Wednesday, October 31, 2007

Massive Black Hole Smashes Record


Using two NASA satellites, astronomers have discovered the heftiest known black hole to orbit a star. The new black hole, with a mass 24 to 33 times that of our Sun, is more massive than scientists expected for a black hole that formed from a dying star.

The newly discovered object belongs to the category of "stellar-mass" black holes. Formed in the death throes of massive stars, they are smaller than the monster black holes found in galactic cores. The previous record holder for largest stellar-mass black hole is a 16-solar-mass black hole in the galaxy M33, announced on October 17.

"We weren’t expecting to find a stellar-mass black hole this massive," says Andrea Prestwich of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., lead author of the discovery paper in the November 1 Astrophysical Journal Letters. "It seems likely that black holes that form from dying stars can be much larger than we had realized."

The black hole is located in the nearby dwarf galaxy IC 10, 1.8 million light-years from Earth in the constellation Cassiopeia. Prestwich’s team could measure the black hole’s mass because it has an orbiting companion: a hot, highly evolved star. The star is ejecting gas in the form of a wind. Some of this material spirals toward the black hole, heats up, and gives off powerful X-rays before crossing the point of no return.

In November 2006, Prestwich and her colleagues observed the dwarf galaxy with NASA’s Chandra X-ray Observatory. The group discovered that the galaxy’s brightest X-ray source, IC 10 X-1, exhibits sharp changes in X-ray brightness. Such behavior suggests a star periodically passing in front of a companion black hole and blocking the X-rays, creating an eclipse. In late November, NASA’s Swift satellite confirmed the eclipses and revealed details about the star’s orbit. The star in IC 10 X-1 appears to orbit in a plane that lies nearly edge-on to Earth’s line of sight, The Swift observations, as well as observations from the Gemini Telescope in Hawaii, told Prestwich and her group how fast the two stars go around each other. Calculations showed that the companion black hole has a mass of at least 24 Suns.

There are still some uncertainties in the black hole’s mass estimate, but as Prestwich notes, "Future optical observations will provide a final check. Any refinements in the IC 10 X-1 measurement are likely to increase the black hole’s mass rather than reduce it."

The black hole’s large mass is surprising because massive stars generate powerful winds that blow off a large fraction of the star’s mass before it explodes. Calculations suggest massive stars in our galaxy leave behind black holes no heavier than about 15 to 20 Suns.

The IC 10 X-1 black hole has gained mass since its birth by gobbling up gas from its companion star, but the rate is so slow that the black hole would have gained no more than 1 or 2 solar masses. "This black hole was born fat; it didn’t grow fat," says astrophysicist Richard Mushotzky of NASA Goddard Space Flight Center in Greenbelt, Md., who is not a member of the discovery team.

The progenitor star probably started its life with 60 or more solar masses. Like its host galaxy, it was probably deficient in elements heavier than hydrogen and helium. In massive, luminous stars with a high fraction of heavy elements, the extra electrons of elements such as carbon and oxygen "feel" the outward pressure of light and are thus more susceptible to being swept away in stellar winds. But with its low fraction of heavy elements, the IC 10 X-1 progenitor shed comparatively little mass before it exploded, so it could leave behind a heavier black hole.

"Massive stars in our galaxy today are probably not producing very heavy stellar-mass black holes like this one," says coauthor Roy Kilgard of Wesleyan University in Middletown, Conn. "But there could be millions of heavy stellar-mass black holes lurking out there that were produced early in the Milky Way’s history, before it had a chance to build up heavy elements."

Hubble Spies Shells Of Sparkling Stars Around Quasar


New images taken with NASA's Hubble Space Telescope -- part of a research project led by UC Riverside's Gabriela Canalizo -- have revealed the wild side of an elliptical galaxy, nearly two billion light-years away, that previously had been considered mild-mannered.

The Hubble photos show shells of stars around a bright quasar, known as MC2 1635+119, which dominates the center of the galaxy. The presence of the shells is an indication of a titanic clash with another galaxy in the relatively recent past.

The collision, which is funneling gas into the galaxy's center, is feeding a supermassive black hole. The accretion onto the black hole is the quasar's energy-source.

"This observation supports the idea that some quasars are born from interactions between galaxies," said Canalizo, an assistant professor of astrophysics in the Department of Physics and Astronomy, and a member of the Institute of Geophysics and Planetary Physics. "It also provides more evidence that mergers are crucial for triggering quasars. Most quasars were active in the early universe, which was smaller, so galaxies collided more frequently.

"Astronomers have long speculated that quasars are fueled by interactions that bring an inflow of gas to the black holes in the centers of galaxies. Since this quasar is relatively nearby, it is a great laboratory for studying how more distant quasars are turned on."

Canalizo explained that the period of time when the central black hole of a galaxy is actively accreting material as a quasar is believed to be an essential phase in the evolution of most galaxies.

"For many decades now, there has been much debate regarding whether galaxy mergers or collisions are responsible for fueling their central black holes and turning them into quasars," she said.

Discovered nearly 50 years ago, quasars are among the brightest objects in the universe. They reside in the centers of galaxies and are powered by supermassive black holes.

Previous studies of the MC2 1635+119 galaxy with ground-based telescopes showed a normal-looking elliptical containing an older population of stars. It took the razor-sharp vision of Hubble's Advanced Camera for Surveys and the spectroscopic acuity of the W.M. Keck Observatory in Hawaii to uncover the faint, thin shells.

The new Hubble observations reveal at least five inner shells and additional debris traveling away from the galaxy's center. The shells, which sparkle with stars, resemble ripples forming in a pond when a stone is tossed in. They formed when a galaxy was shredded by tidal forces during the collision. Some of the galaxy's stars were swept up in the elliptical galaxy's gravitational field, creating the outward-moving shells. The farthest shell is about 40,000 light-years away from the center.

"This is the most spectacular shell galaxy seen at this distance," said team member Francois Schweizer of the Carnegie Observatories in Pasadena, California.

Computer simulations estimate that the encounter happened 1.7 billion years ago. The merger itself occurred over a few hundred million years and stoked a flurry of star birth. Spectroscopic data from Keck reveal that many of the stars in the galaxy are 1.4 billion years old, consistent with the age of the merger.

The shell stars are mixing with the stars in the galaxy as they travel outward. Eventually, the shells will dissipate and the stars will be scattered throughout the galaxy.

"This could be a transitory phase, common to most ellipticals, that lasts only 100 million to a billion years," Canalizo said. "So, seeing these shells tells us that the encounter occurred in the relatively recent past. Hubble caught the shells at the right time."

Canalizo and her team have yet to determine the type of merger responsible for the shells and the quasar activity. Their evidence, however, points to two possible collision scenarios.

"The shells' formation and the current quasar activity may have been triggered by an interaction between two large galaxies or between a large galaxy and a smaller galaxy," explained team member Nicola Bennert of UCR, who did all of the data processing and quantitative measurements, as well as a large fraction of the analysis. "We need high-resolution spectroscopic observations of the quasar host galaxy to determine the type of merger."

The quasar is part of an Advanced Camera for Surveys study of five galaxies, all roughly 2 billion light-years away, that are known to harbor quasars. According to Canalizo, the other four galaxies analyzed also display evidence of encounters. Her team also is using Hubble's Wide Field Planetary Camera 2 to sample 14 more galaxies with quasars.

"We want to know whether most quasars at current epochs begin their lives as mergers, or whether they simply occur in old ellipticals to which nothing very interesting has happened recently," Canalizo said.

Tuesday, October 30, 2007

Two Scientists Say Dark Matter Doesn't Exist


Two Canadian astronomers think there is a good reason dark matter, a mysterious substance thought to make up the bulk of matter in the universe, has never been directly detected: It doesn't exist.

Dark matter was invoked to explain how galaxies stick together. The visible matter alone in galaxies—stars, gas and dust—is nowhere near enough to hold them together, so scientists reasoned there must be something invisible that exerts gravity and is central to all galaxies.

Last August, an astronomer at the University of Arizona at Tucson and his colleagues reported that a collision between two huge clusters of galaxies 3 billion light-years away, known as the Bullet Cluster, had caused clouds of dark matter to separate from normal matter. Many scientists said the observations were proof of dark matter's existence and a serious blow for alternative explanations aiming to do away with dark matter with modified theories of gravity.

Now John Moffat, an astronomer at the University of Waterloo in Canada, and Joel Brownstein, his graduate student, say those announcements were premature.

In a study detailed in the Nov. 21 issue of the Monthly Notices of the Royal Astronomical Society, the pair says their Modified Gravity (MOG) theory can explain the Bullet Cluster observation. MOG differs from other modified gravity theories in its details, but is similar in that it predict that the force of gravity changes with distance.

