Unique New Species of Light-Harvesting Bacteria

Scientists have identified a new species of light harvesting bacteria in Mushroom Spring in Yellowstone National Park, pictured here. The spring gets its unique color from thick microbial mats living on the surface--a cross section of the mat is shown in the inset. Credit: David Ward, Montana State University

n the bubbling muck of Yellowstone National Park, scientists have discovered a new species of bacteria that uses light for energy. Known as Candidatus Chloracidobacterium thermophilium, the new species is different than other types of photosynthetic bacteria, such as cyanobacteria (also called blue-green algae): it carries an antenna loaded with the light-harvesting molecule chlorophyll, which allows it to compete with other species living in the hot springs' brightly colored microbial mats. The findings are published today in the journal Science.

Scientists discovered the bacterium using metagenomics, a variation on genomics that entails sequencing the genomes of entire microbial communities in order to identify new species. Metagenomics provides microbiologists with a new way to identify novel bacterial species, the vast majority of which can't be grown in the lab. (See "Our Microbial Menagerie" and "Why Termite Guts Could Bring Better Biofuels.")

The steaming pools of Yellowstone, which can reach higher than 150 ºF, were also the site of one of the most important microbial discoveries of molecular biology: Thermus aquaticus, a heat-loving bacterium that gave scientists an enzyme crucial for efficiently replicating DNA. Researchers hope that the recent discovery will shed light on how bacteria efficiently harvest light, perhaps inspiring new ways to make energy.

UH astronomer is recognized for discovery about the universe

By Helen Altonn / haltonn@starbulletin.com

A University of Hawaii astronomer won a share of a prestigious international science award yesterday for his role in the astonishing discovery that the universe is expanding at an ever-faster rate.

Astronomer John L. Tonry was part of a research team working on Mauna Kea that won the $500,000 Gruber Cosmology Prize, awarded annually for discoveries that alter our perception and comprehension of the universe.

He couldn't be reached immediately for comment, but UH astronomer Gareth Wynn-Williams said the idea that expansion of the universe is accelerating is "one of the biggest discoveries in science in the last few years. A very important part of the evidence comes from the work this prize is awarded for."

Tonry discovered supernovae explosions in distant galaxies using the Canada-France-Hawaii Telescope on Mauna Kea in 1997.

He said in an Institute for Astronomy news release that the CFHT data coupled with data from the Keck Observatory and Hubble Space Telescope "were the key to identifying the accelerating universe."

Wynn-Williams said the $500,000 will be split between two groups that were working independently using different telescopes and came up with the same answer.

He said the acceleration of the universe's expansion implies "a new constituent of the universe which we call dark energy. We have no real idea of what it is at all. But it seems to resemble matter in the way that it follows the laws of gravity."

Brian Schmidt of Australian National University led one team; Saul Perlmutter of the University of California-Berkeley headed the other one.

The big surprise, Wynn-Williams said, is the astronomers expected to find the universe slowing down as it expands because of gravitational forces between galaxies.

Their finding that the expansion actually is accelerating instead was accepted quickly because it fits into Einstein's general theory of relativity, he said. "It was a very successful theory. It contained an odd little term that people kind of ignored. Even Einstein sort of ignored it. ... So this is perhaps why this was accepted. It hasn't required us to throw out a major theory. We just looked at it more carefully."

The Gruber Foundation in a news release said, "An accelerating universe was a crazy result that was hard to accept. Yet, two teams, racing neck and neck, simultaneously, came to the same conclusion. Their discovery led to the idea of an expansion force, dubbed dark energy. And it suggests that the fate of the universe is to just keep expanding faster and faster."

Top Ten Discoveries of the Mars Rovers

"Space.com brings us the top ten discoveries of the Martian rovers that landed there in 2004. They were expected to last three months but, as Slashdot has covered time and time again, they have lasted over three years. From minor discoveries about the formation of Mars to images of atmospheric phenomena, to final and definitive proof of a Mars with water, these two robots have definitely reserved themselves a place in the history books. Pending a dust storm, they may not even be done with their mission yet."

[+] mars, nasa, science, space, rovers (tagging beta)

What Came Before Alexander The Great? A Multidisciplinary Approach

Science Daily — Our modern western civilization traces its roots to the Mediterranean region, and determining exactly when and where civilizations took hold remains an ongoing quest.

For example, the armies of Alexander the Great swept across the region, leading to the establishment of the city of Alexandria on the shores of the Mediterranean in BC 332. But what came before Alexander?

Was there a settlement that preceded Alexandria, and if so, what can we learn about the people who lived and died there?

These are some of the questions addressed by Jean-Daniel Stanley of the Smithsonian Institution, Washington, D.C., and his co-workers in a paper in the August GSA Today.

By applying a multidisciplinary approach, involving archeology, sedimentology and geochemistry, to the study of sediment cores collected from Alexandria's Eastern Harbor, Stanley and his colleagues have demonstrated that a settlement occupied the region for at least seven centuries prior to the arrival of Alexander.

Ceramic shards, high lead levels, and the use of building stones imported from other regions all attest to a once flourishing urban center as far back as BC 1000. These discoveries indicate that much is still to be learned about the early development of western civilization, and an effective means of achieving this is by integrating geologic and archaeological methodologies.

Study Shows Dinosaurs Lived Alongside Their Precursors

Graduate Students’ Findings From Dig in New Mexico Contradict Widely Held Theory
BY Erin Olivella-Wright
Contributing Writer
Monday, July 23, 2007

After years of excavating fossils in the arroyos of New Mexico, researchers published a report Friday in the journal Science explaining that dinosaurs and their precursors lived contemporaneously, despite what scholars had previously thought.

In the summer of 2005, lead excavators Randall Irmis and Sterling Nesbitt, graduate students at UC Berkeley and Columbia University, respectively, launched the project after visiting the site at Hayden Quarry. The quarry became a hotspot for archeological activity after a group of hikers discovered some fossils there in 2002.

The excavators returned in the summer of 2006 with funding from the National Geographic Society, the Theodore Roosevelt Memorial Fund and the Jurassic Foundation and came away with new discoveries about dinosaurs in the Late Triassic Period.

Before the graduate students’ discoveries, academics thought that the precursors to dinosaurs had died out before the reign of the dinosaurs, but the report says that new evidence proves this to be false.

Using uranium and lead dating from nearby sites, the researchers were able to conclude that dinosaurs were living in New Mexico alongside the basal dinosauromorphs, the precursors to the dinosaurs, for between 15 million and 20 million years.

As there are no radioactive materials in the Hayden Quarry, the authors are giving themselves a 5 million year margin of error, Irmis said.

Irmis said he is excited by the findings, as they are the first of their kind.

“This has never been found anywhere else in the world,” he said.

He stressed that while the team never found a full skeleton, there were enough fossils to deduce the differences between the dinosaurs and the basal dinosauromorphs.

“Overall, they look a lot like dinosaurs, but there are a few anatomical features that are found in the hip and the leg that are found in the dinosaurs but not the dinosaur precursors,” he said.

