Ice cloud over Titan's south pole

Fig :  The recently formed south polar vortex stands out in the color-swaddled atmosphere of Saturn's largest moon, Titan, in this natural color view from NASA's Cassini spacecraft. NASA/JPL-Caltech/Space Science Institute

By Jet Propulsion Laboratory, Pasadena, California, NASA's Goddard Space Flight Center, Greenbelt, Maryland

 Published: April 12, 2013

An ice cloud taking shape over Titan’s south pole is the latest sign that the change of seasons is setting off a cascade of radical changes in the atmosphere of Saturn’s largest moon. Made from an unknown ice, this type of cloud has long hung over Titan’s north pole, where it is now fading, according to observations made by the composite infrared spectrometer (CIRS) on NASA’s Cassini spacecraft.

“We associate this particular kind of ice cloud with winter weather on Titan, and this is the first time we have detected it anywhere but the north pole,” said Donald E. Jennings of NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

The southern ice cloud, which shows up in the far infrared part of the light spectrum, is evidence that an important pattern of global air circulation on Titan has reversed direction. When Cassini first observed the circulation pattern, warm air from the southern hemisphere was rising high in the atmosphere and was transported to the cold north pole. There, the air cooled and sank down to lower layers of the atmosphere and formed ice clouds. A similar pattern, called a Hadley cell, carries warm, moist air from Earth’s tropics to the cooler middle latitudes.

Based on modeling, scientists had long predicted a reversal of this circulation once Titan’s north pole began to warm and its south pole began to cool. The official transition from winter to spring at Titan’s north pole occurred in August 2009. But because each of the moon’s seasons lasts about 7.5 Earth years, researchers still did not know exactly when this reversal would happen or how long it would take.

The first signs of the reversal came in data acquired in early 2012, which came shortly after the start of southern fall on Titan, when Cassini images and visual and infrared mapping spectrometer data revealed the presence of a high-altitude “haze hood” and a swirling polar vortex at the south pole. Both features have long been associated with the cold north pole. Later, Cassini scientists reported that infrared observations of Titan’s winds and temperatures made by CIRS had provided definitive evidence of air sinking, rather than upwelling, at the south pole. By looking back through the data, the team narrowed down the change in circulation to within six months of the 2009 equinox.

Despite the new activity at the south pole, the southern ice cloud had not appeared yet. CIRS didn’t detect it until about July 2012, a few months after the haze and vortex were spotted in the south.

“This lag makes sense because first the new circulation pattern has to bring loads and loads of gases to the south pole. Then, the air has to sink. The ices have to condense. And the pole has to be under enough shadow to protect the vapors that condense to form those ices,” said Carrie Anderson from Goddard.

At first blush, the southern ice cloud seems to be building rapidly. The northern ice cloud, on the other hand, was present when Cassini first arrived and has been slowly fading the entire time the spacecraft has been observing it.

So far, the identity of the ice in these clouds has eluded scientists, though they have ruled out simple chemicals, such as methane, ethane and hydrogen cyanide, which are typically associated with Titan. One possibility is that “species X,” as some team members call the ice, could be a mixture of organic compounds.

“What’s happening at Titan’s poles has some analogy to Earth and to our ozone holes,” said F. Michael Flasar of Goddard. “And on Earth, the ices in the high polar clouds aren’t just window dressing: They play a role in releasing the chlorine that destroys ozone. How this affects Titan chemistry is still unknown. So it’s important to learn as much as we can about this phenomenon, wherever we find it.”

Next Door Earth Like Planets

This artist’s conception shows a hypothetical habitable planet with two moons orbiting a red dwarf star. Astronomers have found that 6 percent of all red dwarf stars have an Earth-sized planet in the habitable zone, which is warm enough for liquid water on the planet’s surface. Since red dwarf stars are so common, then statistically the closest Earth-like planet should be only 13 light-years away. // David A. Aguilar (CfA)

By Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts

Published: February 6, 2013
 
Using publicly available data from NASA’s Kepler space telescope, astronomers at the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Massachusetts, have found that 6 percent of red dwarf stars have habitable Earth-sized planets. Since red dwarfs are the most common stars in our galaxy, the closest Earth-like planet could be just 13 light-years away.

