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Sonntag, 24. März 2013 - 17:15 Uhr

Mars-Curiosity-Chroniken - Curiosity-News Sol 215-224

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This image was taken by Navcam: Right B (NAV_RIGHT_B) onboard NASA's Mars rover Curiosity on Sol 215 (2013-03-14 23:53:06 UTC).

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This image was taken by Navcam: Left B (NAV_LEFT_B) onboard NASA's Mars rover Curiosity on Sol 215 (2013-03-14 23:53:06 UTC).

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This image was taken by Front Hazcam: Left B (FHAZ_LEFT_B) onboard NASA's Mars rover Curiosity on Sol 215 (2013-03-14 23:53:32 UTC).

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This image was taken by Navcam: Right B (NAV_RIGHT_B) onboard NASA's Mars rover Curiosity on Sol 222 (2013-03-22 08:03:16 UTC).

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This image was taken by Navcam: Right B (NAV_RIGHT_B) onboard NASA's Mars rover Curiosity on Sol 222 (2013-03-22 08:02:06 UTC).

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This image was taken by Navcam: Left B (NAV_LEFT_B) onboard NASA's Mars rover Curiosity on Sol 222 (2013-03-22 06:36:16 UTC).

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This image was taken by Navcam: Left B (NAV_LEFT_B) onboard NASA's Mars rover Curiosity on Sol 222 (2013-03-22 06:37:52 UTC).

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This image was taken by Navcam: Right B (NAV_RIGHT_B) onboard NASA's Mars rover Curiosity on Sol 223 (2013-03-23 08:55:02 UTC).

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This image was taken by Navcam: Right B (NAV_RIGHT_B) onboard NASA's Mars rover Curiosity on Sol 223 (2013-03-23 08:57:57 UTC).

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This image was taken by Navcam: Right B (NAV_RIGHT_B) onboard NASA's Mars rover Curiosity on Sol 223 (2013-03-23 09:00:52 UTC).

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This image was taken by Navcam: Left B (NAV_LEFT_B) onboard NASA's Mars rover Curiosity on Sol 223 (2013-03-23 09:05:03 UTC).

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This image was taken by Navcam: Left B (NAV_LEFT_B) onboard NASA's Mars rover Curiosity on Sol 223 (2013-03-23 09:09:39 UTC).

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This image was taken by Navcam: Left B (NAV_LEFT_B) onboard NASA's Mars rover Curiosity on Sol 223 (2013-03-23 09:10:48 UTC).

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This image was taken by Front Hazcam: Left B (FHAZ_LEFT_B) onboard NASA's Mars rover Curiosity on Sol 223 (2013-03-23 02:59:22 UTC).

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This image was taken by Navcam: Right B (NAV_RIGHT_B) onboard NASA's Mars rover Curiosity on Sol 224 (2013-03-24 06:45:12 UTC).

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This image was taken by Navcam: Left B (NAV_LEFT_B) onboard NASA's Mars rover Curiosity on Sol 224 (2013-03-24 08:20:03 UTC).

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This image was taken by Front Hazcam: Left B (FHAZ_LEFT_B) onboard NASA's Mars rover Curiosity on Sol 224 (2013-03-24 03:38:59 UTC).

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Fotos: NASA


2988 Views

Sonntag, 24. März 2013 - 14:30 Uhr

Mars-Curiosity-Chroniken - Mars Curiosity Rover beginnt wieder Schnappschüsse zu senden

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The Curiosity rover's instrument-laden robotic arm is front and center in this mosaic view captured by the Mars rover's NavCam system and assembled by Marco Di Lorenzo and Ken Kremer. The colorized black-and-white imagery was captured on March 23. Click on the image to see the full panorama.

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After a week of down time due to a computer glitch, NASA's Mars Curiosity rover is once again sending back pictures of its rocky Red Planet locale at Yellowknife Bay. In this fresh panorama, the rover looks as if it's sticking its drill-equipped robotic arm right in your face.

"That drill is hungry, looking for something tasty to eat, and 'you' (loaded with water and organics) are it," jokes scientist-writer Ken Kremer, who collaborated with Italian colleague Marco Di Lorenzo to assemble the panorama.

Curiosity's percussive drill played a key role in the science team's most recently reported breakthrough: the finding that powder drilled out of a Martian rock contained the chemical traces of a life-friendly environment that existed on Mars billions of years ago. The team's chemical analysis of the powder indicated that the minerals were probably formed in the presence of drinkable water.

That kind of water no longer exists in liquid form on the Martian surface. The place where Curiosity is currently working may have once been in the vicinity of a riverbed, but it's now a cold and dry wasteland of sand and rock. In the weeks to come, Curiosity's scientists plan to drill into the rock again, looking for confirmatory clues about the potentially habitable environment in the Red Planet's past.

The plan has been held up due to a series of minor setbacks — including a memory failure that may have been due to a cosmic-ray strike, a precautionary stand-down to weather a solar storm, and most recently a computer file glitch that put the rover into safe mode. The Curiosity team has been carefully bringing the rover back to full operation, and this picture is presumably part of the checkout process.

It won't be long before the rover will once more have to reduce its contact with its handlers back on Earth, due to an Earth-Mars-sun conjunction that will interfere with radio signaling. Curiosity's communication gap is expected to last from April 4 to May 1, as detailed in a mission update from NASA's Jet Propulsion Laboratory. During the break, Curiosity is expected to carry on with its experiments, but the transmission of science data and images will have to wait until May. So let's enjoy these fresh images while we can.

