Saturday 6 October 2012

mY liFe mY waY:today univers

Curiosity Set for 1st Martian Scooping at ‘Rocknest’ Ripple

by sandeep janjirala on OCTOBER 6, 2012

Image caption: Context view of Curiosity working at ‘Rocknest’ Ripple. Curiosity’s maneuvers robotic arm for close- up examination of ‘Rocknest’ ripple site and inspects sandy material at “bootlike” wheel scuff mark with the APXS (Alpha Particle X-Ray Spectrometer) and MAHLI (Mars Hand Lens Imager) instruments positioned on the rotatable turret at the arm’s terminus. Mosaic was stitched together from Sol 57 & 58 Navcam raw images and shows the arm extended to fine grained sand ripple in context with the surrounding terrain and eroded rim of Gale Crater rim on the horizon. Rocknest patch measures about 8 feet by 16 feet (2.5 meters by 5 meters).See NASA JPL scooping video below. Credit: NASA/JPL-Caltech/Ken Kremer/Marco Di Lorenzo

NASA’s Curiosity rover is set to scoop up her 1st sample of Martian soil this weekend at a soil patch nicknamed ‘Rocknest’. This marks a major milestone on the path to delivering Mars material to the sample acquisition and processing system for high powered analysis by the robots chemistry labs and looking for the ingredients of life, said the science and engineering team leading the mission at a media briefing on Thursday, Oct 4.

Since landing on the Red Planet two months ago on Aug. 5/6, Curiosity has trekked over 500 yards eastwards across Gale crater towards an intriguing area named “Glenelg” where three different types of geologic terrain intersect.

This week on Oct. 2 (Sol 56), the rover finally found a wind driven patch of dunes at ‘Rocknest’ with exactly the type of fine grained sand that the team was looking for and that’s best suited as the first soil to scoop and injest into the sample acquisition system.

Rare X-Ray Nova Reveals a New Black Hole in the Milky Way

by NANCY ATKINSON on OCTOBER 5, 2012

Swift J1745-26, with a scale of the moon as it would appear in the field of view from Earth. This image is from September 18, 2012 when the source peaked in hard X-rays. Credit: NASA/Goddard Space Flight Center/S. Immler and H. Krimm

Back in mid-September, the Swift satellite was going about its multi-wavelength business of watching for bursts of bright gamma-ray, X-ray, ultraviolet, or optical events in the sky, when it detected a rising tide of high-energy X-rays from a source toward the center of our Milky Way galaxy. But this was different from any other burst the satellite had detected, and after observing the event for a few days, astronomers knew this had to be a rare X-ray nova. What it meant was that Swift had detected the presence of a previously unknown stellar-mass black hole.

“Bright X-ray novae are so rare that they’re essentially once-a-mission events and this is the first one Swift has seen,” said Neil Gehrels from Goddard Space Flight Center, the mission’s principal investigator. “This is really something we’ve been waiting for.”

The object was named Swift J1745-26 after the coordinates of its sky position, the nova is located a few degrees from the center of our galaxy toward the constellation Sagittarius. While astronomers do not know its precise distance, they think the object resides about 20,000 to 30,000 light-years away in the galaxy’s inner region.

An X-ray nova is a short-lived X-ray source that appears suddenly in the sky and dramatically increases in strength over a period of a few days and then decreases, fading out over a few months. Unlike a conventional nova, where the compact component is a white dwarf, an X-ray nova is caused by material – usually gas — falling onto a neutron star or a black hole.

The rapidly brightening source triggered Swift’s Burst Alert Telescope twice on the morning of Sept. 16, and once again the next day.

Ground-based observatories detected infrared and radio emissions, but thick clouds of obscuring dust have prevented astronomers from catching Swift J1745-26 in visible light.

The nova peaked in hard X-rays — energies above 10,000 electron volts, or several thousand times that of visible light — on Sept. 18, when it reached an intensity equivalent to that of the famous Crab Nebula, a supernova remnant that serves as a calibration target for high-energy observatories and is considered one of the brightest sources beyond the solar system at these energies.