“We thought we would have to search vast distances to find an Earth-like planet. Now, we realize another Earth is probably in our own backyard waiting to be spotted,” said Courtney Dressing from CfA.

Red dwarf stars are smaller, cooler, and fainter than our Sun. An average red dwarf is only one-third as large and one-thousandth as bright as the Sun. From Earth, no red dwarf is visible to the naked eye.

Despite their dimness, these stars are good places to look for Earth-like planets. Red dwarfs make up three out of every four stars in our galaxy for a total of at least 75 billion. The signal of a transiting planet is larger since the star itself is smaller, so an Earth-sized world blocks more of the star’s disk. And since a planet has to orbit a cool star closer in order to be in the habitable zone, it’s more likely to transit from our point of view.

Dressing culled the Kepler catalog of 158,000 target stars to identify all the red dwarfs. She then reanalyzed those stars to calculate more accurate sizes and temperatures. She found that almost all of those stars were smaller and cooler than previously thought.

Since the size of a transiting planet is determined relative to the star size, based on how much of the star’s disk the planet covers, shrinking the star shrinks the planet. And a cooler star will have a tighter habitable zone.

Dressing identified 95 planetary candidates orbiting red dwarf stars. This implied that at least 60 percent of such stars have planets smaller than Neptune. However, most weren’t quite the right size or temperature to be considered truly Earth-like. Three planetary candidates were both warm and approximately Earth-sized. Statistically, this means that 6 percent of all red dwarf stars should have an Earth-like planet.

“We now know the rate of occurrence of habitable planets around the most common stars in our galaxy,” said David Charbonneau from CfA. “That rate implies that it will be significantly easier to search for life beyond the solar system than we previously thought.”

Locating nearby Earth-like worlds may require a dedicated small space telescope or a large network of ground-based telescopes. Follow-up studies with instruments like the Giant Magellan Telescope and James Webb Space Telescope could tell scientists whether any warm, transiting planets have an atmosphere and further probe its chemistry.

Such a world would be different from our own. Orbiting so close to its star, the planet would probably be tidally locked. However, that doesn’t prohibit life since a reasonably thick atmosphere or deep ocean could transport heat around the planet. And while young red dwarf stars emit strong flares of ultraviolet light, an atmosphere could protect life on the planet’s surface. In fact, such stresses could help life evolve. “You don’t need an Earth clone to have life,” said Dressing.

Since red dwarf stars live much longer than Sun-like stars, this discovery raises the interesting possibility that life on such a planet would be much older and more evolved than life on Earth. “We might find an Earth that’s 10 billion years old,” said Charbonneau.

The three habitable-zone planetary candidates identified in this study are Kepler Object of Interest (KOI) 1422.02, which is 90 percent the size of Earth in a 20-day orbit; KOI 2626.01, 1.4 times the size of Earth in a 38-day orbit; and KOI 854.01, 1.7 times the size of Earth in a 56-day orbit. All three are located about 300 to 600 light-years away and orbit stars with temperatures between 5700° and 5900° Fahrenheit (3100° and 3300° Celsius). For comparison, our Sun’s surface is 10000° F (5500° C).

New Secrets of Super-Earths

Fig : A diagram comparing Earth, at left, to a cross-section of a super-Earth on the right. The super-Earth has a relatively small rocky core, an atmosphere of methane, water, and hydrogen, and an extended hydrogen envelope. // Credit: H. Lammer

By Royal Astronomical Society, United Kingdom


Published: February 4, 2013

In the past two decades, astronomers have found hundreds of planets in orbit around other stars. One type of these so-called “exoplanets” is the super-Earths that are thought to have a high proportion of rock but at the same time are significantly bigger than our world. Now, a new study led by Helmut Lammer of the Space Research Institute (IWF) of the Austrian Academy of Sciences suggests that these planets are actually surrounded by extended hydrogen-rich envelopes and that they are unlikely to ever become Earth-like. Rather than being super-Earths, these worlds are more like mini-Neptunes.