"MOG gravity is stronger if you go out from the center of the galaxy than it is in Newtonian gravity," Moffat explained. "The stronger gravity mimics what dark matter does. With dark matter, you take Einstein and Newtonian gravity and you shovel in more dark matter. If there's more matter, you get more gravity. Whereas for me, I say dark matter doesn't exist. It's the gravity that's changed."

Using images of the Bullet Cluster made by the Hubble, Chandra X-ray and Spitzer space telescopes and the Magellan telescope in Chile, the scientists analyzed the way the cluster's gravity bent light from a background galaxy—an effect known as gravity lensing. The pair concluded that dark matter was not necessary to explain the results.

"Using Modified Gravity theory, the 'normal' matter in the Bullet Cluster is enough to account for the observed gravitational lensing effect," Brownstein said. "Continuing the search for and then analyzing other merging clusters of galaxies will help us decide whether dark matter or MOG theory offers the best explanation for the large scale structure of the universe."

Moffat compares the modern interest with dark matter to the insistence by scientists in the early 20th century on the existence of a "luminiferous ether," a hypothetical substance thought to fill the universe and through which light waves were thought to propagate.

"They saw a glimpse of special relativity, but they weren't willing to give up the ether," Moffat told SPACE.com. "Then Einstein came along and said we don't need the ether. The rest was history."

Douglas Clowe, the lead astronomer of the team that linked the Bullet Cluster observations with dark matter (and now at Ohio University), says he still stands by his original claim. For him and many other astronomers, conjuring up new particles that might account for dark matter is more palatable than turning a fundamental theory of how the univese works on its head.

"As far as we're concerned, [Moffat] hasn't done anything that makes us retract our earlier statement that the Bullet Cluster shows us that we have to have dark matter," Clowe said. "We're still open to modifying gravity to reduce the amount of dark matter, but we're pretty sure that you have to have most of the mass of the universe still in some form of dark matter."

Astronomers Simulate Life And Death In The Universe



Stars always evolve in the universe in large groups, known as clusters. Astronomers distinguish these formations by their age and size. The question of how star clusters are created from interstellar gas clouds and why they then develop in different ways has now been answered by researchers at the Argelander Institute for Astronomy at the University of Bonn with the aid of computer simulations. The scientists have solved -- at least at a theoretical level -- one of the oldest astronomical puzzles, namely the question of whether star clusters differ in their internal structure.

Astronomical observations have shown that all stars are formed in star clusters. Astronomers distinguish between, on the one hand, small and, by astronomical standards, young star clusters ranging in number from several hundred to several thousand stars and, on the other, large high-density globular star clusters consisting of as many as ten million tightly packed stars which are as old as the universe. No one knows how many star clusters there might be of each type, because scientists have not previously managed to fully compute the physical processes behind their genesis.

Stars and star clusters are formed as interstellar gas clouds collapse. Within these increasingly dense clouds, individual "lumps" emerge which, under their own gravitational pull, draw ever closer together and finally become stars. Similar to our "solar wind", the stars send out strong streams of charged particles. These "winds" literally sweep out the remaining gas from the cloud. What remains is a cluster that gradually disintegrates until its component stars can move freely in the interstellar space of the Milky Way.

Scientists believe that our own sun arose within a small star cluster which disintegrated in the course of its development. "Otherwise our planetary system would probably have been destroyed by a star moving close by," says Professor Dr. Pavel Kroupa of the Argelander Institute for Astronomy at Bonn University. In order to achieve a better understanding of the birth and death of stellar aggregations Professor Kroupa and Dr. Holger Baumgardt have developed a computer programme that simulates the influence of the gases remaining in a cluster on the paths taken by stars.

Heavy star clusters live longer

The main focus of this research has been on the question of what the initial conditions must look like if a new-born star cluster is to survive for a long time. The Bonn astronomers discovered that clusters below a certain size are very easily destroyed by the radiation of their component stars. Heavy star clusters, on the other hand, enjoy significantly better "survival chances".

For astronomers, another important insight from this work is that both light and heavy star clusters do have the same origins. As Professor Kroupa explains, "It seems that when the universe was born there were not only globular clusters but also countless mini star clusters. A challenge now for astrophysics is to find their remains." The computations in Bonn have paved the way for this search by providing some valuable theoretical pointers.

The Argelander Institute has recently been equipped with five "GRAPE Computers", which operate at speeds 1,000 times higher than normal PCs. They are being deployed not only in research but also for research-related teaching: "Thanks to the GRAPE facilities, our students and junior academics are learning to exploit the power of supercomputers and the software developed specially for them." The Argelander Institute is regarded world-wide as a Mecca for the computation of stellar processes. Despite their enormous calculating capacity, the machines require several weeks to complete the simulation.

Dazzling Comet Has Hint of Invisible Tail


A comet that has engaged skywatchers worldwide with its sudden outburt has had one disappointing aspect: no tail.

Comet Holmes brightened suddenly and dramatically last week, going from total obscurity to naked-eye brightness that rivaled some of the brighter stars in the sky. But without a tail, the gas and dust ejected by the comet left it looking like no more than a fuzzy tennis ball through backyard telescopes.

Now astronomers think they've found a hint of a tail. Don't expect to see it for yourself, however.

A new image made using near-infrared light, which humans can't see, shows a small, tail-like feature next to the comet's nucleus. The image was obtained by graduate student Sandie Bouchard and assistant Bernard Malenfant on the pre-dawn hours of Oct. 26 using the Ritchey-Chretien telescope at Mont Megantic Observatory in Canada.

A preliminary analysis, performed by astronomers Pierre Bastien and Rene Doyon from University of Montreal and the Centre de Recherche en Astrophysique du Quebec (CRAQ) clearly shows a bright elongated feature.

However, the direction of the feature does not point directly away from the sun, as expected. Comet tails are formed when pressure from sunlight pushes inexorably on the material in the head, which surrounds the solid nucleus. This material—gas, dust, and ice particles—is typically pushed away from the sun to form the tail.

Astronomers don't know why the outburst occurred. Comet Holmes has been known for more than a century but has been quiet for decades, visible only through powerful telescopes.

Monday, October 29, 2007

Rocketplane Unveils New Suborbital Vehicle Design


Rocketplane Global, Inc. has finalized significant changes to their suborbital vehicle the Rocketplane XP. The changes are focused at making the vehicle more responsive to the emerging sub-orbital tourism market and also represent refinements to the engineering design.

The changes include seating for five passengers in an all new airframe, the addition of afterburning jet engines and an interior designed by internationally renowned and award winning industrial designer, Frank Nuovo.

Key to the engineering changes are:

New Airframe: Rocketplane has moved from a Learjet based airframe to an all new airframe design that affords weight savings and more flexibility in packaging the vehicle systems. The fuselage change has allowed the cabin to be enlarged significantly and provides room for five passengers in a first class seating arrangement. The larger cabin also allows the vehicle to carry more microgravity payloads during science missions.

T-Tail: Through extensive engineering analysis and wind tunnel testing a new T-Tail has been adopted that is lighter, safer and provides more aerodynamic control.

Afterburning Engines: The J-85 afterburning jet engines provide increased thrust and allow the vehicle to reach an altitude of greater than 40,000 ft before the rocket engine is ignited.

Landing Gear: A new landing gear system designed by Loud Engineering and Manufacturing. Loud is the OEM of the F-5 landing gear, of which the XP landing gear will be based.

The culmination of all these changes has resulted in a modest 10% increase in weight that is more than offset by a 40% increase in thrust which allows a 66% increase in the passenger carrying capability of the vehicle.

Dave Faulkner, Program Manager of Rocketplane Global said, "The engineering changes are the culmination of more than 200,000 hours of engineering work by the company and its contractors to date. For almost a year and a half the company has been working on these changes that stemmed from work done in the early days of the project. Since that time these changes have been incorporated into the design, but have not been released to the public."

David also said, "Accompanying the engineering changes is the addition of an innovative new cabin interior designed by Frank Nuovo. We are very pleased to bring Frank Nuovo onto our team to merge the vehicle engineering with the aesthetic and ergonomic design of the interior. We believe that the direction he is taking will complement the truly unique experience the Rocketplane will provide to our passengers."

NASA crew completes second space walk, discovers damage

US astronauts completed the second of five spacewalks Sunday, beginning the relocation of a key supporting truss but also detecting a problem with one of the mechanisms supporting an key energy unit of the International Space Station.

Damage was discovered in a joint supporting the station's solar arrays, a problem that NASA engineers will now have to solve.

US astronaut Daniel Tani noticed metal shavings and unusual wear on a race ring of a rotary joint used to rotate the arrays, NASA officials said.

"The joint has been showing some increased friction lately, and engineers are analyzing potential causes," the National Aeronautics and Space Administration said in a statement.

