Thursday, April 29, 2010

Wrinkle Ridges in Mare Tranquilitatis

Lunar wrinkle ridges can be hundreds of kilometers long, tens of kilometers wide, and hundreds of meters high. Read more in Wilhelms, 1987. They can have a sinuous or linear appearance with asymmetric cross-sections. In other words, the feature that you see could easily be made up of a smaller ridge superposed on a broad rise.

Close up of a northwest trending wrinkle ridge in the high-Ti basaltic lava plains of Mare Tranquillitatis. The bright areas along the steepest parts of the ridge are places where less mature subsurface materials have been exposed by small impacts or fracturing of the bedrock as the original mare surface buckled. Image is 1.25 km wide Credit: NASA/Goddard/Arizona State University.

Lunar wrinkle ridges are found in the mare basalt deposits that filled the giant impact basins on the Moon. Frequently, wrinkle ridges are oriented concentric to large impact basins. Loading of the basin floor with multiple eruptions of mare basalts causes the formation of wrinkle ridges in the basin center and graben, or trenches, along the mare margins (see below). The tremendous weight of the newer basalt layers then causes the center of the basin to sag. As the basin center sags, the basalts slide inward, causing compression that results in folding and faulting of the basalt. The sagging of the basin under the weight of the basalt also causes the opening of graben along the edges of the basalt layers.

Long wrinkle ridges in Mare Tranquillitatis in LRO Wide Angle Camera (WAC) image M117345275M. The section of wrinkle ridge shown in the top image is in the center of this WAC view. Arago crater (lower left), is 26 km in diameter. Credit: NASA/Goddard/Arizona State University.

Idealized cross-section through an impact basin that filled with three episodes of mare basalt eruptions. Loading of the basin floor with mare basalts causes the formation of wrinkle ridges in the basin center and graben along the mare margins. Credit: Hiesinger, 1999, PhD dissertation

We also know, thanks to the samples collected by the Apollo 11 astronauts, that the mare basalts in this region are rich in titanium. Study of the Apollo samples has shown it is relatively straightforward to extract resources (especially oxygen) from titanium-rich lunar soils.

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'Survivor' Black Holes May Be Mid-Sized

New evidence from NASA's Chandra X-ray Observatory and ESA's XMM-Newton strengthens the case that two mid-sized black holes exist close to the center of a nearby starburst galaxy. These “survivor” black holes avoided falling into the center of the galaxy and could be examples of the seeds required for the growth of supermassive black holes in galaxies, including the one in the Milky Way.

For several decades, scientists have had strong evidence for two distinct classes of black hole: the stellar-mass variety with masses about ten times that of the Sun, and the supermassive ones, located at the center of galaxies, that range from hundreds of thousands to billions of solar masses.

Composite image of the nearby starburst galaxy M82. Image credit: X-ray: NASA/ CXC/Tsinghua Univ./H. Feng et al.

But a mystery has remained: what about black holes that are in between? Evidence for these objects has remained controversial, and until now there were no strong claims of more than one such black hole in a single galaxy. Recently, a team of researchers has found signatures in X-ray data of two mid-sized black holes in the starburst galaxy M82 located 12 million light years from Earth.

"This is the first time that good evidence for two mid-sized black holes has been found in one galaxy," said Hua Feng of the Tsinghua University in China, who led two papers describing the results. "Their location near the center of the galaxy might provide clues about the origin of the Universe's largest black holes -- supermassive black holes found in the centers of most galaxies."

One possible mechanism for the formation of supermassive black holes involves a chain reaction of collisions of stars in compact star clusters that results in the buildup of extremely massive stars, which then collapse to form intermediate-mass black holes. The star clusters then sink to the center of the galaxy, where the intermediate-mass black holes merge to form a supermassive black hole.

In this picture, clusters that were not massive enough or close enough to the center of the galaxy to fall in would survive, as would any black holes they contain.

"We can't say whether this process actually occurred in M82, but we do know that both of these possible mid-sized black holes are located in or near star clusters," said Phil Kaaret from the University of Iowa, who co-authored both papers. "Also, M82 is the nearest place to us where the conditions are similar to those in the early Universe, with lots of stars forming."

The evidence for these two "survivor" black holes comes from how their X-ray emission varies over time and analysis of their X-ray brightness and spectra, i.e., the distribution of X-rays with energy.

Chandra and XMM-Newton data show that the X-ray emission for one of these objects changes in a distinctive manner similar to stellar-mass black holes found in the Milky Way. Using this information and theoretical models, the team estimated this black hole's mass is between 12,000 and 43,000 times the mass of the Sun. This mass is large enough for the black hole to generate copious X-rays by pulling gas directly from its surroundings, rather than from a binary companion, like with stellar-mass black holes.

The black hole is located at a projected distance of 290 light years from the center of M82. The authors estimate that, at this close distance, if the black hole was born at the same time as the galaxy and its mass was more than about 30,000 solar masses it would have been pulled into the center of the galaxy. That is, it may have just escaped falling into the supermassive black hole that is presumably located in the center of M82.

The second object, located 600 light years in projection away from the center of M82, was observed by both Chandra and XMM-Newton. During X-ray outbursts, periodic and random variations normally present in the X-ray emission disappear, a strong indication that a disk of hot gas dominates the X-ray emission. A detailed fit of the X-ray data indicates that the disk extends all the way to the innermost stable orbit around the black hole. Similar behavior has been seen from stellar-mass black holes in our Galaxy, but this is the first likely detection in a candidate intermediate-mass black hole.

The radius of the innermost stable orbit depends only on the mass and spin of the black hole. The best model for the X-ray emission implies a rapidly spinning black hole with mass in the range 200 to 800 times the mass of the Sun. The mass agrees with theoretical estimates for a black hole created in a star cluster by runaway collisions of stars.

"This result is one of the strongest pieces of evidence to date for the existence of an intermediate-mass black hole," said Feng. "This looks just like well-studied examples of stellar-mass black holes, except for being more than 20 times as massive."

The two papers describing these results recently appeared in The Astrophysical Journal. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.

The XMM-Newton spacecraft is controlled by the European Space Operations Center. The XMM-Newton Science Operations Center situated at ESAC in Villafranca, Spain, manages observation requests and receives XMM-Newton data. The XMM-Newton Survey Science Centre at Leicester University, UK, processes and correlates all XMM-Newton observations with existing sky data held elsewhere in the world.

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Wednesday, April 28, 2010

Scientists Say Ice Lurks in Asteroid's Cold Heart

Scientists using a NASA funded telescope have detected water-ice and carbon-based organic compounds on the surface of an asteroid. The cold hard facts of the discovery of the frosty mixture on one of the asteroid belt's largest occupants, suggests that some asteroids, along with their celestial brethren, comets, were the water carriers for a primordial Earth. The research is published in today's issue of the journal Nature.

"For a long time the thinking was that you couldn't find a cup's worth of water in the entire asteroid belt," said Don Yeomans, manager of NASA's Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. "Today we know you not only could quench your thirst, but you just might be able to fill up every pool on Earth – and then some."

