Tuesday, October 18, 2011

New Sun-bound probe


A NASA spacecraft set to launch in 2015 will come eight times closer to the Sun than any previous probe, operating within the star's scorching outer atmosphere, or corona. The $750 million Solar Probe will study the birthplace of the solar wind. During its expected seven-year lifetime, Solar Probe will make seven gravity slingshots around Venus, each time getting closer to the Sun. At its closest approach, it will orbit the Sun from within the outer part of the corona, at a distance of between 8 and 10 solar radii from the centre of the Sun. That is much closer than the previous record holder, the Helios spacecraft, which came within 67 solar radii of the star in the 1970s.Scientists hope the probe will help solve two enduring solar mysteries: Why is the Sun's outer atmosphere, or corona, so much hotter than its visible surface, which lies beneath it? And what accelerates the solar wind, a stream of charged particles from the Sun, to supersonic speeds? Heat shield: The idea of studying the Sun at close range was first proposed by the US National Academy of Science in 1958. But scientists have only recently been able to design heat shields for such a spacecraft within NASA's tight budgetary guidelines. The mini-bus sized Solar Probe will be protected from the Sun's fierce radiation by a disc-shaped, carbon-composite heat shield that will be 2.

The probe is 7 meters in diameter and about 15 centimeters thick. The heat shield technology is based on that used in Messenger, a NASA spacecraft that completed its first flyby of Mercury in January and that was also designed by engineers at APL. The side of the shield facing the Sun will heat up to 1400 °Celsius (2600 °F), while the instrument-carrying payload behind the shield will remain at room temperature.

New mystery on Mars

One of the supposedly best understood and least interesting landscapes on Mars is hiding something that could rewrite the planet's history. Or not. In fact, about all that is certain is that decades of assumptions regarding the wide, flat Hesperia Planum are not holding up very well under renewed scrutiny with higher-resolution, more recent spacecraft data.


"Most scientists don't want to work on the flat things," noted geologist Tracy Gregg of University at Buffalo, State University of New York. So after early Mars scientists decided Hesperia Planum looked like a lava-filled plain, no one really revisited the matter and the place was used to exemplify something rather important: The base of a major transitional period in the geologic time scale of Mars. The period is aptly called the Hesperian and it is thought to have run from 3.7 to 3.1 billion years ago.

But when Gregg and her student Carolyn Roberts started looking at this classic Martian lava plain with modern data sets, they ran into trouble.

"There's a volcano in Hesperia Planum that not many people pay attention to because it's very small," Gregg said. "As I started looking closer at the broader region -- I can't find any other volcanic vents, any flows. I just kept looking for evidence of lava flows. It's kind of frustrating. There is nothing like that in the Hesperia Planum."

"A likely cause of this trouble is the thick dust that blankets Hesperia Planum," she said. "It covers everywhere like a snowfall."

So she turned her attention to what could be discerned on Hesperia Planum: about a dozen narrow, sinuous channels, called rilles, just a few hundred meters wide and up to hundreds of kilometers long. These rilles have no obvious sources or destinations and it is not at all clear they are volcanic.

"The question I have is what made the channels," said Gregg. Was it water, lava, or something else? "There are some lavas that can be really, really runny. And both are liquids that run downhill." So either is a possibility.

To begin to sort the matter out, Gregg and Roberts are now looking for help on the Moon. Their preliminary findings are being presented at the Annual Meeting of The Geological Society of America in Minneapolis.

"On the Moon we see these same kinds of features and we know that water couldn't have formed them there," Gregg said. So they are in the process of comparing channels on the Moon and Mars, using similar data sets from different spacecraft, to see if that sheds any light on the matter. She hopes to find evidence that will rule out water or lava on Hesperia Planum.

"Everybody assumed these were huge lava flows," said Gregg. "But if it turns out to be a lake deposit, it's a very different picture of what Mars was doing at that time." It would also make Hesperia Planum a good place to look for life, because water plus volcanic heat and minerals is widely believed to be a winning combination for getting life started.

"The 'volcanic' part is an interpretation that's beginning to fall apart," said Gregg. "What is holding up is that the Hesperian marks a transition between the Noachian (a time of liquid water on the surface and the formation of lots of impact craters) and the Amazonian (a drier, colder Mars)."

She has found that other scientists are interested in her work because of its possible implications on the Mars geological time scale. Gregg is not worried that Mars history will need to be rewritten, but she does suspect that Hesperia Planum is a lot more complicated than people has long thought.

Friday, July 29, 2011

Getting Ready for ALMA’s First Scientific Observations

The first European antenna for the Atacama Large Millimeter/submillimeter Array (ALMA) has reached new heights, having been transported to the observatory's Array Operations Site (AOS) on 27 July 2011. The 12-metre diameter antenna has arrived at the Chajnantor plateau, 5000 metres above sea level. Here, it joins antennas from the other international ALMA partners, bringing the total number at the AOS to 16.



Although 16 sounds like just another number, it is the number of antennas specified for ALMA to begin its first science observations, and is therefore an important milestone for the project. Soon, astronomers will begin conducting new scientific research with ALMA.

The antenna, manufactured by the European AEM Consortium [1] under contract from ESO, was handed over to the observatory in April at the Operations Support Facility (OSF), after six months of testing. The OSF is at an altitude of 2900 metres in the foothills of the Chilean Andes. There, it was equipped with highly sensitive detectors, cooled by liquid helium, and other necessary electronics. Now, one of the giant ALMA transporter vehicles has taken it 28km further, along the dry desert road to the AOS. The AOS is the last port of call in a long journey that began when the component parts of the antenna were manufactured in factories across Europe, under the rigorous oversight of ESO.

The ALMA Antenna Project Manager at ESO, Stefano Stanghellini said, "It's great to see the first European ALMA antenna reach Chajnantor. It is from this arid plateau that these masterpieces of technology will be used to study the cosmos."

ALMA's Early Science observations are planned to begin later this year. Although ALMA will still be under construction, the 16-antenna array that will be available already outmatches all other telescopes of this kind. Astronomers from around the world have submitted almost 1000 proposals for Early Science observations. This level of demand is about nine times the number of observations that are expected be carried out during the first phase of Early Science, which demonstrates how excited researchers are to use ALMA, even at this early stage.

The final step from the OSF to the Chajnantor plateau is a relatively short journey, but for ALMA it makes a great difference. The plateau's elevated location -- 2100 metres higher than the OSF -- gives it the extremely dry conditions that are vital for observing at millimetre and submillimetre wavelengths, since these faint signals from space are easily absorbed by Earth's atmosphere.

While Chajnantor is perfect for ALMA, the extremely high altitude and lack of oxygen make it less pleasant for the site's human visitors. Although there is a Technical Building on Chajnantor -- it is in fact one of the highest buildings in the world -- the people working on ALMA do as much as possible from the lower altitude of the OSF, operating the telescope remotely.

When construction is completed in 2013, ALMA will have a total of 66 state-of-the-art antennas, which will work together as a single powerful telescope observing millimetre- and submillimetre-wavelength light. ALMA will help astronomers study the origins of planets, stars, galaxies and even the Universe itself, by observing cool molecular gas and dust in the Milky Way and beyond, as well as the relic radiation left over from the Big Bang.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

Twenty-five European ALMA antennas, including this one, are being provided by ESO through a contract with the European AEM Consortium. ALMA will also have 25 antennas provided by North America, and 16 by East Asia.

Eclipses Yield First Images of Elusive Iron Line in the Solar Corona

Solar physicists attempting to unlock the mysteries of the solar corona have found another piece of the puzzle by observing the sun's outer atmosphere during eclipses.


Ground-based observations reveal the first images of the solar corona in the near-infrared emission line of highly ionized iron, or Fe XI 789.2 nm. The observations were taken during total solar eclipses in 2006, 2008, and 2009 by astrophysicist Adrian Daw of NASA's Goddard Space Flight Center in Greenbelt, Md., with an international team of scientists led by Shadia Habbal from the University of Hawaii's Institute for Astronomy (IfA).

"The first image of the corona in Fe XI 789.2 nm was taken during the total solar eclipse of March 29, 2006," said Daw.

The images revealed some surprises. Most notably, that the emission extends out at least three solar radii -- that's one-and-a-half times the sun's width at its equator, or middle -- above the surface of the sun, and that there are localized regions of enhanced density for these iron ions.

Combined with observations of other iron charge states, the observations yield the two-dimensional distribution of electron temperature and charge-state measurements for the first time, and establish the first direct link between the distribution of charge states in the corona and in interplanetary space. "These are the first such maps of the 2-D distribution of coronal electron temperature and ion charge state," said Daw.

Mapping the distribution of electron temperature and iron charge states in the corona with total solar eclipse observations represents an important step in understanding the solar corona and how space weather impacts Earth.

The scientists' results will be presented at the American Astronomical Society meeting on January 4 in Washington and published in the January issue of the Astrophysical Journal.

Solar Research Instrument 'Fills the Gap,' Views Sun's

During a total eclipse of the Sun, skywatchers are awed by the shimmering corona -- a faint glow that surrounds the Sun like gossamer flower petals. This outer layer of the Sun's atmosphere is, paradoxically, hotter than the Sun's surface, but so tenuous that its light is overwhelmed by the much brighter solar disk. The corona becomes visible only when the Sun is blocked, which happens for just a few minutes during an eclipse.