Quelle: NBCNEWS


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Sonntag, 24. März 2013 - 09:34 Uhr

Luftfahrt - NASA´s Super Guppy Transportflugzeug im Einsatz

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A NASA Super Guppy transport plane "swallowed" two T-38 aircraft whole on March 18 at Dryden Flight Research Center, prior to ferrying them to El Paso, Texas for disassembly.

The SGT Super Guppy-Turbine, the last of its kind still flying, measures more than 48 feet to the top of its tail and has a wingspan of more than 156 feet with a huge upper cargo bay and a hinged nose that opens 110 degrees.

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Super Guppy Swallows T-38s; Heads for El Paso

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Two retired NASA T-38 trainers mounted on a transport pallet atop a mobile transporter are positioned for loading aboard NASA's Super Guppy prior to ferrying them to El Paso, Texas, for disassembly.

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A NASA Super Guppy transport plane "swallowed" two NASA T-38 aircraft whole March 18, right out on NASA Dryden Flight Research Center's back ramp.

The SGT Super Guppy-Turbine, the last of its kind still flying, is based at Ellington Airport in Houston, near NASA's Johnson Space Center. The aircraft was at Dryden to transport the two T-38s that Dryden hasn't flown in several years and are no longer airworthy to El Paso, Texas, where they will be cannibalized for parts to keep other Johnson-operated T-38s in El Paso flying. After removing the wings and other usable components, the remaining portions of the airframes will be trucked to the Air Force's Aerospace Maintenance and Recovery Center adjacent to Davis-Monthan Air Force Base near Tucson, Ariz., for final disposition.

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Workmen carefully guide the first of the T-38s into place as it is hoisted onto its pallet

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The second retired T-38 joins its companion on the special transport pallet.

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Aside from the Super Guppy's size – it measures more than 48 feet to the top of its tail and has a wingspan of more than 156 feet with a huge upper cargo bay – the aircraft features a hinged nose that opens 110 degrees. Once open, an aircraft cargo loader was used to load the two trainer aircraft. The Guppy's 25-foot diameter cargo bay permitted the two T-38 aircraft to be moved with only the wingtips needing to be removed, said Johnson flight engineer David Elliott, the Guppy's project manager.

After opening the nose section of the Guppy, hoisting the T-38s onto a specially designed pallet atop a mobile transporter, loading the pallet and T-38s onto the Guppy and then reclosing the Guppy's nose section – about a 2.5-hour process – the Guppy departed for El Paso.

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As the Super Guppy awaits its cargo in the background, workmen secure the second T-38 to its transport pallet.

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The Guppy opens its "mouth…"

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Swallowed!

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Closing up…

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Dryden has seen the Super Guppy-Turbine before during the delivery of X-38 vehicle 131R prototype crew return vehicle on July 11, 2000. It also visited NASA Dryden for a landing gear change in 2005.

The Super Guppy is the latest iteration of its kind – the last of three outsized aircraft to have transported a number of NASA's hefty payloads ranging from Saturn rockets to International Space Station modules.

The Space Race had a number of complicated problems to solve, Elliott said. In 1962, California-based Aero Spacelines Industries solved the problem of transporting large components when it introduced the first Guppy aircraft. That first version of the Guppy was evaluated during flight tests flown at NASA's Flight Research Center at Edwards Air Force Base that fall.

Built from a heavily modified KC-97 Stratotanker, the B-377PG Pregnant Guppy featured the largest cargo compartment of any aircraft ever built to that time. At just over 19 feet in diameter, this massive cavity was specifically designed to carry the second stage of a Saturn rocket for the Apollo program, Elliott said. The Pregnant Guppy allowed NASA to deliver crucial oversized cargo to Cape Canaveral in 18 hours as opposed to 18 to 25 days aboard a barge, he added.

The program was so successful that it was followed by an even larger version of the aircraft in 1965. Dubbed the B377SG Super Guppy, it was equipped with a 25-foot diameter cargo bay, more powerful turboprop engines, a pressurized cockpit, and a hinged nose for easier loading of cargo. Aero Spacelines continued to own and operate the aircraft until 1981, when NASA purchased the aircraft.

During its 32 years of service, the original Super Guppy flew over 3 million miles in support of NASA’s Apollo, Gemini, Skylab, and International Space Station programs. It also transported the X-24B and HL-10 lifting bodies lifting bodies from NASA Dryden to the Air Force Museum adjacent to Wright-Patterson Air Force Base in Ohio in 1976. (The HL-10 was subsequently returned to NASA Dryden, and remains on display in front of the center today.)

The Super Guppy-Turbine version currently operated by NASA is the last generation of Guppy that Aero Spacelines built. The most important difference between it and its predecessor was an upgrade to more reliable and readily available Allison T-56 turboprops. Airbus Industries commissioned and operated four SGT Super Guppy-Turbine aircraft to ferry large A300 fuselage sections throughout Europe during the last three decades of the 20th century.

When Airbus retired its fleet to museums in 1997, NASA was able to acquire the number 4 aircraft to replace its aging B377SG Super Guppy under an International Space Station barter agreement with the European Space Agency.

NASA’s Super Guppy-Turbine continues to support America’s space program and is scheduled to transport the Orion Heat Shield from Textron Defense Systems near Boston to NASA's Kennedy Space Center at the end of March. The U.S. Department of Defense and government contractors also have tapped the Guppy's capabilities to move aircraft and large components around the continent, including T-38s for the Air Force and V-22s for the Navy.