In this artist's concept, a narrow asteroid belt filled with rocks and dusty debris orbits a star similar to our own sun. Image credit: NASA/JPL-Caltech

The discovery is a result of six years of observing asteroid 24 Themis by astronomer Andrew Rivkin of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. Rivkin, along with Joshua Emery, of the University of Tennessee in Knoxville, employed the NASA Infrared Telescope Facility to take measurements of the asteroid on seven separate occasions beginning in 2002. Buried in their compiled data was the consistent infrared signature of water ice and carbon-based organic materials.

The study's findings are particularly surprising because it was believed that Themis, orbiting the sun at "only" 479 million kilometers (297 million miles), was too close to the solar system's fiery heat source to carry water ice left over from the solar system's origin 4.6 billion years ago.

Now, the astronomical community knows better. The research could help re-write the book on the solar system's formation and the nature of asteroids.

"This is exciting because it provides us a better understanding about our past – and our possible future," said Yeomans. "This research indicates that not only could asteroids be possible sources of raw materials, but they could be the fueling stations and watering holes for future interplanetary exploration."

Rivkin and Emory's findings were independently confirmed by a team led by Humberto Campins at the University of Central Florida in Orlando.

NASA detects, tracks and characterizes asteroids and comets passing close to Earth using both ground- and space-based telescopes. The Near-Earth Object Observations Program, commonly called "Spaceguard," discovers these objects, characterizes a subset of them, and plots their orbits to determine if any could be potentially hazardous to our planet.

JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena. More information about asteroids and near-Earth objects is at: .

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IceBridge Mission at Halfway Point

The 2010 Operation IceBridge mission to the Arctic is nearing its halfway point and wrapping up flights with NASA's DC-8 research airplane. In just over four weeks since leaving Palmdale, Calif., on March 21, scientists and crew have flown 14 successful missions over the Arctic Ocean and the Greenland Ice Sheet. They have been in the air for more than 120 hours and have flown a distance greater than 1.5 times around the world.

On April 19, 2010, the IceBridge team flew underneath the clouds in difficult conditions to collect critical data for monitoring changes in sea ice in the Arctic Ocean. Credit: Michael Studinger

IceBridge project scientist Michael Studinger, from the Goddard Earth Science and Technology Center at the University of Maryland - Baltimore County, wrote from Thule, Greenland, to discuss some of the mission's accomplishments and critical moments, including one important flight that was almost thwarted by the Arctic weather.

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Tuesday, April 27, 2010

Crew Keeps Eye on Science, Prepares for Progress Docking

With systems aboard the International Space Station performing well Tuesday, the orbiting Expedition 23 crew tackled a variety of experiments, conducted a periodic fire drill and prepared for the docking of an unpiloted Russian cargo craft.

With the launch of the new ISS Progress 37 cargo ship from the Baikonur Cosmodrome in Kazakhstan set for 1:15 p.m. EDT Wednesday, Commander Oleg Kotov and Flight Engineer Alexander Skvortsov reviewed procedures for manual rendezvous techniques with TORU, the Russian telerobotically operated rendezvous system. The crew can use TORU to monitor the Progress’ approach for docking or take control of the process if difficulties arise. Scheduled to dock Saturday, Progress 37 is loaded with 2.6 tons of food, fuel, oxygen, propellant and supplies for the Expedition 23 crew.

Image above: Expedition 23 Commander Oleg Kotov is pictured near fresh fruit floating freely in the Zvezda service module of the International Space Station. Credit: NASA

The old ISS Progress 35 that undocked from the station’s Pirs docking compartment Thursday was deorbited Tuesday as its engines fired for a final time at 2:05 p.m., sending the craft to a destructive re-entry over the Pacific Ocean.

As part of a periodic medical exam, Flight Engineers Tracy Caldwell Dyson, T.J. Creamer and Soichi Noguchi performed ultrasound scans of each other’s eyes. Through diagnostic telemedicine, flight surgeons on Earth can use the data collected during these exams to measure and assess any changes in crew health.

Flight Engineer Mikhail Kornienko, who spent much of his morning performing routine daily servicing on systems in the Zvezda service module, joined the rest of the Expedition 23 crew after lunch for a fire drill to practice initial crew actions in response to an emergency.

The station’s residents also had several opportunities for Earth observation and photography as they orbited the world every 90 minutes. Two sites in South Africa were suggested to the crew for photography, including Cape Town, which is experiencing extensive immigration and a building boom as the city prepares to host the Soccer World Cup in June.

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Planck's View of Orion

An active star-formation region in the constellation Orion, as seen by Planck. This long-wavelength image covers a square region of 13 by 13 degrees (which is equivalent to 26 by 26 full moons). It is a three-color combination constructed from three of Planck's nine frequency channels: 30, 353 and 857 gigahertz.

The giant red arc of Barnard's Loop is thought to be the blast wave from a star that blew up inside the region about two million years ago. The bubble it created is now about 300 light-years across.

Image credit: ESA/LFI & HFI Consortia

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Monday, April 26, 2010

NASA's Global Hawk Completes 28-hour GloPac Science Flight

NASA's Global Hawk completed its longest science flight to date April 24, touching down shortly before 5 a.m. PDT at Edwards Air Force Base in Southern California after a 28-hour and 36-minute flight to the Arctic.

NASA and Northrop Grumman partnered to return this Global Hawk Advanced Concept Technology Demonstrator to flight under NASA operation. NASA and the science community will use this aircraft for high-altitude, long-duration Earth science missions. (NASA photo / Carla Thomas)

The NASA Global Hawk Pacific, or GloPac, campaign is the first Earth Science mission to be conducted on the aircraft. The Global Hawk's ability to autonomously fly long distances and remain aloft for extended periods brings a new capability to the science community for measuring and observing large areas of the Earth. Ten specialized instruments will be installed in the aircraft to explore the trace gases, aerosols, and dynamics of the upper troposphere and lower stratosphere. The instruments will also validate sensors aboard NASA's Aura Earth-monitoring satellite.

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STS-132 to Carry Research Module

In the Space Station Processing Facility at NASA's Kennedy Space Center in Florida, the Russian-built Mini-Research Module-1 is prepared for installation in the payload canister before transport to Launch Pad 39A.

The six-member crew of space shuttle Atlantis' STS-132 mission will deliver the module, known as Rassvet, to the International Space Station. The second in a series of new pressurized components for Russia, it will be permanently attached to the Earth-facing port of the Zarya control module. Rassvet, which translates to "dawn," will be used for cargo storage and will provide an additional docking port to the station.

Image credit: NASA/Gianni Woods
April 5, 2010

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Sunday, April 25, 2010

Solar Flare Activity For First Light

Images taken by SDO immediately after the AIA CCD cameras cooled on March 30, 2010. This image shows several flares and their associated waves across the Sun. Credit: NASA/GSFC/AIA

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Launch Rehearsal Complete, Crew Heads Back to Houston

At NASA's Kennedy Space Center in Florida, space shuttle Atlantis' six STS-132 astronauts completed their Terminal Countdown Demonstration Test, or TCDT, Saturday morning.