Now, an instrument on board NASA's Solar Dynamics Observatory (SDO), developed by Smithsonian scientists, is giving unprecedented views of the innermost corona 24 hours a day, 7 days a week.

"We can follow the corona all the way down to the Sun's surface," said Leon Golub of the Harvard-Smithsonian Center for Astrophysics (CfA).

Previously, solar astronomers could observe the corona by physically blocking the solar disk with a coronagraph, much like holding your hand in front of your face while driving into the setting Sun. However, a coronagraph also blocks the area immediately surrounding the Sun, leaving only the outer corona visible.

The Atmospheric Imaging Assembly (AIA) instrument on SDO can "fill" this gap, allowing astronomers to study the corona all the way down to the Sun's surface. The resulting images highlight the ever-changing connections between gas captured by the Sun's magnetic field and gas escaping into interplanetary space.

The Sun's magnetic field molds and shapes the corona. Hot solar plasma streams outward in vast loops larger than Earth before plunging back onto the Sun's surface. Some of the loops expand and stretch bigger and bigger until they break, belching plasma outward.

"The AIA solar images, with better-than-HD quality views, show magnetic structures and dynamics that we've never seen before on the Sun," said CfA astronomer Steven Cranmer. "This is a whole new area of study that's just beginning."

Cranmer and CfA colleague Alec Engell developed a computer program for processing the AIA images above the Sun's edge. These processed images imitate the blocking-out of the Sun that occurs during a total solar eclipse, revealing the highly dynamic nature of the inner corona. They will be used to study the initial eruption phase of coronal mass ejections (CMEs) as they leave the Sun and to test theories of solar wind acceleration based on magnetic reconnection.

SDO is the first mission and crown jewel in a fleet of NASA missions to study our sun. The mission is the cornerstone of a NASA science program called Living with a Star, the goal of which is to develop the scientific understanding necessary to address those aspects of the sun-Earth system that directly affect our lives and society. Goddard Space Flight Center built, operates, and manages the SDO spacecraft for NASA's Science Mission Directorate in Washington.

Wave Power Can Drive Sun's Intense Heat

A new study sheds light on why the Sun's outer atmosphere, or corona, is more than 20 times hotter than its surface. The research, led by the National Center for Atmospheric Research (NCAR), may bring scientists a step closer to understanding the solar cycle and the Sun's impacts on Earth.


The study uses satellite observations to reveal that magnetic oscillations carrying energy from the Sun's surface into its corona are far more vigorous than previously thought. These waves are energetic enough to heat the corona and drive the solar wind, a stream of charged particles ejected from the Sun that affects the entire solar system.

"We now understand how hot mass can shoot upward from the solar interior, providing enough energy to maintain the corona at a million degrees and fire off particles into the high-speed solar wind," says Scott McIntosh, the study's lead author and a scientist in NCAR's High Altitude Observatory. "This new research will help us solve essential mysteries about how energy gets out of the Sun and into the solar system."

The study, published this week in the journal Nature, was conducted by a team of scientists from NCAR, Lockheed Martin Solar and Astrophysics Lab, Norway's University of Oslo, and Belgium's Catholic University of Leuven. It was funded by NASA. NCAR is sponsored by the National Science Foundation.

Jets and waves

The flow of mass and energy from the corona influences how much ultraviolet radiation reaches Earth. It also drives upper-atmospheric disturbances known as geomagnetic storms, which can disrupt technologies ranging from telecommunications to electrical transmission.

The new study focuses on the role of oscillations in the corona, known as Alfven waves, in moving energy through the corona.

Alfven waves were directly observed for the first time in 2007. Scientists recognized them as a mechanism for transporting energy upward along the Sun's magnetic field into the corona. But the 2007 observations showed amplitudes on the order of about 1,600 feet (0.5 kilometers) per second, far too small to heat the corona to its high levels or to drive the solar wind.

The new satellite observations used in the current study reveal Alfven waves that are over a hundred times stronger than previously measured, with amplitudes on the order of 12 miles (20 km) per second -- enough to heat the Sun's outer atmosphere to millions of degrees and drive the solar wind. The waves are easily seen in high-resolution images of the outer atmosphere as they cause high-speed jets of hot material, called spicules, to sway.

"The new satellite observations are giving us a close look for the first time at how energy and mass move through the Sun's outer atmosphere," McIntosh says.

The research builds on ongoing efforts to study the connection between spicules and Alfven waves. Scientists have known about spicules for decades but were unable to determine if their mass got hot enough to provide heat for the corona until earlier this year, when McIntosh and colleagues published research in the journal Science that used satellite observations to reveal that a new class of the phenomenon, dubbed "Type II" spicules, moves much faster and reaches coronal temperatures.

The new study reveals the role of Alfven waves. These oscillations play a critical role in transporting heat from the Sun by riding on the spicules and carrying energy into the corona.

Photographing our nearest star

The critical satellite observations described in the study come from the Atmospheric Imaging Assembly, a package of instruments aboard NASA's Solar Dynamics Observatory, which was launched in 2010. The instruments boast high spatial and temporal resolution, enough to detect structures and motions across regions of the Sun as small as 310 miles (500 km) and generate images every 12 seconds at different wavelengths.

"It's like getting a microscope to study the Sun's corona, giving us the spatial and temperature coverage to focus in on the way mass and energy circulate." McIntosh says.

Now that the real power of the waves has been revealed in the corona, the next step in unraveling the mystery of its extreme heat is to study how the waves lose their energy, which is transferred to plasma. To do that, scientists will need to develop computer models that are fine enough in detail to capture how the jets and waves work together to power the atmosphere. By studying the Sun's underlying physics with these tools, scientists could better understand the Sun's 11-year sunspot cycle and its impacts on Earth.

Wednesday, July 13, 2011

Hubble's Neptune Photo

Today, Neptune has arrived at the same location in space where it was discovered nearly 165 years ago. To commemorate the event, NASA's Hubble Space Telescope has taken these "anniversary pictures" of the blue-green giant planet.


Neptune is the most distant major planet in our solar system. German astronomer Johann Galle discovered the planet on September 23, 1846. At the time, the discovery doubled the size of the known solar system. The planet is 2.8 billion miles (4.5 billion kilometers) from the Sun, 30 times farther than Earth. Under the Sun's weak pull at that distance, Neptune plods along in its huge orbit, slowly completing one revolution approximately every 165 years.

These four Hubble images of Neptune were taken with the Wide Field Camera 3 on June 25-26, during the planet's 16-hour rotation. The snapshots were taken at roughly four-hour intervals, offering a full view of the planet. The images reveal high-altitude clouds in the northern and southern hemispheres. The clouds are composed of methane ice crystals.

The giant planet experiences seasons just as Earth does, because it is tilted 29 degrees, similar to Earth's 23-degree-tilt. Instead of lasting a few months, each of Neptune's seasons continues for about 40 years.

The snapshots show that Neptune has more clouds than a few years ago, when most of the clouds were in the southern hemisphere. These Hubble views reveal that the cloud activity is shifting to the northern hemisphere. It is early summer in the southern hemisphere and winter in the northern hemisphere.

In the Hubble images, absorption of red light by methane in Neptune's atmosphere gives the planet its distinctive aqua color. The clouds are tinted pink because they are reflecting near-infrared light.

A faint, dark band near the bottom of the southern hemisphere is probably caused by a decrease in the hazes in the atmosphere that scatter blue light. The band was imaged by NASA's Voyager 2 spacecraft in 1989, and may be tied to circumpolar circulation created by high-velocity winds in that region.

The temperature difference between Neptune's strong internal heat source and its frigid cloud tops, about minus 260 degrees Fahrenheit, might trigger instabilities in the atmosphere that drive large-scale weather changes.

Neptune has an intriguing history. It was Uranus that led astronomers to Neptune. Uranus, the seventh planet from the Sun, is Neptune's inner neighbor. British astronomer Sir William Herschel and his sister Caroline found Uranus in 1781, 55 years before Neptune was spotted. Shortly after the discovery, Herschel noticed that the orbit of Uranus did not match the predictions of Newton's theory of gravity. Studying Uranus in 1821, French astronomer Alexis Bouvard speculated that another planet was tugging on the giant planet, altering its motion.

Twenty years later, Urbain Le Verrier of France and John Couch Adams of England, who were mathematicians and astronomers, independently predicted the location of the mystery planet by measuring how the gravity of a hypothetical unseen object could affect Uranus's path. Le Verrier sent a note describing his predicted location of the new planet to the German astronomer Johann Gottfried Galle at the Berlin Observatory. Over the course of two nights in 1846, Galle found and identified Neptune as a planet, less than a degree from Le Verrier's predicted position. The discovery was hailed as a major success for Newton's theory of gravity and the understanding of the universe.

Galle was not the first to see Neptune. In December 1612, while observing Jupiter and its moons with his handmade telescope, astronomer Galileo Galilei recorded Neptune in his notebook, but as a star. More than a month later, in January 1613, he noted that the "star" appeared to have moved relative to other stars. But Galileo never identified Neptune as a planet, and apparently did not follow up those observations, so he failed to be credited with the discovery.