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NASA's outsized SGT Super Guppy-Turbine transport aircraft lifts off the runway at Edwards Air Force Base after a prior visit. (NASA / Tony Landis)


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Sonntag, 24. März 2013 - 09:00 Uhr

Planet Erde - Erste Aufnahmen von Landsat

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Turning on new satellite instruments is like opening new eyes. This week, the Landsat Data Continuity Mission (LDCM) released its first images of Earth, collected at 1:40 p.m. EDT on March 18. The first image shows the meeting of the Great Plains with the Front Ranges of the Rocky Mountains in Wyoming and Colorado. The natural-color image shows the green coniferous forest of the mountains coming down to the dormant brown plains. The cities of Cheyenne, Fort Collins, Loveland, Longmont, Boulder and Denver string out from north to south. Popcorn clouds dot the plains while more complete cloud cover obscures the mountains.

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On the image is shown in natural color, created using data from OLI spectral bands 2 (blue), 3 (green), and 4 (red). The image on the right was created using data from OLI bands 3 (green), 5 (near infrared), and 7 (short wave infrared 2) displayed as blue, green and red, respectively. In the natural color image, the city's elongated Horsetooth Reservoir, a source of drinking water, lies west of the city. A dark wildfire burn scar from the Galena Fire is visible just to the left of the reservoir. The scar shows up bright, rusty red in the false color image.

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LDCM is a joint mission of NASA and the Department of Interior's U.S. Geological Survey.

"It's a really great day," said Jeff Pedelty, an instrument scientist at NASA's Goddard Space Flight Center in Greenbelt, Md., who worked on the LDCM Operational Land Imager, or OLI instrument, that took the natural color image. He's very impressed with the level of detail they can see with the advancements to the sensor. "It's wonderful to see, there's no doubt about it, and it's a relief to know that this is going to work wonderfully in orbit."

The natural color image showed the landscape in the colors our eyes would see, but Landsat sensors also have the ability to see wavelengths of light that our eyes cannot see. LDCM sees eleven bands within the electromagnetic spectrum, the range of wavelengths of light. OLI collects light reflected from Earth's surface in nine of these bands. Wavelengths on the shorter side include the visible blue, green, and red bands. Wavelengths on the longer side include the near infrared and shortwave infrared.

LDCM's second instrument, the Thermal Infrared Sensor (TIRS) detects light emitted from the surface in two even longer wavelengths called the thermal infrared. The intensity of the emitted light at the longer wavelengths measured by TIRS is a function of surface temperature. In the black-and-white image of the first thermal band on TIRS, warmer areas on the surface are brighter while cooler areas are dark.

The first thermal images seen by Dennis Reuter, TIRS instrument scientist at Goddard, were forwarded to him from the data processors. "To say it was exciting was an understatement," said Reuter, who was blown away by the data quality. "Wow! This is beautiful!" he wrote in an email. "Look at those amazing clouds! And the detail!"

Clouds in the colder upper atmosphere stand out as black in stark contrast to a warmer ground surface background. The TIRS images were collected at exactly the same time and place as the OLI data, so all eleven bands can be used together.

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This diagram illustrates how LDCM's observations at different wavelengths are combined to create one image.
Credit: NASA's Goddard Space Flight Center

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The infrared bands on both TIRS and OLI complement the visible bands, said Reuter. "You're seeing things in the visible that you don't necessarily see in the infrared, and vice versa," he said.

Different characteristics on the ground dictate the intensity of the reflection and emission of light in different bands from the surface, ultimately allowing scientists to distinguish between different surface features. To highlight differences across an image, analysts sometimes assign artificial colors to data from different spectral bands for display.

For example, zooming in to the area around Fort Collins, Colo., the natural color image was created from OLI bands 2 (blue), 3 (green), and 4 (red) data. In the image, a dark stripe can be seen just west of the Horsetooth Reservoir, a source of drinking water for the city. The stripe is a scar left in the aftermath of the Galena wildfire. That same burned area bursts out of the image as a bright, rusty red scar with greater contrast between the surrounding areas in the false color image. The false color image was created using data from OLI bands 3 (green), 5 (near infrared), and 7 (short wave infrared 2), assigned the colors blue, green and red respectively. These types of LDCM images and the accompanying data will be used by multi-agency Burned Area Emergency Response teams to plan and carry out wildfire recovery measures.

Similarly, the thermal bands that detect wavelengths dependent on surface temperature show more than just high altitude clouds. This ability to measure differences in temperature across the land surface is essential to one of the major applications of LDCM data: water management. Analysts in western states will use TIRS data in conjunction with OLI data to determine the amount of water being used in irrigated agricultural fields.

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This black-and-white Landsat scene shows the area where the Great Plains meet the Front Range of the Rocky Mountains in Wyoming and Colorado. The image was created using data from the first TIRS thermal infrared band. Warmer surfaces appear light gray to white in the thermal image while cooler areas appear dark gray to black. Clouds in the colder upper atmosphere, for instance, appear black against the lighter background of the warmer ground surface. When the satellite begins normal operations, data products will contain co-registered (simultaneous) data for all of the OLI and TIRS.

Note to Landsat data users: This scene is slightly off set from the standard Path 33, Row 32 Landsat scene as LDCM has not yet reached its nominal 438-mile (705-kilometer) operational orbit.

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"When you water plants they take it in through their roots and it comes up to their leaves, and if they have a plentiful water supply, they transpire," said Reuter. Transpiration, as well as evaporation from the soil, means that the water goes back into the atmosphere.

