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Polygons, Crater Layers, and Defrosting Dunes (PSP_008426_2595) June 30, 2008

Posted by jtintle in Planets, Space Fotos.
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Polygons, Crater Layers, and Defrosting Dunes

Credit:

NASA/JPL/University of Arizona

Description:

The north polar region is surrounded by a large sea (erg) of dark sand dunes that become covered by seasonal carbon dioxide frost. As the northern hemisphere begins to warm in the spring, the frozen carbon dioxide sublimates. The wind blows from an east-northeasterly direction and leaves dark streaks behind (exposed basalt) from the evaporating carbon dioxide. This image displays defrosting sand dunes in an unnamed crater.

The dune morphology in this image is complex. Because of the presence of the ice, it is difficult to determine all of the dune types. These jumbled dunes may result from erosion of the layers within the crater walls that act as a dune source.. However, two common types of dunes can be classified: the outer ring of the dune field is composed of chains of barchan dunes whereas the central area of the field contains transverse dunes.

Barchans are characterized by their crescent-shape with steep horns in the downwind direction. The transverse dunes have asymmetric, nearly parallel ridges and are oriented perpendicular to the wind direction.

Another feature of interest is the sublimating polygons that have very small ripples on top of them. Polygons are created from a freeze-thaw processes similar to features on Earth that undergo annual contraction of the permafrost regolith.

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Pedestal Crater Margin (PSP_008508_1870) June 29, 2008

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Pedestal Crater Margin

Credit:

NASA/JPL/University of Arizona

Description:

This image shows part of the margin of a pedestal crater. A pedestal crater is a crater with its ejecta standing above the surrounding terrain. These form when an impact crater ejects material which forms a resistant layer. This resistant blanket coats material around the crater, which is thus eroded more slowly than the rest of the region. The result is that both the crater and its ejecta blanket stand above the surroundings.

At this site, only a small part of the edge of the ejecta is visible. The ejecta is eroding, leaving a ragged edge with some detached mesas and buttes. The uppermost layer in the small cliffs is clearly strong and erosion-resistant, as it forms steep and even overhanging edges, ultimately breaking up into boulders which fall down the slopes. This layer armors the underlying material against erosion. Sites like this offer the opportunity to study units of rock that otherwise might have been erased by erosion.

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Barred Spiral Galaxy NGC 1300 June 29, 2008

Posted by jtintle in Deep Space, Space Fotos.
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See Explanation.  Clicking on the picture will download  the highest resolution version available.

Credit:

Hubble Heritage Team, ESA, NASA

Explanation:

Big, beautiful, barred spiral galaxy NGC 1300 lies some 70 million light-years away on the banks of the constellation Eridanus. This Hubble Space Telescope composite view of the gorgeous island universe is one of the largest Hubble images ever made of a complete galaxy. NGC 1300 spans over 100,000 light-years and the Hubble image reveals striking details of the galaxy’s dominant central bar and majestic spiral arms. In fact, on close inspection the nucleus of this classic barred spiral itself shows a remarkable region of spiral structure about 3,000 light-years across. Unlike other spiral galaxies, including our own Milky Way, NGC 1300 is not presently known to have a massive central black hole.

M27: Not A Comet June 28, 2008

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See Explanation.  Clicking on the picture will download  the highest resolution version available.

Credit & Copyright:

Nik Szymanek, w/Faulkes Telescope North

Explanation:

Born on June 26th in 1730, astronomer Charles Messier scanned 18th century French skies for comets. To avoid confusion and aid his comet hunting, he diligently recorded this object as number 27 on his list of things which are definitely not comets. In fact, 21st century astronomers would classify it as a Planetary Nebula, but it’s not a planet either, even though it may appear round and planet-like in a small telescope. Messier 27 (M27) is now known to be an excellent example of a gaseous emission nebula created as a sun-like star runs out of nuclear fuel in its core. The nebula forms as the star’s outer layers are expelled into space, with a visible glow generated by atoms excited by the dying star’s intense but invisible ultraviolet light. Known by the popular name of the Dumbbell Nebula, the beautifully symmetric interstellar gas cloud is over 2.5 light-years across and about 1,200 light-years away in the constellation Vulpecula. This impressive color composite highlights subtle jet features in the nebula. It was recorded with a robotic telescope sited in Hawaii using narrow band filters sensitive to emission from oxygen atoms (shown in green) and hydrogen atoms. The hydrogen emission is seen as red (H-alpha) and fainter bluish hues (H-beta).