Neptune is not visible to the naked eye, but may be seen in binoculars or a small telescope. It can be found in the constellation Aquarius, close to the boundary with Capricorn.

Neptune-mass planets orbiting other stars may be common in our Milky Way galaxy. NASA's Kepler mission, launched in 2009 to hunt for Earth-size planets, is finding increasingly smaller extrasolar planets, including many the size of Neptune.

Tuesday, July 5, 2011

Binary Star System Makes Dual Gamma-Ray Flares

In December 2010, a pair of mismatched stars in the southern constellation Crux whisked past each other at a distance closer than Venus orbits the sun. The system possesses a so-far unique blend of a hot and massive star with a compact fast-spinning pulsar. The pair's closest encounters occur every 3.4 years and each is marked by a sharp increase in gamma rays, the most extreme form of light.


The unique combination of stars, the long wait between close approaches, and periods of intense gamma-ray emission make this system irresistible to astrophysicists. Now, a team using NASA's Fermi Gamma-ray Space Telescope to observe the 2010 encounter reports that the system displayed fascinating and unanticipated activity.

"Even though we were waiting for this event, it still surprised us," said Aous Abdo, a Research Assistant Professor at George Mason University in Fairfax, Va., and a leader of the research team.

Few pairings in astronomy are as peculiar as high-mass binaries, where a hot blue-white star many times the sun's mass and temperature is joined by a compact companion no bigger than Earth -- and likely much smaller. Depending on the system, this companion may be a burned-out star known as a white dwarf, a city-sized remnant called a neutron star (also known as a pulsar) or, most exotically, a black hole.

Just four of these "odd couple" binaries were known to produce gamma rays, but in only one of them did astronomers know the nature of the compact object. That binary consists of a pulsar designated PSR B1259-63 and a 10th-magnitude Be-type star known as LS 2883. The pair lies 8,000 light-years away.

The pulsar is a fast-spinning neutron star with a strong magnetic field. This combination powers a lighthouse-like beam of energy, which astronomers can easily locate if the beam happens to sweep toward Earth. The beam from PSR B1259-63 was discovered in 1989 by the Parkes radio telescope in Australia. The neutron star is about the size of Washington, D.C., weighs about twice the sun's mass, and spins almost 21 times a second.

The pulsar follows an eccentric and steeply inclined orbit around LS 2883, which weighs roughly 24 solar masses and spans about nine times its size. This hot blue star sits embedded in a disk of gas that flows out from its equatorial region.

At closest approach, the pulsar passes less than 63 million miles from its star -- so close that it skirts the gas disk around the star's middle. The pulsar punches through the disk on the inbound leg of its orbit. Then it swings around the star at closest approach and plunges through the disk again on the way out.

"During these disk passages, energetic particles emitted by the pulsar can interact with the disk, and this can lead to processes that accelerate particles and produce radiation at different energies," said study co-author Simon Johnston of the Australia Telescope National Facility in Epping, New South Wales. "The frustrating thing for astronomers is that the pulsar follows such an eccentric orbit that these events only happen every 3.4 years."

In anticipation of the Dec. 15, 2010, closest approach, astronomers around the world mounted a multiwavelength campaign to observe the system over a broad energy range, from radio wavelengths to the most energetic gamma rays detectable. The observatories included Fermi and NASA's Swift spacecraft; the European space telescopes XMM-Newton and INTEGRAL; the Japan-U.S. Suzaku satellite; the Australia Telescope Compact Array; optical and infrared telescopes in Chile and South Africa; and the High Energy Stereoscopic System (H.E.S.S.), a ground-based observatory in Namibia that can detect gamma rays with energies of trillions of electron volts, beyond Fermi's range. (For comparison, the energy of visible light is between two and three electron volts.)

"When you know you have a chance of observing this system only once every few years, you try to arrange for as much coverage as you can," said Abdo, the principal investigator of the NASA-funded international campaign. "Understanding this system, where we know the nature of the compact object, may help us understand the nature of the compact objects in other, similar systems."

Despite monitoring of the system with the EGRET telescope aboard NASA's Compton Gamma-Ray Observatory in the 1990s, gamma-ray emission in the billion-electron-volt (GeV) energy range had never been seen from the binary.

Late last year, as the pulsar headed toward its massive companion, the Large Area Telescope (LAT) aboard Fermi discovered faint gamma-ray emission.

"During the first disk passage, which lasted from mid-November to mid-December, the LAT recorded faint yet detectable emission from the binary. We assumed that the second passage would be similar, but in mid-January 2011, as the pulsar began its second passage through the disk, we started seeing surprising flares that were many times stronger than those we saw before," Abdo said.

Stranger still, the system's output at radio and X-ray energies showed nothing unusual as the gamma-ray flares raged.

"The most intense days of the flare were Jan. 20 and 21 and Feb. 2, 2011," said Abdo. "What really surprised us is that on any of these days, the source was more than 15 times brighter than it was during the entire month-and-a-half-long first passage."

The study will appear in the July 20 issue of The Astrophysical Journal Letters and is available online.

"One great advantage of the Fermi LAT observations is the continuous monitoring of the source, which gives us the most complete gamma-ray observations of this system," said Julie McEnery, the Fermi project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.

Astronomers are continuing to analyze their bounty of data and working to understand the surprising flares. And in May 2014, when the pulsar once again approaches its giant companion, they'll be watching.

Friday, July 1, 2011

Gamma-Ray Observatory Challenges Physics Beyond Einstein

The European Space Agency's Integral gamma-ray observatory has provided results that will dramatically affect the search for physics beyond Einstein. It has shown that any underlying quantum 'graininess' of space must be at much smaller scales than previously predicted


Einstein's General Theory of Relativity describes the properties of gravity and assumes that space is a smooth, continuous fabric. Yet quantum theory suggests that space should be grainy at the smallest scales, like sand on a beach.

One of the great concerns of modern physics is to marry these two concepts into a single theory of quantum gravity.

Now, Integral has placed stringent new limits on the size of these quantum 'grains' in space, showing them to be much smaller than some quantum gravity ideas would suggest.

According to calculations, the tiny grains would affect the way that gamma rays travel through space. The grains should 'twist' the light rays, changing the direction in which they oscillate, a property called polarisation.

High-energy gamma rays should be twisted more than the lower energy ones, and the difference in the polarisation can be used to estimate the size of the grains.

Philippe Laurent of CEA Saclay and his collaborators used data from Integral's IBIS instrument to search for the difference in polarisation between high- and low-energy gamma rays emitted during one of the most powerful gamma-ray bursts (GRBs) ever seen.

GRBs come from some of the most energetic explosions known in the Universe. Most are thought to occur when very massive stars collapse into neutron stars or black holes during a supernova, leading to a huge pulse of gamma rays lasting just seconds or minutes, but briefly outshining entire galaxies.

GRB 041219A took place on 19 December 2004 and was immediately recognised as being in the top 1% of GRBs for brightness. It was so bright that Integral was able to measure the polarisation of its gamma rays accurately.

Dr Laurent and colleagues searched for differences in the polarisation at different energies, but found none to the accuracy limits of the data.

Some theories suggest that the quantum nature of space should manifest itself at the 'Planck scale': the minuscule 10-35 of a metre, where a millimetre is 10-3 m.

However, Integral's observations are about 10 000 times more accurate than any previous and show that any quantum graininess must be at a level of 10-48 m or smaller.

"This is a very important result in fundamental physics and will rule out some string theories and quantum loop gravity theories," says Dr Laurent.

Integral made a similar observation in 2006, when it detected polarised emission from the Crab Nebula, the remnant of a supernova explosion just 6500 light years from Earth in our own galaxy.

This new observation is much more stringent, however, because GRB 041219A was at a distance estimated to be at least 300 million light years.

In principle, the tiny twisting effect due to the quantum grains should have accumulated over the very large distance into a detectable signal. Because nothing was seen, the grains must be even smaller than previously suspected.

"Fundamental physics is a less obvious application for the gamma-ray observatory, Integral," notes Christoph Winkler, ESA's Integral Project Scientist. "Nevertheless, it has allowed us to take a big step forward in investigating the nature of space itself."

Now it's over to the theoreticians, who must re-examine their theories in the light of this new result.

Making a Spectacle of Star Formation

Looking like a pair of eyeglasses only a rock star would wear, a new nebula view brings into focus a murky region of star formation. NASA's Spitzer Space Telescope exposes the depths of this dusty nebula with its infrared vision, showing stellar infants that are lost behind dark clouds when viewed in visible light.

Best known as Messier 78, the two round greenish nebulae are actually cavities carved out of the surrounding dark dust clouds. The extended dust is mostly dark, even to Spitzer's view, but the edges show up in mid-wavelength infrared light as glowing, red frames surrounding the bright interiors. Messier 78 is easily seen in small telescopes in the constellation of Orion, just to the northeast of Orion's belt, but looks strikingly different, with dominant, dark swaths of dust. Spitzer's infrared eyes penetrate this dust, revealing the glowing interior of the nebulae.