Image above: The crew of STS-132 discusses the upcoming mission with space shuttle Atlantis standing behind them. The crew, led by Commander Ken Ham, left, will carry the Russian-built Mini-Research Module-1, or MRM-1, to the International Space Station. Atlantis is targeted for launch May 14 at 2:19 p.m. EDT. Image credit: NASA TV

The astronauts headed back home in their T-38 jets to NASA's Johnson Space Center in Houston around 2 p.m. EDT Saturday.

STS-132 mission is targeted for launch at 2:19 p.m. on May 14 to deliver an Integrated Cargo Carrier and a Russian-built Mini Research Module to the International Space Station.

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Thursday, April 22, 2010

NASA's Swift Catches 500th Gamma-ray Burst

In its first five years in orbit, NASA's Swift satellite has given astronomers more than they could have hoped for. Its discoveries range from a nearby nascent supernova to a blast so far away that it happened when our universe was only 5 percent of its present age.

Swift primarily studies gamma-ray bursts (GRBs) -- the biggest and most mysterious explosions in the cosmos. On April 13, the spacecraft's "burst-o-meter" cataloged its 500th GRB.

"On the one hand, it's just a number, but on the other it is a remarkable milestone," said Neil Gehrels, Swift's lead researcher at Goddard Space Flight Center in Greenbelt, Md. "Each burst has turned over a new piece of the puzzle and a clearer picture is emerging."

"Over five years and 500 bursts, Swift has fulfilled every significant promise of its mission and, in addition, brought a wealth of surprises," noted Derek Fox, a Swift team member at Penn State in University Park, Pa.

Watch: Five years of Swift-discovered gamma-ray bursts.
Credit: NASA/Goddard Space Flight Center/Swift

Burst 500, officially known as GRB 100413B, exploded in constellation Cassiopeia as a long burst, a type usually associated with the death of a massive star. It wasn't detected in on-board analysis of data from the spacecraft's Burst Alert Telescope (BAT), which was interrupted 18 seconds after the burst as Swift slewed to a pre-planned target.

Instead, GRB 100413B came to light when David Palmer, an astrophysicist at Los Alamos National Laboratory in New Mexico, later analyzed the data. "The BAT team regularly digs through the data once it comes to the ground and finds weak bursts like this one that take a bit of special care," said Goddard's Judith Racusin, who coordinated burst observations that day.

Summaries of other notable bursts in Swift's storied career are listed below.

This all-sky map shows the locations of Swift's 500 gamma-ray bursts, color coded by the year in which they occurred. In the background, an infrared image shows the location of our galaxy and its largest satellites. Credit: NASA/Swift/Francis Reddy

Swift's main job is to quickly localize each gamma-ray burst, report its position so that others can immediately conduct follow-up observations, and then study the burst using its X-ray and Ultraviolet/Optical telescopes. But it does much more, including ultraviolet studies of exploding stars, monitoring black holes and neutron stars for surges of high-energy radiation, and carrying out a long-term X-ray survey of the entire sky.

The spacecraft rocketed into orbit in November 2004. Managed by NASA's Goddard Space Flight Center, Swift was built and is operated in collaboration with Penn State, the Los Alamos National Laboratory in New Mexico, and General Dynamics of Gilbert, Ariz. Other partners include the University of Leicester and Mullard Space Science Laboratory in the United Kingdom, Brera Observatory and the Italian Space Agency in Italy, with additional collaborators in Germany and Japan.


Because gamma rays are the highest-energy form of light, the brief but brilliant blasts represent a colossal energy release. Gamma-ray bursts were discovered in 1967 by unclassified military satellites designed to look for clandestine nuclear tests. The first observations required extensive analysis to be sure that the bursts were truly originating beyond the solar system, and they weren't published until 1973.

In binary systems containing neutron stars, the emission of gravitational radiation gradually brings the objects closer together. This animation shows such a system after about a billion years, when two equal-mass neutron stars whirl around each other 60,000 times a minute. The stars merge in a few milliseconds, sending out a pulse of gravitational waves and creating a short gamma-ray burst. Credit: NASA/Swift/Dana Berry

Over the following years, astronomers learned that sufficiently sensitive instruments could detect about two bursts per day, on average, somewhere in the sky. Of those twice-daily GRBs, Swift's Burst Alert Telescope snares about one in eight for detailed study.

According to Lorella Angelini, a Goddard astrophysicist now developing a comprehensive burst database, the number of recorded GRBs is approaching 6,000. Yet if one considers only bursts with measured distances, Swift's share of the total is a whopping 75 percent.

An earlier NASA satellite, the Compton Gamma Ray Observatory, showed that bursts come in long and short varieties, with long bursts (those lasting longer than two seconds) outnumbering short bursts three to one. Compton also showed that bursts occur randomly and evenly over the sky. Maps of GRB distribution bear no hint of our galaxy's structure. This means that they are extremely far away — and all the more powerful.

Across the universe

A key breakthrough in understanding GRBs came from the Italian-Dutch satellite Beppo-SAX, which in 1997 provided the first precise burst positions. It later discovered lingering X-ray emission -- dubbed "afterglows" -- at burst locations. Observatories on the ground quickly discovered afterglows in visible light, which provided information that confirmed the burst's enormous distances. Astronomers now regularly study afterglows across the electromagnetic spectrum.

Most of the time, the hard task of measuring burst distances falls to ground-based observatories, which can target a burst's location with telescopes far larger than the Ultraviolet/Optical Telescope aboard Swift.

"Getting on the afterglows quickly with large ground-based telescopes remains a key element in understanding GRBs," said Fox, whose research focuses on follow-up observations. "It's this synergy between Swift and ground observatories that has really moved the ball forward, especially for short bursts."

And the farther the burst, the more important rapid ground follow-up becomes. At distances greater than about 12 billion light-years, gas clouds block ultraviolet wavelengths before they can reach Earth, and all optical light becomes shifted into infrared wavelengths only detectable by specially-equipped ground-based telescopes. Astronomers scramble to detect afterglow from new bursts as soon as they can.

"Thanks to such efforts, we know Swift has seen GRBs as close as about 100 million light-years and as far away as 13 billion light-years," adds Gehrels. Put another way, Swift sees gamma-ray bursts over a span of time equivalent to about 95 percent of the universe's age.

The long and the short of GRBs

By the time Swift launched, mounting evidence already pointed to the deaths of massive stars as the source of most long GRBs -- a scenario that still stands. When such a star runs out of fuel, its core collapses and likely forms a black hole surrounded by a dense hot disk of gas called an accretion disk. Somehow, the black hole diverts part of the infalling matter into a pair of high-energy jets that tear through the collapsing star.

The jets move so fast -- upwards of 99.9 percent the speed of light -- that collisions within them produce gamma rays. As the jet breaches the star's surface, a gamma-ray burst is born. The jet continues on, later striking gas beyond the star to produce afterglows.

Short bursts, however, proved much harder to pin down. "We didn't know their most basic properties," notes Ehud Nakar, an astrophysicist at Tel Aviv University in Israel. "We knew so little we weren't even sure that short GRBs were a unique astrophysical phenomenon."