The second spacewalk started at 0932 GMT and finished at 1605 GMT, with space shuttle Discovery astronauts Tani and Scott Parazynski removing bolts in preparation for the installation Tuesday of a truss that will support a set of the station's key solar panels.

The truss is the biggest piece of equipment yet to be moved around on the station on this latest mission to the ISS, during which the astronauts will perform a record five spacewalks totaling some 30 hours.

The ISS, a giant manned laboratory orbiting 240 miles (390 kilometers) above Earth, is aimed to be a potential jumping-off point for further exploration of the solar system.

The 100-billion-dollar space station, supported by 16 countries, is considered key to US ambitions to send a manned mission to Mars and is due to be completed within three years.

During Sunday's walk mission specialist Parazynski and Tani, a flight engineer, disconnected truss cables from the top of the station, where the assembly was installed temporarily in 2000.

Then the spacestation'sroboticarm, operated by astronauts inside the ISS,movedit toanovernightparkingposition. It will be installed in a new spot on the ISS during further spacewalks over the coming days.

The spacewalkers will also complete theexternaloutfittingofthe Harmony module, a new compartment recently installed on the station.

A team of astronauts earlier entered Harmony, a newly delivered compartment, and began preparing it for its role in connecting two future laboratories to the station -- Japan's Kibo lab and the Colombus from Europe.

"Harmony is a very good name for this module," said space station commander Peggy Whitson. "It represents the culmination of a lot of international partner work and will allow international partner modules to be added on."

The bus-size module was attached to the station during the first spacewalk of the mission on Friday.

"Everything is going great," said Rick LaBrode, the mission manager of the Discovery shuttle that blasted the NASA crew into space, on Saturday.

The current mission is making space exploration history as shuttle Commander Pam Melroy, 46, and Whitson, 47, are the first women to hold the reins of the two spacecraft at the same time.

The shuttle is to be retired in 2010 to make way for Constellation, a new space exploration project that aims to put humans back on the moon by 2020.

Sunday, October 28, 2007

Mars With Ice: Detailed Picture Of Frigid Red Planet Emerges


Mars, like Earth, is a climate-fickle water planet. The main difference, of course, is that water on the frigid Red Planet is rarely liquid, preferring to spend almost all of its time traveling the world as a gas or churning up the surface as ice. That's the global picture literally and figuratively coming into much sharper focus as various Mars-orbiting cameras send back tomes of unprecedented super high-resolution imagery of ever vaster tracts of the planet's surface.

What were just a few years ago small hints about Mars' water and climate, as seen in a few "postage-stamp" high-resolution images and topography, have given way to broader theory that explains not only the features seen on the planet today, but imply a dynamic history of Martian climate change.

"When you have postage stamps, it's like studying a hair on an arm instead of the whole arm," said Mars researcher James Head III of Brown University. Head will present the latest integrated global view of Martian surface features and how they fit with Martian climate models on October 28, 2007, at the Geological Society of America Annual Meeting in Denver.

The pictures now reveal a range of ice-made features that show a strong preference to certain latitudes, Head explains. As on Earth, latitude-dependent features can mean only one thing: latitude-dependent climate.

The signs of water ice are obvious today at Mars' poles. But as you move towards the equator, there is plenty of evidence of water ice having shaped the surface in different ways not so long ago.

Not far from either pole, for instance, widespread bumpy polygonal patterned ground suggests the contraction and expansion of icy permafrost ground — very similar to that seen in Earth's Arctic and Antarctic. Next, between 30 and 60 degrees latitude in both hemispheres, the patterned ground gives way to a pervasive pitted texture of once ice-rich dust deposits. Even closer to the equator on the flanks of Mars' equatorial volcanoes are compelling signs of large glaciers, almost exactly like those of Earth. There are also craters which seem to be filled with glacial debris and small valleys which drop precipitously into canyons — which on Earth is usually a strong indicator that a glacier once filled and widened the canyon.

As for where all the ice went, much of it was sublimed away and deposited at the poles. The ice rules the more temperate latitudes only when the tilt of Mars' spin axis is far more extreme than today — up to 45 degrees. That tilt, or obliquity, exposed the poles to a lot more sun during the course of a Martian year, according to climate models, evaporating the ice caps. That same water refroze on the surface in the then darker and colder equatorial and middle latitudes, hence all the evidence of ice and glaciers.

"It's a quest to understand the Martian water cycle," said Head describing his work.

Among the instruments used to study Mars are the Mars Global Surveyor's Laser Altimeter (MOLA) and Camera (MOC), the Mars Reconnaissance Orbiter's Context Camera (CTX) and High Resolution Imaging Science Experiment (HiRISE), and the Mars Express's High Resolution Stereo Camera (HRSC).

Saturday, October 27, 2007

Mystery Comet Explodes Into Brightness


A once-faint comet has made a sudden leap from obscurity to center stage. Comet 17P Holmes, now visible to northern hemisphere residents, increased its brightness by a factor of one million this week, going from magnitude 17 to 2. This makes it visible to the unaided eye as well as binoculars and telescopes, offering a unique viewing opportunity for sky watchers.

"This is a terrific outburst," said Brian Marsden, director emeritus of the Minor Planet Center, which tracks known comets and asteroids. "And since it doesn’t have a tail right now, some observers have confused it with a nova. We’ve had at least two reports of a new star."

Comet Holmes is located in the constellation Perseus and is visible for most of the night. In fact, for observers at the latitude of Boston, the comet is circumpolar, never setting below the horizon. In appearance, it resembles a fuzzy, yellowish star.

The comet could fade in a matter of days or weeks, so astronomers recommend that viewers take a look now.

Amateur astronomer Edwin Holmes, who was looking at the Andromeda galaxy at the time, discovered Comet Holmes in 1892. The comet has presented a mystery to astronomers ever since. It likely was undergoing a similar outburst when discovered, since it reached 4th magnitude and was faintly visible to the unaided eye. After fading, it brightened again by a factor of 100 in January 1893 before fading again for good.

The comet orbits the Sun once every 7 years at a distance of about 200 million miles (compared to Earth’s 93-million-mile orbit). As a result, it was re-observed in 1899 and 1906 before being lost for nearly six decades. Based on a prediction by Marsden, the comet was recovered in 1964.

"Since then, it’s been behaving well – until now," says Marsden.

On October 23rd, the comet was a dim 17th magnitude, 25,000 times too faint to be seen with the unaided eye. One day later, it had brightened to 7th magnitude, and the most recent observations peg it at magnitude 2 to 3: an increase of a factor of one million. (The magnitude scale used by astronomers is logarithmic.)

"When the Deep Impact probe hit Comet 9P Tempel, there was almost no change in brightness," says Marsden. "This outburst by Comet Holmes is extreme!"

Indeed, the outburst has left experts scratching their heads. How could a tiny comet, whose nucleus is no more than two miles across, grow so bright so fast? Perhaps a crack opened in the comet’s surface, exposing fresh ice to the sun and causing an explosive eruption of dust and gas. No one knows for sure. Undoubtedly, professional astronomers will be studying it closely in the weeks to come.

Friday, October 26, 2007

First Known Belt Of Moonlets In Saturn's Rings Detected


A narrow belt harboring moonlets as large as football stadiums discovered in Saturn's outermost ring probably resulted when a larger moon was shattered by a wayward asteroid or comet eons ago, according to a University of Colorado at Boulder study.

Images taken by a camera onboard the NASA Cassini spacecraft revealed a series of eight propeller-shaped "wakes" in a thin belt of the outermost "A" ring, indicating the presence of corresponding moonlets, said CU-Boulder Research Associate Miodrag Sremcevic, lead author of the study published in the Oct. 25 issue of Nature. The propeller wakes highlight tiny areas of the belt where ring material has been perturbed by the gravitational forces caused by individual moonlets, Sremcevic said.

The team calculated that there likely are thousands of moonlets ranging in size from semi-trailers to sports arenas embedded in the "A" ring's thin moonlet belt that circles the planet. At about 2,000 miles across, the belt of moonlets is only about 1/80th the diameter of Saturn's total ring system, which at roughly 155,000 miles across would stretch about two-thirds of the way from Earth to the moon.

"This is the first evidence of a moonlet belt in any of Saturn's rings," said Sremcevic of CU-Boulder's Laboratory for Atmospheric and Space Physics. "We have firmly established these moonlets exist in a relatively narrow region of the "A" ring, and the evidence indicates they are remnants of a larger moon that was shattered by a meteoroid or comet."

Co-authors of the Nature study include Juergen Schmidt, Martin Seiss and Frank Spahn of the University of Potsdam in Germany, Heikko Salo of the University of Oulu in Finland, and Nicole Albers of CU-Boulder's LASP. The images were taken by the Narrow Angle Camera onboard the NASA Cassini spacecraft, which was launched in 1997 and has been orbiting the Saturn system since July 2004.