Nesbitt, a UC Berkeley alumnus, also said he is impressed with the results, especially given the location of the fossils.

“It’s pretty incredible because we found something that everyone didn’t expect in North America. (Now) North America is just as important for dinosaur origins as South America,” he said.

Irmis said the results of the study show that dinosaurs are prime examples of adaptive radiation and added that perhaps the most significant result of the findings is further support for the theory of evolution.

“I hope that the findings encourage other people to accept evolution as a scientific process,” he said.

Nesbitt said overall that he is pleased to have generated findings that could lead to other discoveries .

“To start the sequence of discovery is pretty neat,” he said. “(We are) going from one leg bone to revising what we know about early dinosaur evolution.”

Ascent of dinosaurs more gradual than once thought

• View Larger Image

This illustration shows four extinct animals -- two dinosaurs and two more primitive dinosaur relatives -- found at a site in northern New Mexico. Shown are the dinosaur precursors Dromomeron romeri (lower left) and a Silesaurus-like animal (bottom center), and the dinosaurs Chindesaurus bryansmalli (top center, with prey in its mouth) and a coelophysoid theropod (upper right). REUTERS/Science/Artwork by Donna Braginetz/Handout

More pictures: <> | Next >

Will Dunham, Reuters

Published: Thursday, July 19, 2007

WASHINGTON (Reuters) - The ascent of the dinosaurs to the throne of the animal kingdom may have been more gradual than previously believed, scientists said on Thursday.

New fossil discoveries dating from about 215 million years ago showed some of the earliest dinosaurs lived for millions of years side by side with related animals long seen as their ancestors and precursors, scientists said on Thursday.

Many scientists had thought these reptiles -- very much like dinosaurs, but more primitive -- died out around the time of the appearance of the first true dinosaurs, which were dog-sized beasts not giants, roughly 230 million years ago.

"When dinosaurs first evolved, they were not very common and they were pretty small," said Randall Irmis of the University of California-Berkeley, who worked on the study.

"So they're not the dominant predators or creatures on land at all during most of the Triassic. And it's only really until the Jurassic when they really explode in diversity and reach these huge sizes that we're so familiar with," Irmis added.

Scientists previously hypothesized that the first dinosaurs quickly out-competed their more primitive cousins, known as "basal dinosauromorphs," condemning them to extinction. But the new findings indicate that any such competition was prolonged.

The newly found fossils from New Mexico dating from the Triassic period showed that the first dinosaurs co-existed with these animals -- "dinosaur wannabes," as one scientist called them -- for perhaps 15 to 20 million years.

"For the first time, we're finding the earliest dinosaurs and their closest relatives together," paleontologist Kevin Padian of the University of California-Berkeley, one of the researchers, said in a telephone interview.

"That tells us that the transition to the beginning of the age of dinosaurs was not a very-rapid affair and that, therefore, it wasn't instant competitive superiority."

Irmis said these dinosaur precursors are not thought to have been direct evolutionary ancestors of the dinosaurs but rather having shared a close common ancestor.

NEWLY DISCOVERED BEASTS

The scientists discovered new dinosaur precursors including one 3 to 5 feet long called Dromomeron and another unnamed one about three times larger that walked on four legs and ate plants with a beaked snout.

Relatively small bipedal carnivorous dinosaurs also were found, including Chindesaurus, which measured about 6 feet (2 meters) long, as well as remains of an apparent close relative of the well-known Triassic dinosaur carnivore Coelophysis.

The fossils were found at the Hayden Quarry at Ghost Ranch, a site that over the decades has yielded many exquisite fossils. For example, hundreds of Coelophysis fossils were found in the 1940s at Ghost Ranch, making it among the best documented of all dinosaurs.

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Mythical satyr may be preserved in salt

Unicorns, giants and fairies — the UFOs of antiquity — have yet to turn up in any archaeologist's shovel.

Aside from their frequent appearances on ancient frescoes, statuary and artwork, such fanciful creatures of mythology don't have a clear origin, although some have linked the mermaid to lonely sailors who glimpsed dugongs (also known as sea cows) in the distance and made a giant leap.

But a recent discovery in an Iranian salt mine, one scholar suggests, may shed light on the origins of a famous satyr of antiquity, one so well known that it merited a visit from the emperor himself. The satyr is a goat-man in Greek legend who dances and frolics, playing pipes and chasing nymphs all day, living in a woodsy version of the Playboy Mansion.

In June, a man's body, naturally mummified within an ancient salt mine, was found outside the Iranian city of Zanjan. Six such discoveries have been made since 1993, according to the Circle of Ancient Iranian Studies foundation based in London. Earlier salt man finds go back as far as 540 B.C., around the time of the ancient Achaemenid dynasty.

Archaeologists treasure natural mummy discoveries — such as "Otzi," the ice-entombed man preserved in an Alpine glacier and uncovered in 1991 — because preservation of soft tissues, even beards in the case of the salt men, allows for DNA analysis and other tools of forensic science.

FIND MORE STORIES IN: Mayor | Roman emperor | Constantine

Stanford University's Adrienne Mayor, a folklorist, specializes in analyzing how fossil discoveries in prehistory may have contributed to legends such as the Titans of Greek mythology (botched reconstructions of mammoth bones) or mystic water serpents in Native American legends (fossilized fish-tailed crocodiles preserved in desert rock deposits).

As far back as the era of the great Roman emperor Constantine, who reigned from 312 to 337, cities had their own special attractions, Mayor explains. The early Christian writer St. Jerome (the patron saint of librarians in the Roman Catholic Church, who died in the year 420) recounted that Constantine made a special trip from Constantinople (Istanbul today) to Antioch, once a great city of his empire, to view an exhibit of a "satyr" that had been extremely well-preserved in salt.

In an earlier book, The First Fossil Hunters: Paleontology in Greek and Roman Times, Mayor suggested that the "satyr" was likely a fake, the patched-together bodies of a man and goat. But now she thinks the recently discovered salt man might provide another explanation. "Obviously, satyrs are mythic creatures," Mayor says. But the head of the man preserved in salt since about 540-300 B.C. "bears a striking resemblance to ancient Greek and Roman depictions of satyrs," she says, which are shown to have similar hair and beard, a snub nose and protruding jaw.

"I think it's very likely that an ancient discovery of a similarly preserved 'salt man' in northwestern Iran is the basis for St. Jerome's account of the 'satyr' preserved in salt and examined by the Emperor Constantine and numerous other curious visitors in Antioch," Mayor concludes.

Expert opinions are mixed. Roman historian Andrew Merrills of England's University of Leicester, says in an e-mail: "Overall, it sounds like a great big 'maybe' to me. Interesting story, fabulous idea, but I wouldn't want to build too much of an argument on it." But archaeologist Bruce Hitchner at Tufts University in Massachusetts calls the idea credible.

The 540 B.C. salt man from Iran most resembles an elderly satyr figure commonly seen in Greek art, called Silenus, says Mayor. Silenus was usually depicted with long golden hair, a beard, a bulging forehead, a snub nose and an open mouth. Mayor suspects the early images of satyrs may have sprung from such discoveries, transformed into art (with the addition of a goat's body) in stories traded by travelers of the ancient world.