It turns out they are. "Long GRBs originate from the collapse of stars just millions of years old, but the objects that give rise to some short GRBs reach ages of billions of years before exploding," Nakar adds.

The emerging picture is that short GRBs arise when two compact objects -- either a pair of neutron stars or a neutron star and a black hole -- collide and merge. These objects, which are the crushed cores of exploded stars, pack more mass than the sun into volumes just a few miles across. For those bound in a binary system, Einstein's relativity seals their fate.

According to Einstein, massive orbiting objects give off a type of energy called gravitational radiation. Although no one has yet detected these waves, astronomers have observed an effect predicted by this energy loss -- the slowly shrinking orbits of binary neutron stars. Over billions of years, the stellar cinders grow ever closer and finally merge in an event that unleashes titanic energies and creates a short GRB.

Gamma-ray bursts longer than two seconds are caused by the collapse of a rap-idly rotating massive star at the end of its life. As the star collapses, jets of parti-cles and gamma radiation produced by a newborn black hole blast in opposite directions from the stellar core. Credit: NASA/Swift/Cruz deWilde

But Nakar thinks the full picture still eludes astronomers. "So far, the data favor merging neutron stars, and that is certainly the most popular idea, but other scenarios remain possible. We still do not know the origin of short GRBs."

Thanks mainly to burst identifications from Swift and the afterglow observations they make possible, scientists now have details on dozens of short bursts and their afterglows. "We're now beginning to understand the home galaxies of short GRBs," Fox said.

Over the past five years, Swift has delivered a great deal of revolutionary science. But its career isn't over yet -- and with a little luck, there will be much more to come.

Swift GRB highlights

April 13, 2010: NASA's Swift discovers its 500th burst. GRB 100413B is a long burst in the constellation Cassiopeia.

April 23, 2009: GRB 090423 in Leo holds the record for the farthest burst yet known -- 13.04 billion light-years away. "The burst is beyond the farthest confirmed galaxies and quasars, making it the most distant object we know in the universe today," Fox said. This find validates models suggesting that galaxy and star formation were well under way in the universe's first billion years and that some early stars died as bursts.

March 19, 2008: GRB 080319B, in Bo├Âtes, is truly extraordinary. It produces enough light to be seen briefly with the unaided eye, cresting at visual magnitude 5.3 despite occurring 7.5 billion light-years away -- or more than halfway across the visible universe. Scientists conclude that one of its particle jets appears to have been aimed squarely at Earth.

July 14, 2007: GRB 070714B explodes in Taurus. Afterglow observations indicate a distance of 7.3 billion light-years, making this one of the farthest short bursts to date.

Feb. 18, 2006: GRB 060218 explodes in Aries 450 million light-years away -- in our back yard, cosmically speaking. Although faint, the burst emits detectable gamma rays for more than 40 minutes and detectable optical and X-ray emission lasts more than 10 days. The event is a hybrid, showing characteristics of both a GRB and a supernova, and leads to the best observations yet exploring connections between these phenomena.

Sept. 4, 2005: At a distance of 12.77 billion light-years, GRB 050904, located in Pisces, is the farthest-known GRB at the time, the first of many such Swift records.

May 9, 2005: GRB 050509B, in Coma Berenices, erupts with a flash of gamma-rays that lasts just 0.03 second. Swift turns to the burst fast enough to detect 11 X-ray photons, making this the first short burst with a detected afterglow.

Dec. 17, 2004: Swift's first burst, in Crater, is eight-second-long GRB 041217.

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SDO First Light Press Conference

This image taken on April 21, 2010 at the Newseum, shows the SDO principles as they address the media at the SDO First Light press conference. Featured in the photo are (l to r): at podium, Dwayne Brown, NASA HQ PAO; seated, Dean Pesnell, SDO Project Scientist; Alan Title, Atmospheric Imaging Assembly (AIA) Principal Investigator (PI); Philip H. Scherrer, Helioseismic and Magnetic Imager (HMI) PI; Tom Woods, Extreme Ultraviolet Variability Experiment (EVE) PI; and Madhulika Guhathakurta, SDO Program Scientist. A large screen above them displays a solar prominence image taken by the SDO spacecraft. Credit: NASA/Carla Cioffi

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Wednesday, April 21, 2010

NASA's New Eye on the Sun Delivers Stunning First Images

NASA's recently launched Solar Dynamics Observatory, or SDO, is returning early images that confirm an unprecedented new capability for scientists to better understand our sun’s dynamic processes. These solar activities affect everything on Earth.

Some of the images from the spacecraft show never-before-seen detail of material streaming outward and away from sunspots. Others show extreme close-ups of activity on the sun’s surface. The spacecraft also has made the first high-resolution measurements of solar flares in a broad range of extreme ultraviolet wavelengths.

"These initial images show a dynamic sun that I had never seen in more than 40 years of solar research,” said Richard Fisher, director of the Heliophysics Division at NASA Headquarters in Washington. "SDO will change our understanding of the sun and its processes, which affect our lives and society. This mission will have a huge impact on science, similar to the impact of the Hubble Space Telescope on modern astrophysics.”

A full-disk multiwavelength extreme ultraviolet image of the sun taken by SDO on March 30, 2010. False colors trace different gas temperatures. Reds are relatively cool (about 60,000 Kelvin, or 107,540 F); blues and greens are hotter (greater than 1 million Kelvin, or 1,799,540 F). Credit: NASA

Launched on Feb. 11, 2010, SDO is the most advanced spacecraft ever designed to study the sun. During its five-year mission, it will examine the sun's magnetic field and also provide a better understanding of the role the sun plays in Earth's atmospheric chemistry and climate. Since launch, engineers have been conducting testing and verification of the spacecraft’s components. Now fully operational, SDO will provide images with clarity 10 times better than high-definition television and will return more comprehensive science data faster than any other solar observing spacecraft.

A movie of the March 30, 2010, solar prominence eruption, as seen by SDO. Credit: NASA/Goddard

SDO will determine how the sun's magnetic field is generated, structured and converted into violent solar events such as turbulent solar wind, solar flares and coronal mass ejections. These immense clouds of material, when directed toward Earth, can cause large magnetic storms in our planet’s magnetosphere and upper atmosphere.

SDO will provide critical data that will improve the ability to predict these space weather events. NASA's Goddard Space Flight Center in Greenbelt, Md., built, operates and manages the SDO spacecraft for the agency’s Science Mission Directorate in Washington.

“I’m so proud of our brilliant work force at Goddard, which is rewriting science textbooks once again.” said Sen. Barbara Mikulski, D-Md., chairwoman of the Commerce, Justice and Science Appropriations Subcommittee that funds NASA. “This time Goddard is shedding new light on our closest star, the sun, discovering new information about powerful solar flares that affect us here on Earth by damaging communication satellites and temporarily knocking out power grids. Better data means more accurate solar storm warnings.”