Even as it dimmed at higher energies, the nova brightened in the lower-energy, or softer, emissions detected by Swift’s X-ray Telescope, a behavior typical of X-ray novae. By Wednesday, Swift J1745-26 was 30 times brighter in soft X-rays than when it was discovered and it continued to brighten.

“The pattern we’re seeing is observed in X-ray novae where the central object is a black hole. Once the X-rays fade away, we hope to measure its mass and confirm its black hole status,” said Boris Sbarufatti, an astrophysicist at Brera Observatory in Milan, Italy, who currently is working with other Swift team members at Penn State in University Park, Pa.

Here’s usually happens in events like this: The black hole is part of a binary system with a normal Sun-like star. A stream of material flows into an accretion disk around the black hole. Usually, the disk of gas spirals in steadily to the black hole, heats up and produces a steady X-ray glow. But sometimes, for reasons unknown, the material is held up in the outer regions, held back by some mechanism, almost like a dam. Once enough gas accumulates, the dam breaks and a flood of gas surges towards the black hole, creating the X-ray nova outburst.

“Each outburst clears out the inner disk, and with little or no matter falling toward the black hole, the system ceases to be a bright source of X-rays,” said John Cannizzo, a Goddard astrophysicist. “Decades later, after enough gas has accumulated in the outer disk, it switches again to its hot state and sends a deluge of gas toward the black hole, resulting in a new X-ray outburst.”

This phenomenon, called the thermal-viscous limit cycle, helps astronomers explain transient outbursts across a wide range of systems, from protoplanetary disks around young stars, to dwarf novae — where the central object is a white dwarf star — and even bright emission from supermassive black holes in the hearts of distant galaxies.

It is estimated that our galaxy must harbor some 100 million stellar-mass black holes. Most of these are invisible to us, and only about a dozen have been identified.

Swift discovers about 100 bursts per year. The Burst Alert Telescope detects GRBs and other events and accurately determines their positions on the sky. Swift then relays a 3 arcminute position estimate to the ground within 20 seconds of the initial detection, enabling ground-based observatories and other space observatories the chance to observe the event as well. The Swift spacecraft itself “swiftly” –in less than approximately 90 seconds — and autonomously repoints itself to bring the burst location within the field of view of the sensitive narrow-field X-ray and UV/optical telescopes to observe the afterglow and gather data.

Video: 55 Years of Space Exploration

by sandeep janjirala on OCTOBER 5, 2012

Yesterday marked the 55th anniversary of the Sputnik launch, which sent the first artificial satellite into orbit. It was actually a fairly small satellite, about the size of a basketball, but it had a big impact. It set in motion not only the space race, but jump-started a push for education and technology development. Thanks to the giant leap of Sputnik, we now use satellites for telecommunications, weather prediction, remote sensing, and navigation, not to mention the exploration of space.

Once in a Lifetime Image: Emperor Penguins Under the Aurora Australis

by sandeep janjirala on OCTOBER 5, 2012

Emperor Penguins on the Antarctic Sea Ice Under the Aurora Australis. Credit and copyright: Stefan Christmann. Used by permission.

Photographer Stefan Christmann called this incredible Antarctic view a once in a lifetime experience.

“It was the most impressive experience to sit on the sea-ice and watch the Aurora Australis dance above the penguin colony with the sounds of the chicks and the adult penguins. I feel truly blessed for having had the opportunity to witness this once in a lifetime experience,” he told Universe Today.

Christmann is currently based in Antarctica, working at the German Antarctic research station Neumayer III. He is an “overwinterer” — scientific and technical staff who stay at the base for the entire southern winter — and will stay in Antarctica for an uninterrupted 14 months. “As a physicist, my duty is to maintain the data acquisition of our seismological and geomagnetic observatories as well as the analysis of the collected data,” Christmann said.

But he is also an accomplished photographer. His website and Facebook page are filled with beautiful nature images from around the world, and recently feature the Emperor penguins and their adorable chicks, as well as the stark beauty of the Antarctic landscape.

Originally from Germany, he studied photography in the US, and his work has now brought him to an extended stay in Antarctica.

Christmann explained the conditions and the difficulties in obtaining this shot, one he had long hoped for, the planning of it always in the back of his mind.