The light from young, newborn stars are starting to carve out cavities within the dust, and eventually, this will become a larger nebula like the "green ring" imaged by Spitzer (see http://www.jpl.nasa.gov/news/news.cfm?release=2011-183).

A string of baby stars that have yet to burn their way through their natal shells can be seen as red pinpoints on the outside of the nebula. Eventually these will blossom into their own glowing balls, turning this two-eyed eyeglass into a many-eyed monster of a nebula.

This is a three-color composite that shows infrared observations from two Spitzer instruments. Blue represents 3.6- and 4.5-micron light, and green shows light of 5.8 and 8 microns, both captured by Spitzer's infrared array camera. Red is 24-micron light detected by Spitzer's multiband imaging photometer.

Wednesday, June 29, 2011

Time Distorts Near Neutron Stars As Einstein Predicted

Using European and Japanese/NASA X-ray satellites, astronomers have seen Einstein’s predicted distortion of space-time around three neutron stars, and in doing so they have pioneered a groundbreaking technique for determining the properties of these ultradense objects.


Neutron stars contain the most dense observable matter in the universe. They cram more than a sun’s worth of material into a city-sized sphere, meaning a few cups of neutron-star stuff would outweigh Mount Everest. Astronomers use these collapsed stars as natural laboratories to study how tightly matter can be crammed under the most extreme pressures that nature can offer.

"This is fundamental physics," says Sudip Bhattacharyya of NASA’s Goddard Space Flight Center in Greenbelt, Md. and the University of Maryland, College Park. "There could be exotic kinds of particles or states of matter, such as quark matter, in the centers of neutron stars, but it’s impossible to create them in the lab. The only way to find out is to understand neutron stars."

To address this mystery, scientists must accurately and precisely measure the diameters and masses of neutron stars. In two concurrent studies, one with the European Space Agency’s XMM-Newton X-ray Observatory and the other with the Japanese/NASA Suzaku X-ray observatory, astronomers have taken a big step forward.

Using XMM-Newton, Bhattacharyya and his NASA Goddard colleague Tod Strohmayer observed a binary system known as Serpens X-1, which contains a neutron star and a stellar companion. They studied a spectral line from hot iron atoms that are whirling around in a disk just beyond the neutron star’s surface at 40 percent the speed of light.

Previous X-ray observatories detected iron lines around neutron stars, but they lacked the sensitivity to measure the shapes of the lines in detail. Thanks to XMM-Newton’s large mirrors, Bhattacharyya and Strohmayer found that the iron line is broadened asymmetrically by the gas’s extreme velocity, which smears and distorts the line because of the Doppler effect and beaming effects predicted by Einstein’s special theory of relativity. The warping of space-time by the neutron star’s powerful gravity, an effect of Einstein’s general theory of relativity, shifts the neutron star’s iron line to longer wavelengths.

"We've seen these asymmetric lines from many black holes, but this is the first confirmation that neutron stars can produce them as well. It shows that the way neutron stars accrete matter is not very different from that of black holes, and it gives us a new tool to probe Einstein’s theory," says Strohmayer.

A group led by Edward Cackett and Jon Miller of the University of Michigan, which includes Bhattacharyya and Strohmayer, used Suzaku’s superb spectral capabilities to survey three neutron-star binaries: Serpens X-1, GX 349+2, and 4U 1820-30. This team observed a nearly identical iron line in Serpens X-1, confirming the XMM-Newton result. It detected similarly skewed iron lines in the other two systems as well.

"We’re seeing the gas whipping around just outside the neutron star’s surface," says Cackett. "And since the inner part of the disk obviously can’t orbit any closer than the neutron star’s surface, these measurements give us a maximum size of the neutron star’s diameter. The neutron stars can be no larger than 18 to 20.5 miles across, results that agree with other types of measurements."

"Now that we’ve seen this relativistic iron line around three neutron stars, we have established a new technique," adds Miller. "It’s very difficult to measure the mass and diameter of a neutron star, so we need several techniques to work together to achieve that goal."

Knowing a neutron star’s size and mass allows physicists to describe the "stiffness," or "equation of state," of matter packed inside these incredibly dense objects. Besides using these iron lines to test Einstein’s general theory of relativity, astronomers can probe conditions in the inner part of a neutron star’s accretion disk.

The XMM-Newton paper appeared in the August 1 Astrophysical Journal Letters. The Suzaku paper has been submitted for publication in the same journal.

Neutron Star Bites Off

The European Space Agency's XMM-Newton space observatory has watched a faint star flare up at X-ray wavelengths to almost 10 000 times its normal brightness. Astronomers believe the outburst was caused by the star trying to eat a giant clump of matter.


The flare took place on a neutron star, the collapsed heart of a once much larger star. Now about 10 km in diameter, the neutron star is so dense that it generates a strong gravitational field.

The clump of matter was much larger than the neutron star and came from its enormous blue supergiant companion star.

"This was a huge bullet of gas that the star shot out, and it hit the neutron star allowing us to see it," says Enrico Bozzo, ISDC Data Centre for Astrophysics, University of Geneva, Switzerland, and team leader of this research.

The flare lasted four hours and the X-rays came from the gas in the clump as it was heated to millions of degrees while being pulled into the neutron star's intense gravity field. In fact, the clump was so big that not much of it hit the neutron star. Yet, if the neutron star had not been in its path, this clump would probably have disappeared into space without trace.

XMM-Newton caught the flare during a scheduled 12.5-hour observation of the system, which is known only by its catalogue number IGR J18410-0535, but the astronomers were unaware of their catch immediately.

The telescope works through a sequence of observations carefully planned to make the best use of the space observatory's time, then sends the data to Earth.

It was about ten days after the observation that Dr Bozzo and his colleagues received the data and quickly realised they had something special. Not only were they pointing in the right direction to see the flare, but the observation had lasted long enough for them to see it from beginning to end.

"I don't know if there is any way to measure luck, but we were extremely lucky," says Dr Bozzo. He estimates that an X-ray flare of this magnitude can be expected a few times a year at the most for this particular star system.

The duration of the flare allowed them to estimate the size of the clump. It was much larger than the star, probably 16 million km across, or about 100 billion times the volume of the Moon. Yet, according to the estimate made from the flare's brightness, the clump contained only one-thousandth of our natural satellite's mass.

These figures will help astronomers understand the behaviour of the blue supergiant and the way it emits matter into space. All stars expel atoms into space, creating a stellar wind. The X-ray flare shows that this particular blue supergiant does it in a clumpy fashion, and the estimated size and mass of the cloud allow constraints to be placed on the process.

"This remarkable result highlights XMM-Newton's unique capabilities," comments Norbert Schartel, XMM-Newton Project Scientist. "Its observations indicate that these flares can be linked to the neutron star attempting to ingest a giant clump of matter."

Monday, June 27, 2011

Sun and Planets Constructed Differently Than Thought Nasa

Researchers analyzing samples returned by NASA's 2004 Genesis mission have discovered that our sun and its inner planets may have formed differently than previously thought.


Data revealed differences between the sun and planets in oxygen and nitrogen, which are two of the most abundant elements in our solar system. Although the difference is slight, the implications could help determine how our solar system evolved.

"We found that Earth, the moon, as well as Martian and other meteorites which are samples of asteroids, have a lower concentration of the O-16 than does the sun," said Kevin McKeegan, a Genesis co-investigator from UCLA, and the lead author of one of two Science papers published this week. "The implication is that we did not form out of the same solar nebula materials that created the sun -- just how and why remains to be discovered."

The air on Earth contains three different kinds of oxygen atoms which are differentiated by the number of neutrons they contain. Nearly 100 percent of oxygen atoms in the solar system are composed of O-16, but there are also tiny amounts of more exotic oxygen isotopes called O-17 and O-18. Researchers studying the oxygen of Genesis samples found that the percentage of O-16 in the sun is slightly higher than on Earth or on other terrestrial planets. The other isotopes' percentages were slightly lower.

Another paper detailed differences between the sun and planets in the element nitrogen. Like oxygen, nitrogen has one isotope, N-14, that makes up nearly 100 percent of the atoms in the solar system, but there is also a tiny amount of N-15. Researchers studying the same samples saw that when compared to Earth's atmosphere, nitrogen in the sun and Jupiter has slightly more N-14, but 40 percent less N-15. Both the sun and Jupiter appear to have the same nitrogen composition. As is the case for oxygen, Earth and the rest of the inner solar system are very different in nitrogen.

"These findings show that all solar system objects including the terrestrial planets, meteorites and comets are anomalous compared to the initial composition of the nebula from which the solar system formed," said Bernard Marty, a Genesis co-investigator from Centre de Recherches Pétrographiques et Géochimiques and the lead author of the other new Science paper. "Understanding the cause of such a heterogeneity will impact our view on the formation of the solar system."

Data were obtained from analysis of samples Genesis collected from the solar wind, or material ejected from the outer portion of the sun. This material can be thought of as a fossil of our nebula because the preponderance of scientific evidence suggests that the outer layer of our sun has not changed measurably for billions of years.