"When I saw the picture of the salt man, I was just struck by how much like a satyr he looks," Mayor says. "Satyr plays were very popular in antiquity, so everyone knew what satyrs looked like. There's no reason to think people back then wouldn't have made the same connection."

New discoveries about red planet keeps professor well read

Every time NASA sends a probe to Mars, Sacramento State Professor Chris Taylor has to toss out his text book.

Taylor teaches astrophysics at the university. His specialty is galaxy formation but he also teaches planetary science. With all the attention given to Mars lately, the text books he uses are outdated almost as soon as they are printed.

“The Mars missions do not directly influence my research, but they do influence what I teach because what we know about Mars changes so rapidly,” Taylor says. “I just switched text books because the one I had was published in 2000, and now it’s just about useless.”

He’ll need an even newer text book in a few years. Next month, NASA will launch a new probe that will continue the search for water, and possibly life, on the red planet. The probe, called Phoenix, will explore an area near the northern polar cap, and new discoveries can be expected, Taylor says. “The entire thrust of NASA’s missions to Mars has been figuring out whether or not there was life on Mars at one point. So each mission brings us a new piece of the puzzle,” he says.

Phoenix will dig into the icy soil to determine whether frozen water near the surface was ever liquid enough to sustain a livable environment for microbes, according to NASA. “The theory is that if there were once large oceans or lakes there may have been life in those environments. If the water retreated and went underground, life may have adapted to those conditions and gone there as well,” Taylor says.

Meanwhile, the two rovers, Spirit and Opportunity, which were sent to Mars in 2003, continue to patrol the planet and provide new information. The rovers were expected to function for about 90 days, Taylor says, but they are still sending back information, even though they are a little beaten up by the Martian terrain, harsh climate and age. “A wheel on one of the rovers is broken, so it drags as it moves,” Taylor says. “Technicians turned the onboard camera around to look at the track and saw that the wheel had dug out a trench a few millimeters deep exposing a layer containing silica. When you see this mineral on earth that means there is water. So even when you make a mistake you discover something new on Mars.” Those discoveries and others like it are helping rewrite the book on Mars and that’s okay with Taylor. “Planetary science, at its most basic level, tells us more about the Earth and directly impacts our knowledge of things like the greenhouse effect. By studying other planets we can learn more about what could happen here on Earth,” he says.

Scientists find new links to genetic conditions, including "restless legs syndrome"

Scientists have uncovered more genetic links to a number of well known diseases, as well as new connections to two health conditions that aren't as well understood.

It's those discoveries that may pack the biggest punch for patients. Among the latest batch of genetic discoveries are new genes for heart disease and new insight into genes linked to macular degeneration.

The first gene links to two common but poorly understood and often questioned conditions, a severe form of premenstrual syndrome called PMDD, and the even more common restless leg syndrome were also discovered.

The hallmark symptom of restless leg syndrome is an uncontrollable urge to move the legs, especially at night. NBC reporter Jaye Watson now knows she can blame a gene for the nighttime kick-fest."It's that feeling in my legs, the unbearable need to move them, and it starts, like that and it starts like every 20 seconds," explained Watson.

Emory University's Dr. David Rye, also a restless leg suffer, helped find the connection.A genetic link can work wonders at validating conditions like PMDD and RLS. It's an endorsement that brings peace of mind for patients,and the potential to revolutionize treatment.

Six new sulphide zones discovered at Argentex Zinc-Indium Pinguino Project, Argentina

TORONTO, July 19 /PRNewswire-FirstCall/ - Argentex Mining Corporation announced today that the company has successfully tested six new zones during its fourth drill program at the polymetallic Pinguino property in Santa Cruz, Argentina.

In total, 18 HQ diamond drill holes covering 1,357 meters (4,452 feet) were concluded before the onset of winter conditions in the Patagonia region. The six new zones were drilled to test near-surface gossanous vein in bedrock within newly completed trenches. Visual inspection of the core shows that all zones returned significant intersections of vein sulphides.

"These intersections confirm an increase in the number of known sulphide veins at Pinguino. In addition to Marta Centro and Yvonne we now have a further six sulphide-rich zones that remain open at depth and along strike," said Ken Hicks, President of Argentex. "We are excited about the potential for expansion of mineralization at Pinguino and we look forward to further drill testing of these new discoveries as well as other high-priority targets."

Prior to this latest drill program, drill testing of known mineralization had been limited to the Marta Centro and Yvonne veins, which represent only 10% of the extensive geophysical anomalies defined to date. Preparations for further drilling are scheduled to commence in September.

Following the completion of previous drill programs at the sulphide-rich Marta Centro and Yvonne zones, Argentex intensified exploration work at Pinguino earlier this year to include additional trenching and drilling at Yvonne Sur, Yvonne Norte, Sonia, Kasia, Savary and Luna. Surface targets were identified based on their geological signature, which combines anomalous geophysics and geochemistry, and a total of 20 individual trenches tested these six distinct and previously unexplored overburden-covered zones.

Visual inspection of the HQ diamond drill core shows that significant sulphide intersections were returned in all six of these trenched areas.

Results from previous drill programs at Marta Centro and Yvonne revealed consistent polymetallic zinc-lead-indium-silver-gold-copper mineralization, which remains open-ended along strike and to depth. A total of 23 holes drilled into Marta Centro showed a consistent high-grade base metal core surrounded by wide intervals of disseminated mineralization.

Samples have been submitted to Acme Analytical Labs for analysis and findings will be reported upon receipt and compilation of results.
About Pinguino

Argentex's Pinguino property is located in Argentina's Patagonia region, within the Deseado Massif of Santa Cruz province. Both silver-gold and base metal discoveries have been made through the completion of approximately 9,350 meters (30,675 feet) of diamond drilling to date. Mineralization remains open-ended along strike and at depth, and numerous targets remain to be tested by drilling. Previous exploration has focused on zinc-indium-lead-silver-gold-copper discoveries in the Marta Centro and Yvonne areas of the property. Recent machine trenching and shallow drilling have intersected new sulphide veins at Yvonne Sur, Yvonne Norte, Sonia, Kasia, Savary and Luna.

Pinguino is easily accessible, situated approximately 500 meters (1,640 feet) above sea level in low-relief topography. An existing system of all-weather roads provides year-round access to the property.

Quality Assurance

Exploration on the Pinguino property is being conducted under the supervision of Mr. Kenneth Hicks, P.Geo., Argentex's President and a "qualified person" as defined by Canada's National Instrument 43-101.

Samples selected for analysis are sent to Acme Analytical Laboratories' sample preparation lab in Mendoza, Argentina. From there sample pulps are sent to Santiago, Chile for fire assay gold analysis and to Vancouver, Canada for Group 1DX multi-element MS-ICP analysis. Samples with over-limit zinc, lead, silver and/or copper are reanalyzed using an ore-grade high detection limit 7AR analysis, also conducted in Vancouver. Acme Analytical Laboratories is an accredited ISO 9000:2001 full-service commercial laboratory with its head office in Vancouver. Referee analyses will be carried out by Alex Stewart (assayers) Argentina S.A. in Mendoza, Argentina. Argentex, Acme and Alex Stewart all maintain comprehensive and independent Quality Control/Quality Assurance programs. Drilling was conducted by Connors Drilling, a Canadian company with an office in Mendoza, Argentina.