“The picture was taken at Atka-Bay on the sea-ice. The bay is roughly 8 km away from our station so the penguin colony is a popular destination for free-time trips. The idea of a photo of the Aurora Australis above the penguin colony had been in my head for a long time, but the conditions have to be just right –which usually never happens. You need a full Moon, high magnetic activity and a cloudless sky. Also the penguins should be standing close enough to the ice-berg. I made multiple attempts to get the photo, but we either had incoming clouds, low activity or had to cancel our stay because of wind picking up (which can be really dangerous out on the sea-ice).”

And time was short, as after he had been outside for a few hours the wind picked up and he and his accomplices had to leave the ice for safety reasons. “Otherwise we probably would have sat there all night!” Christmann said. The image was taken on October 1, 2012.

Christmann shared what equipment he uses as well as a few tips for Antarctic and cold weather photography.

“I used a Nikon D700 Fullframe DSLR with an AF-S G-Nikkor 14-24mm f/2.8. ISO settings varied with the intensity of the aurora from ISO 500-800,” he said. “F-Stops in the range of 4.0-5.6 and Exposure times from 20s to 30s. I try to keep ISO as low as possible for noise reasons and also try to limit the exposure time in order not to get star trails. It’s either super long star trails or almost star-dots, but I don’t really like the in between. A full battery charge (in my case around 2500mAh) lasts around 1h in the cold, so I had to switch batteries twice during our stay out on the ice!”

Asked what other details he felt was important to share about this image, Christmann said, “Antarctica is an incredible place where nature dwarfs anything made by humans. Hopefully people will gain even more interest in this continent and help to protect it as well as its inhabitants.”

Two Stars Do a Short-Orbit Tango Around the Milky Way’s Black Hole

by sandeep janjirala on OCTOBER 5, 2012

Astronomers have known for some time there was one star orbiting fairly close to the black hole at the center of our galaxy. But now another star has been found dipping close and orbiting even faster around the Milky Way’s central black hole. Astronomer Andrea Ghez from UCLA says the ability to watch these two stars in a short-period ‘tango’ around the black hole will help scientist measure the effects of space-time curvature, and they should be able to determine whether Albert Einstein was right in his prediction of how black holes could warp space and time.

“I’m extremely pleased to find two stars that orbit our galaxy’s supermassive black hole in much less than a human lifetime,” said Ghez. “It is the tango of [these stars] that will reveal the true geometry of space and time near a black hole for the first time. This measurement cannot be done with one star alone.”

There are nearly 3,000 stars that orbit somewhat close to the black hole, and most of them have orbits of 60 years or longer.
The previously known close-in star, S0-2, orbits the black hole every 15.5 years. And now, the newly found star, called S0-102, orbits the black hole in a blazing 11.5 years, the shortest known orbit of any star near this black hole.

Reconstruction of the orbits of two stars—S0-2 and S0-102—near the black hole at the Milky Way’s center. (Other stars’ orbits are also depicted by fainter lines.) The background is a real high-resolution infrared image of the region. Credit: Andrea Ghez et al./UCLA/Keck

In the same way that planets orbit around the sun, S0-102 and S0-2 are each in an elliptical orbit around the central black hole. Ghez said that the planetary motion in our solar system was the ultimate test for Newton’s gravitational theory 300 years ago, and now the motion of S0-102 and S0-2 will be the ultimate test for Einstein’s theory of general relativity, which describes gravity as a consequence of the curvature of space and time.

“The exciting thing about seeing stars go through their complete orbit is not only that you can prove that a black hole exists but you have the first opportunity to test fundamental physics using the motions of these stars,” Ghez said. “Showing that it goes around in an ellipse provides the mass of the supermassive black hole, but if we can improve the precision of the measurements, we can see deviations from a perfect ellipse — which is the signature of general relativity.”

As the stars come to their closest approach, their motion will be affected by the curvature of spacetime, and the light traveling from the stars to us will be distorted, Ghez said.

S0-2, which is 15 times brighter than S0-102, will go through its closest approach to the black hole in 2018. S0-102 makes its closest approach in 2021, so the team will be keeping an eye on these stars as they get tantalizingly close, but not close enough to get sucked in, Ghez said.