Super-Earths follow a different evolutionary track from the planets found in our solar system, but the question is whether they can evolve to become rocky bodies like the terrestrial planets Mercury, Venus, Earth, and Mars. To try to answer this, Lammer and his team looked at the impact of radiation on the upper atmospheres of super-Earths orbiting the stars Kepler-11, Gliese 1214, and 55 Cancri.

These planets are each a few times more massive and slightly larger than Earth and orbit close to their respective stars. The way in which the mass of planets scales with their sizes suggests that they have solid cores surrounded by hydrogen or hydrogen-rich atmospheres, probably captured from the clouds of gas and dust — nebulae — from which the planets formed.

The new model suggests that the short wavelength of extreme ultraviolet light — much bluer than the blue light we see with our eyes — of the host stars heats up the gaseous envelopes of these worlds so that they expand to several times the radius of each planet, and gas escapes from them fairly quickly. Nonetheless, most of the atmosphere remains in place over the whole lifetime of the stars that they orbit.

“Our results indicate that although material in the atmosphere of these planets escapes at a high rate, unlike lower-mass Earth-like planets, many of these super-Earths may not get rid of their nebula-captured hydrogen-rich atmospheres,” said Lammer.

Rather than becoming more like Earth, the super-Earths may more closely resemble Neptune, which together with Uranus is a smaller “gas giant” in our solar system. If the scientists’ results are right, then super-Earths farther out from their stars in the “habitable zone,” where the temperature would allow liquid water to exist, would hold on to their atmospheres even more effectively. If that happens, they would be much less likely to be habitable.
 

Glowing Titan in the Dark

Figure : This set of images from NASA's Cassini spacecraft shows Saturn's moon Titan glowing in the dark. Titan was behind Saturn at the time, in eclipse from the sun. The image on the left is a calibrated, but unprocessed image from Cassini's imaging camera. The image on the right was processed to exclude reflected light off Saturn, and it is clear that even where Titan did not receive any Saturnshine, it is still emitting light. Some light appears to be emanating from high in the atmosphere (noted by the outer dashed line at about 625 miles [1,000 kilometers] in altitude). But more surprisingly, most of it is diffusing up from lower down in the moon's haze, from about 190 miles (300km) above the surface. //Credit: NASA/JPL-Caltech/SSI

By Cassini Imaging Central Lab, Boulder, Colorado, Jet Propulsion Laboratory, 
Pasadena, California

Published: November 6, 2012
A literal shot in the dark by imaging cameras on NASA’s Cassini spacecraft has yielded an image of a visible glow from Titan, emanating not just from the top of Titan’s atmosphere, but also from deep in the atmosphere through the moon’s haze. A person in a balloon in Titan’s haze layer wouldn’t see the glow because it’s too faint — something like a millionth of a watt. Scientists were able to detect it with Cassini because the spacecraft’s cameras are able to take long-exposure images.

“It turns out that Titan glows in the dark, though very dimly,” said Robert West at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California. “It’s a little like a neon sign, where electrons generated by electrical power bang into neon atoms and cause them to glow. Here we’re looking at light emitted when charged particles bang into nitrogen molecules in Titan’s atmosphere.”

Scientists are interested in studying the input of energy from the Sun and charged particles into Titan’s atmosphere because it is at the heart of the natural organic chemistry factory that exists in Titan’s atmosphere.

“Scientists want to know what galvanizes the chemical reactions forming the heavy molecules that develop into Titan’s thick haze of organic chemicals,” said Linda Spilker, also from JPL. “This kind of work helps us understand what kind of organic chemistry could have existed on an early Earth.” The light, known as airglow, is produced when atoms and molecules are excited by ultraviolet sunlight or electrically charged particles. Cassini scientists already have seen an airglow from Titan’s nitrogen molecules caused by X-rays and ultraviolet radiation from the Sun when Titan was illuminated by our star. During 2009, Titan passed through Saturn’s shadow, offering a unique opportunity for Cassini instruments to observe any luminescence from Titan while in darkness. Cassini’s imaging cameras could see in very dim light by using exposure times of 560 seconds.