DNA discovery reveals Greenland's warm past

Scientists have uncovered evidence that within the past million years southern Greenland was warmer than previously thought, and even covered in lush forests, a discovery suggesting its ice sheet could be more stable than previously thought against climate change temperature rises.
An analysis of DNA found at the bottom of ice cores drilled to a depth of more than a mile (2km) in south Greenland, and dated to between 450,000 and 800,000 years ago, has shown a surprising variety of plant and insect life was present then.

There were trees such as alder, spruce, pine and members of the yew family, and invertebrates related to beetles, flies, spiders, butterflies and moths.
"We have shown for the first time that southern Greenland, which is currently hidden under more than 2km of ice, was once very different to the Greenland we see today," said Eske Willerslev, an archaeologist at the University of Copenhagen. "Back then it was inhabited by a diverse array of conifer trees and insects."

Martin Sharp, a glaciologist at the University of Alberta and co-author of the paper, said that the silty ice found underneath the Greenland glacier created a natural freezer that preserved prehistoric DNA - the samples have provided the oldest authenticated DNA obtained to date. "These findings allow us to make a more accurate environmental reconstruction of the time period from which these samples were taken." The area was "significantly warmer than most people thought".

The results of the studies are published today in the journal Science.

Over geological timescales the Earth's temperature rises and falls, leading to ice ages and periods of relative warmth. Between 450,000 and 800,000 years ago it would have been about 10C in summer and -17C in winter. When temperatures later fell the area was covered in ice and this ice sheet seems surprisingly to have remained in place when temperatures rose again about 130,000 years ago. During this last interglacial period temperatures were 5C warmer than today.

"If our data is correct, then this means that the southern Greenland ice cap is more stable than previously thought," said Professor Willerslev. "This may have implications for how the ice sheets respond to global warming."

According to climate change models, a two-degree rise in global temperatures could cause a collapse of the Greenland ice sheet and dangerously high sea levels by the end of the century. Recent data suggests the rate of ice loss from Greenland has tripled since 2004.

The results also show that biological molecules from the ice cores can be used to reconstruct environments - the material available is in very low concentrations but the information would be worth the effort, said Enrico Cappellini, of York university. "Given that 10% of the terrestrial surface is covered by thick ice sheets it could open up a world of new discoveries."

NASA looking in wrong places for alien life

EXTRATERRESTRIAL life may well be so weird we would not immediately recognise it, space experts said yesterday.

Scientists looking for alien life should be seeking the unfamiliar as well as the familiar, they said.

NASA's current approach to "follow the water" is logical assuming alien life is comparable to that on Earth - based on water, carbon and DNA - but the "life as we know it" approach could easily miss something exotic, the US National Academy of Sciences panel advised.

"The purpose of this whole report was to be able to look for life on other planets and moons with an open mind ... and not maybe miss some other life form because we are looking for some obvious life form," said John Baross, professor of oceanography at the University of Washington in Seattle, who chaired the committee.

The US space agency commissioned the report from the National Research Council.

The panel of biochemists, planetary scientists, geneticists and other experts considered all possible ways life can arise and exist.

Recent discoveries of extremophiles - organisms living in conditions of heat, cold and dark and using chemicals once thought incompatible with life - have changed ideas of where life can survive.

Prof Baross said lab experiments also showed water did not necessarily have to be the basis for life.

It might be possible for a living organism to use methane, ethane, ammonia or even more bizarre chemicals.

"We had some discussion about how weird to make this because there are so many concepts out here.

"There are so many theories about what life is and what could be a living system."

NASA and other groups are looking hard for extraterrestrial life.

Telescopes search for spectral signatures from other planets that might suggest water is on the surface.

Robots on Mars are seeking evidence of water, past or present.

"We wanted to actually think outside of that box a little bit and at least try to articulate some of the other possibilities besides water-carbon life."

They suggested NASA should return to some of the more promising places in our own solar system to look for evidence of life, such as Saturn's moons Titan and Enceladus, and even steamy Venus.

Understanding how explosions on the Sun affect the Earth

By Danielle Reeves

Scientists who study violent activity on our Sun are explaining how large explosions of particles from the Sun can affect satellites, space craft and even electrical power lines on Earth, at the Royal Society Summer Science Exhibition this week.

The exhibit explains what happens when an immense eruption known as a Coronal Mass Ejection (CME) happens on the Sun. CMEs are the largest explosions in the solar system and when they occur a mass of particles weighing roughly the same as Mount Everest is launched out into space. The exhibit was organised by scientists from Imperial College London, University College London, University of Wales, Aberystwyth, Armagh Observatory, University of Cambridge, Rutherford Appleton Laboratory and The University of Central Lancashire.

If a CME occurs in the direction of the Earth, the particles can cause significant problems to the electrical systems of spacecraft and satellites in orbit around the planet. Some CMEs have also been known to affect electrical power lines on Earth, and the highly energetic particles that are thrown out of the Sun could pose a radiation risk to astronauts in space, and even to passengers in aeroplanes that pass near the Earth’s poles.

The exhibit’s stand at the Royal Society will enable members of the public to talk to scientists involved in research to predict when CMEs are headed towards Earth. There will be 3D videos and posters describing the journey of a CME from its initiation on the Sun to its arrival at the Earth, and models of the satellites scientists use to observe them.

Dr Steve Bradshaw from Imperial’s Department of Physics, one of the scientists involved in the exhibition, explained: "Our best defence against CMEs is to have plenty of warning when one is heading towards the Earth, so that pre-emptive action can be taken to protect ourselves and the sensitive electronic equipment that we depend on."

Two solar observing missions were recently launched that should give scientists significantly more warning and time to be prepared than they have had in the past. The Hinode satellite will help solar physicists to better understand the physical processes taking place on the Sun that lead to CMEs, which will lead to more accurate forecasting of when a CME will erupt. The STEREO satellites will allow researchers to track CMEs in-flight between the Sun and the Earth, and by providing a stereoscopic view of their path through space - in the same way that our two eyes provide us with depth perception – the research team will be more quickly able to determine whether the CME is heading straight for us.

Dr Bradshaw added: "The Royal Society’s Summer Science Exhibition provides scientists with an ideal opportunity to talk to the public about their work. The research we’re doing on CMEs gives a new insight into some impressive explosions on our nearest star, which are fascinating for both scientists and the public to see, and I’m looking forward to sharing our discoveries this week."

From Recovering T-Rex Blood Cells to New Discoveries in Heredity

NOVA science

NOW looks at startling new research that has recovered ancient proteins from dinosaur bones. Could dino DNA be next? Speaking of DNA, it may be the master code of life but something else is pulling the switches. Understanding this switching system, called the epigenome, may lead to cancer cures and even an explanation of why identical twins are not identical. Host and astrophysicist Neil deGrasse Tyson investigates this exciting work in the opening two segments of the latest NOVA scienceNOW, airing Tuesday, July 24 at 8 pm ET/PT on PBS (check local listings).

