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Entries in NASA (13)

Friday
Mar012013

Radiation ring around Earth mysteriously appears, then dissipates

RING AROUND THE WORLD In September, a third ring appeared between the two known Van Allen radiation belts that girdle the Earth thousands of miles above. Johns Hopkins Univ. Applied Physics Laboratory/Univ. of Colorado Boulder Laboratory for Atmospheric and Space Physics

High above Earth’s surface float two rings of energetic charged particles, and for about four weeks in September, they were joined by a third. The temporary ring may have formed in response to a solar shock wave that passed by Earth, researchers report online February 28 in Science.

The discovery could force scientists to revisit decades of ideas about the structure of the Van Allen belts, donut-shaped rings of radiation trapped in orbit by the planet’s magnetic field. Those revisions could improve predictions of space weather and scientists’ understanding of the space environment near Earth, resulting in better protection for manned and unmanned spacecraft that navigate those areas.

“It's a very important discovery,” says Yuri Shprits of the University of California, Los Angeles, who wasn’t involved in the study. “Over half a century after the discovery of the radiation belts, this most important region of space where most of the satellites operate presents us with new puzzles.”

Until the discovery, researchers thought the Van Allen belts always contained two zones of high-energy particles: an inner zone made mostly of protons and some electrons, and an outer zone dominated by electrons. A sparsely populated area separates the zones. The belts run from the top of the atmosphere, some 1,000 kilometers above Earth’s surface, to as far as five or six Earth radii from the planet’s surface.

NASA’s early Explorer and Pioneer spacecraft discovered and mapped the belts in 1958. Scientists have since learned that the radiation reservoirs can fluctuate dramatically, especially in the outer zone. Disturbances such as solar storms that disrupt Earth’s magnetic field can cause the outer zone to change shape or to gain or lose particles.

On August 30, NASA launched twin space probes to study the fine details of such disruptions and take a closer look at the belts’ composition. The probes repeatedly pass through the belts, completing an orbit about every nine hours. Just days after the probes launched, researchers led by Daniel Baker of the University of Colorado Boulder watched a third ring grow between the two existing belts, and the outer ring to expand. After a month, it disappeared, as did the outer zone, temporarily leaving only one ring. In the following months, the normal two-ring structure gradually returned.

“I'm delighted that observations so early in the program could reveal such new things,” Baker says.

A sun-produced shock wave that passed Earth in early September may have created the third ring, the researchers propose. Another shock wave came through in early October and may have obliterated the outer two rings.

Researchers don’t know how often a third ring forms. “I would be amazed if in the past 4.5 billion years this hasn't happened before,” Baker says. The probes could provide answers about the third ring’s frequency.

No reports have emerged of satellite damage from the third ring’s brief existence, though operators often do not reveal that information, says Joe Kunches of the National Weather Service’s Space Weather Prediction Center.

Scientists will continue to comb through data from the probes to refine theoretical and observational knowledge of the belts. The probes’ findings could also help engineers design spacecraft better protected against the belts’ harmful radiation. And forecasters could use real-time data feeds from the probes to give satellite operators better warnings and predictions about the belts’ activity. “That's what we're really excited about,” Kunches says.

Source:

http://www.sciencenews.org/view/generic/id/348664/title/Radiation_ring_around_Earth_mysteriously_appears_then_dissipates


Wednesday
Feb272013

NASA's Aquarius Sees Salty Shifts

NASA has released the first full year of validated ocean surface salinity data from the agency's Aquarius instrument aboard the Aquarius/SAC-D spacecraft. The data cover the period from Dec. 2011 through Dec. 2012. Red colors represent areas of high salinity, while blue shades represent areas of low salinity. Among the prominent salinity features visible in this view are the large area of highly saline water across the North Atlantic. This area, the saltiest anywhere in the open ocean, is analogous to deserts on land, where little rainfall and much evaporation occur. Aquarius is a focused effort to measure ocean surface salinity and will provide the global view of salinity variability needed for climate studies. The mission is a collaboration between NASA and the Space Agency of Argentina (Comision Nacional de Actividades Espaciales). Image credit: NASA/GSFC/JPL-Caltech

The colorful images chronicle the seasonal stirrings of our salty world: Pulses of freshwater gush from the Amazon River's mouth; an invisible seam divides the salty Arabian Sea from the fresher waters of the Bay of Bengal; a large patch of freshwater appears in the eastern tropical Pacific in the winter. These and other changes in ocean salinity patterns are revealed by the first full year of surface salinity data captured by NASA's Aquarius instrument. 

"With a bit more than a year of data, we are seeing some surprising patterns, especially in the tropics," said Aquarius Principal Investigator Gary Lagerloef, of Earth & Space Research in Seattle. "We see features evolve rapidly over time." 