"It's just like when we sweat, we cool down. [Plants] cool down when they have a lot of water," said Reuter. "It's a beautiful illustration of the physics of radiative transfer and also the usefulness of the data." This application of LDCM data will be essential to the effective management of scarce water resources in our arid and semi-arid states.Both Reuter and Pedelty were impressed with the level of detail they see in the OLI and TIRS data. Part of that detail comes from the push broom design of both instruments. Instead of instruments that scan back and forth across a swath on the ground, push broom data collection looks across whole swath at once, allowing the sensors to observe each patch of ground longer.

"It's like taking a thermometer and letting it sit there longer to get a more stable measurement," said Reuter.

But the work is only beginning for validating the data quality and getting ready for normal mission operations. These images were processed using pre-launch settings, which must be checked and adjusted now that LDCM is in orbit to ensure that the data accurately measure the intensity of reflected and emitted light received by the instruments. The mission operations team also needs to ensure that each pixel is accurately located on Earth's surface.

Among the first activities planned in the next two months are reference checks for both OLI and TIRS. OLI will look indirectly at the sun with its solar diffuser panel.

"We let the sun shine on the panel so it makes a bright uniform target and we image that," said Pedelty, who adds that while it may seem mundane compared to an image of Earth, it's a key reference measurement for updating OLI's calibration.

In addition, for both OLI and TIRS calibration, LDCM will view deserts, the ocean and the moon, surfaces with relatively stable and well-known reflectance and emittance properties. The mission operations team also plans to fly underneath the currently orbiting Landsat 7 to collect data at the same time in order to cross-calibrate the two LDCM sensors with the Landsat 7 Enhanced Thematic Mapper-Plus (ETM+) instrument.

"Everything has been very exciting," said Reuter. These first images are the culmination of a lot of hard work from the people at NASA and USGS, the Landsat Science Team and their industry partners at Ball Aerospace Corp. in Boulder, Colo., that built OLI, and Orbital Science Corp. of Gilbert, Ariz., that built and tested the spacecraft, he said. "As a tool for science, for looking at the whole planet and seeing how we're affecting it, and how it's affecting us, it's gratifying in all ways."

Pedelty agrees. "I was privileged to work onsite at Ball Aerospace as they designed, built and tested the OLI. Then I moved to Orbital Sciences to help test the LDCM observatory. A lot of talented people worked very hard and everything had to work. And it has."

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The area around Boulder, Colo., is shown here in a true color image collected by the OLI aboard LDCM on March 18, 2013. The OLI and an important component of TIRS, its cryocooler, were built at the Ball Aerospace & Technologies Corporation facility in Boulder.
Credit: USGS/NASA Earth Observatory

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LDCM's normal operations are scheduled to begin in late May when the instruments have been calibrated and the spacecraft has been fully checked out. At that time, NASA will hand over control of the satellite to the USGS, which will operate the satellite throughout its planned five-year mission life. The satellite will be renamed Landsat 8, and data from OLI and TIRS will be processed and added to the Landsat Data Archive at the Earth Resources Observation and Science Center in South Dakota, where it will be distributed for free over the Internet.

Quelle: NASA


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Samstag, 23. März 2013 - 19:45 Uhr

Astronomie - Meteorit sorgt für Aufregung in der USA

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Die Himmelserscheinung war von Maine bis Florida zu sehen: Ein ungewöhnlich heller Meteor hat entlang der gesamten Ostküste der USA für Wirbel gesorgt.

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Frams: FOX5

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Update: 13.30 MEZ

Reports about East Coast meteor flood in, setting off a media scramble

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A Friday night flash of light in the skies over the East Coast sparked a rash of meteor sighting reports, followed by a mad dash to track down photos and videos of the event.

The American Meteor Society logged more than 300 reports from a region ranging from  North Carolina to Washington to New York to New England to Canada. Hundreds more registered their observations on Twitter.  One Twitter user, known as @Married2TheNite, reported from New Jersey that he saw — and heard — the object pass by. "It was making almost a hissing noise as it flew brightly overhead," he wrote. "I saw it around 7:55 p.m. EDT."

That time frame meshed with the many other reports. Some witnesses said they saw flashes of green, red and blue as the object streaked past.

The reports were consistent with a fireball — similar to the one that flashed over Russia on Feb. 15, but much, much smaller.

"It's not an incredibly rare event, but it is very unusual to have that many people observe it, and also it was unusually bright," Ron Dantowitz, director of the Clay Center Observatory, told NBC station WDHD-TV in Boston. "These types of meteors happen once or twice a year. The unusual thing is that it was so well observed not so long after sunset."

Bill Cooke of NASA's Meteoroid Environmental Office told The Associated Press that the flash appeared to be "a fireball that moved roughly toward the southeast, going on visual reports."

"Judging from the brightness, we're dealing with something as bright as the full moon," Cooke said. "The thing is probably a yard across. We basically have (had) a boulder enter the atmosphere over the Northeast."

For a while, Twitter buzzed with tweets and retweets highlighting pictures that falsely purported to show the Friday night light — but eventually, bona fide views surfaced. The paucity of honest-to-goodness meteor shots contrasted with the wealth of dashboard videos that came to light after last month's Russian meteor blast.

"The meteor has taught us one thing tonight," Cara Lynch tweeted, "the East Coast needs more dash cameras." 