Ghez and her colleagues have been observing S0-2 since 1995. In 2000, she and her team reported — for the first time – that astronomers had seen stars accelerate around the supermassive black hole. Their research demonstrated that three stars had accelerated by more than 250,000 mph a year as they orbited the black hole. The speed of S0-102 and S0-2 should also accelerate by more than 250,000 mph at their closest approach, Ghez said.

“The fact that we can find stars that are so close to the black hole is phenomenal,” said Ghez. “Now it’s a whole new ballgame, in terms of the kinds of experiments we can do to understand how black holes grow over time, the role supermassive black holes play in the center of galaxies, and whether Einstein’s theory of general relativity is valid near a black hole, where this theory has never been tested before. It’s exciting to now have a means to open up this window.”

mY liFe mY waY:NASA -Archives

NASA's Swift Satellite Discovers a New Black Hole in our Galaxy

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An X-ray outburst caught by NASA's Swift on Sept. 16, 2012, resulted from a flood of gas plunging toward a previously unknown black hole. Gas flowing from a sun-like star collects into a disk around the black hole. Normally, this gas would steadily spiral inward. But in this system, named Swift J1745-26, the gas collects for decades before suddenly surging inward. Credit: NASA's Goddard Space Flight Center
› Download video in high resolution from Goddard's Scientific Visualization Studio

NASA's Swift satellite recently detected a rising tide of high-energy X-rays from a source toward the center of our Milky Way galaxy. The outburst, produced by a rare X-ray nova, announced the presence of a previously unknown stellar-mass black hole.

"Bright X-ray novae are so rare that they're essentially once-a-mission events and this is the first one Swift has seen," said Neil Gehrels, the mission's principal investigator, at NASA's Goddard Space Flight Center in Greenbelt, Md. "This is really something we've been waiting for."

An X-ray nova is a short-lived X-ray source that appears suddenly, reaches its emission peak in a few days and then fades out over a period of months. The outburst arises when a torrent of stored gas suddenly rushes toward one of the most compact objects known, either a neutron star or a black hole.

The rapidly brightening source triggered Swift's Burst Alert Telescope twice on the morning of Sept. 16, and once again the next day.

Named Swift J1745-26 after the coordinates of its sky position, the nova is located a few degrees from the center of our galaxy toward the constellation Sagittarius. While astronomers do not know its precise distance, they think the object resides about 20,000 to 30,000 light-years away in the galaxy's inner region.

Ground-based observatories detected infrared and radio emissions, but thick clouds of obscuring dust have prevented astronomers from catching Swift J1745-26 in visible light.

The nova peaked in hard X-rays -- energies above 10,000 electron volts, or several thousand times that of visible light -- on Sept. 18, when it reached an intensity equivalent to that of the famous Crab Nebula, a supernova remnant that serves as a calibration target for high-energy observatories and is considered one of the brightest sources beyond the solar system at these energies.

Even as it dimmed at higher energies, the nova brightened in the lower-energy, or softer, emissions detected by Swift's X-ray Telescope, a behavior typical of X-ray novae. By Wednesday, Swift J1745-26 was 30 times brighter in soft X-rays than when it was discovered and it continued to brighten.

"The pattern we're seeing is observed in X-ray novae where the central object is a black hole. Once the X-rays fade away, we hope to measure its mass and confirm its black hole status," said Boris Sbarufatti, an astrophysicist at Brera Observatory in Milan, Italy, who currently is working with other Swift team members at Penn State in University Park, Pa.

The black hole must be a member of a low-mass X-ray binary (LMXB) system, which includes a normal, sun-like star. A stream of gas flows from the normal star and enters into a storage disk around the black hole. In most LMXBs, the gas in the disk spirals inward, heats up as it heads toward the black hole, and produces a steady stream of X-rays.

But under certain conditions, stable flow within the disk depends on the rate of matter flowing into it from the companion star. At certain rates, the disk fails to maintain a steady internal flow and instead flips between two dramatically different conditions -- a cooler, less ionized state where gas simply collects in the outer portion of the disk like water behind a dam, and a hotter, more ionized state that sends a tidal wave of gas surging toward the center.