This image compares the relative size of SDO's imagery to that of other missions. Credit: NASA

Space weather has been recognized as a cause of technological problems since the invention of the telegraph in the 19th century. These events produce disturbances in electromagnetic fields on Earth that can induce extreme currents in wires, disrupting power lines and causing widespread blackouts. These solar storms can interfere with communications between ground controllers, satellites and airplane pilots flying near Earth's poles. Radio noise from the storm also can disrupt cell phone service.

More "Hello, SDO!" videos from NASA Goddard's Scientific Visualization Studio. Credit: NASA/Goddard/Chris Smith

SDO will send 1.5 terabytes of data back to Earth each day, which is equivalent to a daily download of half a million songs onto an MP3 player. The observatory carries three state-of the-art instruments for conducting solar research.

The Helioseismic and Magnetic Imager maps solar magnetic fields and looks beneath the sun’s opaque surface. The experiment will decipher the physics of the sun’s activity, taking pictures in several very narrow bands of visible light. Scientists will be able to make ultrasound images of the sun and study active regions in a way similar to watching sand shift in a desert dune. The instrument’s principal investigator is Phil Scherrer of Stanford University. HMI was built by a collaboration of Stanford University and the Lockheed Martin Solar and Astrophysics Laboratory in Palo Alto, Calif.

The Atmospheric Imaging Assembly is a group of four telescopes designed to photograph the sun’s surface and atmosphere. The instrument covers 10 different wavelength bands, or colors, selected to reveal key aspects of solar activity. These types of images will show details never seen before by scientists. The principal investigator is Alan Title of the Lockheed Martin Solar and Astrophysics Laboratory, which built the instrument.

The Extreme Ultraviolet Variability Experiment measures fluctuations in the sun’s radiant emissions. These emissions have a direct and powerful effect on Earth’s upper atmosphere -- heating it, puffing it up, and breaking apart atoms and molecules. Researchers don't know how fast the sun can vary at many of these wavelengths, so they expect to make discoveries about flare events. The principal investigator is Tom Woods of the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder. LASP built the instrument.

"These amazing images, which show our dynamic sun in a new level of detail, are only the beginning of SDO's contribution to our understanding of the sun," said SDO Project Scientist Dean Pesnell of Goddard.

SDO is the first mission of NASA's Living with a Star Program, or LWS, and the crown jewel in a fleet of NASA missions that study our sun and space environment. The goal of LWS is to develop the scientific understanding necessary to address those aspects of the connected sun-Earth system that directly affect our lives and society.

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Another World

This other worldly landscape is actually Dagze Co, one of many inland lakes in Tibet. In glacial times, the region was considerably wetter, and lakes were correspondingly much larger, as evidenced by the numerous fossil shorelines that circle the lake and attest to the presence of a previously larger, deeper lake. Over millennia changes in climate have resulted in greater aridity of the Tibetan Plateau.

Image Credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

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Tuesday, April 20, 2010

Experience Hubble's Universe in 3-D

This image depicts a vast canyon of dust and gas in the Orion Nebula from a 3-D computer model based on observations by NASA's Hubble Space Telescope and created by science visualization specialists at the Space Telescope Science Institute (STScI) in Baltimore, Md. A 3-D visualization of this model takes viewers on an amazing four-minute voyage through the 15-light-year-wide canyon.

The model takes viewers through an exhilarating ride through the Orion Nebula, a vast star-making factory 1,500 light-years away. This virtual space journey isn't the latest video game but one of several groundbreaking astronomy visualizations created by specialists at STScI, the science operations center for NASA's Hubble Space Telescope. The cinematic space odysseys are part of the new Imax film Hubble 3D, which opens today at select IMAX theaters worldwide.

The 43-minute movie chronicles the 20-year life of Hubble and includes highlights from the May 2009 servicing mission to the Earth-orbiting observatory, with footage taken by the astronauts. The giant-screen film showcases some of Hubble's breathtaking iconic pictures, such as the Eagle Nebula's "Pillars of Creation," as well as stunning views taken by the newly installed Wide Field Camera 3.

While Hubble pictures of celestial objects are awe-inspiring, they are flat 2-D photographs. For this film, those 2-D images have been converted into 3-D environments, giving the audience the impression they are space travelers taking a tour of Hubble's most popular targets.

Based on a Hubble image of Orion released in 2006, the visualization was a collaborative effort between science visualization specialists at STScI, including Greg Bacon, who sculpted the Orion Nebula digital model, with input from STScI astronomer Massimo Roberto; the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign; and the Spitzer Science Center at the California Institute of Technology in Pasadena.

For some of the sequences, STScI imaging specialists developed new techniques for transforming the 2-D Hubble images into 3-D. STScI image processing specialists Lisa Frattare and Zolt Levay, for example, created methods of splitting a giant gaseous pillar in the Carina Nebula into multiple layers to produce a 3-D effect, giving the structure depth.

Image Credit: NASA, G. Bacon, L. Frattare, Z. Levay, and F. Summers (STScI/AURA)

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Ashes to Ashes, Dust to Dust

This new composite image from NASA's Chandra X-ray Observatory and Spitzer Space Telescope shows the dusty remains of a collapsed star, the dust from which is flying past and engulfing a nearby family of stars. Scientists believe the stars in the image are part of a stellar cluster in which a supernova exploded. Material ejected in the explosion now blows past these stars at high velocities.

In this image of G54.1+0.3, X-ray data from Chandra are shown in blue, and data from Spitzer in green (a shorter wavelength) and red-yellow (a longer one). The white source near the center of the image is a dense, rapidly rotating neutron star, or pulsar, all that remains of a core-collapse supernova explosion. The pulsar generates a wind of high-energy particles -- seen in the Chandra data -- that expands into the surrounding environment, illuminating the material ejected in the supernova explosion.

The unique environment into which this supernova exploded makes it possible for astronomers to observe the condensed dust from the supernova that is usually too cold to emit in the infrared.

Image Credits: X-ray: NASA/CXC/SAO/T. Temim et al. Infrared: NASA/JPL/Caltech
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Deputy Administrator Views STS-131 Landing

NASA Kennedy Space Center Director Bob Cabana, left, Special Assistant to the Director Robert Hubbard, center, and NASA Deputy Administrator Lori Garver scan the sky for the space shuttle Discovery as it approaches for landing at the Kennedy Space Center in Cape Canaveral, Florida, Tuesday, April 20, 2010. Discovery and the STS-131 crew returned from their mission to the International Space Station.

Image Credit: NASA/Bill Ingalls

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Monday, April 19, 2010

NASA Sets Payload Record as Part of Parachute Development Test

Under a brilliant early morning Arizona sky, NASA conducted a successful, record-breaking test of a drogue parachute being designed to return next-generation space vehicles safely to Earth.

The 77,000-pound payload used in the test was dropped from the back of a U.S. Air Force C-17 at an altitude of 25,000 feet, setting a record for the heaviest single load ever extracted out of a C-17 during flight. NASA conducted the drop test, April 14, at the U.S. Army's Yuma Proving Ground near Yuma, Ariz.