Launched June 10, 2011, aboard the Argentine spacecraft Aquarius/Satelite de Aplicaciones Cientificas (SAC)-D, Aquarius is NASA's first satellite instrument specifically built to study the salt content of ocean surface waters. Salinity variations, one of the main drivers of ocean circulation, are closely connected with the cycling of freshwater around the planet and provide scientists with valuable information on how the changing global climate is altering global rainfall patterns. 

The salinity sensor detects the microwave emissivity of the top approximately 1 inch (1 to 2 centimeters) of ocean water - a physical property that varies depending on temperature and saltiness. The instrument collects data in 240-mile-wide (386 kilometers) swaths in an orbit designed to obtain a complete survey of global salinity of ice-free oceans every seven days. 

The Changing Ocean 

The animated version of Aquarius' first year of data unveils a world of varying salinity patterns. The Arabian Sea, nestled up against the dry Middle East, appears much saltier than the neighboring Bay of Bengal, which gets showered by intense monsoon rains and receives freshwater discharges from the Ganges and other large rivers. Another mighty river, the Amazon, releases a large freshwater plume that heads east toward Africa or bends up north to the Caribbean, depending on the prevailing seasonal currents. Pools of freshwater carried by ocean currents from the central Pacific Ocean's regions of heavy rainfall pile up next to Panama's coast, while the Mediterranean Sea sticks out in the Aquarius maps as a very salty sea. 

One of the features that stand out most clearly is a large patch of highly saline water across the North Atlantic. This area, the saltiest anywhere in the open ocean, is analogous to deserts on land, where little rainfall and a lot of evaporation occur. A NASA-funded expedition, the Salinity Processes in the Upper Ocean Regional Study (SPURS), traveled to the North Atlantic's saltiest spot last fall to analyze the causes behind this high salt concentration and to validate Aquarius measurements. 

"My conclusion after five weeks out at sea and analyzing five weekly maps of salinity from Aquarius while we were there was that indeed, the patterns of salinity variation seen from Aquarius and by the ship were similar," said Eric Lindstrom, NASA's physical oceanography program scientist, NASA Headquarters, Washington, and a participant of the SPURS research cruise. 

Future Goals 

"The Aquarius prime mission is scheduled to run for three years but there is no reason to think that the instrument could not be able to provide valuable data for much longer than that," said Gene Carl Feldman, Aquarius project manager at NASA's Goddard Space Flight Center in Greenbelt, Md. "The instrument has been performing flawlessly and our colleagues in Argentina are doing a fantastic job running the spacecraft, providing us a nice, stable ride." 

In future years, one of the main goals of the Aquarius team is to figure out ways to fine-tune the readings and retrieve data closer to the coasts and the poles. Land and ice emit very bright microwave emissions that swamp the signal read by the satellite. At the poles, there's the added complication that cold polar waters require very large changes in their salt concentration to modify their microwave signal. 

Still, the Aquarius team was surprised by how close to the coast the instrument is already able to collect salinity measurements. 

"The fact that we're getting areas, particularly around islands in the Pacific, that are not obviously badly contaminated is pretty remarkable. It says that our ability to screen out land contamination seems to be working quite well," Feldman said. 

Another factor that affects salinity readings is intense rainfall. Heavy rain can affect salinity readings by attenuating the microwave signal Aquarius reads off the ocean surface as it travels through the soaked atmosphere. Rainfall can also create roughness and shallow pools of freshwater on the ocean surface. In the future, the Aquarius team wants to use another instrument aboard Aquarius/SAC-D, the Argentine-built Microwave Radiometer, to gauge the presence of intense rain simultaneously to salinity readings, so that scientists can flag data collected during heavy rainfall. 

An ultimate goal is combining the Aquarius measurements with those of its European counterpart, the Soil Moisture and Ocean Salinity satellite (SMOS) to produce more accurate and finer maps of ocean salinity. In addition, the Aquarius team, in collaboration with researchers at the U.S. Department of Agriculture, is about to release its first global soil moisture dataset, which will complement SMOS' soil moisture measurements. 

"The first year of the Aquarius mission has mostly been about understanding how the instruments and algorithms are performing," Feldman said. "Now that we have overcome the major hurdles, we can really begin to focus on understanding what the data are telling us about how the ocean works, how it affects weather and climate, and what new insights we can gain by having these remarkable salinity measurements." 

Aquarius was built by NASA's Jet Propulsion Laboratory, Pasadena, Calif.; and NASA Goddard. JPL managed Aquarius through its commissioning phase and is archiving mission data. Goddard now manages Aquarius mission operations and processes science data. Argentina's space agency, Comision Nacional de Actividades Espaciales (CONAE), provided the SAC-D spacecraft, optical camera, thermal camera with Canada, microwave radiometer, sensors from various Argentine institutions and the mission operations center. France and Italy also contributed instruments. For more information about NASA's Aquarius mission, visit: http://www.nasa.gov/aquarius . 