In other explorations, NOVA scienceNOW takes a trip to the courtyard of CIA headquarters where an enigmatic sculpture displays a coded message that has so far stymied the nation's top code breakers, not to mention legions of amateurs. The show also profiles the amazing rise of a poor kid from Belize to the abstract realm of cosmological research, and Tyson closes with another mind-bending "Cosmic Perspective.

All we know about dinosaurs comes from fossils. Thanks to paleobiologist Mary Schweitzer these old bones are telling us more than ever. Schweitzer defied the long-held belief that it was fruitless to search for preserved soft tissues in dinosaur remains. Most experts held that such structures should have decayed away long ago, but Schweitzer has found evidence of delicate structures such as blood vessels and red blood cells that miraculously survived for millions of years. Recently she examined one cross section of 68-million-year-old bone and confidently announced: What we have here is a pregnant Tyrannosaurus rex!

Once nurture seemed clearly distinct from nature. Now it appears that our diets and lifestyles literally change the expression of our genes. How? By influencing a vast network of chemical switches inside our cells. Called collectively the epigenome, the switches turn genes on and off and may account for the fact that identical twins grow less identical as they age. This new understanding may give us potent new medical therapies and even cures, because many diseases now appear to stem from errors in the epigenome, and such epigenetic errors seem easier to correct than genetic ones. Epigenetic cancer therapy, for example, seems already to be yielding stunning results.

Robot Dives Deep for Sinkhole Slime

By Henry Bortman


In May, researchers successfully conducted the third and final field test of the autonomous underwater robot, DEPTHX. Their objective was to explore Cenote Zacatón, the world’s deepest water-filled sinkhole.

Zacatón lies near one end of a chain of sinkholes stretching nearly half a mile across Rancho La Azufroza (Sulfur Ranch), located in northeastern México, roughly 20 miles from the Gulf Coast. Even without the sinkholes, the biology of the region would make a fascinating subject of study. The landscape is dotted with a muddle of tropical deciduous trees and bromeliads growing side-by-side with agaves and cacti typical of desert climates. Each day, as dawn approaches, a flock of green parrots takes wing, shrieking and squawking as they circle the rim of Zacatón. Later in the day, the air grows thick with butterflies, more than a dozen different species, some with wingspans exceeding six inches. It is a languid, sun-drenched setting.

But what lies below ground, in the dark waters of Zacatón, where only microbial life can survive, is what has piqued the interest of scientists and engineers from Stone Aerospace, the University of Texas at Austin, Carnegie Mellon University’s Robotics Institute, the Colorado School of Mines, and other institutions, who make up the DEPTHX team.

The DEPTHX project was funded by NASA’s ASTEP (Astrobiology Science and Technology for Exploring Planets) program. ASTEP projects typically involve both technology and science components. The robot incorporates a number of innovative technologies. It is the first underwater vehicle that can be placed in an enclosed water-filled space and, without any previous knowledge, safely navigate its way around, build a three-dimensional map of its environment, and collect samples of scientific interest -- all without human intervention.

Mapping and sampling Zacatón was DEPTHX’s most challenging task to date. In March of this year, the craft explored Poza La Pilita, a smaller sinkhole near Zacatón.

DEPTHX enabled investigators to explore an otherwise inaccessible ecosystem that extends far below the Earth’s surface. The robot had a mechanical arm that could be extended 2 to 3 meters (6.5 to 10 feet); at its end was a spring-loaded penetrator that could sense when it came within a few inches of the cenote’s wall. Once in position, it grabbed a gob of the microbial biofilm that coats the entire interior surface of the sinkhole, and brought it back to the surface for later laboratory analysis. Positioning the 1.5-ton robot precisely -- not too far from the uneven surface of the cenote wall to obtain a sample, but not so close that the penetrator slams into rock and gets bent -- was challenging, particularly when the robot was doing its own navigation. But DEPTHX successfully obtained half a dozen samples of microbial Zacatón wall slime. The deepest of these came from close to the bottom of the cenote, at a depth of 272 meters (892 feet).

Finding the bottom of Zacatón was another of DEPTHX’s accomplishments. Previously, no-one had been able to determine for certain how deep the cenote was. As it turns out, the bottom is sloped, ranging from 315 meters (1033 feet) at its high end down to 320 meters (1050 feet). And it may go even deeper. At the low end of the cenote, the robot found what appeared to be a narrow tunnel that extended outward, and perhaps farther downward. Because the research team was pressed for time, however, and because they wanted to make sure they could safely get the craft back to the surface, they told DEPTHX to come home without exploring the tunnel.

John Spear, the lead microbiologist on the DEPTHX team, speculates that this deep channel is connected to an underground system of thermally heated water. About one million years ago, geologists believe, the Zacatón region was a site of intense hydrothermal activity, not unlike Mammoth Hot Springs in present-day Yellowstone National Park. Although thermal activity around Zacatón has calmed down considerably since those fiery days, there are clear signs that something is still stirring underground: a pervasive scent of sulfur hovers around the cenote, and Zacatón’s water is a constant 30 degrees C (86 degrees F). In fact, says Spears, one of the surprising discoveries made by DEPTHX is that the temperature in Zacatón is constant all the way through its thousand-foot water column. He expected to find temperature variation with depth, a more common scenario.

“If we stuck DepthX in a place like Yellowstone Lake, for example, you would see gradients of change in temperature. It would probably be warm on the surface, cold in the middle, and then down at the thermal vents warm again,” Spear said. But something is keeping Zacatón unusually well-mixed. I asked Spear what caused the mixing. “Don’t know,” he replied, but in a later email he added that “there is a large amount of geothermally heated water flowing through the system.”

Whatever its cause, the unexpected uniformity put a kink in the research team’s sample-collection plans. They had hoped to use gradients in the water’s temperature, in its salinity and in its level of dissolved oxygen to guide DEPTHX toward the best sampling locations. Places where such changes occur are interesting because they are often accompanied by an ecological change. Different types of organisms thrive in cooler water than in warmer water, for example.

Often, there is also a visual indicator of such changes. In Yellowstone, where Spear has worked extensively, “I could walk up to a hot spring and say, ‘I want a sample right there,’ mainly because of my visual interpretation of it, what I see,” he says. Green, for example, indicates the presence of photosynthetic organisms, which can survive only in relatively cool water. Yellow-, orange- and red-hued organisms dominate in hotter waters.

“You’d like the robot to do the same thing, use a visual cue to understand a place,” Spear says. He was hoping to be able to use “color changes on the walls of the cenote,” which “might correlate with chemistry,” to guide the robot toward good places to collect samples. But, apart from a shallow oxygenated zone near Zacatón’s surface, the microbial life that clung to the cenote walls was visually uniform, from top to bottom.