One of the most widely distributed videos of Friday night's flash came from someone who didn't actually see it when it happened. "I wish I would have seen it for real," said Kim Fox, a first-grade teacher from Thurmont, Md.

Fox told NBC News that she checked her security-camera system after hearing about the meteor. At around the time that news reports said the meteor was widely sighted, she saw a bright flash on one of the camera views. She took out her mobile phone, recorded a video of the video, and posted it to her Facebook page. From there, the video went viral on the Web and on TV newscasts.

"The phones have been ringing all night," Fox said.

Quelle: NBC

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Grafik: AMS

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Update: 19.45 MEZ

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In this image taken from video provided by Tom Hopkins of Hopkins Automotive Group, a bright flash of light, top center, streaks across the early-evening sky in what experts say was almost certainly a meteor coming down, Friday, March 22, 2013 in Seaford, Del. Bill Cooke of NASA's Meteoroid Environmental Office said the flash appears to be "a single meteor event." He said it "looks to be a fireball that moved roughly toward the southeast, going on visual reports." MANDATORY CREDIT: HOPKINS AUTOMOTIVE GROUP Photo: Hopkins Automotive Group

Quelle: San Francisco Chronicle


Tags: Meteor USA 

3314 Views

Samstag, 23. März 2013 - 08:55 Uhr

Astronomie - Wunderschöne Spiralgalaxie NGC 1637 verziert mit schwächer werdender Supernova

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Diese Aufnahme vom Very Large Telescope am Paranal-Observatorium der ESO in Chile zeigt NGC 1637, eine Spiralgalaxie, die sich etwa 35 Millionen Lichtjahre von der Erde entfernt im Sternbild Eridanus (der Fluss Eridanus) befindet. Im Jahr 1999 entdeckten Wissenschaftler eine Supernova vom Typ II in dieser Galaxie und verfolgten ihr langsames Schwächerwerden über die nächsten Jahre.

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Etwa 35 Millionen Lichtjahre von der Erde entfernt im Sternbild Eridanus (der Fluss Eridanus) befindet sich die Spiralgalaxie NGC 1637. Im Jahr 1999 wurde die ruhige Erscheinung dieser Galaxie von einer hellen Supernova gestört. Der Arbeit von Astronomen, die die Überreste dieser Explosion mit dem Very Large Telescope am Paranal-Observatorium der ESO in Chile untersucht haben, verdanke wir dieses atemberaubende Bild dieser vergleichsweise nahegelegenen Galaxie.

Supernovae gehören zu den gewaltsamsten Ereignissen in der Natur. Ihr helles Aufleuchten zeugt vom Tod eines Sterns und kann zeitweise die das vereinte Licht von Milliarden von Sternen einer Galaxie überstrahlen.

Im Jahr 1999 meldete das kalifornische Lick-Observatorium die Entdeckung einer neuen Supernova in der Spiralgalaxie NGC 1637 mit einem Teleskop, das speziell für die Suche nach diesen seltenen, aber besonders wichtigen kosmischen Ereignissen gebaut worden war [1]. Sofort wurden Nachfolgebeobachtungen beantragt, um den Fund zu bestätigen und weiter zu untersuchen. Die Supernova erhielt den Namen SN 1999em und wurde von vielen Observatorien verfolgt. Nach ihrer spektakulären Explosion im Jahr 1999 haben die Wissenschaftler ihre Helligkeit sorgfältig vermessen und so einen relativ langsamen Rückgang über die Jahre dokumentieren können.

Der Vorläuferstern von SN 1999em war vor seinem Tod sehr massereich – er hatte mehr als acht Sonnenmassen. Am Ende seines Lebens fiel sein Kernbereich in sich zusammen, als Folge dessen entstand eine kataklysmische Explosion [2].

Im Rahmen der Nachfolgebeobachtungen von SN 1999em entstanden viele Bilder ihrer Heiatgalaxie NGC 1637 mit dem VLT, aus denen das hier gezeigte scharfe Bild zusammengesetzt wurde. Die Spiralstruktur der Galaxie zeigt sich als ausgeprägtes Muster durch das bläuliche Leuchten junger Sterne. Hinzu kommen Gaswolken und dunkle Staubbänder.

Obwohl NGC 1637 auf den ersten Blick sehr symmetrisch zu sein erscheint, hat sie einige interessante Eigenschaften: Der relativ locker gewundene Spiralarm links oberhalb des Kernbereichs erstreckt sich viel weiter als der viel kompaktere Arm unten rechts, der dadurch wie um die Hälfte verkürzt aussieht. Die Galaxie hat sozusagen Schlagseite.

Das Bild zeigt außerdem Vordergrundsterne aus unserer eigenen Heimatgalaxie, der Milchstraße, und ferne Hintergrundgalaxien, die zufällig in derselben Richtung am Himmel zu sehen sind.

Endnoten

[1] Die Supernova wurde mit dem Katzman Automatic Imaging Telescope am Lick-Observatorium auf dem Mount Hamilton in Kalifornien entdeckt.

[2] SN1999em wurde als sogenannte Kernkollaps-Supernova klassifiziert, genauergesagt als Supernova vom Typ IIp. Das p steht dabei für Plateau, was bedeutet, dass Supernovae dieses Typs nach dem Helligkeitsmaximum noch für eine vergleichsweise lange Zeit in etwa so hell bleiben (ihre Lichtkurve zeigt also ein Plateau).