Each propeller feature is about 10 miles long, said Sremcevic, who with Spahn first predicted the existence of such propellers in Saturn's rings as an undergraduate at the University of Belgrade in 2000. While four propellers were discovered in the "A" ring in 2006 by a team led by Cornell University, Sremcevic and his colleagues looked at a much larger image sequence, allowing them to extrapolate statistically and confirm the presence of thousands of small objects in the "A" ring's moonlet belt.

The moonlets may be the result of the break-up of a ring-moon similar to Pan -- Saturn's innermost 20-mile diameter moon -- that was smashed by a comet or meteor, the team concluded. The team calculated the mass of the unseen moonlets in the belt greater than 50 feet in diameter to arrive at the estimated size of the moon involved in the collision creating the belt.

The finding supports the theory that Saturn's rings initially were created in a "collisional cascade" of ring debris begun by a catastrophic break-up of an even larger moon in the Saturn system first proposed by CU-Boulder planetary scientists Larry Esposito and Joshua Colwell in 1987. The moonlets in the newly discovered belt may have formed after Saturn's rings already were in place, which planetary scientists speculate could have been hundreds of millions or even billions of years ago.

"It seems unlikely that moonlets are remainders of a single catastrophic event that created the whole ring system, because in this case a uniform distribution would emerge," the researchers wrote in Nature. "Instead, the moonlet belt is compatible with a more recent body orbiting in the A ring."

Esposito, who was not involved in the study, said the propellers "show a striking demonstration of the lingering effects of the gravity from these small, embedded moonlets." Esposito is the chief scientist on the NASA Cassini mission's $12.5 million Ultra-Violet Imaging Spectrograph designed and built at LASP.

Sremcevic said the discovery of the moonlet belt is another piece in the puzzle regarding the formation and evolution of Saturn's rings. "We believe future studies of ring evolution will need to incorporate the findings and implications from this study."

Possible Cosmic Defect, Remnant From Big Bang, Discovered


Scientists from the Institute of Physics of Cantabria (IFCA) and the University of Cambridge may have discovered an example of a cosmic defect, a remnant from the Big Bang called a texture. If confirmed, their discovery, reported in Science, will provide dramatic new insight into how the universe evolved following the Big Bang.

Textures are defects in the structure of the vacuum left over from the hot early universe. Professor Neil Turok of Cambridge's Department of Applied Mathematics and Theoretical Physics first showed how textures form in the 1990s, highlighting that some would survive from the Big Bang and should be visible in today's universe. Textures can be observed by the hot and cold spots they create in the cosmic microwave background radiation (CMB) which fills the universe and was released in the Big Bang 14 billion years ago.

The Big Bang theory proposes that the cosmos began in a very high density, high temperature state, cooling as it expands. In the early hot universe, physicists believe that the different types of elementary particle (particles such as a quark from which larger particles are created) behaved identically. As the universe cooled, the vacuum changed and the symmetry between the particles was broken, in a phase transition analogous to the freezing of water. During this kind of phase transition, quarks become distinct from electrons and neutrinos, for example.

Just as misalignments in the crystalline structure of ice lead to defects, misalignments in the symmetry-breaking pattern form cosmic defects. Textures, such as the one which may have been discovered, are one type of defect.

Professor Turok provides the following analogy: "Imagine a large crowd of people with everyone standing. To any person in it, the crowd looks roughly the same in all directions. Now tell them all to lie down. People would tend to lie in the same direction as their neighbours, but over large distances the direction chosen would vary. In some places, people would be unable to decide which was the best direction to lie in: if everyone lies down pointing directly away from you, you are forced to stand. You are now a defect in the symmetry, a texture."

It is believed that textures collapse and unwind on progressively larger scales, creating intense energy as well as gravitational potential. This unwinding also creates areas of extreme cold or hot, such as the very cold spot in the South Galactic Hemisphere discovered by the IFCA team in 2004.

Marcos Cruz and his colleagues, Dr. Patricio Vielva and Professor Enrique Martínez-González with the IFCA, pursued numerous possibilities for the existence of the cold spot. In particular, they thoroughly explored the possibility of being due to systematic effects, foreground contamination from our own galaxy or due to the scattering of cosmic microwave background radiation by large galaxy clusters.

Each time they came to the same conclusion: there were not any convincing arguments for any of these possibilities. They also hypothesised that it could be a texture and with the assistance of Dr Mike Hobson, a member of the Astrophysics Group at Cambridge's Cavendish Laboratory, and Professor Neil Turok, they were able to examine this possibility in detail.

Professor Turok performed large scale simulations using the COSMOS supercomputer at Cambridge to more accurately compare the theory with the event. Dr Hobson ranked the relative probabilities that the cold spot is due to a texture rather than just an extreme statistical fluctuation. The researchers concluded that the texture hypothesis is the most plausible explanation for the cold spot but acknowledge that additional tests are necessary.

"The possibility that this is a texture is very exciting," said Professor Turok. "If it is, it will revolutionise our understanding of how the fundamental symmetries between the particles and forces were broken as the universe emerged from the big bang. The current data is suggestive but not yet compelling. There are a number of follow-up tests which can be made with future data. It's a very testable hypothesis and we will know the answer within the next decade."

Dr Hobson said: "The prominent cold spot in the image of the cosmic microwave background taken by the WMAP satellite is a very puzzling feature that has attracted a lot of attention in the cosmological community, but has not as yet been convincingly explained.

"Our work investigates the exciting possibility that the cold spot is due to the presence of a cosmic texture; some current particle physics theories predict textures to be produced as the universe evolves, but they had never been observed. Somewhat to our surprise, we found that the cold spot, and in fact the cosmic microwave background radiation over the whole sky, is indeed consistent with such a texture model. Although the current data are not yet compelling, we suggest future observations that should be able to test our hypothesis definitively. If the cold spot is indeed proven to be a texture it will completely change our view of how the universe evolved following the Big Bang."

Reference: "A Feature in the Cosmic Background Radiation Consistent with a Cosmic Texture," by M. Cruz, P. Vielva and E. Martínez-González of the Instituto de Física de Cantabria (CSIC, Univ. Cantabria) , in Santander, Spain; N. Turok of the University of Cambridge in Cambridge, UK; and M. Hobson of Cavendish Laboratory in Cambridge, UK, Science, October 25, 2007. This research was supported by the Spanish National Research Council (CSIC) and the Ministerio de Educación y Ciencia.

Thursday, October 25, 2007

Solar Telescope Soars Into Sky On Jumbo-jet-sized Balloon


In a landmark test flight, the National Center for Atmospheric Research (NCAR) and a team of research partners this month successfully launched a solar telescope to an altitude of 120,000 feet, borne by a balloon larger than a Boeing 747 jumbo jet. The test clears the way for long-duration polar balloon flights beginning in 2009 that will capture unprecedented details of the Sun's surface.

This unique research project will enable us to view features of the Sun that we've never seen before.

"We hope to unlock important mysteries about the Sun's magnetic field structures, which at times can cause electromagnetic storms in our upper atmosphere and may have an impact on Earth's climate."

The project, known as Sunrise, is an international collaboration involving NCAR, NASA, Germany's Max Planck Institute for Solar System Research and Kiepenheuer Institute for Solar Physics, Spain's Astrophysics Institute of the Canary Islands, and the Swedish Space Corporation. Additional U.S. partners include the Lockheed Martin Corporation and the University of Chicago. Funding for NCAR's work on the project comes from NASA and from the National Science Foundation, which is NCAR's primary sponsor.

The project may usher in a new generation of balloon-borne scientific missions that cost less than sending instruments into space. Scientists also can test an instrument on a balloon before making a commitment to launch it on a rocket.

The balloon, with its gondola of scientific instruments, was launched successfully on the morning of October 3 from the Columbia Scientific Balloon Facility in Fort Sumner, New Mexico. It flew for about 10 hours, capturing stable images of the solar surface and additional data from the various instruments of the sophisticated payload. The gondola then separated from the balloon and descended with a parachute, landing safely in a field outside Dalhart, Texas.

"We were able to verify the workings of the entire system end to end," says David Elmore, an NCAR engineer who oversaw the test flight. "We can now move on to planning the first full-scale mission with confidence."

Observing the midnight Sun

The ultimate goal of the Sunrise project is to investigate the structure and dynamics of the Sun's magnetic fields. The fields fuel solar activity, including plasma storms that buffet Earth's outer atmosphere and affect sensitive telecommunications and power systems. The fields also cause variations in solar radiation, which may be significant factors in long-term changes in Earth's climate.

The Sunrise project is scheduled next for a multiday flight over the Arctic in the summer of 2009, launching from Kiruna, Sweden. By taking advantage of the midnight Sun, the telescope will be able to capture continuous images for a period of several days to as long as two weeks, possibly orbiting the Arctic. It may be launched later on another long-distance flight over the Arctic or the Antarctic.