Scientists expected to see a glow in the high atmosphere (above 400 miles [700 kilometers] in altitude) where charged particles from the magnetic bubble around Saturn strip electrons off atmospheric molecules at Titan. Although an extremely weak emission was seen in that region, they were surprised to see Titan’s dark face glow in visible wavelengths of light from deeper in the atmosphere (at about 190 miles [300km] above the surface), as though illuminated by moonshine from nearby satellites.

The scientists took into account sunlight reflected off Saturn. There was still a glow from the part of Titan that was dark. The luminescence was diffusing up from too deep for charged particles from the Sun to be exciting atmospheric particles. The area also was not affected by the shooting of charged particles into the magnetic fields, which is what causes aurorae.

Scientists’ best guess is that the glow is being caused by deeper-penetrating cosmic rays or by light emitted due to some kind of chemical reaction deep in the atmosphere.

“This is exciting because we’ve never seen this at Titan before,” West said. “It tells us that we don’t know all there is to know about Titan and makes it even more mysterious.”

Scientists have previously reported that the night side of Venus’ atmosphere also produces a glow, called the ashen light. Some have suggested that lightning on Venus is responsible, although that explanation is not universally accepted. While Cassini’s radio-wave instrument has detected lightning at Saturn, it has not detected lightning at Titan. Scientists plan to keep looking for clues as Cassini continues to make its way around the Saturn system for another season.

Planets can form in the galactic center (Near a Black Hole)

Fig : In this artist's conception, a protoplanetary disk of gas and dust (red) is being shredded by the powerful gravitational tides of our galaxy's central black hole. // Credit: David A. Aguilar (CfA)
  
By Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts

  
Published: September 12, 2012
 
At first glance, the center of the Milky Way seems like a very inhospitable place to try to form a planet. Stars crowd each other as they whiz through space like cars on a rush-hour freeway. Supernova explosions blast out shock waves and bathe the region in intense radiation. Powerful gravitational forces from a supermassive black hole twist and warp the fabric of space itself.

Yet new research by astronomers at the Harvard-Smithsonian Center for Astrophysics (CfA) shows that planets still can form in this cosmic maelstrom. For proof, they point to the recent discovery of a cloud of hydrogen and helium plunging toward the galactic center. They argue that this cloud represents the shredded remains of a planet-forming disk orbiting an unseen star.

“This unfortunate star got tossed toward the central black hole. Now it’s on the ride of its life, and while it will survive the encounter, its protoplanetary disk won’t be so lucky,” said Ruth Murray-Clay of the CfA.

Last year, a team of astronomers discovered the cloud in question using the Very Large Telescope in Chile. The group speculated that it formed when gas streaming from two nearby stars collided, like windblown sand gathering into a dune.

Murray-Clay and colleague Avi Loeb propose a different explanation. Newborn stars retain a surrounding disk of gas and dust for millions of years. If one such star dived toward our galaxy’s central black hole, radiation and gravitational tides would rip apart its disk in a matter of years.

They also identify the likely source of the stray star — a ring of stars known to orbit the galactic center at a distance of about one-tenth of a light-year. Astronomers have detected dozens of young, bright O-type stars in this ring, which suggests that hundreds of fainter Sun-like stars also exist there. Interactions between the stars could fling one inward along with its accompanying disk.

Although this protoplanetary disk is being destroyed, the stars that remain in the ring can hold onto their disks. Therefore, they may form planets despite their hostile surroundings.

As the star continues its plunge over the next year, more and more of the disk’s outer material will be torn away, leaving only a dense core. The stripped gas will swirl down into the maw of the black hole. Friction will heat it to high enough temperatures that it will glow in X-rays.

“It’s fascinating to think about planets forming so close to a black hole,” said Loeb. “If our civilization inhabited such a planet, we could have tested Einstein’s theory of gravity much better, and we could have harvested clean energy from throwing our waste into the black hole.”