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Quelle: ESO


Tags: NGC 1637 

2967 Views

Samstag, 23. März 2013 - 08:20 Uhr

Astronomie - Haben Exoplaneten-Jäger mit Objekt 2MASS0103(AB)b ein Planeten mit zwei Sonnen gefunden?

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The binary system 2M0103, with its central pair of stars and mystery third object in orbit around them. This infrared image was produced by the Very Large Telescope at ESO-Paranal in Chile (Image: ESO 2013)

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Snapshot of a two-faced Tatooine world

Exoplanet hunters may have bagged the first direct picture of a planet with two suns. But the object, catchily dubbed 2MASS0103(AB)b, has a double life. It is so massive that it may also be a failed star with a relatively tight orbit around the central binary stars. Astronomers have not yet unravelled the truth. Deciding its identity could teach us more about how stars and planets form.

Philippe Delorme of the Joseph Fourier University in Grenoble, France, and colleagues took the picture in November last year using a telescope in Chile. Searches in the telescope's archives turned up data on the object's position in 2002 (, marked in the picture by a green arrow), allowing them to trace its orbital motion around the binary stars.

Also known as Tatooines, after a fictional world in Star Wars, planets that orbit binary stars have only been found before through indirect methods. The new object orbits at a distance of about 12.5 billion kilometres, close enough to its stars to have been born from a disc of dust surrounding them, like a planet. But it is 12 to 14 times the mass of Jupiter, placing it near the dividing line between planets and failed stars called brown dwarfs.

"It's either one of the most massive planets you can form or the lowest-mass star you can imagine," says Delorme.

Definitely maybe

If it is a planet, it must have formed via gravitational instability, in which clumps in the dust disc quickly collapse into planets. It is too large in relation to the stars to have been made by core accretion, a more widely accepted model in which planets grow via slow accumulation.

Delorme notes that the current mass-based dividing line between planets and failed stars "is more of a working definition, as it is easier to measure the mass of an object than its past formation history". His team is now analysing the object's light spectrum to learn more about its atmosphere.

Figuring out the chemical makeup of 2MASS0103(AB)b could confirm the object as a Jupiter-like planet, lending weight to the instability model. Or it could reveal that the object is in fact a rare type of brown dwarf that was born together with the binary pair. All three would have formed when turbulence inside an embryonic star caused it to break into pieces. That in turn might be crucial to properly identifying such bodies in the future.

"It's a really cool image," says Ben Burningham of the University of Hertfordshire, UK, even though it further muddies the waters separating planets and brown dwarfs.

As to whether he thinks 2MASS0103(AB)b is really a Tatooine planet, Burningham says, "I'm giving it a firm maybe."

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Quelle: NewScientist

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2954 Views

Freitag, 22. März 2013 - 13:00 Uhr

Astronomie - LRO sieht dunkelste und kälteste Mond-Krater

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On the Moon, NASA Probe Sees Where Sun Never Shines

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Some parts of the moon haven't seen the sun in millions, and even billions, of years but an unmanned NASA spacecraft is shedding light on these lunar lands of permanent darkness.
A new video from NASA's Goddard Space Flight Center Scientific Visualization Studio explains just how the agency's powerful Lunar Reconnaissance Orbiter (LRO) is collecting data on the moon's coldest, darkest craters.
Earth's axis is titled about 23.4 degrees from vertical, meaning sunlight reaches every surface, even the north and south poles, for at least part of the year. The moon, meanwhile, is tilted just 1.6 degrees, nearly perpendicular to the direction of the sun's light. This means that there are some deep craters near the moon's poles that haven't seen the sun for over two billion years.
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Elevation color coding lights up the inside of the moon's Shackleton crater, a permanently shadowed region.
CREDIT: NASA's Goddard Space Flight Center Scientific Visualization Studio
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Scientists are interested in the moon's permanently shadowed regions because they are thought to have the right conditions to trap volatiles like water, which would normally vaporize and escape into space, according to NASA. In fact, LRO helped confirm the presence of water ice on the moon along with other lunar probes from Japan and India. In October 2009, LRO detected the presence of frozen water when its sister craft, Lunar CRater Observation and Sensing Satellite, crashed into a permanently shadowed crater near the moon's south pole.
NASA launched the $504 million LRO mission in June 2009. The spacecraft is equipped with a suite of instruments, including a laser ranging tool, to create the most-detailed ever topographical maps of the lunar surface of its mysterious shadowed regions. The lunar probe also has tools designed to measure temperature and neutron absorption in the moon's darkest corners.
And while the sun can't get into the moon's permanently shadowed regions, LRO's Lyman Alpha Mapping Project (LAMP) instrument can detect how faint light from others stars reaches some of these craters.
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Quelle: NASA

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Freitag, 22. März 2013 - 09:00 Uhr