Nevertheless, Spear expects the DNA analysis that his lab will perform over the next few months on the Zacatón samples to yield valuable results. Preliminary analysis of samples collected a couple of years ago by a diver, at a depth of 85 meters (280 feet), turned up “six new groups of bacteria.” And by “six new groups” Spear emphasized, he didn’t mean six new species. “The bacteria domain [one of the three main branches on the tree of life] has about 100 different divisions or phyla in it. So we found six new ones, from here,” he explained. “That’s kind of equivalent to walking out your door in the morning and finding plants for the first time.” To be fair, Spear points out that “you can often find new groups” even in places as pedestrian as common garden soil. “It could even be something that’s living between your teeth.” Still, six is a pretty good haul for one sinkhole. “And we think we can find more,” he adds.

The samples that Spear’s lab will analyze were collected while DEPTHX was under human control. Because the robot’s time in Zacatón was limited, DEPTHX engineers had to choose between pursuing science goals or technology goals, and they decided to tell the robot where to collect its samples, rather than to let the craft’s onboard computers make autonomous choices.

But the robot’s software-engineering team, which hails from Carnegie Mellon’s Robotics Institute, also got a chance to put the robot’s sophisticated technology to the test. In Poza Verde (Spanish for “Green Pool”), a wider but shallower cenote near Zacatón, DEPTHX was tested in “exploration mode." In this mode, the robot is not given any instructions about where to go or what to do. It’s dropped into the water and simply told to go find interesting stuff. It is responsible both for navigating its way around and for deciding what is interesting. The engineering team judged this test a success.

That is promising, because exploration mode will have to work well for the next phase of the robot’s life. Later this year, DEPTHX will morph into ENDURANCE, the same robot but with a slightly different configuration, and will transition from exploring balmy semitropical waters to swimming about in chilly ice-covered lakes.

The first such cold-water test will take place in February 2008, in the Midwest. That will be a trail run for an even more challenging mission late in 2008: autonomous exploration of the waters of Antarctica’s Lake Bonney, an ice-covered lake about 3 km (1.8 miles) long and 1.5 km (0.9 miles) wide.

To date, very little is known about Lake Bonney. Peter Doran, a University of Illinois at Chicago associate professor and the principal investigator for the ENDURANCE project, and his colleagues have been studying the lake for several years, measuring its temperature, salinity and a handful of other parameters. But those measurements have all been made “in the center of the lake,” Doran says. “We go back to the same spot every year.” ENDURANCE, he says, will enable researchers for the first time to develop a portrait of the lake - its temperature, its chemistry, and its microbial ecology - in three dimensions.

New Discoveries In Neural Stem Cells Have Implications For The Design Of Brain Therapies

Scientists have discovered that adult neural stem cells, which exist in the brain throughout life, are not a single, homogeneous group. Instead, they are a diverse group of cells, each capable of giving rise to specific types of neurons. The finding, the team says, significantly shifts the perspective on how these cells could be used to develop cell-based brain therapies.

The results of their study are reported online in Science Express, and will be published in an upcoming issue of Science.

Adult neural stem cells give rise to the three major types of brain cells -- astrocytes, oligodendrocytes and neurons. Their role in producing neurons is of particular interest to scientists because neurons orchestrate brain functions -- thought, feeling and movement. If scientists could figure out how to create specific types of new neurons, they potentially could use them to replace damaged cells, such as the dopamine-producing neurons destroyed in Parkinson's disease.

In recent years, scientists have determined that adult neural stem cells are located primarily in two regions of the brain -- the lining of the brain's fluid-filled cavity, known as the subventricular zone, and a horseshoe shaped area known as the hippocampus. The laboratory of the senior author of the current study, UCSF's Arturo Alvarez-Buylla identified the stem cells in the subventricular zone in 1999 (Cell, June 11, 1999).

While scientists have known that neural stem cells in the developing brain produce particular types of neurons based on where the stem cells are located in the embryo, studies carried out in cell culture have suggested that adult neural stem cells of the fully formed brain can give rise to many types of brain cells.

In the current study, conducted in mice, the team set out to explore whether neural stem cells in different locations of the subventricular zone are all the same. They did so using a method they developed to follow the fate of early neonatal and adult neural stem cells in 15 different regions of the subventricular zone. These cells typically produce young neurons that migrate to the olfactory bulb, where they mature into several distinct types of interneurons, neurons that are essential for the sense of smell.

To the team's surprise, the adult neural stem cells in the various regions of the subventricular zone each gave rise to only very specific subsets of interneurons. Moreover, the stem cells were not susceptible to being re-specified. When they were taken out of their niche and transplanted into another region of the subventricular zone, they continued to produce the same subset of interneurons. Similarly, they retained their specialized production of distinct subtypes of neurons when removed from the animals' brains and exposed to a cocktail of growth factors in a culture dish.

The findings, says the lead author of the study, Florian T. Merkle a graduate student in the Alvarez-Buylla lab, suggests that while adult neural stem cells of the subventricular zone can produce the three major types of brain cells -- astrocytes, neurons and oligodendrocytes -- when it comes to neurons they seem to be specified, or programmed, to produce very specific subtypes.

"The data supporting the finding is remarkably clean and was highly unexpected," says senior author Alvarez-Buylla, UCSF Heather and Melanie Muss Professor of Neurological Surgery. "We've been studying this region of the brain for many years and Florian's data has produced a different scenario, so we have to readjust now."

"We should abandon the idea that these cells are good for making any kind of neuron. This is just not going to be the case unless we find ways to reprogram these cells genetically."

The insight, says Merkle, is a key step toward understanding the molecular mechanisms of neural stem cell potential. "Now you could compare adult stem cells in different regions at the genetic level. Since different neural stem cells make different types of neurons, maybe you could determine which genes are important for making, say, dopaminergic cells. In theory you could activate these genes in embryonic stem cells in the culture dish to try to create the desired type of neuron."

The Alvarez-Buylla lab has identified neural stem cells in the adult human brain, but it is not known if these cells are heterogeneous. If human brains show a similar regionalization of stem cells, it might also be possible, says Alvarez-Buylla, to harvest them from the brains of patients, expand their numbers in the culture dish to obtain a particular neuron type, and transplant them back into patients.

Notably, the distribution of adult neural stem cells throughout the subventricular zone raises the possibility, he says, that the cells' activity is regionally modulated in order to regulate the production of different types of neurons. "This may provide a mechanism for the brain to dynamically fine tune the olfactory bulb circuitry, raising a fascinating basic question about neuronal replacement: Why are so many different types of neurons, with such diverse origins, required for olfactory function?"

"The implication for cell-based therapies might be that it isn't sufficient to replace one neuron," he says. "You might have to replace combinations of different neuronal types when it comes to reestablishing neural function."

The finding, he says, has not been without its hints. In 1996, the lab reported (PNAS, Dec. 1996) what he describes as "an amazing network of pathways" that collect adult neural stem cells from throughout the wall of the lateral ventricle of the subventricular zone.

"It's taken us 10 years," he says, "to figure out that these pathways reflect the transport of young neurons of different types born in unique locations."

