This result comes from a very long observation of the Tycho supernova remnant with NASA's Chandra X-ray Observatory. It could explain how some of the extremely energetic particles bombarding the Earth, called cosmic rays, are produced.

“We've seen lots of intriguing structures in supernova remnants, but we’ve never seen stripes before,” said Kristoffer Eriksen of Rutgers University, who led the study. “This made us think very hard about what's happening in the blast wave of this powerful explosion.” This latest study from Chandra provides support for a theory about how magnetic fields can be dramatically amplified in such blast waves.

In this theory, the magnetic fields become highly tangled and the motions of the particles very turbulent near the expanding supernova shock wave at the front edge of the supernova remnant. High-energy charged particles can bounce back and forth across the shock wave repeatedly, gaining energy with each crossing. Theoretical models of the motion of the most energetic particles -- which are mostly protons -- are predicted to leave a messy network of holes and dense walls corresponding to weak and strong regions of magnetic fields, respectively.

The X-ray stripes discovered by the Chandra researchers are thought to be regions where the turbulence is greater and the magnetic fields more tangled than surrounding areas, and may be the walls predicted by the theory. Electrons become trapped in these regions and emit X-rays as they spiral around the magnetic field lines.

However, the regular and almost periodic pattern of the X-ray stripes was not predicted by the theory.

"It was a big surprise to find such a neatly arranged set of stripes," said co-author Jack Hughes, also of Rutgers. "We were not expecting so much order to appear in so much chaos. It could mean that the theory is incomplete, or that there's something else we don't understand."

Assuming that the spacing between the X-ray stripes corresponds to the radius of the spiraling motion of the highest energy protons in the supernova remnant, the spacing corresponds to energies about 100 times higher than reached in the Large Hadron Collider. These energies equal the highest energies of cosmic rays thought to be produced in our Galaxy.

Because cosmic rays are composed of charged particles, like protons and electrons, their direction of motion changes when they encounter magnetic fields throughout the galaxy. So, the origin of individual cosmic rays detected on Earth cannot be determined.

Supernova remnants have long been considered a good candidate for producing the most energetic cosmic rays in our Galaxy. The protons can reach energies that are hundreds of times higher than the highest energy electrons, but since they do not radiate efficiently like the electrons, direct evidence for the acceleration of cosmic ray protons in supernova remnants has been lacking.

These results also support the prediction that magnetic fields in interstellar space are greatly amplified in supernova remnants, but the difference between the observed and predicted structures means that other interpretations cannot be ruled out.

"We were excited to discover these stripes because they might allow us to directly track, for the first time, the origin of the most energetic particles produced in our galaxy," said Eriksen. "But, we're not claiming victory yet."

The Tycho supernova remnant is named for the famous Danish astronomer Tycho Brahe, who reported observing the supernova in 1572. Scientists think the explosion occurred when a white dwarf star grew in mass and exceeded its weight limit, forming a so-called Type Ia supernova. The Tycho remnant is located in the Milky Way, about 13,000 light years from Earth.

"Supernova remnants are our best cosmic laboratories for understanding how nature accelerates the highest energy cosmic rays," said Roger Blandford of Stanford University, a noted expert in this field who was not involved with these findings. "These careful measurements provide a very strong clue as to what actually happens at these giant shock fronts."

These results were published in the February 20th, 2011 issue of The Astrophysical Journal Letters. The other co-authors are Carles Badenes from Tel-Aviv University and the Weizmann Institute of Science in Israel, Robert Fesen from Dartmouth College, NH, Parviz Ghavamian from Space Telescope Science Institute, Baltimore, MD, David Moffett, from Furman University, Greenville, SC, Paul Plucinsky from Harvard-Smithsonian Center for Astrophysics (CfA), Cambridge, MA, Cara Rakowski from the Naval Research Laboratory, Washington, DC, Estela M. Reynoso from the Institute of Astronomy and Space Physics and University of Buenos Aires, Argentina and Patrick Slane from CfA.

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.

For more information visit http://www.nasa.gov/mission_pages/chandra/news/tycho.html

At first glance, the burn is something of an insignificant event. After all, the venerable spacecraft has executed 40 major flight path maneuvers since its 1999 launch, and between these main engines and the reaction control system, its rocket motors have collectively fired more than 2 million times. But the March 24 burn will be different from all others. This burn will effectively end the life of NASA's most traveled comet hunter.

"We call it a 'burn to depletion,' and that is pretty much what we're doing – firing our rockets until there is nothing left in the tank," said Stardust-NExT project manager Tim Larson of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "It's a unique way for an interplanetary spacecraft to go out. Essentially, Stardust will be providing us useful information to the very end."