The design load limit test will provide engineers with a better understanding of the full structural capabilities of the drogue parachute, currently under development for the Ares launch vehicles. The 68-foot-diameter drogue and all test hardware functioned properly and landed safely.

NASA drogue parachute drop test at the U.S. Army Yuma Proving Ground. Image credit: U.S. Army Yuma Proving Ground

"Testing of a deceleration system is a very complicated process," said Ron King, Ares I first stage deceleration subsystem manager for the Ares Projects at the Marshall Space Flight Center in Huntsville, Ala. "All elements must work together in a carefully timed sequence to ensure a successful test. Through continued development and fine-tuning of the recovery system, our team is establishing a solid foundation for safe, reliable payload recovery."

The test team is managed by the Marshall Center and included engineers with ATK Space Systems near Promontory, Utah, the prime contractor for the first stage booster and United Space Alliance -- ATK's subcontractor, responsible for design, development and testing of the parachutes at its facilities at NASA's Kennedy Space Center, Fla.

The 68-foot-diameter drogue parachute and jumbo dart used for NASA's load limit test functioned properly and landed safely. Image credit: U.S. Army Yuma Proving Ground

This was the second in a series of three planned load limit tests designed to place the loads expected in flight on the parachute canopy. The next test series, called overload tests, will subject the parachute canopy to loads greater than what would typically be experienced in flight, to prove the parachute is strong enough to survive some degree of unexpected events.

A load limit test, as the name implies, pushes the parachute’s canopy to its designed limit -- supporting a 450,000-pound opening dynamic load, or force in pounds exerted on the parachute generated by the drag and pull of the parachute when it opens. The primary test objective was to deploy or open the parachute at a dynamic pressure of 420 pounds per square foot, simulating the opening load conditions the drogue parachute will experience when it is deployed to slow the rapid descent of the rocket's spent first-stage motor.

The complete motor recovery system consists of the pilot parachute, drogue parachute and three main parachutes. Similar to those used for the space shuttle boosters, these parachutes have been redesigned to accommodate larger, more powerful motors that will travel faster and fall from a higher altitude than the shuttle boosters.

All systems were go as engineers conducted last-minute checks in preparations for NASA's drogue parachute test. Image credit: NASA

The drogue parachute is the workhorse of the parachute recovery system, providing the initial deceleration and taking the brunt of impact as it slows the rapid descent of the rocket's spent first-stage motor.

As the test series progresses, engineers perform three classifications of testing: development, design load and overload. Each level of testing is intended to test the performance of the new parachute design with payloads of different size and weight, under varying conditions.

The jumbo dart used as part of the Ares I parachute test is loaded into the back of a U.S. Air Force C-17. Image credit: NASA

The U.S. Army's Yuma Proving Ground provides the test range, support facilities and equipment to NASA for parachute testing. The U.S. Air Force Flight Test Center at Edwards Air Force Base, Calif., provided the C-17 test aircraft and crew.

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Lunar Polar Craters May Be Electrified

As the solar wind flows over natural obstructions on the moon, it may charge polar lunar craters to hundreds of volts, according to new calculations by NASA’s Lunar Science Institute team.

Polar lunar craters are of interest because of resources, including water ice, which exist there. The moon’s orientation to the sun keeps the bottoms of polar craters in permanent shadow, allowing temperatures there to plunge below minus 400 degrees Fahrenheit, cold enough to store volatile material like water for billions of years. "However, our research suggests that, in addition to the wicked cold, explorers and robots at the bottoms of polar lunar craters may have to contend with a complex electrical environment as well, which can affect surface chemistry, static discharge, and dust cling," said William Farrell of NASA’s Goddard Space Flight Center, Greenbelt, Md. Farrell is lead author of a paper on this research published March 24 in the Journal of Geophysical Research. The research is part of the Lunar Science Institute’s Dynamic Response of the Environment at the moon (DREAM) project.

"This important work by Dr. Farrell and his team is further evidence that our view on the moon has changed dramatically in recent years," said Gregory Schmidt, deputy director of the NASA Lunar Science Institute at NASA's Ames Research Center, Moffett Field, Calif. "It has a dynamic and fascinating environment that we are only beginning to understand."

Solar wind inflow into craters can erode the surface, which affects recently discovered water molecules. Static discharge could short out sensitive equipment, while the sticky and extremely abrasive lunar dust could wear out spacesuits and may be hazardous if tracked inside spacecraft and inhaled over long periods.

New research from NASA's Lunar Science Institute indicates that the solar wind may be charging certain regions at the lunar poles to hundreds of volts. In this short video Dr. Bill Farrell discusses this research and what it means for future exploration of the moon's poles. Credit: NASA/Goddard Space Flight Center

The solar wind is a thin gas of electrically charged components of atoms -- negatively charged electrons and positively charged ions -- that is constantly blowing from the surface of the sun into space. Since the moon is only slightly tilted compared to the sun, the solar wind flows almost horizontally over the lunar surface at the poles and along the region where day transitions to night, called the terminator.

The researchers created computer simulations to discover what happens when the solar wind flows over the rims of polar craters. They discovered that in some ways, the solar wind behaves like wind on Earth -- flowing into deep polar valleys and crater floors. Unlike wind on Earth, the dual electron-ion composition of the solar wind may create an unusual electric charge on the side of the mountain or crater wall; that is, on the inside of the rim directly below the solar wind flow.

Since electrons are over 1,000 times lighter than ions, the lighter electrons in the solar wind rush into a lunar crater or valley ahead of the heavy ions, creating a negatively charged region inside the crater. The ions eventually catch up, but rain into the crater at consistently lower concentrations than that of the electrons. This imbalance in the crater makes the inside walls and floor acquire a negative electric charge. The calculations reveal that the electron/ion separation effect is most extreme on a crater's leeward edge – along the inside crater wall and at the crater floor nearest the solar wind flow. Along this inner edge, the heavy ions have the greatest difficulty getting to the surface. Compared to the electrons, they act like a tractor-trailer struggling to follow a motorcycle; they just can’t make as sharp a turn over the mountain top as the electrons. "The electrons build up an electron cloud on this leeward edge of the crater wall and floor, which can create an unusually large negative charge of a few hundred Volts relative to the dense solar wind flowing over the top," says Farrell.

The negative charge along this leeward edge won’t build up indefinitely. Eventually, the attraction between the negatively charged region and positive ions in the solar wind will cause some other unusual electric current to flow. The team believes one possible source for this current could be negatively charged dust that is repelled by the negatively charged surface, gets levitated and flows away from this highly charged region. "The Apollo astronauts in the orbiting Command Module saw faint rays on the lunar horizon during sunrise that might have been scattered light from electrically lofted dust," said Farrell. "Additionally, the Apollo 17 mission landed at a site similar to a crater environment – the Taurus-Littrow valley. The Lunar Ejecta and Meteorite Experiment left by the Apollo 17 astronauts detected impacts from dust at terminator crossings where the solar wind is nearly-horizontal flowing, similar to the situation over polar craters."