Astronomers Find Thousands of New Galaxies

By SPACE.com

More than a thousand previously unknown dwarf galaxies have been detected in the Coma cluster of galaxies 320 million light-years away by NASA's Spitzer Space Telescope.

Though tiny compared to bigger galaxies, dwarf galaxies play a crucial role in cosmic evolution. Astronomers think they were the first galaxies to form, providing the building blocks for larger galaxies. They're also the most numerous type of galaxies around: Computer simulations, in fact, suggest that giant clusters of galaxies should contain more dwarf galaxies than astronomers have observed.

To find the thousands of "missing" galaxies, astronomers at NASA's Goddard Space Flight Center in Greenbelt, Maryland, stitched together 288 individual exposures from the Spitzer Space Telescope. Each exposure lasted 70 to 90 seconds, forming a large mosaic covering 1.3 square degrees of sky when combined with the image data from the Sloan Digital Sky Survey.

Though a small chunk of the sky, the team found almost 30,000 new objects in a relatively short period of time.

To the team's surprise, many of the new objects turned out to be Coma galaxies, not galaxies beyond the cluster. Leigh Jenkins, a GSFC astronomer, estimates that about 1,200 of the faint objects are dwarf galaxies-many more than have been previously identified.

"We have suddenly been able to detect thousands of faint galaxies that weren't seen before," Jenkins said. Her team's study of the Coma cluster is detailed in a recent issue of the Astrophysical Journal.

How can astronomers see such faint galaxies? The universe emits a wealth of visible light, which allows us to se stars with an unaided eye. But most of the light from space is invisible to humans-which is why telescopes like Spitzer that can "see" infrared light help astronomers make new discoveries in well-studied parts of the cosmos.

The team may have found thousands of new objects, but additional Coma dwarf galaxies might be lurking in the Spitzer telescope data, the team said. By using telescopes that can see even "deeper" into the cosmos, the astronomers are currently trying to find out how many of the faintest objects belong to the Coma cluster.

why menthol feels fresh

Scientists have identified the receptor in cells of the peripheral nervous system that is most responsible for the body's ability to sense cold.


The finding, reported on-line in the journal "Nature" (May 30, 2007), reveals one of the key mechanisms by which the body detects temperature sensation. But in so doing it also illuminates a mechanism that mediates how the body experiences intense stimuli – temperature, in this case – that can cause pain.


As such, the receptor – known as menthol receptor TRPM8 -- provides a target for studying acute and chronic pain, as can result from inflammatory or nerve injury, the researchers say, and a potential new target for treating pain.


"By understanding how sensory receptors work, how thresholds for temperature are determined, we gain insight into how these thresholds change in the setting of injury, such as inflammatory and nerve injury, and how these changes may contribute to chronic pain," says senior author David Julius, PhD, chairman and professor of physiology at UCSF.


The methanol receptor, and other temperature receptors discovered in recent years by the Julius lab, offer potential targets for developing analgesic drugs that act in the peripheral, nervous system, rather than centrally, where opiate receptors act, he says.


The finding is a milestone in an investigation the team began several years ago. In 2002, the researchers discovered that the receptor was activated by chemical cooling agents such as menthol, a natural product of mint, and cool air. They reported their discovery, or "cloning," of the receptor in "Nature" (March 7, 2002), hypothesizing that the receptor would play a key role in sensing cold. However, some subsequent papers questioned this theory.


In the current study, the team confirmed their hypothesis by "knocking out" the gene that synthesizes the receptor, both in sensory neurons in cell culture and in mice. The cells in culture were unresponsive to cooling agents, including menthol. The genetically engineered mice did not discriminate between warm and cold surfaces until the temperature dropped to extremes.


"It's been known for years that menthol and related cooling agents evoke the psychophysical sensation of cold – somehow by interacting with the aspect of the sensory nervous system that's related to cold detection," says Julius.


The current study, he says -- led by Diana M. Bautista, PhD, and Jan Siemens, PhD, of the Julius lab and Joshua M. Glazer, PhD, of the lab of co-senior author Cheryl Stucky, PhD, of the Medical College of Wisconsin – puts that question to rest.


As the mice lacking the gene were not completely insensitive to cold -- they avoided contact with surfaces below 10 degrees C, though with reduced efficiency -- the next step, says Julius, will be to illuminate this residual aspect of cold sensation.


The finding is the latest of a series of discoveries led by the Julius lab on the molecular mechanisms of temperature sensation and pain. In 1997, the lab cloned the gene for the capsaicin receptor, the main pungent ingredient in some chili peppers (Nature, Oct. 23, 1997), and in 2000 reported that, in mice, the receptor triggers the nerves to fire pain signals when they are exposed to high ambient heat or the fiery properties of peppery food. (Science, April 14, 2000). The study demonstrated that capsaicin and noxious heat elicit the sensation of burning pain through activation of the same receptor on sensory neurons.


Most recently, they identified the receptor of isothiocyanate compounds, which constitute the pungent ingredients in such plants as wasabi and yellow mustard. In response to high temperatures, the receptor produces pain and irritation.


"All of these studies use natural products to understand pain mechanisms in the periphery of the body, where they are first sensed," says Julius.


Ultimately, pain signals are transmitted from the peripheral nervous system into the body's central nervous system – moving through nerves in the spinal cord and brain stem up to the brain, which prompts a response, or "feeling." Co-author of the current study Allan Basbaum, PhD, also of UCSF, is a pioneer of research into the mechanism of chronic pain within the central nervous system.


The Julius team's complementary work is focused at the level of the sensory nerve fiber, where the signals are first initiated. "We want to know," Julius says, "how do you detect these stimuli to begin with" How do your sensory nerve endings do this to begin with" And what are the biochemical and biophysical mechanisms that account for this""


All three receptors the Julius lab has discovered are members of the TRP family of ion channels expressed on sensory neurons. The latest finding adds to the evidence, says Julius, that TRP channels are the principal transducers of thermal stimuli in the mammalian periphery nervous system.

These planets are way out there

The discovery of dozens of new "exoplanets" was reported Monday at a meeting of astronomers at the Hawaii Convention Center.

Attendees at the semiannual meeting of the American Astronomical Society heard about the discovery of 28 new planets outside our own solar system, raising the total number of known exoplanets 12 percent to 236.

These bodies, previously too distant for Earthbound astronomers to see, have been spotted in part by using the Keck Observatory atop Mauna Kea.

Jason Wright and John Asher Johnson of the University of California Berkeley reported the new exoplanets and said they're getting better at finding them, spotting smaller gas giants than they could see before.

"We're just now getting to the point where, if we were observing our own solar system from afar, we would be seeing Jupiter," Wright said.

The California and Carnegie Planet Search team is headed by Geoffrey Marcy of UC Berkeley and also includes Paul Butler of the Carnegie Institution of Washington and Steve Vogt of UC Santa Cruz. Discoveries have also been made or confirmed by the Anglo-Australian Planet Search team, headed by Chris Tinney of the University of New South Wales and Hugh Jones of the University of Hertfordshire, and by Debra Fischer of San Francisco State University, Shannon Patel of UC Santa Cruz and Simon O'Toole of the Anglo-Australian Observatory.