Burn to depletion will answer the question about how much fuel Stardust had left in its tank.

"We'll take those data and compare them to what our estimates told us was left," said Allan Cheuvront, Lockheed Martin Space Systems program manager for Stardust-NExT. "That will give us a better idea how valid our fuel consumption models are and make our predictions even more accurate for future missions."

Fuel consumption models are necessary because no one has invented an entirely reliable fuel gauge for spacecraft. Until that day arrives, mission planners can approximate fuel usage by looking at the history of the vehicle's flight and how many times and for how long its rocket motors have fired.

Stardust's burn to depletion is expected to impart valuable information, because the spacecraft has essentially been running on borrowed time -- for some time. Launched on Feb. 7, 1999, Stardust had already flown past an asteroid (Annefrank), flown past and collected particle samples from a comet (Wild 2), and returned those particles to Earth in a sample return capsule in January 2006 – and in so doing racked up 4.63 billion kilometers (2.88 billion miles) on its odometer. NASA then re-tasked the still-healthy spacecraft to perform a flyby of comet Tempel 1, a new, low-cost mission that required another five years and 1.04 billion kilometers (646 million miles). After all those milestones and all that time logged on the spacecraft, the Stardust team knew the end was near. They just didn't know exactly how close.

Prior to this final burn, Stardust will point its medium-gain antenna at Earth – some 312 million kilometers (194 million miles) away. As there is no tomorrow for Stardust, the spacecraft is expected to downlink information on the burn as it happens. The command from the spacecraft computer ordering the rockets to fire will be sent for 45 minutes, but the burn is expected to last only between a couple of minutes to somewhat above 10 minutes. It is estimated the burn could accelerate the spacecraft anywhere from 2.5 to 35.2 meters per second (6 to 79 mph). ?

"What we think will happen is that when the fuel reaches a critically low level, gaseous helium will enter the thruster chambers," said Larson. "The resulting thrust will be less than 10 percent of what was expected. While Stardust will continue to command its rocket engines to fire until the pre-planned firing time of 45 minutes has elapsed, the burn is essentially over."

Twenty minutes after the engines run dry, the spacecraft's computer will command its transmitters off. They actively shut off their radios to preclude the remote chance that at some point down the road Stardust's transmitter could turn on and broadcast on a frequency being used by other operational spacecraft. Turning off the transmitter ensures that there will be no unintended radio interference in the future.

Without fuel to power the spacecraft's attitude control system, Stardust's solar panels will not remain pointed at the sun. When this occurs, the spacecraft's batteries are expected to drain of power and deplete within hours.

"When we take into account all the possibilities for how long the burn could be and then the possible post-burn trajectories, we project that over the next 100 years, Stardust will not get any closer than 1.7 million miles of Earth's orbit, or within 13 million miles of Mars orbit," said Larson. "That is far enough from protected targets to meet all of NASA's Planetary Protection directives. "

Some planetary spacecraft, like the Galileo mission to Jupiter, are intentionally sent into the planet's atmosphere to make sure it is destroyed in a controlled way. Others have their transmitters shut off or just fade away, said Larson. "I think this is a fitting end for Stardust. It's going down swinging."

Stardust-NExT is a low-cost mission to expand the investigation of comet Tempel 1 initiated by NASA's Deep Impact spacecraft. JPL, a division of the California Institute of Technology in Pasadena, manages the Stardust-NExT project for the NASA Science Mission Directorate, Washington, D.C., and is part of the Discovery Program managed by NASA's Marshall Space Flight Center in Huntsville, Ala. Joe Veverka of Cornell University, Ithaca, N.Y., is the mission's principal investigator. Lockheed Martin Space Systems, Denver, built the spacecraft and manages day-to-day mission operations.

For more information visit http://www.jpl.nasa.gov/news/news.cfm?release=2011-094

Recent data from NASA's Cassini spacecraft show that the variation in radio waves controlled by the planet's rotation is different in the northern and southern hemispheres. Moreover, the northern and southern rotational variations also appear to change with the Saturnian seasons, and the hemispheres have actually swapped rates. These two radio waves, converted to the human audio range, can be heard in a new video available online at: http://www.nasa.gov/multimedia/videogallery/index.html?media_id=74390781

"These data just go to show how weird Saturn is," said Don Gurnett, Cassini's radio and plasma wave science instrument team lead and professor of physics at the University of Iowa, Iowa City. "We thought we understood these radio wave patterns at gas giants, since Jupiter was so straightforward. Without Cassini's long stay, scientists wouldn't have understood that the radio emissions from Saturn are so different."