At an altitude of 120,000 feet, the telescope will rise above most of the turbulence of the atmosphere and ultraviolet-absorbing water vapor and ozone. It will be able to view stable images in the ultraviolet range, which allow for higher resolution than can be obtained from Earth's surface.

The telescope will capture features on the solar surface as small as 30 kilometers across (about 19 miles), more than double the resolution achieved by any other instrument to date. This will enable scientists to examine structures on the Sun that are believed to be key to understanding the mechanisms driving solar activity. In addition, by observing the same area during an entire flight over high latitudes in summer, the telescope will enable scientists to continually witness changes in the magnetic fields without the interruption of night.

The Sunrise project has presented engineers with a number of extraordinary challenges. The balloon is designed to carry 6,000 pounds of equipment, including a 1-meter (39-inch) solar telescope, additional observing instruments, communications equipment, computers and disk drives, solar panels, and roll cages and crush pads to protect the payload on landing. The equipment must be able to withstand dramatic changes in temperature, and the steel and aluminum gondola cannot vibrate in ways that could interfere with the operation of the telescope.

One of the most difficult aspects of the engineering work was to design the gondola in such a way that the telescope in flight would remain focused on a specific and relatively tiny area of the Sun, even while twisting on a soaring balloon for a week or longer during the full-scale research missions. To accomplish this, the gondola includes both a torque motor drive to keep the gondola and telescope in the correct orientation and a precision guiding and compensation system to constantly correct the telescope's aim.

In addition to the telescope, the gondola on its full-scale research missions will carry a polarimetric spectrograph that will measure wavelengths in the Sun's electromagnetic spectrum and enable scientists to make inferences about its magnetic fields. Another instrument, known as an imaging magnetograph, will provide two-dimensional magnetic field maps.

Because the gondola is designed to withstand considerable force when it lands, the instruments can be launched on repeated missions.

"This is a very economical way of rising above the atmosphere and capturing images that cannot be captured from Earth," Knölker says. "What we are doing is laying the groundwork for the next generation of space flights."

Wednesday, October 24, 2007

Massive Star's Afterlife: A Supernova Seeds New Planets


A spectacular new image shows how complex a star's afterlife can be. By studying the details of this image made from a long observation by NASA's Chandra X-ray Observatory, astronomers can better understand how some stars die and disperse elements like oxygen into the next generation of stars and planets.

At a distance of about 20,000 light years, G292.0+1.8 is one of only three supernova remnants in the Milky Way known to contain large amounts of oxygen. The image shows a rapidly expanding, intricately structured, debris field that contains, along with oxygen, other elements such as neon and silicon that were forged in the star before it exploded.

"We are finding that, just like snowflakes, each supernova remnant is complicated and beautiful in its own way," said Sangwook Park of Penn State who led the work, released in conjunction with the "8 Years of Chandra" symposium in Huntsville, Ala.

By mapping the distribution of X-rays in different energy bands, the Chandra image traces the distribution of chemical elements ejected in the supernova. The results imply that the explosion was not symmetrical. For example, blue (silicon and sulfur) and green (magnesium) are seen strongly in the upper right, while yellow and orange (oxygen) dominate the lower left. These elements light up at different temperatures, indicating that the temperature is higher in the upper right portion of G292.0+1.8.

Slightly below and to the left of the center of G292.0+1.8 is a pulsar, a dense, rapidly rotating neutron star that remained behind after the original star exploded. Assuming that the pulsar was born at the center of the remnant, it is thought that recoil from the lopsided explosion may have kicked the pulsar in this direction.

Surrounding the pulsar is a so-called pulsar wind nebula, a magnetized bubble of high-energy particles. The narrow, jet-like feature running from north to south in the image is likely parallel to the spin axis of the pulsar. This structure is most easily seen in high energy X-rays. In the case of G292.0+1.8, the spin direction and the kick direction do not appear to be aligned, in contrast to apparent spin-kick alignments in some other supernova remnants.

Another intriguing feature of this remnant is the bright equatorial belt of X-ray emission that extends across the center of the remnant. This structure is thought to have been created when the star - before it died - expelled material from around its equator via winds. The orientation of the equatorial belt suggests that the parent star maintained the same spin axis both before and after it exploded.

The detection of the pulsar and its wind nebula confirms that the supernova that led to G292 produced a neutron star through the collapse of the core of a massive star. The ability to study the asymmetry of the original explosion using X-ray images of the remnant gives us a powerful new technique for learning about these cataclysmic events.

Tuesday, October 23, 2007

Old Galaxy Finds Fountain of Youth


In a galaxy far, far away, a theft of cosmic proportions is taking place in an effort to claim the fountain of youth.

A massive galaxy is stealing a billion suns worth of gas from a smaller galactic neighbor. In space, gas is a hot commodity. Really hot. In this case, about 1,340 degrees Fahrenheit (730 degrees Celsius). And it's great for making new stars.

"We may be viewing the larger galaxy in a rare, brief stage of its reincarnation from an old galaxy to a youthful one studded with brilliant stars," said Patrick Ogle of NASA's Spitzer Science Center at the California Institute of Technology.

The robber, called 3C 326 North, is about the mass of our Milky Way galaxy, and its victim, 3C 326 South, is about half its mass. They are close enough to perturb each other gravitationally and might eventually collide. Such galaxy mergers are common in the universe: Gas and stars in two nearby galaxies become tangled until they become one larger galaxy. The case of 3C 326 is the clearest example yet of large quantities of gas being heated and siphoned from one galaxy to another.

"This could be an important phase in galaxy mergers that we are just now witnessing," Ogle said.

The scene was imaged by NASA's Spitzer Space Telescope and are reported in the Oct. 20 issue of the Astrophysical Journal.

The scene of the crime is about a billion light-years away. So in reality, the theft took place a billion years ago, but the light revealing it has only just arrived.

Successful Ariane 5 Upper Stage Engine Re-Ignition Experiment


A successful re-ignition of the Ariane 5 upper stage engine performed during the most recent mission has consolidated Ariane 5's readiness for the launch of the Jules Verne Automated Transfer Vehicle. The launch of ESA's Automated Transfer Vehicle (ATV), which carries supplies to the International Space Station, will require multiple firings of the Ariane 5 ES upper stage engine. In this context, hundreds of re-ignition tests under various thermal conditions have been undertaken at the DLR Test Centre in Lampoldshausen to qualify the Aestus engine for several re-ignitions.

In order to consolidate this on ground qualification a re-ignition experiment was performed during the last Ariane-5 launch - on the evening of 5 October - when an Ariane 5 GS launcher lifted off from Europe's Spaceport in French Guiana carrying two commercial telecommunications satellites into geostationary transfer orbit.

Once the commercial payloads were safely on their way, a successful experimental re-ignition of the Aestus engine took place - 54 minutes after the release of the second payload. The experiment was done to validate operational conditions (mainly temperatures and pressures) and procedures (propellant settling in tanks) of the launcher upper stage, which will be applied during the ATV orbital injection mission. It also verified the behaviour of the composite during the re-ignition phase.

Analysis of the many temperature and pressure parameters is ongoing and confirms a nominal behaviour very close to expectations. "We are extremely satisfied with the results of the Aestus re-ignition experiment, which confirms the on ground qualification of the re-ignition capability and adds to our confidence of mission success for the launch of ATV Jules Verne in the early part of next year" said ESA's Ariane Programme Manager, Toni Tolker-Nielsen.

Launch to geostationary transfer orbit
A communications satellite launch requires the engine on the Ariane 5 upper stage to fire only once. A few seconds after the Ariane 5 main stage separates, the upper stage engine ignites to continue propelling the upper stage and payloads towards geostationary transfer orbit. The engine is shut down once the correct orbit for the injection of the payloads into their transfer orbits has been reached.

The standard geostationary transfer orbits for communications satellites are elliptical, with a perigee of 250 km and an apogee of 36 000 km. Once injected into this transfer orbit, the satellites use an apogee boost motor to raise the orbit perigee to 36 000 km by firing the motor when the satellites are at the apogee of the transfer orbit. This staged approach is the optimum from an energetic point of view and allows the placing of the highest mass into a circular geostationary orbit at an altitude of 36 000 km.

Automated Transfer Vehicle launch
Launching the ATV will be more complex because the target orbit is circular, rather than elliptical.

After main stage separation over the Atlantic Ocean, the Aestus engine of the upper stage will perform a first boost lasting 8 minutes to reach an elliptical orbit (136 km x 260 km). Then, after a coasting phase to the apogee of the elliptical orbit lasting 48 minutes, a second boost with a duration of 30 seconds serves to reach the ATV circular injection orbit at an altitude of 260 km.