Next steps for the team include more complex computer models. "We want to develop a fully three-dimensional model to examine the effects of solar wind expansion around the edges of a mountain. We now examine the vertical expansion, but we want to also know what happens horizontally," said Farrell. As early as 2012, NASA will launch the Lunar Atmosphere and Dust Environment Explorer (LADEE) mission that will orbit the moon and could look for the dust flows predicted by the team’s research.

This work was enabled by support from NASA Goddard’s Internal Research and Development program and NASA’s Lunar Science Institute. The team includes researchers from NASA Goddard, the University of California, Berkeley, and the University of Maryland, Baltimore County.

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Sunday, April 18, 2010

STEREO Captures Huge Eruptive Prominence

The STEREO (Ahead) spacecraft caught this spectacular eruptive prominence in extreme UV light as it blasted away from the Sun (Apr. 12-13, 2010). This was certainly among the largest prominence eruptions seen by either the STEREO or SOHO missions. The length of the prominence appears to stretch almost halfway across the sun, about 50 million miles. Prominences are cooler clouds of plasma that hover above the Sun’s surface, tethered by magnetic forces. They are notoriously unstable and commonly erupt as this one did in a dramatic fashion. The video clip shows about 19 hours of activity.

Still from video for downloading

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Deputy Administrator Greets the President

NASA Deputy Administrator Lori Garver shakes hands with President Barack Obama as she and NASA Kennedy Space Center Director Bob Cabana, left, welcome the President to Kennedy in Cape Canaveral, Fla. on Thursday, April 15, 2010. President Obama visited Kennedy to deliver remarks on the new course the administration is charting to maintain U.S. leadership in human space flight.

Image Credit: NASA/Bill Ingalls

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Thursday, April 15, 2010

President Outlines Exploration Goals, Promise

Astronauts will soar spaceward in commercial spacecraft while NASA develops technology so humans can venture to Mars and out into the solar system, President Barack Obama told a space conference Thursday at NASA's Kennedy Space Center in Florida.

Laying out his plans, President Obama committed NASA to a series of development milestones he said would lead to new spacecraft for astronauts to ride to the International Space Station, a modified Orion capsule developed as an emergency return spacecraft, and a powerful new rocket. He also promised a host of new technologies that would protect space travelers from radiation and other unique hazards.

"Early in the next decade, a set of crewed flights will test and prove the systems required for exploration beyond low Earth orbit," the president said. "And by 2025, we expect new spacecraft designed for long journeys to allow us to begin the first-ever crewed missions beyond the moon into deep space. We’ll start by sending astronauts to an asteroid for the first time in history. By the mid-2030s, I believe we can send humans to orbit Mars and return them safely to Earth. And a landing on Mars will follow. And I expect to be around to see it."

The president spoke to 200 senior officials, space and industry leaders, and academic experts inside the Operations and Checkout Building at Kennedy in the same area that was used to process Apollo spacecraft for the missions to the moon in the 1960s and 70s.

Standing in front of one of the space shuttle main engines that launched former U.S. Senator and astronaut John Glenn into orbit, President Obama said, "It was from here that men and women, propelled by sheer nerve and talent, set about pushing the boundaries of humanity's reach.

President Barack Obama discusses his plans and ambitions for NASA during an address at NASA's Kennedy Space Center in Florida. Photo credit: NASA/Jim Grossman

"The question for us now is whether that was the beginning of something, or the end of something. I prefer to believe it was the beginning of something."

The president's fiscal year 2011 budget proposal increases NASA's budget by $6 billion throughout the next five years to fund the plans.

Noting "the sense that folks in Washington -- driven less by vision than by politics -- have for years neglected NASA’s mission and undermined the work of the professionals who fulfill it," the president said the budget increase changes that.

The president's address comes at a critical juncture for NASA because the space shuttle fleet is scheduled to be retired after three more missions. The president said it will be quicker and less costly to let private companies develop new spacecraft for astronauts rather than continue with NASA's Constellation Program, which was deemed too expensive and behind schedule.

"Pursuing this new strategy will require that we revise the old strategy. In part, this is because the old strategy -- including the Constellation Program -- was not fulfilling its promise in many ways," the president said. "That’s not just my assessment; that’s also the assessment of a panel of respected non-partisan experts charged with looking at these issues closely."

President Obama's plan largely mirrors the "flexible path" option offered by a blue-ribbon panel established by the president last year to help decide the best map for future space exploration.

The outline does not do away with all the research and development from Constellation . Noting the success of the agency's development of the Orion crew capsule, Obama called on NASA to develop a version of that spacecraft so it can be launched without a crew to the International Space Station. It will be based there as an emergency craft for astronauts living on the orbiting laboratory.

The speech kicked off the Conference on the American Space Program for the 21st Century.

Norm Augustine, chairman of the blue-ribbon panel called the Review of U.S. Human Space Flight Plans Committee, that evaluated Constellation and came up with the "flexible path" option, endorsed the presidential strategy as the conference got under way.

Saying NASA is largely "trapped" in low Earth orbit, Augustine said industry, with NASA's guidance, can do its part for the plan.

The president acknowledged the need to get the decision right.

"Now, the challenges facing our space program are different, and our imperatives for this program are different than in decades past," the president said. "But while the measure of our achievements has changed a great deal over the past fifty years, what we do -- or fail to do -- in seeking new frontiers is no less consequential for our future in space and here on Earth."

The plan, the president said, would free NASA's designers and engineers to develop spacecraft, large rockets and new technologies that can extend the frontier of human space exploration to asteroids and even Mars.

About $3.1 billion of the additional funding would go into research and development for a heavy-lift rocket. A design for a large booster would be chosen in 2015 with the goal of launching the spacecraft a few years later. The bigger rocket could be used to loft payloads too large for most boosters, including giant fuel depots that would be parked in distant orbits so spacecraft could refuel on their way to asteroids, the moons of Mars and eventually Mars itself.

In addition to more funding, President Obama said his initiative brings more jobs than previous schedules.

"My plan will add more than 2,500 jobs along the Space Coast in the next two years compared to the plan under the previous administration," he said. "I’m proposing a $40 million initiative led by a high-level team from the White House, NASA, and other agencies to develop a plan for regional economic growth and job creation. And I expect this plan to reach my desk by Aug. 15. It’s an effort that will help prepare this already skilled work force for new opportunities in the space industry and beyond."

Taken together, the space strategy proves America is poised for a future as bright as its remarkable past, the president said.

"Fifty years after the creation of NASA, our goal is no longer just a destination to reach," Obama said. "Our goal is the capacity for people to work and learn, and operate and live safely beyond the Earth for extended periods of time, ultimately in ways that are more sustainable and even indefinite. And in fulfilling this task, we will not only extend humanity’s reach in space -- we will strengthen America’s leadership here on Earth."

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NASA to Launch Human-Like Robot to Join Space Station Crew

NASA will launch the first human-like robot to space later this year to become a permanent resident of the International Space Station. Robonaut 2, or R2, was developed jointly by NASA and General Motors under a cooperative agreement to develop a robotic assistant that can work alongside humans, whether they are astronauts in space or workers at GM manufacturing plants on Earth.