Mars-Chroniken - Opportunity und Curiosity finden ähnliche Gesteine auf dem Mars

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The Opportunity rover is studying the most ancient rocks it has yet seen on Mars - and they resemble those found by its one-tonne cousin Curiosity.
The findings could help build a picture of early Mars - and whether it would have been amenable to primitive life.
The ancient rocks found by Opportunity occur as a light-toned outcrop known as Whitewater Lake.
The outcrop is thought to contain clays, similar to a rock recently drilled by Curiosity.
But there are other uncanny similarities between Whitewater Lake - which lies on the rim of a 22km-wide bowl called Endeavour Crater - and rocks from Gale Crater to the east, where Curiosity landed.
Opportunity's chief scientist Prof Steve Squyres outlined details of the latest findings at the 44th Lunar and Planetary Science Conference in The Woodlands, Texas.
He said one of the factors that had drawn the science team towards Endeavour was the evidence gathered by Nasa's Mars Reconnaissance Orbiter (MRO) for the presence of phyllosilicates (clay-bearing rocks) along the crater's rim.
The Whitewater Lake outcrop coincides closely with the signature of smectite clays from MRO, Prof Squyres, from Cornell University in Ithaca, US, explained.
It is very fine-grained, soft, similar in composition to the Martian soil and has fine ridges when seen in cross-section.
Snaking features
Whitewater Lake is "shot through" with light-toned, snaking features called veins, which appear to be filled with calcium sulphate. These are the result of water flowing through fractures in the rocks after the impact that carved out Endeavour Crater.
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Mars is telling us something. I'm not sure what it is because it's speaking Martian. But it's telling us something”
Prof Steve Squyres
Cornell University
There are also numerous rounded structures called "spherules" embedded in the rock. Opportunity has seen similar small structures out on Mars' Meridiani plains, which the rover team nicknamed "blueberries".
"The spherules are for the most part distributed throughout the Whitewater Lake rocks, but there are places locally where we find incredible concentrations," Prof Squyres told the conference.
But the comparison to the blueberries, seen earlier in the mission, may only be superficial.
"There are a few small visual differences and then a big compositional difference. These do not have the very high iron content… to be the blueberries we see on the plains.
"They are hard on the outside and chewy on the inside… and the composition is different from the [rock] matrix."
Such spherules can form through the action of water, but a volcanic or impact origin is also possible.
Most habitable environment
Prof Squyres added: "These Whitewater Lake materials are the oldest rocks yet explored by the Opportunity rover. They record an epoch before the Endeavour impact when there was aqueous activity at a near-neutral pH.
"They therefore represent the most habitable palaeo-environment found [by Opportunity]."
Previous sites explored by the rover are thought to have been shaped by the activity of acidic water, which would pose a more challenging proposition for any simple microbes that might have evolved on the early Mars.
They cannot put an exact age on the outcrop, but it could date to more than three billion years ago, when Mars was a wetter place.
Prof Squyres showed a comparison of the Whitewater Lake outcrop and rocks found at the location Curiosity is exploring in Gale Crater. They showed many similarities, he said, including the spherules, calcium sulphate veins and fine-grained structure.
"Mars is telling us something. I'm not sure what it is because it's speaking Martian. But it's telling us something," he said.
Opportunity landed on the Red Planet in January 2004, about three weeks after its "twin", the Spirit rover. Spirit's mission ended after getting caught in soft soil in 2009 and succumbing to the Martian winter.
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Quelle: NASA

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Donnerstag, 21. März 2013 - 10:25 Uhr

Raumfahrt - Bermuda Dreieck im All, Anomalien über Südatlantik bedroht Satelliten

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The Bermuda Triangle of Space: The High-Energy South Atlantic Anomaly Threatens Satellites