"Each outburst clears out the inner disk, and with little or no matter falling toward the black hole, the system ceases to be a bright source of X-rays," said John Cannizzo, a Goddard astrophysicist. "Decades later, after enough gas has accumulated in the outer disk, it switches again to its hot state and sends a deluge of gas toward the black hole, resulting in a new X-ray outburst."

This phenomenon, called the thermal-viscous limit cycle, helps astronomers explain transient outbursts across a wide range of systems, from protoplanetary disks around young stars, to dwarf novae -- where the central object is a white dwarf star -- and even bright emission from supermassive black holes in the hearts of distant galaxies.

Swift, launched in November 2004, is managed by Goddard Space Flight Center. It is operated in collaboration with Penn State, the Los Alamos National Laboratory in New Mexico and Orbital Sciences Corp. in Dulles, Va., with international collaborators in the United Kingdom and Italy and including contributions from Germany and Japan.

NASA Observatory Measures Expansion of Universe

Astronomers using NASA's Spitzer Space Telescope have greatly improved the cosmic distance ladder used to measure the expansion rate of the universe, as well as its size and age

The cosmic distance ladder, symbolically shown here in this artist's concept, is a series of stars and other objects within galaxies that have known distances. Image credit: NASA/JPL-Caltech › Full image and caption

This graph illustrates the Cepheid period-luminosity relationship, which scientists use to calculate the size, age and expansion rate of the universe. Image credit: NASA/JPL-Caltech/Carnegie
› Full image and caption

PASADENA, Calif. -- Astronomers using NASA's Spitzer Space Telescope have announced the most precise measurement yet of the Hubble constant, or the rate at which our universe is stretching apart.

The Hubble constant is named after the astronomer Edwin P. Hubble, who astonished the world in the 1920s by confirming our universe has been expanding since it exploded into being 13.7 billion years ago. In the late 1990s, astronomers discovered the expansion is accelerating, or speeding up over time. Determining the expansion rate is critical for understanding the age and size of the universe.

Unlike NASA's Hubble Space Telescope, which views the cosmos in visible light, Spitzer took advantage of long-wavelength infrared light to make its new measurement. It improves by a factor of 3 on a similar, seminal study from the Hubble telescope and brings the uncertainty down to 3 percent, a giant leap in accuracy for cosmological measurements. The newly refined value for the Hubble constant is 74.3 plus or minus 2.1 kilometers per second per megaparsec. A megaparsec is roughly 3 million light-years.

"Spitzer is yet again doing science beyond what it was designed to do," said project scientist Michael Werner at NASA's Jet Propulsion Laboratory in Pasadena, Calif. Werner has worked on the mission since its early concept phase more than 30 years ago. "First, Spitzer surprised us with its pioneering ability to study exoplanet atmospheres," said Werner, "and now, in the mission's later years, it has become a valuable cosmology tool."

In addition, the findings were combined with published data from NASA's Wilkinson Microwave Anisotropy Probe to obtain an independent measurement of dark energy, one of the greatest mysteries of our cosmos. Dark energy is thought to be winning a battle against gravity, pulling the fabric of the universe apart. Research based on this acceleration garnered researchers the 2011 Nobel Prize in physics.

"This is a huge puzzle," said the lead author of the new study, Wendy Freedman of the Observatories of the Carnegie Institution for Science in Pasadena. "It's exciting that we were able to use Spitzer to tackle fundamental problems in cosmology: the precise rate at which the universe is expanding at the current time, as well as measuring the amount of dark energy in the universe from another angle." Freedman led the groundbreaking Hubble Space Telescope study that earlier had measured the Hubble constant.

Glenn Wahlgren, Spitzer program scientist at NASA Headquarters in Washington, said infrared vision, which sees through dust to provide better views of variable stars called cepheids, enabled Spitzer to improve on past measurements of the Hubble constant.

"These pulsating stars are vital rungs in what astronomers call the cosmic distance ladder: a set of objects with known distances that, when combined with the speeds at which the objects are moving away from us, reveal the expansion rate of the universe," said Wahlgren.