Dark matter near the Sun

Fig: The high-resolution simulation of the Milky Way used to test the mass-measuring technique. Image credit: Dr. A. Hobbs

By Royal Astronomical Society, United Kingdom

Published: August 9, 2012

 Astronomers have found large amounts of invisible dark matter near the Sun. Their results are consistent with the theory that the Milky Way Galaxy is surrounded by a massive “halo” of dark matter, but this is the first study of its kind to use a method rigorously tested against mock data from high-quality simulations. The scientists also have found tantalizing hints of a new dark matter component in our galaxy.

Swiss astronomer Fritz Zwicky first proposed dark matter in the 1930s. He found that clusters of galaxies were filled with a mysterious dark matter that kept them from flying apart. At nearly the same time, Jan Oort in the Netherlands discovered that the density of matter near the Sun was nearly twice what could be explained by the presence of stars and gas alone.

In the intervening decades, astronomers developed a theory of dark matter and structure formation that explains the properties of clusters and galaxies in the universe, but the amount of dark matter in the solar neighborhood has remained more mysterious. For decades after Oort’s measurement, studies found three to six times more dark matter than expected. Then last year new data and a new method claimed far less than expected. The community was left puzzled, generally believing that the observations and analyzes simply weren’t sensitive enough to perform a reliable measurement.

In this latest study, the astronomers are more confident in their measurement and its uncertainties. This is because they used a state-of-the-art simulation of our galaxy to test their mass-measuring technique before applying it to real data. This threw up a number of surprises. They found that standard techniques used over the past 20 years were biased, always tending to underestimate the amount of dark matter. They then devised a new unbiased technique that recovered the correct answer from the simulated data. Applying their technique to the positions and velocities of thousands of orange K dwarf stars near the Sun, they obtained a new measure of the local dark matter density.

“We are 99 percent confident that there is dark matter near the Sun,” said Silvia Garbari from the University of Zürich. “In fact, our favored dark matter density is a little high. There is a 10 percent chance that this is merely a statistical fluke. But with 90 percent confidence, we find more dark matter than expected. If future data confirms this high value, the implications are exciting. It could be the first evidence for a disk of dark matter in our galaxy, as recently predicted by theory and numerical simulations of galaxy formation. Or it could be that the dark matter halo of our galaxy is squashed, boosting the local dark matter density.”

Many physicists are placing their bets on dark matter being a new fundamental particle that interacts only weakly with normal matter — but strongly enough to be detected in experiments deep underground where confusing cosmic-ray events are screened by over a mile of solid rock.

An accurate measure of the local dark matter density is vital for such experiments. “If dark matter is a fundamental particle, billions of these particles will have passed through your body by the time you finish reading this article,” said George Lake from ETH Zürich. “Experimental physicists hope to capture just a few of these particles each year in experiments like XENON and CDMS currently in operation. Knowing the local properties of dark matter is the key to revealing just what kind of particle it consists of.”

NASA's New Mars Rover Sends Higher-Resolution Image

This is one of the first images taken by NASA's Curiosity rover, which landed on Mars the evening of Aug. 5 PDT (morning of Aug. 6 EDT). It was taken through a "fisheye" wide-angle lens on the left "eye" of a stereo pair of Hazard-Avoidance cameras on the left-rear side of the rover. The image is one-half of full resolution. The clear dust cover that protected the camera during landing has been sprung open. Part of the spring that released the dust cover can be seen at the bottom right, near the rover's wheel.

On the top left, part of the rover's power supply is visible.

Some dust appears on the lens even with the dust cover off.

The cameras are looking directly into the sun, so the top of the image is saturated. Looking straight into the sun does not harm the cameras. The lines across the top are an artifact called "blooming" that occurs in the camera's detector because of the saturation.

As planned, the rover's early engineering images are lower resolution. Larger color images from other cameras are expected later in the week when the rover's mast, carrying high-resolution cameras, is deployed.