The 300-pound R2 consists of a head and a torso with two arms and two hands. R2 will launch on space shuttle Discovery as part of the STS-133 mission planned for September. Once aboard the station, engineers will monitor how the robot operates in weightlessness.

R2 will be confined to operations in the station's Destiny laboratory. However, future enhancements and modifications may allow it to move more freely around the station's interior or outside the complex.

"This project exemplifies the promise that a future generation of robots can have both in space and on Earth, not as replacements for humans but as companions that can carry out key supporting roles," said John Olson, director of NASA's Exploration Systems Integration Office at NASA Headquarters in Washington. "The combined potential of humans and robots is a perfect example of the sum equaling more than the parts. It will allow us to go farther and achieve more than we can probably even imagine today."

Robonaut2 – or R2 for short – is the next generation dexterous robot, developed through a Space Act Agreement by NASA and General Motors. Credit: NASA.

The dexterous robot not only looks like a human but also is designed to work like one. With human-like hands and arms, R2 is able to use the same tools station crew members use. In the future, the greatest benefits of humanoid robots in space may be as assistants or stand-in for astronauts during spacewalks or for tasks too difficult or dangerous for humans. For now, R2 is still a prototype and does not have adequate protection needed to exist outside the space station in the extreme temperatures of space.

Testing the robot inside the station will provide an important intermediate environment. R2 will be tested in microgravity and subjected to the station's radiation and electromagnetic interference environments. The interior operations will provide performance data about how a robot may work side-by-side with astronauts. As development activities progress on the ground, station crews may be provided hardware and software to update R2 to enable it to do new tasks.

R2 is undergoing extensive testing in preparation for its flight. Vibration, vacuum and radiation testing along with other procedures being conducted on R2 also benefit the team at GM. The automaker plans to use technologies from R2 in future advanced vehicle safety systems and manufacturing plant applications.

"The extreme levels of testing R2 has undergone as it prepares to venture to the International Space Station are on par with the validation our vehicles and components go through on the path to production," said Alan Taub, vice president of GM's global research and development. "The work done by GM and NASA engineers also will help us validate manufacturing technologies that will improve the health and safety of our GM team members at our manufacturing plants throughout the world. Partnerships between organizations such as GM and NASA help ensure space exploration, road travel and manufacturing can become even safer in the future."

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Wednesday, April 14, 2010

Einstein's Theory Fights Off Challengers

Two new and independent studies have put Einstein's General Theory of Relativity to the test like never before. These results, made using NASA's Chandra X-ray Observatory, show Einstein's theory is still the best game in town.

Each team of scientists took advantage of extensive Chandra observations of galaxy clusters, the largest objects in the Universe bound together by gravity. One result undercuts a rival gravity model to General Relativity, while the other shows that Einstein's theory works over a vast range of times and distances across the cosmos.

The first finding significantly weakens a competitor to General Relativity known as "f(R) gravity".

"If General Relativity were the heavyweight boxing champion, this other theory was hoping to be the upstart contender," said Fabian Schmidt of the California Institute of Technology in Pasadena, who led the study. "Our work shows that the chances of its upsetting the champ are very slim."

In recent years, physicists have turned their attention to competing theories to General Relativity as a possible explanation for the accelerated expansion of the universe. Currently, the most popular explanation for the acceleration is the so-called cosmological constant, which can be understood as energy that exists in empty space. This energy is referred to as dark energy to emphasize that it cannot be directly detected.

In the f(R) theory, the cosmic acceleration comes not from an exotic form of energy but from a modification of the gravitational force. The modified force also affects the rate at which small enhancements of matter can grow over the eons to become massive clusters of galaxies, opening up the possibility of a sensitive test of the theory.

Schmidt and colleagues used mass estimates of 49 galaxy clusters in the local universe from Chandra observations, compared them with theoretical model predictions and studies of supernovas, the cosmic microwave background, and the large-scale distribution of galaxies.

Composite image of the galaxy cluster Abell 3376. Image credit: X-ray: NASA/CXC/SAO/A. Vikhlinin; ROSAT Optical: DSS Radio: NSF/NRAO/ VLA/IUCAA/J.Bagchi

They found no evidence that gravity is different from General Relativity on scales larger than 130 million light years. This limit corresponds to a hundred-fold improvement on the bounds of the modified gravitational force's range that can be set without using the cluster data.

"This is the strongest ever constraint set on an alternative to General Relativity on such large distance scales," said Schmidt. "Our results show that we can probe gravity stringently on cosmological scales by using observations of galaxy clusters."

The reason for this dramatic improvement in constraints can be traced to the greatly enhanced gravitational forces acting in clusters as opposed to the universal background expansion of the universe. The cluster-growth technique also promises to be a good probe of other modified gravity scenarios, such as models motivated by higher- dimensional theories and string theory.

A second, independent study also bolsters General Relativity by directly testing it across cosmological distances and times. Up until now, General Relativity had been verified only using experiments from laboratory to Solar System scales, leaving the door open to the possibility that General Relativity breaks down on much larger scales.

To probe this question, a group at Stanford University compared Chandra observations of how rapidly galaxy clusters have grown over time to the predictions of General Relativity. The result is nearly complete agreement between observation and theory.

“Einstein's theory succeeds again, this time in calculating how many massive clusters have formed under gravity's pull over the last five billion years,” said David Rapetti of the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) at Stanford University and SLAC National Accelerator Laboratory, who led the new study. “Excitingly and reassuringly, our results are the most robust consistency test of General Relativity yet carried out on cosmological scales."

Rapetti and his colleagues based their results on a sample of 238 clusters detected across the whole sky by the now-defunct ROSAT X-ray telescope. These data were enhanced by detailed mass measurements for 71 distant clusters using Chandra, and 23 relatively nearby clusters using ROSAT, and combined with studies of supernovas, the cosmic microwave background, the distribution of galaxies and distance estimates to galaxy clusters.

Galaxy clusters are important objects in the quest to understand the Universe as a whole. Because the observations of the masses of galaxy clusters are directly sensitive to the properties of gravity, they provide crucial information. Other techniques such as observations of supernovas or the distribution of galaxies measure cosmic distances, which depend only on the expansion rate of the universe. In contrast, the cluster technique used by Rapetti and his colleagues measure in addition the growth rate of the cosmic structure, as driven by gravity.

"Cosmic acceleration represents a great challenge to our modern understanding of physics," said Rapetti's co-author Adam Mantz of NASA's Goddard Space Flight Center in Maryland. "Measurements of acceleration have highlighted how little we know about gravity at cosmic scales, but we're now starting to push back our ignorance."

The paper by Fabian Schmidt was published in Physics Review D, Volume 80 in October 2009 and is co-authored by Alexey Vikhlinin of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and Wayne Hu of the University of Chicago, Illinois. The paper by David Rapetti was recently accepted for publication in the Monthly Notices of the Royal Astronomical Society and is co- authored by Mantz, Steve Allen of KIPAC at Stanford and Harald Ebeling of the Institute for Astronomy in Hawaii.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.

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