Saturn emits radio waves known as Saturn Kilometric Radiation, or SKR for short. To Cassini, they sound a bit like bursts of a spinning air raid siren, since the radio waves vary with each rotation of the planet. This kind of radio wave pattern had been previously used at Jupiter to measure the planet's rotation rate, but at Saturn, as is the case with teenagers, the situation turned out to be much more complicated.

When NASA's Voyager spacecraft visited Saturn in the early 1980s, the radiation emissions indicated the length of Saturn's day was about 10.66 hours. But as its clocking continued by a flyby of the joint ESA-NASA Ulysses spacecraft and Cassini, the radio burst varied by seconds to minutes. A paper in Geophysical Research Letters in 2009 analyzing Cassini data showed that the Saturn Kilometric Radiation was not even a solo, but a duet, with two singers out of sync. Radio waves emanating from near the north pole had a period of around 10.6 hours; radio waves near the south pole had a period of around 10.8 hours.

A new paper led by Gurnett that was published in Geophysical Research Letters in December 2010 shows that, in recent Cassini data, the southern and northern SKR periods crossed over around March 2010, about seven months after equinox, when the sun shines directly over a planet's equator. The southern SKR period decreased from about 10.8 hours on Jan. 1, 2008 and crossed with the northern SKR period around March 1, 2010, at around 10.67 hours. The northern period increased from about 10.58 hours to that convergence point.

Seeing this kind of crossover led the Cassini scientists to go back into data from previous Saturnian visits. With a new eye, they saw that NASA's Voyager data taken in 1980, about a year after Saturn's 1979 equinox, showed different warbles from Saturn's northern and southern poles. They also saw a similar kind of effect in the Ulysses radio data between 1993 and 2000. The northern and southern periods detected by Ulysses converged and crossed over around August 1996, about nine months after the previous Saturnian equinox.

Cassini scientists don't think the differences in the radio wave periods had to do with hemispheres actually rotating at different rates, but more likely came from variations in high-altitude winds in the northern and southern hemispheres. Two other papers involving Cassini investigators were published in December, with results complementary to the radio and plasma wave science instrument -- one by Jon Nichols, University of Leicester, U.K., in the same issue of Geophysical Research Letters, and the other led by David Andrews, also of University of Leicester, in the Journal of Geophysical Research.

In the Nichols paper, data from the NASA/ESA Hubble Space Telescope showed the northern and southern auroras on Saturn wobbled back and forth in latitude in a pattern matching the radio wave variations, from January to March 2009, just before equinox. The radio signal and aurora data are complementary because they are both related to the behavior of the magnetic bubble around Saturn, known as the magnetosphere. The paper by Andrews, a Cassini magnetometer team associate, showed that from mid-2004 to mid-2009, Saturn's magnetic field over the two poles wobbled at the same separate periods as the radio waves and the aurora.

"The rain of electrons into the atmosphere that produces the auroras also produces the radio emissions and affects the magnetic field, so scientists think that all these variations we see are related to the sun's changing influence on the planet," said Stanley Cowley, a co-author on both papers, co-investigator on Cassini's magnetometer instrument, and professor at the University of Leicester.

As the sun continues to climb towards the north pole of Saturn, Gurnett's group has continued to see the crossover trend in radio signals through Jan. 1, 2011. The period of the southern radio signals continued to decrease to about 10.54 hours, while the period of the northern radio signals increased to 10.71 hours.

"These papers are important in helping to explain the complicated dance between the sun and Saturn's magnetic bubble, something normally invisible to the human eye and imperceptible to the human ear," said Marcia Burton, a Cassini fields and particles scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif., who was not involved in the work. "Cassini will continue to keep an eye on these changes."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The radio and plasma wave science team is based at the University of Iowa, Iowa City, where the instrument was built. The magnetometer team is based at Imperial College, London, U.K.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

For More information visit http://www.nasa.gov/mission_pages/cassini/whycassini/cassini20110322.html

"Last week, we gently 'woke up' Dawn's three science instruments, which typically spend most of their time sleeping during the three-and-a-half-year journey to Vesta," said Robert Mase, Dawn project manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "This activity confirms that Dawn is on track for the first close examination of one of the last unexplored worlds of the inner solar system."

The framing camera activities were led by scientists from the Max Planck Institute for Solar System Research in Katlenburg-Lindau, Germany. "The camera system is working flawlessly. The dry run was a complete success," said Andreas Nathues, lead investigator for the framing camera, based at the Institute.

The international team of Dawn scientists and engineers in Germany and the United States spent three days interacting with the camera system, confirming the excellent health of the mechanical and electrical components and updating the software.