Image Credit: NASA/JPL-Caltech 

By NASA Jet Propulsion Laboratory, CalTech
Published on : 6th August, 2012

About two hours after landing on Mars and beaming back its first image, NASA's Curiosity rover transmitted a higher-resolution image of its new Martian home, Gale Crater. Mission Control at NASA's Jet Propulsion Laboratory in Pasadena, Calif., received the image, taken by one of the vehicle's lower-fidelity, black-and-white Hazard Avoidance Cameras - or Hazcams.
The black-and-white, 512 by 512 pixel image, taken by Curiosity's rear-left Hazcam, can be found at: http://www.nasa.gov/mission_pages/msl/multimedia/msl5.html .

"Curiosity's landing site is beginning to come into focus," said John Grotzinger, project manager of NASA's Mars Science Laboratory mission, at the California Institute of Technology in Pasadena. "In the image, we are looking to the northwest. What you see on the horizon is the rim of Gale Crater. In the foreground, you can see a gravel field. The question is, where does this gravel come from? It is the first of what will be many scientific questions to come from our new home on Mars."

While the image is twice as big in pixel size as the first images beamed down from the rover, they are only half the size of full-resolution Hazcam images. During future mission operations, these images will be used by the mission's navigators and rover drivers to help plan the vehicle's next drive. Other cameras aboard Curiosity, with color capability and much higher resolution, are expected to be sent back to Earth over the next several days.

Curiosity landed at 10:32 p.m. Aug. 5, PDT, (1:32 a.m. EDT, Aug. 6) near the foot of a mountain three miles (about five kilometers) tall inside Gale Crater, 96 miles (nearly 155 kilometers) 7in diameter. During a nearly two-year prime mission, the rover will investigate whether the region has ever offered conditions favorable for microbial life, including the chemical ingredients for life.

The mission is managed by JPL for NASA's Science Mission Directorate in Washington. The rover was designed, developed and assembled at JPL, a division of Caltech.
For more information on the mission, visit:
http://www.nasa.gov/mars and http://marsprogram.jpl.nasa.gov/msl .
Follow the mission on Facebook and Twitter at
http://www.facebook.com/marscuriosity and http://www.twitter.com/marscuriosity
2012-231

Guy Webster / D.C. Agle 818-354-6278 / 818-393-9011
Jet Propulsion Laboratory, Pasadena, Calif.
guy.webster@jpl.nasa.gov / agle@jpl.nasa.gov

Dwayne Brown 202-358-1726
NASA Headquarters, Washington
dwayne.c.brown@nasa.gov

Higgs Boson's like Boson Found at CERN : A Ground Breaking Discovery in Particle Physics

Fig : A proton-proton collision event in the CMS experiment producing two high-energy photons (red towers). This is what we would expect to see from the decay of a Higgs boson but it is also consistent with background Standard Model physics processes. © CERN 2012

By CERN, Geneva

Published on 4 July 2012. 

At a seminar held at CERN today as a curtain raiser to the year’s major particle physics conference, ICHEP2012 in Melbourne, the ATLAS and CMS experiments presented their latest preliminary results in the search for the long sought Higgs particle. Both experiments observe a new particle in the mass region around 125-126 GeV.

“We observe in our data clear signs of a new particle, at the level of 5 sigma, in the mass region around 126 GeV. The outstanding performance of the LHC and ATLAS and the huge efforts of many people have brought us to this exciting stage,” said ATLAS experiment spokesperson Fabiola Gianotti, “but a little more time is needed to prepare these results for publication.”

"The results are preliminary but the 5 sigma signal at around 125 GeV we’re seeing is dramatic. This is indeed a new particle. We know it must be a boson and it’s the heaviest boson ever found,” said CMS experiment spokesperson Joe Incandela. “The implications are very significant and it is precisely for this reason that we must be extremely diligent in all of our studies and cross-checks."