"The sun houses more than 99 percent of the material currently in our solar system, so it's a good idea to get to know it better," said Genesis Principal Investigator Don Burnett of the California Institute of Technology, Pasadena, Calif. "While it was more challenging than expected, we have answered some important questions, and like all successful missions, generated plenty more."

Genesis launched in August 2000. The spacecraft traveled to Earth's L1 Lagrange Point about 1 million miles from Earth, where it remained for 886 days between 2001 and 2004, passively collecting solar-wind samples.

On Sept. 8, 2004, the spacecraft released a sample return capsule, which entered Earth's atmosphere. Although the capsule made a hard landing as a result of a failed parachute in the Utah Test and Training Range in Dugway, Utah, it marked NASA's first sample return since the final Apollo lunar mission in 1972, and the first material collected beyond the moon. NASA's Johnson Space Center in Houston curates the samples and supports analysis and sample allocation.

The Jet Propulsion Laboratory, Pasadena, Calif., managed the Genesis mission for NASA's Science Mission Directorate, Washington. The Genesis mission was part of the Discovery Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems, Denver, developed and operated the spacecraft. Analysis at the Centre de Recherches Pétrographiques et Géochimiques, Nancy, France, was supported by the Centre National d'Etudes Spatiales, Paris, and the Centre National de la Recherche Scientifique, Paris, France.

For more information on the Genesis mission, visit: http://genesismission.jpl.nasa.gov .

Tuesday, June 21, 2011

ESA's Space Hazards Programme

 In April 2011, the European Commission (EC) released a communication entitled "Towards a space strategy for the European Union that benefits its citizens" outlining the crucial role of space for European economies and societies.


The document provided a powerful endorsement for the goals of ESA's Space Situational Awareness (SSA) Preparatory Programme, which was authorised the ESA Member states at the Ministerial Council in 2008 and formally started in January 2009.

SSA: detecting space environment hazards

ESA's SSA preparatory programme aims to support European autonomy through the provision of timely and accurate information and services regarding the space environment, and particularly regarding hazards to critical satellites in orbit and infrastructure on the ground.

In general, these hazards stem from:
Possible collisions between functioning satellites and orbital debris
Harmful effects of space weather on satellites and ground infrastructure
Potential strikes on Earth by natural objects such as asteroids and comets

Yet today, Europe lacks the full compliment of operational telescopes, scanning radar and data processing capabilities that would warn of space hazards.

Strong agreement at European levels

"There is strong agreement at national and European levels that we need services based on European assets that help us to protect our satellites and ground infrastructure against threats from orbital debris, space weather or possible impacts," says ESA's Nicolas Bobrinsky, Head of the SSA Programme Office.

In 2011, SSA activities are accelerating with the opening of a space surveillance data analysis capability located at ESAC, the European Space Astronomy Centre, Spain. It will serve as the test-bed for enhanced debris data analysis and for issuing test warnings to satellite operators.

Similar test facilities are also being established for space weather and NEOs.

SSA: helping European autonomy and creating high-tech jobs

In 2012, the initial phase of the SSA preparatory programme will reach fruition, producing a detailed technical roadmap for the future fully operational SSA system to be decided at the ESA Ministerial Council scheduled for the end of that year.

"The plan will show how existing European research capabilities, such as the scanning radar at the Fraunhofer Institute near Bonn or ESA's own Optical Ground Station on the Spanish island of Tenerife, can be efficiently integrated into the system. It will also specify the new sensors that must be built in order to secure Europe's autonomy," says Bobrinsky.

He adds that SSA is a major opportunity for European industry that will provide skilled jobs and targeted investment. "SSA will ultimately help secure in Europe a satisfactory level of autonomy in a strategic space domain and enable us to better cooperate with and assist all space-faring nations.

Monday, June 6, 2011

Astronomers Spot Black Holes Using NASA's Chandra X-Ray Observatory

Years:2006
Not even light can escape a black hole's grip, but gas falling into a black hole can heat up and become an intense source of X-rays, at temperatures up to 1,000 times hotter than the sun. Astronomers use the Chandra X-Ray Observatory -- a NASA satellite -- to map these X-ray sources and study their properties

ANN ARBOR, Mich. -- They are deep and dense, and not even light can escape their grip. We're talking about black holes, but they may not be as dark as you think.

"If you have binoculars, you might be able to make out a smudge, which would be the nearest galaxies," says Jon Miller, an assistant professor of astronomy at the University of Michigan in Ann Arbor.

But what you won't see -- even with a telescope -- black holes! In fact, Miller doesn't even use one to study black holes. He uses his computer.

"I think it's really for the best that NASA doesn't let people like me drive billion-dollar satellites. So instead, we get data distributed through the computer networks," Miller tells DBIS.

These data reveal just how complex black holes are. As gravity pulls matter into the hole, it is heated 1,000-times hotter than the sun and forms mega-heated gases. As the hole's magnetic field pulls these gases into its center, it creates a light show.

Miller says, "Just before matter falls into the black hole, it can glow very brightly in X-rays." The Chandra X-ray Observatory takes X-ray photographs of these holes all over the universe.

According to Miller, every galaxy probably harbors a super massive black hole at the center of that galaxy. "I mean something that's a million or even billions of times the mass of our sun," he says. He hopes his research will help to prove not only what happens after black holes are formed, but also how they grow.

BACKGROUND: A team of astronomers led by the University of Michigan may know how black holes are lighting up the universe. New data from NASA's Chandra X-ray Observatory show for the first time that powerful magnetic fields are the key to these brilliant and startling light shows. By gaining deeper understanding of how black holes gather matter into themselves, astronomers also hope to learn more about other properties of black holes, including how they grow.

LIGHT FROM DARK: Black holes are the darkest objects in the universe. If a gas in a disk around a black hole loses energy, it will swirl toward the black hole, generating light along the way. In 1973, physicists suggested that magnetic fields could drive the generation of light by black holes. They would do this by generating friction in the gas and driving a wind from the disk that carries momentum outward. It is estimated that up to half of the total radiation in the universe since the Big Bang comes from material falling towards super-massive black holes.

WHAT CHANDRA FOUND: Chandra measures the amount of X-rays emitted at different energies, called X-ray spectroscopy. Spectroscopy is the study of light's "fingerprint," according to its color, which indicates its energy. Chemical elements each shine brightly at certain energies, so scientists can determine the chemical composition of an object. Chandra studied the X-ray spectra coming from a black hole system known as J1655 located in the Milky Way galaxy. The black hole was pulling material from a companion star into a disk, emitting the telltale radiation. The Michigan astronomers showed that the speed and density of the wind from the disk in J1655 corresponded to computer simulation predictions for winds driven by magnetic fields.

ABOUT BLACK HOLES: A black hole forms when a massive star has used up all its fuel. The reason the Sun and other stars emit light is because trillions of nuclear reactions are taking place at the cores. With core temperatures of millions of degrees, hydrogen atoms can convert into helium atoms, emitting radiation in the process. At some point, however, all the atoms are used up and no more nuclear fusion can take place. Without that outward counter-force to the pull of gravity, a star collapses inward, eventually reaching a point where the attractive gravitational force is so strong, not even light can escape. No one has ever observed the center of a black hole; until quite recently, such objects only existed in theory. But scientists surmise that a black hole has at its center an infinite density and an infinite gravitational field, as well as infinite entropy, which means no further change can take place. This is known as a "singularity." The event horizon of a black hole is not so much a physical surface as the theoretical point of no return for any object that gets caught in the black hole's powerful gravitational field.

Saturday, June 4, 2011

Black Holes Spin Faster

Two UK astronomers have found that the giant black holes in the centre of galaxies are on average spinning faster than at any time in the history of the Universe. Dr Alejo Martinez-Sansigre of the University of Portsmouth and Prof. Steve Rawlings of the University of Oxford made the new discovery by using radio, optical and X-ray data. They publish their findings in the journal Monthly Notices of the Royal Astronomical Society.


There is strong evidence that every galaxy has a black hole in its centre. These black holes have masses of between a million and a billion Suns and so are referred to as 'supermassive'. They cannot be seen directly, but material swirls around the black hole in a so-called accretion disk before its final demise. That material can become very hot and emit radiation including X-rays that can be detected by space-based telescopes whilst associated radio emission can be detected by telescopes on the ground.

As well as radiation, twin jets are often associated with black holes and their accretion disks. There are many factors that can cause these jets to be produced, but the spin of the supermassive black hole is believed to be important. However, there are conflicting predictions about how the spins of the black holes should be evolving and until now this evolution was not well understood.

Dr Martinez-Sansigre and Professor Rawlings compared theoretical models of spinning black holes with radio, optical and X-ray observations made using a variety of instruments and found that the theories can explain very well the population of supermassive black holes with jets.

Using the radio observations, the two astronomers were able to sample the population of black holes, deducing the spread of the power of the jets. By estimating how they acquire material (the accretion process) the two scientists could then infer how quickly these objects are spinning.

The observations also give information on how the spins of supermassive black holes have evolved. In the past, when the Universe was half its the present size, practically all of the supermassive black holes had very low spins, whereas nowadays a fraction of them have very high spins. So on average, supermassive black holes are spinning faster than ever before.

This is the first time that the evolution of the spin of the supermassive black holes has been constrained and it suggests that those supermassive black holes that grow by swallowing matter will barely spin, while those that merge with other black holes will be left spinning rapidly.