This second firing of the Aestus engine will take place over southeast Australia, just over an hour into the flight. Four minutes later, the ATV will separate over the Pacific, ready to fly to the International Space Station using its own navigation and propulsion systems.

One orbit later, now over Western Australia, the Aestus engine will re-ignite briefly, for a third time, causing the launcher's upper stage to de-orbit safely and burn up during a precise destructive re-entry over of the South Pacific Ocean.

China plans to launch first moon orbiter on Wednesday


China, which plans one day to send a human to the moon, said it expected to launch its first lunar orbiter on Wednesday, state media reported, quoting the country's space agency.

The launch of the Chang'e I rocket and orbiter will likely take place on Wednesday at 6:00 pm (1000 GMT) from the Xichang Satellite Launch Centre in southwestern Sichuan province, the official Xinhua news agency reported.

The launch of the moon orbiter is part of a three-step lunar exploration programme China hopes will eventually see moon samples brought back to Earth.

The probe will be followed by robotic missions and, eventually, a lunar base to allow astronauts to live longer on the moon and utilise its resources.

China successfully launched astronaut Yang Liwei into orbit in 2003, becoming the third country after the former Soviet Union and the United States to put a man in space.

China has offered 2,000 tickets to the public to view the launch.

Monday, October 22, 2007

China plans Wednesday launch for moon orbiter


China's preparations to launch its first lunar orbiter are on schedule for lift-off later this week, a Chinese official said on Monday, as the country steps up efforts in a new international race for the moon.

The launch of the Chang'e One orbiter is set for Wednesday at 1000 GMT but could take place on the two days after then, depending on conditions, spokesman for the China National Space Administration, Li Guoping, told a news conference.

Li said the orbiter would circle the moon for over a year, mapping and analyzing its surface.

"It's implementation will lay a technological foundation for our country's development of deep space exploration activities," Li said of the launch.

The United States, Japan and India are also seeking to mark their interest in the moon with fresh exploration efforts.

In 2003, China became only the third country -- after the United States and the former Soviet Union -- to launch a man into space aboard its own rocket. In October 2005, it sent two men into orbit and it plans a space walk by 2008.

Beijing plans to follow the Chang'e One orbiter -- named after a mythical Chinese goddess who flew to the moon -- with a moon rover mission, probably in 2012.

Last month, Japan launched its first lunar probe.

India is planning its first unmanned mission to orbit the moon in 2008. The United States plans to launch a lunar orbiter next year.


Sunday, October 21, 2007

First Malaysian astronaut returns home



Malaysia's first astronaut landed safely back in Kazakhstan to a hero's welcome on Sunday with two Russian cosmonauts after spending 11 days in space, officials at Moscow's mission control said.

The Soyuz capsule carrying Sheikh Muszaphar Shukor, an orthopedic surgeon from Kuala Lumpur, touched down about 200 km (124 miles) off course at 1037 GMT (6:37 a.m. EDT) because the trajectory of the capsule was changed after entering the atmosphere.

International Space Station commander, Fyodor Yurchikhin, and flight engineer, Oleg Kotov, who had both spent 197 days in space, accompanied Shukor on his return to earth.

Dashing towards earth in what officials call a "ballistic" landing put more stress on the astronauts but all three were in good health, Russian Space Agency chief Anatoly Perminov said.

In such a landing, the capsule follows a much steeper and shorter trajectory to earth, causing more spin and resulting in a bumpier ride that puts a greater strain on its occupants.

"They all feel satisfactory, I would even say well. And Sheikh Muszaphar feels best of all as his trip to space was much shorter than the other astronauts," Perminov said.

"The load on the astronauts was a little more than under a normal landing, that is natural. But the so called ballistic trajectory was held only for the last few minutes," he said.

A Malaysian deputy prime minister welcomed Shukor to earth saying his flight would go down in the annals of the Southeast Asian state's history.

Feted as a hero in Malaysia, Shukor's relatives at Mission Control outside Moscow clapped with joy when he landed after having said prayers for his safe return.

PART OF ARMS DEAL

Shukor says he wants to inspire Malaysia like Russian astronaut Yuri Gagarin did in 1961 when he became the first man in space.

He was selected from 11,000 candidates in a deal Malaysia arranged with Russia as part of a $1 billion purchase of Russian jets.

Malaysia's deputy Prime Minister Najib Razak was at Mission Control to watch as his return was traced on giant monitors.

"I congratulate you all on our success. For Malaysia this is an historical event that will go down in the annals of our history because this is our first cosmonaut," Najib told reporters in English.

"For Malaysia this is a major leap forward and I am convinced this will be an example for the future generations."

Russia's Space Agency head, Perminov, said he would discuss future space cooperation with Najib. Shukor will travel to Moscow after undergoing medical tests.

Friday, October 19, 2007

First Stop Moon. Next Stop, Mars


The distant red planet Mars has captured the imagination of humankind for generations. It has inspired novelists to write stories about its exploration and motivated scientists to find ways to make space travel there a viable possibility. Now, for the first time in Europe, scholars such as historians, philosophers and sociologists are banding together with space scientists to share their thoughts and ideas on how humankind will be taking these first steps.

The 'Humans in Outer Space - Interdisciplinary Odysseys' conference recently held in Vienna was the first such forum where scholars from a humanities background together with scientists could discuss humankind's presence in space from non-traditional perspectives.

The benefits of creating such a cross-disciplinary forum is that it was able to give guiding insight into how humankind will face possible issues, issues that can be best addressed in the light of modern understanding of historical events.

Some of the wide-ranging issues that conference delegates explored include the philosophical and theological consequences of contacting alien intelligences, the marketing of space exploration, and the legal frameworks that will be needed if space-faring nations are to cooperate peacefully.

The event was organised in part by an ESF Steering Committee chaired by Professor Luca Codignola, a historian at the University of Genoa. At the conference he expressed his interest in what history can tell us about the challenges we may face if space explorers make contact with alien civilisations.

Delving into history for an example, he drew correlations with the so-called "Columbian Exchange" that took place around 1492. 'It changed the Western way of conceiving the globe; it forcefully challenged its theology; it allowed for a free flow of bacteria, germs and microbes that almost wiped out the American peoples,' he explained.

The science community does not really seem to be aware of the fact that a number of issues and concerns that they are dealing with, such as the consequences of meeting with unknown pathogens, are known and have long been studied by historians and ethnologists.

As for the humanities scholars, technical difficulties relating to space-voyaging and especially its timeframe, usually escape them. We all felt it was rather strange that the two groups rarely, if ever, meet to discuss space-related issues.

The conclusions from these sessions will be documented by the ESF in a position paper entitled 'Vienna Vision on Humans in Outer Space'. The ESF will distribute this paper to all interested stakeholders in the academic world, space agencies, intergovernmental bodies such as the United Nations, the media and politicians involved in space- and research-related initiatives.

Prof. Kai-Uwe Schrogl, Secretary General of the ESPI and Chair of the conference, commented: 'Mankind's future in outer space will require a comprehensive view, including the input in particular by the humanities and social sciences, as well as the reflection of the manifold trans-utilitarian aspects that make space exploration a province of all mankind.'

The Fantastic Skies Of Orphan Stars


What a view! It's late summer, after dark, and you're flat on your back in a sleeping bag watching the camp fire's last embers drift up to the heavens. Overhead a magnificent band of stars divides the night-it's the Milky Way. Now, imagine that scene doubled in brightness and beauty. No, that's not quite right. Imagine an entire galaxy of stars spinning overhead. The galaxy's blue-white core of young stars is surrounded by yellow octopus-arms of older siblings.

Off to one side a faint red column of gas meanders away from the starry whirlpool and turns in mid-sky toward ... you.

Astronomers using NASA's Chandra X-ray observatory have found a place in the Universe where the view may be like that. "It's near a galaxy named ESO 137-001," says Ming Sun of Michigan State University who led the study.

ESO 137-001 is a member of Abell Cluster 3627-a swarm of galaxies 65 Megaparsecs (212 million light years) from Earth. ESO 137-001 stands out among other galaxies in the cluster because it has a gigantic comet-like tail peppered with young stars. "We call them orphan stars," says MSU team member Megan Donahue, "because they are separating from their parent."

No one knows if there is life in these orphan star systems, but if there are lifeforms, "they would have a fantastic view," says Sun. Here on Earth we see our own galaxy, the Milky Way, from the inside. Too bad! The interior of the Milky Way is choked with space-dust, which dims our view of all but the nearest stars. On any given summer night, the Milky Way displays only a fraction of its total glory. If only we could be lifted out of our busy, dusty spiral arm.

That's exactly what is happening in ESO 137-001, explains Sun. "Orphan stars are drifting away from their galaxy" to a point where the entire galaxy can be seen in hindsight. It's a stargazers dream come true.