“It’s hard not to get excited by these results,” said CERN Research Director Sergio Bertolucci. “ We stated last year that in 2012 we would either find a new Higgs-like particle or exclude the existence of the Standard Model Higgs. With all the necessary caution, it looks to me that we are at a branching point: the observation of this new particle indicates the path for the future towards a more detailed understanding of what we’re seeing in the data.”

The results presented today are labelled preliminary. They are based on data collected in 2011 and 2012, with the 2012 data still under analysis.  Publication of the analyses shown today is expected around the end of July. A more complete picture of today’s observations will emerge later this year after the LHC provides the experiments with more data.

The next step will be to determine the precise nature of the particle and its significance for our understanding of the universe. Are its properties as expected for the long-sought Higgs boson, the final missing ingredient in the Standard Model of particle physics? Or is it something more exotic? The Standard Model describes the fundamental particles from which we, and every visible thing in the universe, are made, and the forces acting between them. All the matter that we can see, however, appears to be no more than about 4% of the total. A more exotic version of the Higgs particle could be a bridge to understanding the 96% of the universe that remains obscure.

“We have reached a milestone in our understanding of nature,” said CERN Director General Rolf Heuer. “The discovery of a particle consistent with the Higgs boson opens the way to more detailed studies, requiring larger statistics, which will pin down the new particle’s properties, and is likely to shed light on other mysteries of our universe.”

Positive identification of the new particle’s characteristics will take considerable time and data. But whatever form the Higgs particle takes, our knowledge of the fundamental structure of matter is about to take a major step forward.

Cracks in the standard model

The latest results from the BaBar experiment may suggest a surplus over standard model predictions of a type of particle decay called “B to D-star-tau-nu.” In this conceptual art, an electron and positron collide, resulting in a B meson (not shown) and an antimatter B-bar meson, which then decays into a D meson and a tau lepton as well as a smaller antineutrino. Credit: Greg Stewart, SLAC National Accelerator Laboratory

Published by Science and Technology Facilities Council, United Kingdom
Published: June 19, 2012

Recently analyzed data from BaBar, a high-energy physics experiment in the U.S., may suggest possible flaws in the standard model of particle physics — the reigning description of how the universe works on subatomic scales. The data from BaBar, a particle accelerator at the U.S. Department of Energy’s (DOE) SLAC National Accelerator Laboratory, which was built by 10 countries including the United Kingdom, show that a particular type of particle decay happens more often than the standard model says it should.

The data refers to a particle called the B-bar meson that decays into a D meson, an antineutrino, and a tau lepton. This particular decay of a B meson should, theoretically, only happen in one in every 100 cases, but the new results from BaBar show it is happening too often. While the level of certainty of the difference, or excess, is not enough to claim a break from the standard model, the results are a potential sign of something amiss and are likely to impact existing theories.

“The excess over the standard model prediction is exciting,” said Michael Roney from the University of Victoria in Canada. “The results are significantly more sensitive than previously published studies of these decays. But before we can claim an actual discovery, other experiments have to replicate it and rule out the possibility this isn’t just an unlikely statistical fluctuation.”

“This result is very interesting, and, if confirmed, could be a sign of physics beyond the standard model,” said Adrian Bevan from Queen Mary, University of London.

“Our current theory about the fundamental forces of the universe, which has been around for nearly 40 years, is beginning to show signs of failure,” said Fergus Wilson from STFC’s Rutherford Appleton Laboratory. “Just as exciting, our new measurement indicates that any replacement theory will need to be more exotic and complex than we could have hoped or imagined. Although we must not jump to conclusions based on just one measurement, this new result is one of the most compelling yet. It follows on from previous indications recently reported by us, all of which point in the same direction.”

The BaBar experiment, which collected data from 1999 to 2008, was designed to explore various mysteries of particle physics, including why the universe contains matter but no antimatter. Data from the collaboration, which includes 75 institutions from Canada, France, Germany, Italy, Norway, Russia, Spain, the United Kingdom, and the U.S., helped confirm a matter-antimatter theory for which two researchers won the 2008 Nobel Prize in physics. At its peak, some 90 British particle physicists and engineers from 11 institutions took part in the experiment.