Commenting on the new results, Dr Martinez-Sansigre said: "The spin of black holes can tell you a lot about how they formed. Our results suggest that in recent times a large fraction of the most massive black holes have somehow spun up. A likely explanation is that they have merged with other black holes of similar mass, which is a truly spectacular event, and the end product of this merger is a faster spinning black hole."

Professor Rawlings adds: "Later this decade we hope to test our idea that these supermassive black holes have been set spinning relatively recently. Black hole mergers cause predictable distortions in space and time -- so-called gravitational waves. With so many collisions, we expect there to be a cosmic background of gravitational waves, something that will change the timing of the pulses of radio waves that we detect from the remnants of massive stars known as pulsars.

If we are right, this timing change should be picked up by the Square Kilometre Array, the giant radio observatory due to start operating in 2019."

NASA's Mars Exploration Rover Opportunity

 A drive of 482 feet (146.8 meters) on June 1, 2011, took NASA's Mars Exploration Rover Opportunity past 30 kilometers (18.64 miles) in total odometry during 88 months of driving on Mars. That's 50 times the distance originally planned for the mission and more than 12 times the distance racehorses will run at the Belmont Stakes.


Opportunity has passed many craters on its crater-hopping tour. One of the youngest of them is "Skylab" crater, which the rover passed last month. Rocks scattered by the impact of a meteorite surround the resulting crater in a view recorded by Opportunity on May 12. The view is at http://photojournal.jpl.nasa.gov/catalog/PIA14132 , and in 3-D stereo at http://photojournal.jpl.nasa.gov/catalog/PIA14133 .

This crater, informally named after America's first space station, is only about 9 meters (30 feet) in diameter. Opportunity passed it as the rover made progress toward its long-term destination, Endeavour crater, which is about 22 kilometers (14 miles) in diameter.

The positions of the scattered rocks relative to sand ripples suggest that Skylab is young for a Martian crater. Researchers estimate it was excavated by an impact within the past 100,000 years.

Opportunity and its twin, Spirit, completed their three-month prime missions on Mars in April 2004. Both rovers continued for years of bonus, extended missions. Both have made important discoveries about wet environments on ancient Mars that may have been favorable for supporting microbial life. Spirit has not communicated with Earth since March 2010.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover Project for the NASA Science Mission Directorate, Washington. More information about the rovers is online at: http://www.nasa.gov/rovers .

Thursday, June 2, 2011

Solar Panels for NASA's

The three massive solar panels that will provide power for NASA's Juno spacecraft during its mission to Jupiter have seen their last photons of light until they are deployed in space after launch. The last of the Jupiter-bound spacecraft's panels completed pre-flight testing at the Astrotech payload processing facility in Titusville, Fla., and was folded against the side of the spacecraft into its launch configuration Thursday, May 26. The solar-powered Juno spacecraft will orbit Jupiter's poles 30 times to find out more about the gas giant's origins, structure, atmosphere and magnetosphere.



"Completing the testing and stow of solar panels is always a big pre-launch milestone, and with Juno, you could say really big because our panels are really big," said Jan Chodas, Juno's project manager from NASA's Jet Propulsion Laboratory in Pasadena, Calif. "The next time these three massive solar arrays are extended to their full length, Juno will be climbing away from the Earth at about seven miles per second."

This is the first time in history a spacecraft has used solar power so far out in space (Jupiter is five times farther from the sun than Earth). To operate on the sun's light that far out requires solar panels about the size of the cargo section of a typical tractor-trailer you'd see on the interstate highway. Even with all that surface area pointed sunward, all three panels, which are 2.7 meters wide (9 feet), by 8.9 meters long (29 feet), will only generate about enough juice to power five standard light bulbs -- about 450 watts of electricity. If the arrays were optimized to operate at Earth, they would produce 12 to 14 kilowatts of power.

In other recent events, the 106-foot-long (32-meter-long), 12.5-foot-wide (3.8-meter-wide) first stage of the United Launch Alliance Atlas V launch vehicle that will carry Juno into space arrived at the Skid Strip at Cape Canaveral Air Force Station on May 24, aboard the world's second largest cargo aircraft -- a Volga-Dnepr Antonov AN-124-100. The two-stage Atlas V, along with the five solid rocket boosters that ring the first stage, will be assembled and tested on site at Launch Complex-41 at Cape Canaveral this summer.

The launch period for Juno opens Aug. 5, 2011, and extends through Aug. 26. For an Aug. 5 liftoff, the launch window opens at 8:39 a.m. PDT (11:39 am EDT) and remains open through 9:39 a.m. PDT (12:39 p.m. EDT).

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Juno mission for the principal investigator, Scott Bolton, of Southwest Research Institute in San Antonio. The Juno mission is part of the New Frontiers Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems, Denver, built the spacecraft. Launch management for the mission is the responsibility of NASA's Launch Services Program at the Kennedy Space Center in Florida. JPL is a division of the California Institute of Technology in Pasadena.

More information about Juno is online at http://www.nasa.gov/juno .
Two digital color cameras riding high on the mast of NASA's next Mars rover will complement each other in showing the surface of Mars in exquisite detail.




They are the left and right eyes of the Mast Camera, or Mastcam, instrument on the Curiosity rover of NASA's Mars Science Laboratory mission, launching in late 2011.

The right-eye Mastcam looks through a telephoto lens, revealing details near or far with about three-fold better resolution than any previous landscape-viewing camera on the surface of Mars. The left-eye Mastcam provides broader context through a medium-angle lens. Each can acquire thousands of full-color images and store them in an eight-gigabyte flash memory. Both cameras are also capable of recording high-definition video at about eight frames per second. Combining information from the two eyes can yield 3-D views of the telephoto part of the scene.

Motivation to put telephoto capability in Curiosity's main science imaging instrument grew from experience with NASA's Mars Exploration Rover Opportunity and its studies of an arena-size crater in 2004. The science camera on that rover's mast, which can see details comparably to what a human eye can see at the same distance, showed intriguing patterns in the layers of Burns Cliff inside Endurance Crater.

"We tried to get over and study it, but the rover could not negotiate the steep slope," recalled Mastcam Principal Investigator Michael Malin, of Malin Space Science Systems, San Diego. "We all desperately coveted a telephoto lens." NASA selected his Mastcam proposal later that year for the Mars Science Laboratory rover.

The telephoto Mastcam, called "Mastcam 100" for its 100-millimeter focal-length lens, provides enough resolution to distinguish a basketball from a football at a distance of seven football fields, or to read "ONE CENT" on a penny on the ground beside the rover. Its images cover an area about six degrees wide by five degrees tall.

Its left-eye partner, called "Mastcam 34" for its 34-millimeter lens, catches a scene three times wider -- about 18 degrees wide and 15 degrees tall -- with each exposure.

Researchers will use the Mastcams and nine other science instruments on Curiosity to study past and present environments in a carefully chosen area of Mars. They will assess whether conditions have been favorable for life and favorable for preserving evidence about whether life has existed there. Mastcam imaging of the shapes and colors of landscapes, rocks and soils will provide clues about the history of environmental processes that have formed them and modified them over time. Images and videos of the sky will document contemporary processes, such as movement of clouds and dust.

Previous color cameras on Mars have taken a sequence of exposures through different color filters to be combined on Earth into color views. The Mastcams record color the same way consumer digital cameras do: They have a grid of tiny red, green and blue squares (a "Bayer pattern" filter) fitted over the electronic light detector (the charge-coupled device, or CCD). This allows the Mastcams to get the three color components over the entire scene in a single exposure.

Mastcam's color-calibration target on the rover deck includes magnets to keep the highly magnetic Martian dust from accumulating on portions of color chips and white-gray-balance reference chips. Natural lighting on Mars tends to be redder than on Earth due to dust in Mars' atmosphere. "True color" images can be produced that incorporate that lighting effect -- comparable to the greenish look of color-film images taken under fluorescent lights on Earth without a white-balancing adjustment. A white-balance calculation can yield a more natural look by adjusting for the tint of the lighting, as the human eye tends to do and digital cameras can do. The Mastcams are capable of producing both true-color and white-balanced images.

Besides the affixed red-green-blue filter grid, the Mastcams have wheels of other filters that can be rotated into place between the lens and the CCD. These include science spectral filters for examining the ground or sky in narrow bands of visible-light or near-infrared wavelengths. One filter on each camera allows it to look directly at the sun to measure the amount of dust in the atmosphere, a key part of Mars' weather.

"Something we're likely to do frequently is to look at rocks and features with the Mastcam 34 red-green-blue filter, and if we see something of interest, follow that up with the Mastcam 34 and Mastcam 100 science spectral filters," Malin said. "We can use the red-green-blue data for quick reconnaissance and the science filters for target selection."

When Curiosity drives to a new location, Mastcam 34 can record a full-color, full-circle panorama about 60 degrees tall by taking 150 images in about 25 minutes. Using Mastcam 100, the team will be able to broaden the swath of terrain evaluated on either side of the path Curiosity drives, compared to what has been possible with earlier Mars rovers. That will help with selection of the most interesting targets to approach for analysis by Curiosity's other instruments and will provide additional geological context for interpreting data about the chosen targets.