Much fanfare accompanied the Sept. 25, 2010, launch of the Air Force’s Space Based Space Surveillance satellite. The $833 million craft was finally going up to do its job: monitor orbiting items from space itself, free of the time constraints and atmospheric interference that hamper its earthbound counterpart, the Space Fence. Its 30-centimeter telescope, mounted on a two-axis gimbal, would help keep tabs on satellites as far away as geosynchronous orbit as well as thousands of bits of space junk closer in. The builders said SBSS would be on the job within 60 days, and forecast a working life of at least 5½ years.
Shortly after launch, the satellite passed over the South Atlantic, and things went awry. The satellite was hit by radiation that sent the sensors reeling and knocked out an electronics board payload. Suddenly, the expensive, specially-designed satellite could no longer do what it was built for.
The effects of radiation are part of the price of doing business in space. There are solar flares, random magnetic distortions and what some NASA scientists call euphemistically the “killer electrons” of the Van Allen radiation belts. The place where spacecraft are most vulnerable, though, is an area slightly larger than the United States, centered 300 kilometers off the coast of Brazil, where the trapped charged particles of the doughnut-shaped Van Allen radiation belts and cosmic rays from sun storms combine and bottom out at about 200 kilometers above the planet. Its formal name is the South Atlantic Anomaly, but some call it the Bermuda Triangle of space.
It’s directly in the path of satellites in low Earth orbit, which fly through it regularly — in some cases, multiple times a day.
“The South Atlantic Anomaly is the rocky road of radiation storms,” said Vic Scuderi, manager of satellite electronics at BAE Systems in Manassas, Va.
NASA scientists believe that there is a cloud of protons, followed by a cloud of electrons, followed by a cloud of protons, etc., where the inner Van Allen radiation belt dips down in the anomaly.
“A lot of theoretical people have tried to justify it,” said Old Dominion University professor Francis Badavi. “The typical spacecraft engineer hasn’t been able to come up with a reason” for it.
All they know is that radiation in the South Atlantic Anomaly is intense, that spacecraft have to be designed to deal with it and that, even then, there is potential for peril.
KILLER ELECTRONS
Scientists have a working theory that the Earth’s magnetic field is caused by its molten iron center. Because that core rotates at a slightly different pace than the planet’s surface, the field generates magnetic North and South poles slightly away from the geographic poles that form the Earth’s rotational axis.
That’s the explanation for something even every hiker knows: that the magnetic north shown on a compass is not true north.
That offset also is believed to be the reason that the Earth’s magnetic field is weakest in the area off Brazil. Less hindered, the inner Van Allen radiation belt dips closest to Earth there.
The anomaly was discovered in 1958 as part of a study of space radiation belts by University of Iowa physicist James Van Allen, whose suspicion was aroused by the Soviet Union’s Sputnik satellites. Soviet scientists believed the primitive data-recording device on board Sputnik I was faulty because it told of radiation levels well beyond anything they believed possible.
But Van Allen postulated that the device was fine and that the inexplicable radiation did indeed exist. Four months after Sputnik went up, the U.S. launched its first satellite, Explorer I, and Van Allen began to investigate the radiation belts that today bear his name.
In the 1960s and early ’70s, the Air Force and NASA flew a covey of 22 satellites to map the Van Allen radiation belts between altitudes of 200 and 36,000 kilometers. The flights generated databases that are still in use today.
On Aug. 30, NASA launched its Radiation Belt Storm Probes (later renamed Van Allen Probes), twin satellites on a two-year mission to do more mapping and to update those databases. Shielded by quarter-inch aluminum, the sensors are flying into the radiation belts for long periods, trying to solve a puzzle. Sometimes, when solar storms hit the belts, they fill with energetic particles, the so-called “killer electrons.” At other times, the belts lose particles. And sometimes nothing at all happens.
“The problem is, there is no unified idea of what phenomena are most important inside the belts,” said mission scientist David Sibeck. “If there are 100 people at a [scientific] meeting, there will be 100 answers for every question: ‘How are ‘killer electrons’ energized?’ “
QUICK AND NOT-SO-QUICK FIXES
The Space Based Space Surveillance satellite that was bashed so badly in 2010 was eventually brought back to life. A software patch was developed and tested over the course of more than a year, and the SBSS was declared operationally capable 23 months after launch.
SBSS builders Boeing and Ball Aerospace referred questions to the Air Force, which did not respond by press time.
The satellites’ fate illustrates the problems the South Atlantic Anomaly can cause even to the most well-planned ISR missions.
Tom Logsdon, a former Rockwell Collins engineer, now retired, explained that the radiation can confound the very heart of the software on a satellite.
“One of the things that happens is, you can get logic upsets,” Logsdon said. “You get a charged particle coming through the satellite, and it can flip some of the binary ones to binary zeros, and vice versa.
“Someone would have to upload the memory again or command it to reset, and it would start all over.”
Not every satellite damaged by the Anomaly takes so long to fix. In October, the SpaceX Dragon, part of a $1 billion contract with NASA to supply the International Space Station, suffered a single-event upset en route to docking with the ISS. A remote electronic unit became inoperable as the craft passed through the South Atlantic Anomaly. A quick power cycle and re-synching remedied the issue.
Other programs work around the Anomaly. To avoid exposing astronauts to intense radiation, spacewalks are not scheduled on the International Space Station when it’s passing through the Anomaly — which happens two to five times a day.
As a precaution, NASA engineers simply shut down the Hubble Telescope as it is going through the SAA, to protect its equipment. Smaller commercial and military satellites carry radiation detection devices — themselves vulnerable to radiation — that trigger shutdowns and power-ups of sensors and computers.
Satellites carry radiation-hardened electronics of varying degrees to deal with the energy that accumulates.
“Commercial and defense-contracted satellites are typically on a 15-year mission timeframe, and they have to withstand hammering the whole time,” BAE’s Scuderi said. “The electronics that we put on board the satellites can accumulate up to 500,000 rads” or radiation absorbed doses.
“A human being can only absorb about 400 rads in a lifetime,” he said, by way of comparison. That accumulative effect is called a “total ionizing dose,” and it’s largely predictable, in part because orbital trips through the SAA are predictable. As the ions pile up, the satellite can become impaired.
“Solar arrays become less efficient,” Logsdon said. “Silicon solar cells get damaged, so they generate less electricity.”
NO ESCAPE FROM RADIATION
On March 8, 2012, a flurry of eruptions on the sun began sending enough energy into the Earth’s upper atmosphere to power every home in New York City for two years. Over three days, 26 billion kilowatt-hours pounded the thermosphere, which begins about 53 miles up. Infrared radiation from the thermosphere’s carbon dioxide and nitrous oxide re-radiated about 95 percent of that energy back into space. Some satellites orbiting Earth were hit going and coming by radiation that, NASA assessed, would cut their lives short. And there are more storms ahead because, this year, the planet reaches the apex of an 11-year solar event cycle.
Around the world, a satellite is launched about every four days with varying radiation mitigation capability, generally dictated by its budget. While the day-to-day radiation in the South Atlantic Anomaly and throughout the Van Allen radiation belts can be anticipated, the inability to predict solar storms makes the jobs of designers and operators more difficult. With more notice, operators could do things like shut down equipment to lessen vulnerability.
But they understand the problem.
“We can’t produce an accurate forecast for rain here on Earth more than three days ahead,” Scuderi said. “The number of variables in space is probably 10 to 100 times more than on Earth.”
Still, NASA and NOAA try, albeit with diminishing funding and satellites that are wearing out. The Radiation Belt Storm Probes twin-satellite mission is another in a long line of research efforts.
“We’ve spent a lot of resources trying to predict solar activity, but we’re still not there,” Badavi said.
A former DoD intelligence official said the South Atlantic Anomaly is just part of the ISR challenge.
“We’re just lucky,” he said, “there’s not a lot of demand for satellite imagery over the South Atlantic.”
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Quelle: Defense-News

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