How did this happen? Abell Cluster 3627 is filled with a diffuse atmosphere of hot gas which surrounds all the galaxies in the cluster. ESO 137-001 is moving through this gas as it plunges toward the cluster's center. The entire galaxy, therefore, feels a sort of 'hot wind' in its face." Note: Stick your head out the window of a car driving through Death Valley and you will feel a hot wind, too. It's the same concept. The wind pushes raw, star-forming gas out the back of ESO 137-001, creating the comet-like tail where orphan stars are born.

This isn't the first time astronomers have detected stars being born outside a parent galaxy. Other examples include Stephen's Quintet and NGC 4388. ESO 137-001 is special, however, because the rate of orphan star formation is so high: 36 to 5700 times greater than anything we've ever seen before. Sun estimates there could be a million stars spilling out of ESO 137-001, a million unbelievable night skies.

Eventually, as the stars slowly drift away from their parent, the view will change: ESO 137-001 will fade into the distance and a dark inter-galactic void will fill the night sky. The only stars in view then will be the orphans themselves--a handful of very nearby, very bright points of light. A few billion years from now these stars will be in a pretty lonely region of space.

Such isolation could be a good thing if life ever struggles to gain a foothold in these systems: Planets circling orphan stars may be less affected by the occasional 'comet of death' perturbed out of its orbit by gravitational interactions with a passing star.

The orphan stars of ESO 137-001 may represent a whole population of cosmic wanderers, blessed in the beginning with breathtaking nights and in the end with the safety of the void. How many more are out there? No one knows.

This is why we explore.

China reveals space plans


China on Thursday revealed its plans for space -- including space walking, spacecraft docking and the setting up of a space laboratory before 2010, state media reported.

The government would also give priority to developing an earth observation system using satellites, aircraft and airships, Xinhua news agency reported, quoting a blueprint approved by the State Council, or the cabinet.

The document, part of China's 11th five-year plan for space development, said China would improve a navigation system that is based on plans to launch dozens of satellites, it said.

The system is aimed at providing navigation and positioning services in transportation, meteorology, petroleum prospecting, disaster forecasting, telecommunications and public security, it said.

Apart from launching the country's first lunar orbiter at the end of this month, China would also study the second and third stages of its moon exploration projects, said a senior official with the Commission of Science, Technology and Industry for National Defence.

Officials earlier said China is also planning to land a human on the moon and to make a series of robotic missions with a view to building a base there after 2020.

Thursday, October 18, 2007

Heaviest Stellar Black Hole Discovered In Nearby Galaxy


Astronomers have located an exceptionally massive black hole in orbit around a huge companion star. This result has intriguing implications for the evolution and ultimate fate of massive stars.

The black hole is part of a binary system in M33, a nearby galaxy about 3 million light years from Earth. By combining data from NASA's Chandra X-ray Observatory and the Gemini telescope on Mauna Kea, Hawaii, the mass of the black hole, known as M33 X-7, was determined to be 15.7 times that of the Sun. This makes M33 X-7 the most massive stellar black hole known. A stellar black hole is formed from the collapse of the core of a massive star at the end of its life.

"This discovery raises all sorts of questions about how such a big black hole could have been formed," said Jerome Orosz of San Diego State University, lead author of the paper appearing in the October 18th issue of the journal Nature.

M33 X-7 orbits a companion star that eclipses the black hole every three and a half days. The companion star also has an unusually large mass, 70 times that of the Sun. This makes it the most massive companion star in a binary system containing a black hole.

This is a huge star that is partnered with a huge black hole. Eventually, the companion will also go supernova and then we'll have a pair of black holes.

The properties of the M33 X-7 binary system - a massive black hole in a close orbit around a massive companion star - are difficult to explain using conventional models for the evolution of massive stars. The parent star for the black hole must have had a mass greater than the existing companion in order to have formed a black hole before the companion star.

Such a massive star would have had a radius larger than the present separation between the stars, so the stars must have been brought closer while sharing a common outer atmosphere. This process typically results in a large amount of mass being lost from the system, so much that the parent star should not have been able to form a 15.7 solar-mass black hole.

The black hole's progenitor must have shed gas at a rate about 10 times less than predicted by models before it exploded. If even more massive stars also lose very little material, it could explain the incredibly luminous supernova seen recently as SN 2006gy. The progenitor for SN 2006gy is thought to have been about 150 times the mass of the Sun when it exploded.

Massive stars can be much less extravagant than people think by hanging onto a lot more of their mass toward the end of their lives. This can have a big effect on the black holes that these stellar time-bombs make.

Coauthor Wolfgang Pietsch was also the lead author of an article in the Astrophysical Journal that used Chandra observations to report that M33 X-7 is the first black hole in a binary system observed to undergo eclipses. The eclipsing nature enables unusually accurate estimates for the mass of the black hole and its companion.

Because it's eclipsing and because it has such extreme properties, this black hole is an incredible test-bed for studying astrophysics.

The length of the eclipse seen by Chandra gives information about the size of the companion. The scale of the companion's motion, as inferred from the Gemini observations, gives information about the mass of the black hole and its companion. Other observed properties of the binary were used to constrain the mass estimates.

NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass. Gemini is an international partnership managed by the Association of Universities for Research in Astronomy under a cooperative agreement with the National Science Foundation.

Wednesday, October 17, 2007

China counts down to man on moon


China launches its first lunar orbiter next week as it counts down to putting a man on the moon within 15 years, state media said on Wednesday.

Advanced cameras and x-ray "spectrometers" have been installed on the orbiter, the Chang'e One, for mapping 3D images of the moon's surface and analyzing moon dust, Xinhua news agency said.

The next step in the program is to launch a moon vehicle, and bring it back to Earth, and to put a man on the moon "within 15 years", the China Daily said.

"We have taken hundreds of preventative measures directed towards a successful launch," Zhang Qingwei, minister in charge of the Commission of Science, Technology and Industry for National Defense, told reporters.

Zhang said the probe had already been transported to the launch site in Xichang in the southwestern province of Sichuan.

"Although the risks are great, we have confidence it will be a success."

The launch is set for next Wednesday, a date chosen "with the consideration of weather and celestial conditions", Zhang said.

China's space exploration program has come far since late leader Mao Zedong lamented that China could not even launch a potato into space.

In 2003, it became only the third country after the former Soviet Union and the United States to launch a man into space aboard its own rocket. In October 2005, it sent two men into orbit and plans a space walk by 2008.

But China's space plans have faced increasing international scrutiny. Fears of a potential space arms race with the United States and other powers have mounted since it blew up one of its own weather satellites using a ground-based missile in January.

Japan plans to launch its first mission to land a spacecraft on the moon in the next decade -- a feat so far achieved only by the former Soviet Union and the United States.


Digg!

Hubble Shows 'Baby' Galaxy Is Not So Young After All


The NASA/ESA Hubble Space Telescope has found out the true nature of a dwarf galaxy that astronomers had for a long time identified as one of the youngest galaxies in the Universe. Astronomers using the NASA/ESA Hubble Space Telescope have made observations of the galaxy I Zwicky 18 which seem to indicate that it is in fact much older and much farther away than previously thought.

Observations of I Zwicky 18 at the Palomar Observatory around 40 years ago seemed to show that it was one of the youngest galaxies in the nearby Universe. The studies suggested that the galaxy had erupted with star formation billions of years after its galactic neighbours, like our galaxy the Milky Way. Back then it was an important finding for astronomers, since this young galaxy was also nearby and could be studied in great detail; something that is not possible with observations made across great distances when the universe was much younger.

But these new Hubble data have quashed that possibility. The telescope found fainter older red stars contained within the galaxy, suggesting its star formation started at least one billion years ago and possibly as much as 10 billion years ago. The galaxy, therefore, may have formed at the same time as most other galaxies.

“Although the galaxy is not as youthful as was once believed, it is certainly developmentally challenged and unique in the nearby Universe,” said astronomer Alessandra Aloisi, who led the new study. Spectroscopic observations with ground-based telescopes have shown that I Zwicky 18 is mostly composed of hydrogen and helium, the main ingredients created in the Big Bang. In other words the stars within it have not created the same amounts of heavier elements as seen in other galaxies nearby.

Thus the galaxy’s primordial makeup suggests that its rate of star formation has been much lower than that of other galaxies of similar age. The galaxy has been studied with most of NASA’s telescopes, including the Spitzer Space Telescope, the Chandra X-ray Observatory, and the Far Ultraviolet Spectroscopic Explorer (FUSE). However, it remains an outstanding mystery why I Zwicky 18 formed so few stars in the past, and why it is forming so many new stars right now.