The Mastcams will provide still images and video to study motions of the rover -- both for science, such as seeing how soils interact with wheels, and for engineering, such as aiding in use of the robotic arm. In other videos, the team may use cinematic techniques such as panning across a scene and using the rover's movement for "dolly" shots.

Each of the two-megapixel Mastcams can take and store thousands of images, though the amount received on Earth each day will depend on how the science team chooses priorities for the day's available data-transmission volume. Malin anticipates frequent use of Mastcam "thumbnail" frames -- compressed roughly 150-by-150-pixel versions of each image -- as an index of the full-scale images held in the onboard memory.

Malin Space Science Systems built the Mastcam instrument and will operate it. The company's founder, Michael Malin, participated in NASA's Viking missions to Mars in the 1970s, provided the Mars Orbiter Camera for NASA's Mars Global Surveyor mission, and is the principal investigator for both the Context Camera and the Mars Color Imager on NASA's Mars Reconnaissance Orbiter.

The science team for Mastcam and two other instruments the same company provided for Curiosity includes the lead scientist for the mast-mounted science cameras on Mars rovers Spirit and Opportunity (James Bell of Arizona State University); the lead scientist for the mast camera on NASA's Phoenix Mars Lander (Mark Lemmon of Texas A&M University); James Cameron, director of such popular movies as "Titanic" and "Avatar"; and 17 others with expertise in geology, soils, frost, atmosphere, imaging and other topics.

Mastcam 100 and Mastcam 34 were installed onto Curiosity in 2010. Until March 2011, a possibility remained open that they might be replaced with a different design: two identical zoom cameras. A zoom camera has adjustable focal length, to change from wider-angle to telephoto or vice-versa. That design had been Malin's original proposal. NASA changed the plan to two different fixed-focal-length cameras in 2007 as a cost-cutting measure that preserves the capability for meeting the science goals of the mission and the instrument. The agency funded a renewed possibility for using the zoom-camera design in 2010, but the zoom development presented challenges that could not be fully overcome with enough time for required testing on the rover.

Mastcam 34 took images for a mosaic showing Curiosity's upper deck during tests in March 2011 inside a chamber simulating Mars surface temperature and air pressure. Testing of the rover at NASA's Jet Propulsion Laboratory, Pasadena, Calif., will wrap up in time for shipping the rover to NASA Kennedy Space Center in June. Testing and other launch preparations will continue there. The launch period for the Mars Science Laboratory is Nov. 25 to Dec. 18, 2011, with landing on Mars in August 2012.

Wednesday, June 1, 2011

Oxygen-Rich Soil on Moon

The Moon's surface is covered with oxygen-rich soils, Hubble Space Telescope images show. Planetary scientists believe the oxygen could be tapped to power rockets and be a source of oxygen to breathe for future astronauts.



ORLANDO, Fla.--The moon's surface hasn't been stepped on since the Apollo missions in the 1970's. Now, for the first time in more than 30 years, NASA is going back to the moon.

When the last astronaut took the final step on the moon, many people thought we'd never visit it again. Jim Garvin, a planetary scientist at the NASA/Goddard Space Flight Center in Greenbelt, Md., says, "We went. We came. We saw. We conquered ... And we left."

Now, planetary scientists are going back, but this time through the eyes of the Hubble telescope. Brand new images show a side of our moon we've never seen.

"This is the first time we've looked at the moon with Hubble's spectacular vision to understand things about the moon that today we haven't fully understood. This is why exploration's so exciting," Garvin says.

The amazing pictures were captured using ultra-violet light reflected off the moon's surface. They reveal signs of oxygen-rich soils that scientists believe can be used to power rockets and be a source of oxygen to breathe for future life on the moon.

Garvin says, "So, finding resources, learning where they are, and how much there are, and learning then how to use them for people and utilization of human beings on the moon -- women and men -- is really our long-term goal."

A goal that may seem like light years away -- but thanks to these helpful images, living on the moon may be a closer reality. "We're going to learn to live there, we're going to learn to put human exploration and robot exploration together," Garvin says.

The Hubble telescope is normally meant to look at objects light years away, and researchers found focusing Hubble on the moon -- a mere 250,000 miles away -- was more challenging than expected.

BACKGROUND: For years, the Hubble Space Telescope has given scientists spectacular photographs of the farthest reaches of space, but recently the telescope turned its attention a bit closer to home, taking images of the moon. These images -- the first taken with ultraviolet light -- reveal new information about the composition of the moon, with implications for future lunar exploration.

HOW HUBBLE WORKS: Hubble has a long tube that is open at one end, with mirrors to gather and focus light to its "eyes" -- various instruments that enable it to detect different types of light, such as ultraviolet and infrared. Light enters the telescope through the opening and bounces off a primary mirror to a secondary mirror, which reflects the light through a hole in the center of the primary mirror to a focal point behind the primary mirror.

Smaller mirrors distribute the light to the various scientific instruments, which analyze the different wavelengths. Each instrument uses the same kind of array of diodes that are used in digital cameras to capture light. The captured light is stored in on-board computers and relayed to Earth as digital signals, and this data is then transformed into images.

WHAT WE CAN LEARN: Astronomers can glean a lot of useful scientific information from these images. The colors, or spectrum, of light coming from a celestial object form a chemical fingerprint of that object, indicating which elements are present, while the intensity of each color tells us how much of that element is present. The spectrum can also tell astronomers how fast a celestial object is moving away or towards us through an effect called the Doppler shift. Light emitted by a moving object is perceived to increase in frequency (a blue shift) if it is moving toward the observer; if the object is moving away from us, it will be shifted toward the red end of the spectrum.

NEW INSIGHTS: Thanks to Hubble's high resolution and sensitivity to ultraviolet light, astronomers are able to search for minerals in the lunar crust that may be critical for establishing a sustained human presence on the moon. These include titanium and iron oxides, both of which are sources of oxygen. Since the moon lacks a breathable atmosphere (as well as water), the presence of such minerals is critical. This new data, along with other measurements will help NASA scientists identify the most promising sites for future robotic and human missions.

Researchers Track Space Junk

A team of researchers from the Royal Institute and Observatory of the Navy (ROA) in Cádiz (Spain) has developed a method to track the movement of geostationary objects using the position of the stars, which could help to monitor space debris. The technique can be used with small telescopes and in places that are not very dark.


Objects or satellites in geostationary orbit (GEO) can always be found above the same point on the Equator, meaning that they appear immobile when observed from Earth. By night, the stars appear to move around them, a feature that scientists have taken advantage of for decades in order to work out the orbit of these objects, using images captured by telescopes, as long as these images contain stars to act as a reference point.

This method was abandoned when satellites started to incorporate transponders (devices that made it possible to locate them using the data from emitted and reflected signals). However, the classic astrometric techniques are now combing back into vogue due to the growing problem of space waste, which is partly made up of the remains of satellites engines without active transponders.

"Against this backdrop, we developed optical techniques to precisely observe and position GEO satellites using small and cheap telescopes, and which could be used in places that are not particularly dark, such as cities," says Francisco Javier Montojo, a member of the ROA and lead author of a study published in the journal Advances in Space Research.

The method can be used for directly detecting and monitoring passive objects, such as the space junk in the geostationary ring, where nearly all communications satellites are located. At low orbits (up to around 10,000 km) these remains can be tracked by radar, but above this level the optical technique is more suitable.

Montojo explains that the technique could be of use for satellite monitoring agencies "to back up and calibrate their measurements, to check their manoeuvres, and even to improve the positioning of satellites or prevent them from colliding into other objects."

"The probability of collisions or interferences occurring between objects is no longer considered unappreciable since the first collision between two satellites on 10 February 2009 between America's Iridium33 and the Russians' Cosmos 2251," the researcher points out.

Image software and 'double channel'

The team has created software that can precisely locate the centre of the traces or lines that stars leave in images (due to photograph time exposure). The main advantage of the programme is that it "globally reduces" the positions of the object to be followed with respect to the available stellar catalogues. To do this, it simultaneously uses all the stars and all the photographs taken by the telescope's CCD camera on one night. It does not matter if there are not sufficient reference stars in some shots, because they are all examined together as a whole.

Optical observation allows the object to be located at each moment. Using these data and another piece of (commercial) software, it is possible to determine the orbit of the GEO object, in other words to establish its position and speed, as well as to predict its future positions. The method was validated by tracking three Hispasat satellites (H1C, H1D and Spainsat) and checking the results against those of the Hispasat monitoring agency.

"As an additional original application, we have processed our optical observations along with the distances obtained using another technique known as 'double channel' (signals the travel simultaneously between two clocks or oscillators to adjust the time)," says Montojo. The Time Section of the ROA uses this methodology to remotely compare patterns and adjust the legal Spanish time to International Atomic Time.

Incorporating these other distance measurements leads to a "tremendous reduction" in uncertainty about the satellite's position, markedly improving the ability to determine its orbit.