Researchers continue to apply BaBar data to a variety of questions in particle physics. “This result will help guide teams of researchers looking for potentially related new physics effects at the Large Hadron Collider and at other particle physics labs around the world,” said Bevan.

“If the excess decays shown are confirmed, it will be exciting to figure out what is causing it," said Abner Soffer from Tel Aviv University in Israel. “Other theories involving new physics are waiting in the wings, but the BaBar results already rule out one important model called the Two Higgs Doublet Model. We hope our results will stimulate theoretical discussion about just what the data are telling us about new physics.”

The researchers also hope their colleagues in the Belle collaboration, which studies the same types of particle collisions, see something similar. "If they do, the combined significance could be compelling enough to suggest how we can finally move beyond the standard model,” said Roney.

NASA Mars rover team aims for landing closer to prime science site

This image shows changes in the target landing area for Curiosity, the rover of NASA's Mars Science Laboratory project. The larger ellipse was the target area prior to early June 2012, when the project revised it to the smaller ellipse centered nearer to the foot of Mount Sharp, inside Gale Crater. Credit: NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS

By NASA Headquarters, Washington, D.C.

Published: June 18, 2012
 
NASA has narrowed the target for its most advanced Mars rover, Curiosity, which will land on the Red Planet in August. The car-sized rover will arrive closer to its ultimate destination for science operations, but also closer to the foot of a mountain slope that poses a landing hazard.

"We're trimming the distance we'll have to drive after landing by almost half," said Pete Theisinger from NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California. "That could get us to the mountain months earlier."

It was possible to adjust landing plans because of increased confidence in precision landing technology aboard the Mars Science Laboratory (MSL) spacecraft, which is carrying the Curiosity rover. That spacecraft can aim closer without hitting Mount Sharp at the center of Gale Crater. Rock layers located in the mountain are the prime location for research with the rover.

Curiosity is scheduled to land at approximately 1:31 a.m. EDT August 6. Following checkout operations, Curiosity will begin a two-year study of whether the landing vicinity ever offered an environment favorable for microbial life.

The landing target ellipse had been approximately 12 miles (20 kilometers) wide and 16 miles (25km) long. Continuing analysis of the new landing system's capabilities has allowed mission planners to shrink the area to approximately 4 miles (7km) wide and 12 miles (20km) long, assuming winds and other atmospheric conditions are as predicted.

Even with the smaller ellipse, Curiosity will be able to touch down at a safe distance from steep slopes at the edge of Mount Sharp.

"We have been preparing for years for a successful landing by Curiosity, and all signs are good," said Dave Lavery from NASA. "However, landing on Mars always carries risks, so success is not guaranteed. Once on the ground, we'll proceed carefully. We have plenty of time since Curiosity is not as life-limited as the approximate 90-day missions like NASA’s Mars Exploration Rovers and the Phoenix lander.”

Since the spacecraft was launched in November 2011, engineers have continued testing and improving its landing software. MSL will use an upgraded version of flight software installed on its computers during the past two weeks. Additional upgrades for Mars surface operations will be sent to the rover about a week after landing.

Other preparations include upgrades to the rover's software and understanding effects of debris coming from the drill the rover will use to collect samples from rocks on Mars. Experiments at JPL indicate that Teflon from the drill could mix with the powdered samples. Testing will continue past landing with copies of the drill. The rover will deliver the samples to onboard instruments that can identify mineral and chemical ingredients.

"The material from the drill could complicate but will not prevent analysis of carbon content in rocks by one of the rover's 10 instruments. There are workarounds,” said John Grotzinger from the California Institute of Technology in Pasadena. "Organic carbon compounds in an environment are one prerequisite for life. We know meteorites deliver non-biological organic carbon to Mars, but not whether it persists near the surface. We will be checking for that and for other chemical and mineral clues about habitability."

Curiosity will be in good company as it nears landing. Two NASA Mars orbiters, along with a European Space Agency (ESA) orbiter, will be in position to listen to radio transmissions as MSL descends through Mars' atmosphere.