whose basic physical dynamics are only dimly understood.
The experiment, displayed in a video posted Monday to arXiv, was a variation on one performed 70 years ago by Japanese physicist Yositsi Oyama, who observed that beads of different sizes placed in a rotating circular drum would eventually self-sort by size.
That intriguing result set in motion the study of granular solids, which behave in ways that can't be predicted with known physical laws. And though research has accelerated in the last decade, scientific understanding of granularity is roughly akin to that of fluid dynamics in the 18th century.
In the latest experiment, conducted by Otto von Guericke University physicists Ralf Stannarius and Frank Rietz, a partially-full rotating box of beads displayed the self-sorting patterns seen by Oyama. But when they filled the box nearly to the top — which, they expected, would cause the beads to clog — the beads instead moved in graceful, swirling currents.
Why this should happen is unclear. No equations exist to describe why such a slight change in packing density should produce such different system-wide behavior. "Known mechanisms for granular convection could not be applied," wrote Rietz and Stannarius.
Intriguingly, similar currents can be seen in clouds, or ocean currents. In a paper published last February in Physical Review Letters, the pair described the mysterious movements of beads in their box as suggesting "the existence of comparable phenomena in situations where so far no systematic search for dynamic patterns has been performed."
Image and video: Frank Rietz and Ralf Stannarius
Citations: 1)"Convection rolls in a rotating box filled with beads." By Frank Rietz and Ralf Stannarius. arXiv, October 26, 2009.
2) "On the Brink of Jamming: Granular Convection in Densely Filled Containers." By Frank Rietz and Ralf Stannarius. Physical Review Letters, Vol. 100 Issue 7, February 20, 2009.
Posted: 28 Oct 2009 11:28 AM PDT
Fueled by previously unappreciated links between climate and ecology, the North Sea has undergone a radical ecological shift in the last half-century, say scientists.
The very shape of the food web has changed, from plankton on up to the cod and flatfish that once dominated the icy waters, supporting rich commercial fisheries. They've been largely replaced by jellyfish and crabs.
The full scope of the change has gone relatively unnoticed, and could foreshadow changes in waters around the world.
"Climate-driven changes in the biology of the sea are largely hidden from view," said Richard Kirby, a marine biologist at the University of Plymouth. "If similar changes occurred in a temperate forest, we would be shocked."
In a study published in the upcoming December Proceedings of the Royal Society B, Kirby and Gregory Bertrand, an oceanologist at the Lille University of Science and Technology, analyze decades of climate and ecosystem data gathered in the North Sea, a pocket of ocean bordered by the United Kingdom and Scandinavia.
Though relatively small, the North Sea has historically been a fabulously fertile fishing ground. Even now, it provides about five percent of the global fish harvest — but that's barely a third of what it yielded just a century ago.
Declining stocks have been blamed almost entirely on overfishing. However, though fishing pressures have indeed been intense, some scientists have suspected that water temperatures are also a factor.
Over the last quarter-century, the North Sea's upper layers have warmed by about 1 degree Fahrenheit. That seems like little, but in the North Sea, summer and winter water temperatures differ by just a few degrees. Even a single degree of change is relatively profound, and enough to disrupt aquatic organisms accustomed to functioning in a very narrow thermal range.
Whether the warming is man-made or not, it's a sign of times to come. Global ocean temperatures are expected to experience a comparable or greater rise during the next century. And the consequences, as anticipated by the North Sea, have been relatively unacknowledged. Most discussions of climate change impacts focus on the terrestrial. When ocean life is mentioned, it's in the context of of coral reef bleaching or acidifying waters.
Both those threats are grave, but the possibility of oceans completely changing their character, independent of acidification or reef effects, may be just as troubling.
"The effect of climate on the marine food web, the way small changes can be amplified through the web, that's the moral of the story here," said Kirby. "And food webs everywhere will be affected in a similar way."
At the heart of Kirby and Bertrand's findings is data from the Continuous Plankton Recorder Survey, which has been run in the North Atlantic since 1931, when explorer Alister Hardy invented the recorder — a specialized box that's dragged behind commercial ships, allowing researchers to take sea-wide samples of plankton and juvenile members of other species.
Combined with temperature records, the CPRS provides the most comprehensive climate-ecosystem dataset of any ocean, if not the entire world. And as temperatures have changed, so has every part of the food web, starting with its foundation.
"If you were to divide zooplankton into those that prefer warmer southern waters, and those that prefer colder northern waters, and look at the boundaries between those groups, it's moved north by over 700 miles in the last 40 years," said Kirby. "That's one of the largest range shifts, if not the largest, that's been recorded."
The distribution of hundreds of species have changed, in every niche from plankton up to the North Sea's top predators. Cod and flatfish numbers have plummeted, and tuna have vanished. The ecological roles they once played are now occupied by jellyfish and bottom-dwelling crabs.
"The North Sea has fundamentally changed. It's a totally different ecosystem from what it was," said Kirby.
When Kirby and Bertrand crunched the numbers describing these patterns with equations designed to separate cause from coincidence, they found that temperature drove the changes. They also found evidence for what they call "trophic amplification."
"Because temperature acts on different components of the food web, the gross effect is amplified," said Kirby. "It affects the phytoplankton that copepods feed on; it affects the copepods; it affects the predators who eat the copepods; and all those effects, magnified, are much greater than any one alone." This compounding dynamic is responsible for the extreme rapidity of the shift, he added.