Several of these scientists have published discoveries over the past year but the Honolulu conference Monday was the first time they all presented together.

The Keck Observatory, which employs more than 200 on the Big Island, has played a pivotal role in the discovery of planets beyond our local solar system. It is one of several observatories atop Mauna Kea.

A small number of technicians actually work on the top of the mountain, which is more than 13,000 feet high, while the actual astronomers work in Waimea-Kamuela (if working with Keck) or Hilo (if working with some other Mauna Kea facilities) or get telescope data sent via Internet2 to universities in other parts of the world.

Mars Rover Spirit Unearths Surprise Evidence Of Wetter Past

Science Daily — A patch of Martian soil analyzed by NASA's rover Spirit is so rich in silica that it may provide some of the strongest evidence yet that ancient Mars was much wetter than it is now. The processes that could have produced such a concentrated deposit of silica require the presence of water.

Members of the rover science team heard from a colleague during a recent teleconference that the alpha particle X-ray spectrometer, a chemical analyzer at the end of Spirit's arm, had measured a composition of about 90 percent pure silica for this soil.

"You could hear people gasp in astonishment," said Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for the Mars rovers' science instruments. "This is a remarkable discovery. And the fact that we found something this new and different after nearly 1,200 days on Mars makes it even more remarkable. It makes you wonder what else is still out there."

Spirit's miniature thermal emission spectrometer observed the patch, and Steve Ruff of Arizona State University, Tempe, noticed that its spectrum showed a high silica content. The team has laid out plans for further study of the soil patch and surrounding deposits.

Exploring a low range of hills inside a Connecticut-sized basin named Gusev Crater, Spirit had previously found other indicators of long-ago water at the site, such as patches of water-bearing, sulfur-rich soil; alteration of minerals; and evidence of explosive volcanism.

"This is some of the best evidence Spirit has found for water at Gusev," said Albert Yen, a geochemist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. One possible origin for the silica could have been interaction of soil with acid vapors produced by volcanic activity in the presence of water. Another could have been from water in a hot spring environment. The latest discovery adds compelling new evidence for ancient conditions that might have been favorable for life, according to members of the rover science team.

David Des Marais, an astrobiologist at NASA's Ames Research Center, Moffett Field, Calif., said, "What's so exciting is that this could tell us about environments that have similarities to places on Earth that are clement for organisms."

Spirit and its twin rover, Opportunity, completed their original three-month prime missions in April 2004. Both are still operating, though showing signs of age. One of Spirit's six wheels no longer rotates, so it leaves a deep track as it drags through soil. That churning has exposed several patches of bright soil, leading to some of Spirit's biggest discoveries at Gusev, including this recent discovery.

Doug McCuistion, director of NASA's Mars Exploration Program, said, "This unexpected new discovery is a reminder that Spirit and Opportunity are still doing cutting-edge exploration more than three years into their extended missions. It also reinforces the fact that significant amounts of water were present in Mars' past, which continues to spur the hope that we can show that Mars was once habitable and possibly supported life."

The newly discovered patch of soil has been given the informal name "Gertrude Weise," after a player in the All-American Girls Professional Baseball League, according to Ray Arvidson of Washington University in St. Louis, deputy principal investigator for the rovers.

"We've looked at dozens of disturbed soil targets in the rover tracks, and this is the first one that shows a high silica signature," said Ruff, who last month proposed using Spirit's miniature thermal emission spectrometer to observe this soil. That instrument provides mineral composition information about targets viewed from a distance. The indications it found for silica in the overturned soil prompted a decision this month to drive Spirit close enough to touch the soil with the alpha particle X-ray spectrometer. Silica commonly occurs on Earth as the crystalline mineral quartz and is the main ingredient in window glass. The Martian silica at the Gertrude Weise patch is non-crystalline, with no detectable quartz.

Spirit worked within about 50 yards or meters of the Gertrude Weise area for more than 18 months before the discovery was made. "This discovery has driven home to me the value of in-depth, careful exploration," Squyres said. "This is a target-rich environment, and it is a good thing we didn't go hurrying through it."

Meanwhile, on the other side of the planet, Opportunity has been exploring Victoria Crater for about eight months. "Opportunity has completed the initial survey of the crater's rim and is now headed back to the area called Duck Bay, which may provide a safe path down into the crater," said John Callas, project manager for the rovers at JPL.

NASA's Mars Rover Finds Evidence of Ancient Volcanic Explosion

PASADENA, Calif., (AScribe Newswire) -- NASA's Mars Exploration Rover Spirit has discovered evidence of an ancient volcanic explosion at "Home Plate," a plateau of layered bedrock approximately 2 meters (6 feet) high within the "Inner Basin" of Columbia Hills, at the rover's landing site in Gusev Crater. This is the first explosive volcanic deposit identified with a high degree of confidence by Spirit or its twin, Opportunity.

There is strong evidence that those layers are from a volcanic explosion, said Steve Squyres of Cornell University, Ithaca, N.Y. Squyres is principal investigator for the rovers' science instruments. The findings about volcanic activity are reported in a paper published in the May 4 issue of the journal Science.

Evidence shows the area near Home Plate is dominated by basaltic rocks. "When basalt erupts, it often does so as very fluid lava, rather than erupting explosively," Squyres said. "One way for basaltic lava to cause an explosion is for it to come into contact with water - it's the pressure from the steam that causes it to go boom."

Scientists suspect that the explosion that formed Home Plate may have been caused by an interaction of basaltic lava and water. "When you look at composition of the rocks in detail, there are hints that water may have been involved," Squyres said. One example is the high chlorine content of the rocks, which might indicate that basalt had come into contact with a brine.
One of the strongest pieces of evidence for an explosive origin for Home Plate is a "bomb sag" preserved in layered rocks on the lower slopes of the plateau. Bomb sags form in volcanic explosions on Earth when rocks ejected skyward by the explosion fall into soft deposits, deforming them as they land.

Spirit arrived at Home Plate in February 2006 and spent several months exploring it in detail before driving to "Low Ridge" to pass the Martian winter. Spirit has now returned to Home Plate to continue exploration there. "We decided to go back to Home Plate, once the Martian winter ended, because it is one of the most interesting places that we've found on Gusev Crater," Squyres said. "Last year we primarily explored the northern and eastern sides of it.

This time we're hoping to get to the southern and western sides." Spirit's continued exploration of Home Plate will focus largely on testing the idea that water was involved in its formation process.

Spirit and Opportunity are in their fourth year of exploring Mars. They successfully completed their three-month prime missions in April 2004, and the missions have been extended four times. As of April 26, Spirit had spent 1,177 sols, or Martian days, on the surface of Mars and had driven 7,095 meters (4.4 miles), and Opportunity had spent 1,157 sols and driven 10,509 meters (6.5 miles).

"Considering their age, both rovers are in good health. All science instruments are functioning and continuing to return superb science data," said John Callas, project manager of the Mars Exploration Rover mission at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

JPL manages the Mars Exploration Rover project for NASA's Science Mission Directorate. JPL is a division of the California Institute of Technology in Pasadena.