The new Hubble data also suggest that I Zwicky 18 is 59 million light-years from Earth, almost 10 million light-years more distant than previously believed. On extragalactic standards this is still in our own backyard yet the galaxy’s larger-than-expected distance may now explain why astronomers have had difficulty detecting older, fainter stars within the galaxy until now. In fact, the faint old stars in I Zwicky 18 are almost at the limit of Hubble’s sensitivity and resolution.

Aloisi and her team discerned the new distance by observing blinking stellar distance-markers within I Zwicky 18. These massive stars, called Cepheid variables, pulse with a regular rhythm. The timing of their pulsations is directly related to their brightness. By comparing their actual brightness with their observed brightness, astronomers can precisely measure their distance.

The team determined the observed brightness of three Cepheids and compared it to the actual brightness predicted by theoretical models specifically calculated for the low metal content of I Zwicky 18 in order to determine the galaxy’s distance. The Cepheid distance was also validated through another distance indicator, specifically the observed brightness of the brightest red stars in a characteristic stellar evolutionary phase (the so-called “giant” phase).

Cepheid variable stars have been studied for decades (especially by Hubble) and have been instrumental in the determination of the scale of our universe. This is the first time, however, that variable stars with so few heavy elements were found. This may provide unique new insights into the properties of variable stars, which is now a topic of ongoing study.

Mars Express: Hummocky And Shallow Maunder Crater


The High Resolution Stereo Camera (HRSC) on ESA’s Mars Express orbiter has obtained pictures of the Noachis Terra region on Mars, in particular, the striking Maunder crater.

Maunder crater lies at 50° South and 2° East, approximately in the center of Noachis Terra.

The impact crater, named after the british astronomer Edward W. Maunder (1851-1928), is located halfway between Argyre Planitia and Hellas Planitia on the southern Highlands of Mars.

With a diameter of 90 kilometres and a depth of barely 900 metres, the crater is not one of the largest impact craters on Mars at present, but it used to be much deeper. It has since been filled partially with large amounts of material.

The west of the crater experienced a major slope failure, during which a large landslide transported loose material eastward, to the inner parts of the crater. The edges of the crater rim that collapsed exhibit gullies which might be associated with the mass transport of the material.

The transition zone from the western rim of the crater to the rather smooth crater floor on the eastern edge shows hummocky terrain. Such terrain exhibits small, irregularly-shaped hills and valleys. The hummocky terrain in the Maunder crater was formed by deposition of landslide debris.

In the east, the crater floor is bounded by a trough, approximately 700 metres deep. The trough may be associated with a landslide on the western edge of the crater. Some gullies can be seen on the upper edge of the trough which is possible evidence for water seepage.

The small, 500 to 2500-metre long, dark features on the crater floor are eye-catching. These features are called Barchan dunes, one of the most abundant dune forms in arid environments. Dunes of this kind are also found on Earth, for example in the West-African Namib desert.

The colour scenes have been derived from the three HRSC-colour channels and the nadir channels. The perspective views have been calculated from the digital terrain model derived from the HRSC stereo channels. The anaglyph image was calculated from the nadir channels and two stereo channels, stereoscopic glasses are required for viewing. The 3-D (anaglyph) picture has been put together from several individual 3-D images of different scenes, enhancing the view over larger areas.

Tuesday, October 16, 2007

Astronomers from NASA, Harvard and U of Colorado: "May be on Brink of Finding Habitable Second Earth"


"It could happen almost any time now. We now have the technological capability to identify Earth-like planets around the smallest stars."

David Latham -Harvard-Smithsonian Center for Astrophysics

To date, Planet hunters have spotted more than 200 planets beyond our solar system, but the vast majority are hot, Jupiter-sized planets that would dwarf the Earth and are almost certainly lifeless.

Astronomers may be on the brink of discovering a second Earth-like planet, a find that would add fresh impetus to the search for extraterrestrial life, according to the US journal Science. Astronomers from six major centers, including NASA, Harvard and the University of Colorado, outline how advances in technology suggest scientists are on the verge of being able to detect the presence of small, rocky planets, much like our own, around distant stars for the first time. The planets are considered the most likely habitats for extraterrestrial life.

One technique relies on observing the shift in light coming from a star as a planet swings around it. Until recently, this "radial velocity" method has only been sensitive enough to pick up planets far more massive than Earth, but improvements now make the discovery of a second Earth highly likely.

It could happen almost any time now. We have the technological capability to identify Earth-like planets around the smallest stars even now.

Earlier this year, the world's largest and most prolific team of planet hunters, the Anglo-Australian, California and Carnegie Planet Searches ( AAPS), reported their findings of 37 exoplanets that have been discovered over the past couple of years, 7 of which were previously unreported brown dwarfs.

Depending on whose number you go by, the total number of exoplanets currently discovered is 212 or 240, the majority of which have been discovered by the AAPS and their colleagues in the California and Carnegie searches.

The method of discovery primarily implemented is studying the Doppler wobble of stars. As a planet orbits its parent star, its gravitational pull causes the star to wobble. Using the Doppler Effect, the scientists are able to determine the velocity of the planet. When the planet moves away from Earth, its star moves toward the Earth, causing it to emit shorter wavelengths, which appear bluer. The opposite is true as well; as a planet moves closer to Earth, its star moves further away, emitting longer (redder) wavelengths of light. The AAPS uses highly advanced, sensitive spectographs to record these very small wavelengths.

But there are things that Doppler searches cannot tell researchers. With Doppler readings, they are able to calculate the velocities of the planets being studied as they move towards and away from the Earth. What Doppler readings are unable tell researchers are the angles of inclination of the orbital planet to the line of sight. This is important information because by being able to calculate the angles of inclination of the orbiting planet, scientists are able to determine the actual physical size of the planet.

The AAPS has developed a technique to find the angle of inclination: transit searches. Transit searches are a relatively new technique which has only just begun giving them results within the past few years. As a planet transits in front of its parent star, passing our line of sight from Earth, scientists are able to calculate its angle of inclination, thereby determining its eccentricity (how elliptical or round its orbital path is). In the years to come, the method of transit searches should advance, resulting in more information about already discovered planets.

Although the next generation of techniques such as interferometric astrometry and direct imaging will be the most promising new methods of detection in the future study and discovery of extrasolar planets, as Chris Tinney of AAPS explains, the most successful and powerful form of study currently in use is complementing Doppler searches with transit searches. By doing so, You can essentially know everything you can know about a planet. You know exactly its mass and its radius, which means you can work out its density, and therefore, you can make estimates as to whether it’s a gas giant or an ice giant planet, or whether it’s rocky.

As these techniques develop, the smaller and smaller the extrasolar planets being discovered will become.

So when does Tinney expect an Earth-sized planet discovery, now that they’ve gotten down to Venus-sized planets when once they only found those with a mass that of Jupiter’s?

Finding a planet of Earth mass is probably a only couple of years away, all of the things they are finding of very low mass are moving in very short orbital periods, which means that they are orbiting close to their parent stars. So although there they are like Earth in terms of their mass and size, these planets are very unlike the Earth in terms of their orbit.

To find an Earth-mass planet in an Earth-like orbit is just not going to happen with the Doppler technique. It is simply beyond the technology currently developed. Essentially, it would mean that they would need to be performing measurements 100 times better than any technology is capable of doing.

So does this rule out the possibility of finding a habitable planet?

Not quite. There is a “trick” to planet hunting. Scientists can look for Earth-mass planets in short period orbits around lower mass stars. These types of stars are called M dwarfs and have a mass one tenth the size of the Sun, which means that the velocity signal is ten times larger, and therefore the radius at which the planet must be from the star in order to have water or liquid on its surface is much smaller. For now, it’s Tinney’s opinion that some of the recent reports about habitable planets being discovered “is more hype than reality,” but that the discovery of such planets “will come in due course.”

In fact, that’s precisely what Tinney is currently working on, aside from his AAPS commitment. He has convinced the Gemini Observatory—a collaboration of the US, Canada, UK, Australia, Brazil, and Argentina—to build a spectrograph on one of its largest class of telescopes. In order to perform the types of studies needed to find other Earth-mass planets, scientists would need to being studying the near infrared, rather than the green wavelengths of visible light. This new Gemini spectrograph, called the Precision Radial Velocity Spectrometer, will specifically be designed to do very high precision Doppler work in the near infrared, rather than the optical. Once that type of technology is developed, Tinney believes that rather than finding the occasional one or two Earth-sized planets around M dwarf stars, finding more and more will be much more straightforward, thereby dispelling some of the current hype and allowing scientists to gather actual statistics about these types of systems.

NASA's mantra of "follow the water" has defined the search for extraterrestrial life on Mars and other planets. If water is crucial for life, then the most likely sanctuaries will be planets which lie in a "habitable zone" just the right distance from a star, so that it is neither so hot that water evaporates, or so cold that it remains permanently frozen.