"The findings seem plausible to me," said Marten Scheffer, a Wageningen University ecologist who specializes in ecosystem-wide transitions. Scheffer, who was not involved in the study, also said that marine shifts are notoriously difficult to study. "Compared to work on lakes, or terrestrial grazing systems, there is little scope for experimental testing," he said.
According to Kirby, models by fisheries managers need to incorporate these dynamics and and policymakers contemplating global warming need to consider the magnitude of the change.
A similar dynamic may be at work in the Sea of Japan, which in recent years has become dominated by giant jellyfish.
"Marine ecosystems have always changed, but people don't realize how responsive they are, and how rapidly they may change," he said. "Humans shouldn't forget that we don't live in isolation from the food web."
Images: 1. Flickr/PhillipC 2. A model of North Sea ecosystem dynamics, from Richard Kirby and Gregory Bertrand.
Citation: "Trophic ampliﬁcation of climate warming." By Richard R. Kirby and Gregory Beaugrand. Proceedings of the Royal Society B, Vol. 276 No. 1676, December 7, 2009.
Posted: 28 Oct 2009 10:48 AM PDT
Nothing gets the NASA boys fired up quite like a rocket launch.
The Ares I-X rocket, a modified prototype of the Ares I rocket that may send humans back to the Moon, and the 2.6 million pounds of thrust it put out, sent the engineers at Kennedy Space Center in Cape Canaveral into paroxysms of joy.
"You all did frickin' fantastic," said Ed Mango, the new launch director at Kennedy, shortly before having his tie cut just above the navel by the director of Kennedy, Bill Parsons.
The tie-cutting is an old tradition borrowed from the Air Force — and it matched the back-to-the-future mood of the event perfectly.
All the giddiness comes at an odd time for Ares I, and the Constellation program of which it's a part. An Obama-requested review of NASA's plans for human spaceflight wrapped up its work last week with a thumbs-down for the Ares I.
"I got tears in my eyes. All the naysayers…" said Parsons, before breaking off and continuing along a more positive line. "That was just one of the most beautiful rocket launches I've ever seen."
The NASA engineers are also looking to get some real data from the 700 sensors aboard the vehicles to test their models of how the new rocket is supposed to behave.
"The most valuable learning is through experience and observation," said Bob Ess, Ares I-X mission manager, in a release. "Tests such as this — from paper to flight — are vital in gaining a deeper understanding of the vehicle, from design to development."
Image: flickr/Matthew Simantov
Posted: 28 Oct 2009 10:13 AM PDT
In some African villages, nearly everyone is infected with Mansonella perstans, a parasitic worm that's remarkably hard to kill. It's resistant to standard anti-worm medications, but researchers have learned that an old antibiotic can vanquish the tiny beasts — in a roundabout way.
The parasites are stuffed with a type of bacteria called wolbachia, and apparently they depend upon those microbes for their own survival. By killing the bacteria inside of the worms, doctors can destroy the worms themselves.
To test that concept, an international team recruited volunteers with M. Perstans infections from four villages in Mali, and gave 69 of them a dose of doxycycline each day. After one year, all but two of the patients who took the antibiotic were free from worms in their blood.
"Doxycycline is the first drug that has been shown to be effective in clearing Mansonella perstans parasites from the blood of infected people," said Amy Klion, a doctor at the National Institutes of Health who led the study. "The fact that the parasites were not detectable in the blood 3 years after the 6 week treatment suggests that doxycycline also had an effect on the adult worms, which live in the tissues surrounding the lungs, heart and abdomen."
Roughly 120 million people worldwide are infected with filarial parasites. Many of those worms will fall after a single dose of albendazole and ivermectin, but M. Perstans is too tough for both drugs. Thankfully, it's far less destructive than other types of nematodes. It usually results in itching, fatigue, and dermatitis.
Wolbachia have proven to be the Achilles' heel of nastier parasites too. Before Klion and her team showed that doxycycline can be used to treat the annoying worm infections, other doctors learned that it is an effective way to eliminate their nasty cousins, the parasites that cause elephantiasis and river blindness.
Despite the success of those treatments, nobody knows for sure why the worms and bacteria are interdependent.
"The basis of the endosymbiosis between wolbachia endosymbionts and their wormy hosts is currently not understood.," wrote Achim Hoerauf, a doctor at the Bonn University Clinic in a commentary for the New England Journal of Medicine. "Some conclusions can be drawn from the fact that worms lack essential genes for certain metabolic pathways that are present in wolbachia, and vice versa."
Hoerauf suggested that the treatment might not work everywhere. In other parts of Africa, researchers have found worms that can live without wolbachia. Despite that concern, he is convinced that the antibiotic will work in some parts of the world. When the infectious disease expert emailed us, he was on his way to distribute the antibiotic in Ghana.
At less than two dollars for a six-month supply. Doxycycline is a bargain for nongovernment organizations. But they might not buy it for the purpose of eliminating M. Perstans.
"Doxycycline is not very easy to administer as a mass drug treatment since it absolutely cannot be given to pregnant women or children under the age of 12 because of effects on developing teeth and bones," said Klion. "Second, courses shorter than 4 weeks have not been very effective in other filarial infections, and this is a very impractical for mass administration."
Because the symptoms of M. Perstans infections are pretty mild, Hoerauf doubts that charities will try to eradicate it with doxycycline. But he thinks that the versatile drug will be used to treat many cases of river blindness.
Citation: A Randomized Trial of Doxycycline for Mansonella perstans Infection, New England Journal of Medicine, 361, 2009
Photo: DraconianRain / flickr
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