For a narrated global tour of Aquarius ocean surface salinity measurements, see: http://www.youtube.com/watch?v=5xQP_B18vMw . A visualization showing changes in global ocean surface salinity as measured by Aquarius from Dec. 2011 through Dec. 2012 can be seen at: http://www.youtube.com/watch?v=RJVnZnZUUYc . - See more at: http://www.jpl.nasa.gov/news/news.php?release=2013-074&cid=release_2013-074#sthash.B43H9PQd.dpuf

Source:

http://www.jpl.nasa.gov/news/news.php?release=2013-074&cid=release_2013-074


Tuesday
Feb262013

Second SpaceX Space Station Resupply Flight Ready to Go

The Dragon spacecraft stands inside a processing hangar at Cape Canaveral Air Force Station where teams had just installed the spacecraft's solar array fairings on Jan. 12, 2013. (Credit: NASA/Kim Shiflett)

The second International Space Station Commercial Resupply Services flight by Space Exploration Technologies (SpaceX) is set for liftoff at 10:10 a.m. EST on March 1 from Space Launch Complex 40 at Cape Canaveral Air Force Station in Florida.

Carried by a Falcon 9 rocket, the Dragon spacecraft will ferry 1,268 pounds of supplies for the space station crew and for experiments being conducted aboard the orbiting laboratory.

The Falcon 9 and Dragon were manufactured at SpaceX headquarters in Hawthorne, Calif., and arrived at the Florida launch site by truck. The rocket, topped with the spacecraft, stands 157-feet tall.

The two-stage rocket uses nine engines to power the first stage, generating 855,000 pounds of thrust at sea level, rising to nearly 1,000,000 pounds of thrust as Falcon 9 climbs out of Earth's atmosphere. One engine powers the second stage to complete the climb to space. The 14.4-foot-tall Dragon spacecraft is capable of carrying more than 7,000 pounds of cargo split between pressurized and unpressurized sections.

On March 2, Expedition 34 Commander Kevin Ford and Flight Engineer Tom Marshburn of NASA are scheduled use the station's robot arm to grapple Dragon following its rendezvous with the orbiting outpost. Ground commands will be sent to attach the spacecraft to the Earth-facing port of the station's Harmony module where it will remain for a few weeks while astronauts unload cargo. The crew then will load more than 2,600 pounds of experiment samples and equipment for return to Earth.

Dragon is scheduled for a parachute-assisted splashdown in the Pacific Ocean off the coast of Baja California on March 25.

This SpaceX flight is the second of at least 12 missions to the space station that the company will fly for NASA under the Commercial Resupply Services contract.

Source:

http://www.sciencedaily.com/releases/2013/02/130225185751.htm

Saturday
Dec082012

Image of the Day: NASA Captures Earthly Anti-Matter Explosions (VIDEO)

Lightning in the clouds is directly linked to events that produce some of the highest-energy light naturally made on Earth: terrestrial gamma-ray flashes (TGFs). An instrument aboard NASA's Fermi Gamma-ray Space Telescope was recently fine-tuned to better catch TGFs, which allowed scientists to discover that TGFs emit radio waves, too. The outbursts, known as terrestrial gamma-ray flashes (TGFs), last only a few thousandths of a second, but their gamma rays rank among the highest-energy light that naturally occurs on Earth. The enhanced GBM discovery rate helped scientists show most TGFs also generate a strong burst of radio waves, a finding that will change how scientists study this little understood phenomenon.

NASA’s scientists also observed antimatter structures formed above thunderstorms on Earth, a phenomenon which until recently was not seen before. Scientists believe the antimatter explosions are formed due to a short burst of energy inside the storms such as the lightning. It is thought that about 500 such antimatter beams are generated daily in terrestrial gamma-ray flash but most of them remain unobserved. The antimatter beams were detected by Fermi Gamma-Ray Telescope which is used to monitor gamma rays, the highest energy light form. If antimatter hitting Fermi Telescope collides with a matter particle, both particles quickly annihilate each other releasing gamma beams.

So far Fermi has recorded gamma radiation with energies of 511,000 eV, a signal showing that an electron has collided with its antimatter counterpart, a positron. Fermi GRT’s discovery was a great one regarding the fact that people invested billions in facilities for production of antimatter.

Thanks to improved data analysis techniques and a new operating mode, the Gamma-ray Burst Monitor (GBM) aboard NASA's Fermi Gamma-ray Space Telescope is now 10 times better at catching the brief outbursts of high-energy light mysteriously produced above thunderstorms. Before being upgraded, the GBM could capture only TGFs that were bright enough to trigger the instrument's on-board system, which meant many weaker events were missed.