In the months to come, the camera system will provide images needed to navigate the spacecraft to its rendezvous with Vesta, and will begin to image the asteroid's surface. These early images on approach will be the start of a campaign to systematically map Vesta's surface in detail and will provide tantalizing clues as to its mineralogical composition. In addition, the framing cameras will search for moons in Vesta's vicinity and look for evidence of past volcanic activity.

The full release on the framing camera from Max Planck is available at: http://www.mps.mpg.de/en/aktuelles/pressenotizen/pressenotiz_20110321.html .

The Dawn mission to Vesta and Ceres is managed by the Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, for NASA's Science Mission Directorate, Washington. The Dawn mission is part of the Discovery Program managed by NASA's Marshall Space Flight Center in Huntsville, Ala. UCLA is responsible for overall Dawn mission science. The framing cameras have been developed and built under the leadership of the Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany, with significant contributions by DLR German Aerospace Center, Institute of Planetary Research, Berlin, and in coordination with the Institute of Computer and Communication Network Engineering, Braunschweig. The framing camera project is funded by the Max Planck Society, DLR, and NASA. The visible and infrared mapping spectrometer was provided by the Italian Space Agency and is operated by Italy's National Institute for Astrophysics in collaboration with Galileo Avionica, where it was built. The gamma ray and neutron detector was built by Los Alamos National Laboratory and is operated by the Planetary Science Institute, Tucson, Ariz.

For more information visit http://www.jpl.nasa.gov/news/news.cfm?release=2011-089

Those expectations are not lost on the team putting the finishing touches on the AMS and packing it for launch.

"This kind of has grains of Hubble, looking at the universe in a different perspective," said Boeing's Bob Hart, the payload flow manager for the AMS. "The science, the exploration potential that will come out of this makes it very exciting to be a part of."

Professor Sam Ting, a Nobel Prize winner for his 1974 discovery of a heavy elemental particle, sees the AMS as a revolutionary observatory to measure invisible cosmic rays as they traverse the universe.

The AMS is a 2-ton ring of powerful magnets and ultrasensitive detectors built to track, but not capture, cosmic rays. The 15,251-pound instrument will be connected to the outside of the International Space Station, braced on the orbiting laboratory's right hand truss and tilted a bit so it will not interfere with any of the station's mechanisms and storage platforms. It will be operated remotely from Earth and should not require any attention from astronauts in orbit.

"The astronauts on the space station have many things to do," Ting said. "We wouldn't dare bother them."

By recording the traces cosmic rays make as they pass through, the AMS might uncover a universe that is now invisible. Although Ting is hesitant to make predictions about what the instrument will find, he said the instrument was designed with dark matter and antimatter in mind. Very little is known about dark matter although it makes up an estimated 90 percent of the mass in the universe.

Although Earth-based facilities have been built to create powerful streams of subatomic particles, Ting said their limits are more than 14 million times weaker than the power produced by cosmic rays in space.

"No matter how large an accelerator you build, you're not going to compete with space," Ting told reporters recently. Ting offered the news media a close look at the AMS before it was packed for loading into Endeavour's cargo bay for launch.

How much of a difference is that? Well, according to the organization that operates the Large Hadron Collider near Geneva, Switzerland, a single trillion electron volt particle is about the same amount of energy produced by a mosquito in motion. The fastest cosmic ray yet observed was a subatomic particle with the force of a baseball, according to a University of Utah account of the observation.

The AMS going up on Endeavour is the second one built in the program. The first one was a prototype instrument that flew on shuttle Discovery during STS-91. It spent about two weeks in orbit proving the merits of the design. Even with that very short mission, the instrument provided enough information to make physicists reanalyze some of their theories. Four unique scientific papers were published following the mission, Ting said.

"None of the results we see can be explained by existing theory," Ting said of the findings.

The second AMS, the one flying on Endeavour, is designed to operate as long as the space station itself is operational. That's why Ting said the team opted to replace a ring of supercold magnets designed for a 3-year lifespan with a set of permanent, though weaker, magnets that can work 20 years.

"The longer you stay, the longer you learn," Ting said.

The AMS was assembled and tested in Europe, including calibration work in the Large Hadron Collider in Switzerland. It was flown aboard a U.S. Air Force transport plane to NASA's Kennedy Space Center in Florida in August 2010, and spent the next several months in a work stand in the Space Station Processing Facility where technicians went through the last steps of processing for flight.

The payload processing teams are used to dealing carefully with anything designed to go into space and many precautions are taken. Still, there is a new level of anticipation for the AMS.

"This is probably the most exciting one I've been on," said Joe Delai, payloads mission manager for STS-134.

For more information visit http://www.nasa.gov/mission_pages/shuttle/main/amsprocessing.html