Cepheids are crucial to the calculations because their distances from Earth can be measured readily. In 1908, Henrietta Leavitt discovered these stars pulse at a rate directly related to their intrinsic brightness.

To visualize why this is important, imagine someone walking away from you while carrying a candle. The farther the candle traveled, the more it would dim. Its apparent brightness would reveal the distance. The same principle applies to cepheids, standard candles in our cosmos. By measuring how bright they appear on the sky, and comparing this to their known brightness as if they were close up, astronomers can calculate their distance from Earth.

Spitzer observed 10 cepheids in our own Milky Way galaxy and 80 in a nearby neighboring galaxy called the Large Magellanic Cloud. Without the cosmic dust blocking their view, the Spitzer research team was able to obtain more precise measurements of the stars' apparent brightness, and thus their distances. These data opened the way for a new and improved estimate of our universe's expansion rate.

"Just over a decade ago, using the words 'precision' and 'cosmology' in the same sentence was not possible, and the size and age of the universe was not known to better than a factor of two," said Freedman. "Now we are talking about accuracies of a few percent. It is quite extraordinary."

The study appears in the Astrophysical Journal. Freedman's co-authors are Barry Madore, Victoria Scowcroft, Chris Burns, Andy Monson, S. Eric Person and Mark Seibert of the Observatories of the Carnegie Institution and Jane Rigby of NASA's Goddard Space Flight Center in Greenbelt, Md.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA. For more information about Spitzer, visithttp://spitzer.caltech.edu and http://www.nasa.gov/spitzer .

SpaceX Launch to Resupply Station Set for Sunday

SpaceX is set to launch the first of a dozen operational missions for NASA to deliver more than 1,000 pounds of supplies to the International Space Station on Oct. 7. Launch time is 8:35 p.m. from Space Launch Complex 40 at Cape Canaveral Air Force Station in Florida, just a few miles south of the space shuttle launch pads. The spacecraft will be joined to the station three days later.

The flight, known as CRS-1, will launch and perform the same rendezvous with the station as a previous SpaceX craft.

The SpaceX Dragon capsule will ride into space on the strength of the company's Falcon 9 rocket and the booster's nine first stage kerosene- and oxygen-powered Merlin engines. The Falcon 9's second stage uses a single Merlin engine to boost the Dragon into its final orbit.

Eleven minutes after launch, when the Dragon capsule is safely in orbit, a pair of solar arrays will deploy from the sides of the Dragon and controllers on Earth will begin testing rendezvous sensors.

The mission is similar to the demonstration flight in May when a Dragon was grappled by the station's robotic arm to complete the first rendezvous and berthing by a private spacecraft at the space station.

The SpaceX craft will spend about three weeks connected to the station then it will be released to return to Earth.

A major difference for this mission is that the Dragon will be filled with an amount of cargo suitable for an operational mission. The prior flight carried just enough items to prove the capsule would do its job as a cargo hauler. This time, the manifest will include a freezer for the station's scientific samples, a powered middeck locker with an experiment inside along with a variety of materials for the astronauts living and working on the space station.

The supply flight is part of NASA's Commercial Resupply Services contract, which is paying SpaceX for 12 cargo runs to the orbiting laboratory. The station also is serviced by Russian Progress cargo capsules, European-made and launched Automated Transfer Vehicles, or ATVs, and Japanese-produced H-II Transfer Vehicles, or HTVs. All the cargo ships operate without astronauts or crew members aboard.

Once the spacecraft arrive at the station, the astronauts and cosmonauts onboard unload them and fill them with used materials or unneeded equipment before releasing them.

Here, SpaceX again does something unique. The Dragons are built with heat shields to survive a plunge through the atmosphere and splashdown safely in the ocean under billowing parachutes. The other cargo craft do not carry heat shields, so they just burn up in the atmosphere.

On its return trip, the Dragon capsule will carry more than a ton of scientific samples collected during space station research, along with the freezer the samples have been stored in. Astronauts also will load used station hardware into the capsule for return to Earth where engineers can get a firsthand look at it.

A second kind of American cargo craft is also being developed. The Orbital Sciences' Cygnus spacecraft and Antares rocket are due to make a demonstration flight later this year.