Data from the ROA's veteran telescope in San Fernando (Cádiz) were used to carry out this study, but in 2010 the institution unveiled another, more modern one at the Montsec Astronomical Observatory in Lleida, co-managed by the Royal Academy of Sciences and Arts of Barcelona. This is the Fabra-ROA Telescope at Montsec (TFRM), which makes remote, robotic observations.

"The new telescope has features that are particularly well suited to detecting space junk, and we hope that in the near future it will play an active part in international programmes to produce catalogues of these kinds of orbital objects," the researcher concludes.

Sending Humans to Mars

What would it take to make a manned mission to Mars a reality? A team of aerospace and textile engineering students from North Carolina State University believe part of the solution may lie in advanced textile materials. The students joined forces to tackle life-support challenges that the aerospace industry has been grappling with for decades.



"One of the big issues, in terms of a manned mission to Mars, is creating living quarters that would protect astronauts from the elements -- from radiation to meteorites," says textile engineering student Brent Carter. "Currently, NASA uses solid materials like aluminum, fiberglass and carbon fibers, which while effective, are large, bulky and difficult to pack within a spacecraft."

Using advanced textile materials, which are flexible and can be treated with various coatings, students designed a 1,900-square-foot inflatable living space that could comfortably house four to six astronauts. This living space is made by layering radiation-shielding materials like Demron™ (used in the safety suits for nuclear workers cleaning up Japan's Fukushima plant) with a gas-tight material made from a polyurethane substrate to hold in air, as well as gold-metalicized film that reflects UV rays -- among others. The space is dome-shaped, which will allow those pesky meteors, prone to showering down on the red planet, to bounce off the astronauts' home away from home without causing significant damage.

"We're using novel applications of high-tech textile technology and applying them to aerospace problems," explains Alex Ray, a textile engineering student and team member. "Being able to work with classmates in aeronautical engineering allowed us to combine our knowledge from both disciplines to really think through some original solutions."

Students also tackled another major issue preventing a manned mission to Mars -- water supply. Currently, astronauts utilize something called a Sabatier reactor to produce water while in space. The Sabatier process involves the reaction of carbon dioxide and hydrogen, with the presence of nickel, at extremely high temperatures and pressure to produce water and methane.

"We wanted to find a way to improve the current Sabatier reactor so we could still take advantage of the large quantities of carbon dioxide available on Mars, and the fact that it is relatively easy to bring large quantities of hydrogen on the spacecraft, since it is such a lightweight element," says recent aerospace engineering graduate Mark Kaufman, who was also on the design team.

Current Sabatier reactors, Kaufman explains, are long, heavy tubes filled with nickel pellets -- not ideal for bringing on a spacecraft. The student groups worked to develop a fiber material to which they applied nickel nanoparticles to create the same reaction without all the weight and volume. They believe their redesigned Sabatier reactor would be more feasible to carry along on a future space shuttle.

In addition to Carter, Ray and Kaufman, the team also included Kris Tesh, Grant Gilliam, Kasey Orrell, Daniel Page and Zack Hester. Textile engineering professor and former aerospace engineer, Dr. Warren Jasper, served as the faculty sponsor. The team also received valuable feedback from Fred Smith, an advanced life support systems engineer with NASA.

Jasper and the student team will present their project at the NASA-sponsored Revolutionary Aerospace Systems Concepts Academic Linkage (RASC-AL) competition, held June 6-8 in Cocoa Beach, Fla. The project will be judged by NASA and industry experts against other undergraduate groups from across the country. RASC-AL was formed to provide university-level engineering students the opportunity to design projects based on NASA engineering challenges, as well as offer NASA access to new research and design projects by students

'Dead' Galaxies

University of Michigan astronomers examined old galaxies and were surprised to discover that they are still making new stars. The results provide insights into how galaxies evolve with time. U-M research fellow Alyson Ford and astronomy professor Joel Bregman presented their findings May 31 at a meeting of the Canadian Astronomical Society in London, Ontario.



Using the Wide Field Camera 3 on the Hubble Space Telescope, they saw individual young stars and star clusters in four galaxies that are about 40 million light years away. One light year is about 5.9 trillion miles.

"Scientists thought these were dead galaxies that had finished making stars a long time ago," Ford said. "But we've shown that they are still alive and are forming stars at a fairly low level."

Galaxies generally come in two types: spiral galaxies, like our own Milky Way, and elliptical galaxies. The stars in spiral galaxies lie in a disk that also contains cold, dense gas, from which new stars are regularly formed at a rate of about one sun per year.

Stars in elliptical galaxies, on the other hand, are nearly all billions of years old. These galaxies contain stars that orbit every which way, like bees around a beehive. Ellipticals have little, if any, cold gas, and no star formation was known.

"Astronomers previously studied star formation by looking at all of the light from an elliptical galaxy at once, because we usually can't see individual stars," Ford said. "Our trick is to make sensitive ultraviolet images with the Hubble Space Telescope, which allows us to see individual stars."

The technique enabled the astronomers to observe star formation, even if it is as little as one sun every 100,000 years.

Ford and Bregman are working to understand the stellar birth rate and likelihood of stars forming in groups within ellipticals. In the Milky Way, stars usually form in associations containing from tens to 100,000 stars. In elliptical galaxies, conditions are different because there is no disk of cold material to form stars.

"We were confused by some of the colors of objects in our images until we realized that they must be star clusters, so most of the star formation happens in associations," Ford said.

The team's breakthrough came when they observed Messier 105, a normal elliptical galaxy that is 34 million light years away, in the constellation Leo. Though there had been no previous indication of star formation in Messier 105, Ford and Bregman saw a few bright, very blue stars, resembling a single star 10 to 20 times the mass of the sun.

They also saw objects that aren't blue enough to be single stars, but instead are clusters of many stars. When accounting for these clusters, stars are forming in Messier 105 at an average rate of one sun every 10,000 years, Ford and Bregman concluded. "This is not just a burst of star formation but a continuous process," Ford said.

These findings raise new mysteries, such as the origin of the gas that forms the stars.

"We're at the beginning of a new line of research, which is very exciting, but at times confusing," Bregman said. "We hope to follow up this discovery with new observations that will really give us insight into the process of star formation in these 'dead' galaxies."

Friday, May 27, 2011

Spitzer Sees Crystal 'Rain' in Outer Clouds of Infant Star

Tiny crystals of a green mineral called olivine are falling down like rain on a burgeoning star, according to observations from NASA's Spitzer Space Telescope.

This is the first time such crystals have been observed in the dusty clouds of gas that collapse around forming stars. Astronomers are still debating how the crystals got there, but the most likely culprits are jets of gas blasting away from the embryonic star.

"You need temperatures as hot as lava to make these crystals," said Tom Megeath of the University of Toledo in Ohio. He is the principal investigator of the research and the second author of a new study appearing in Astrophysical Journal Letters. "We propose that the crystals were cooked up near the surface of the forming star, then carried up into the surrounding cloud where temperatures are much colder, and ultimately fell down again like glitter."

Spitzer's infrared detectors spotted the crystal rain around a distant, sun-like embryonic star, or protostar, referred to as HOPS-68, in the constellation Orion.

The crystals are in the form of forsterite. They belong to the olivine family of silicate minerals and can be found everywhere from a periodot gemstone to the green sand beaches of Hawaii to remote galaxies. NASA's Stardust and Deep Impact missions both detected the crystals in their close-up studies of comets.

"If you could somehow transport yourself inside this protostar's collapsing gas cloud, it would be very dark," said Charles Poteet, lead author of the new study, also from the University of Toledo. "But the tiny crystals might catch whatever light is present, resulting in a green sparkle against a black, dusty backdrop."

Forsterite crystals were spotted before in the swirling, planet-forming disks that surround young stars. The discovery of the crystals in the outer collapsing cloud of a proto-star is surprising because of the cloud's colder temperatures, about minus 280 degrees Fahrenheit (minus 170 degrees Celsius). This led the team of astronomers to speculate the jets may in fact be transporting the cooked-up crystals to the chilly outer cloud.

The findings might also explain why comets, which form in the frigid outskirts of our solar system, contain the same type of crystals. Comets are born in regions where water is frozen, much colder than the searing temperatures needed to form the crystals, approximately 1,300 degrees Fahrenheit (700 degrees Celsius). The leading theory on how comets acquired the crystals is that materials in our young solar system mingled together in a planet-forming disk. In this scenario, materials that formed near the sun, such as the crystals, eventually migrated out to the outer, cooler regions of the solar system.

Poteet and his colleagues say this scenario could still be true but speculate that jets might have lifted crystals into the collapsing cloud of gas surrounding our early sun before raining onto the outer regions of our forming solar system. Eventually, the crystals would have been frozen into comets. The Herschel Space Observatory, a European Space Agency-led mission with important NASA contributions, also participated in the study by characterizing the forming star.

"Infrared telescopes such as Spitzer and now Herschel are providing an exciting picture of how all the ingredients of the cosmic stew that makes planetary systems are blended together," said Bill Danchi, senior astrophysicist and program scientist at NASA Headquarters in Washington.

The Spitzer observations were made before it used up its liquid coolant in May 2009 and began its warm mission.

NASA's Jet Propulsion Laboratory in Pasadena, Calif., manages the Spitzer Space Telescope mission for the agency's Science Mission Directorate in Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.