"In mid-2010, we began testing a mode where the GBM directly downloads full-resolution gamma-ray data even when there is no on-board trigger, and this allowed us to locate many faint TGFs we had been missing," said lead researcher Valerie Connaughton, a member of the GBM team at theUniversity of Alabama in Huntsville (UAH).

The results were so spectacular that on Nov. 26 the team uploaded new flight software to operate the GBM in this mode continuously, rather than in selected parts of Fermi's orbit. Connaughton's team gathered GBM data for 601 TGFs from August 2008 to August 2011, with most of the events, 409 in all, discovered through the new techniques. The scientists then compared the gamma-ray data to radio emissions over the same period.

Lightning emits a broad range of very low frequency (VLF) radio waves, often heard as pop-and-crackle static when listening to AM radio. The World Wide Lightning Location Network (WWLLN), a research collaboration operated by the University of Washington in Seattle, routinely detects these radio signals and uses them to pinpoint the location of lightning discharges anywhere on the globe to within about 12 miles (20 km).

Scientists have known for a long time TGFs were linked to strong VLF bursts, but they interpreted these signals as originating from lightning strokes somehow associated with the gamma-ray emission.

"Instead, we've found when a strong radio burst occurs almost simultaneously with a TGF, the radio emission is coming from the TGF itself," said co-author Michael Briggs, a member of the GBM team.

The researchers identified much weaker radio bursts that occur up to several thousandths of a second before or after a TGF. They interpret these signals as intracloud lightning strokes related to, but not created by, the gamma-ray flash.

Scientists suspect TGFs arise from the strong electric fields near the tops of thunderstorms. Under certain conditions, the field becomes strong enough that it drives a high-speed upward avalanche of electrons, which give off gamma rays when they are deflected by air molecules.

"What's new here is that the same electron avalanche likely responsible for the gamma-ray emission also produces the VLF radio bursts, and this gives us a new window into understanding this phenomenon," said Joseph Dwyer, a physics professor at the Florida Institute of Technology in Melbourne, Fla., and a member of the study team.

Because the WWLLN radio positions are far more precise than those based on Fermi's orbit, scientists will develop a much clearer picture of where TGFs occur and perhaps which types of thunderstorms tend to produce them.

The GBM scientists predict the new operating mode and analysis techniques will allow them to catch about 850 TGFs each year. While this is a great improvement, it remains a small fraction of the roughly 1,100 TGFs that fire up each day somewhere on Earth, according to the team's latest estimates. Likewise, TGFs detectable by the GBM represent just a small fraction of intracloud lightning, with about 2,000 cloud-to-cloud lightning strokes for every TGF.

The Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership and is managed by NASA's Goddard Space Flight Center in Greenbelt, Md. Fermi was developed in collaboration with the U.S. Department of Energy, with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.

Source: http://www.dailygalaxy.com/my_weblog/2012/12/image-of-the-day-nasa-captures-earthly-anti-matter-explosions-video.html

Monday
Nov122012

Astronauts on ISS Use interplanetary Internet to Test Controlling Robots from Space

NASA and the European Space Agency (ESA) used an experimental version of interplanetary Internet in late October to control an educational rover from the International Space Station, NASA says. The European-led experiment used NASA’s Disruption Tolerant Networking (DTN) protocol to simulate a scenario in which an astronaut in a vehicle orbiting a planetary body controls a robotic rover on the planet’s surface.

Space station Expedition 33 commander Sunita Williams in late October used a NASA-developed laptop to remotely drive a small LEGO robot at the European Space Operations Center in Darmstadt, Germany.

“The demonstration showed the feasibility of using a new communications infrastructure to send commands to a surface robot from an orbiting spacecraft and receive images and data back from the robot,” said Badri Younes, deputy associate administrator for space communications and navigation at NASA Headquarters. “The experimental DTN we’ve tested from the space station may one day be used by humans on a spacecraft in orbit around Mars to operate robots on the surface, or from Earth using orbiting satellites as relay stations.”

The DTN architecture is a new communications technology that enables standardized communications similar to the Internet to function over long distances and through time delays associated with on-orbit or deep space spacecraft or robotic systems. The core of the DTN suite is the Bundle Protocol (BP), which is roughly equivalent to the Internet Protocol (IP) that serves as the core of the Internet on Earth.

While IP assumes a continuous end-to-end data path exists between the user and a remote space system, DTN accounts for disconnections and errors. In DTN, data move through the network “hop-by-hop.” While waiting for the next link to become connected, bundles are temporarily stored and then forwarded to the next node when the link becomes available.

Source: http://www.dailygalaxy.com/my_weblog/2012/11/astronaut-on-iss-uses-interplanetary-internet-to-control-robot-in-germany.html