First American Spacewalk June 5, 2008

Posted by jtintle in NASA, Space Fotos.
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Description:

During the Gemini 4 mission on June 3, 1965, Ed White became the first American to conduct a spacewalk. The spacewalk started at 3:45 p.m. EDT on the third orbit when White opened the hatch and used the hand-held manuevering oxygen-jet gun to push himself out of the capsule.

The EVA started over the Pacific Ocean near Hawaii and lasted 23 minutes, ending over the Gulf of Mexico. Initially, White propelled himself to the end of the 8-meter tether and back to the spacecraft three times using the hand-held gun. After the first three minutes the fuel ran out and White maneuvered by twisting his body and pulling on the tether.

In a photograph taken by Commander James McDivitt taken early in the EVA over a cloud-covered Pacific Ocean, the maneuvering gun is visible in White’s right hand. The visor of his helmet is gold-plated to protect him from the unfiltered rays of the sun.

Following in the footsteps of their predecessor, the STS-124 mission specialists Mike Fossum and Ron Garan will conduct a spacewalk at 11:32 a.m. today. for more information on the STS-124 mission, visit www.nasa.gov/shuttle.

Credit: NASA

Ulysses, the end of an extraordinary mission June 4, 2008

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Ulysses
Ulysses

After more than 17 years relentlessly exploring the effects of solar activity on the space that surrounds us, the Ulysses mission is now approaching its end. Representatives of the media are invited to a joint ESA/NASA press conference on 12 June 2008 taking place at ESA Headquarters in Paris, France, to hear about the achievements that will form the Ulysses legacy.

Ulysses, a pioneering ESA/NASA mission, was launched in October 1990 to explore uncharted territories – the regions above and below the Sun’s poles – and study our star’s sphere of influence, or heliosphere, in the four dimensions of space and time.

Originally designed for a lifetime of five years, the mission has surpassed all expectations. The reams of data Ulysses has returned have forever changed the way scientists view the Sun and its effect on the space surrounding it.

Fortunate View June 4, 2008

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Credit:

NASA/JPL/Space Science Institute

Description:

From a highly inclined orbit, Cassini looks toward far northern latitudes on Tethys.

Here, the spacecraft was above a position about 45 degrees north of the moon’s equator. This vantage point afforded a view of the moon’s three most recognizable features: the Ithaca Chasma canyon system (at lower right), Odysseus crater (at upper left) and the equatorial band of darker terrain (at lower left).

Lit terrain seen here is on the leading hemisphere of Tethys (1,062 kilometers, 660 miles across). North is up.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on April 29, 2008. The view was obtained at a distance of approximately 991,000 kilometers (616,000 miles) from Tethys and at a Sun-Tethys-spacecraft, or phase, angle of 73 degrees. Image scale is 6 kilometers (4 miles) per pixel.

HiRISE camera captures image of the Phoenix landing site 22 hours after landing. June 3, 2008

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Phoenix
Phoenix Lander Hardware: EDL +22 (PSP_008591_2485)
Credit: NASA/JPL/University of Arizona

MRO’s HiRISE camera acquired this image of the Phoenix landing site 22 hours after landing. The image shows three unusual features; seen also is the image acquired 11 hours after landing. These three features were not present in a pre-landing HiRISE image.

We expect to find three main pieces of hardware: the parachute attached to the backshell, the heat shield, and the lander itself.

The parachute (bottom) is easy to identify because it is especially bright, and this image also clearly shows the backshell. We can even see the stripes on the parachute.

The dark marking (middle right) appears most consistent with disturbance of the ground from impact and bouncing of the heat shield, which fell from a height of about 13 kilometers.

The last object (top) is the lander, and we can clearly see the solar arrays on each side. The solar arrays were relatively dark in the image acquired 11 hours after landing, but are brighter than the Mars surface in this daytime image acquired with the HiRISE blue-green filter.

There are dark halos around all three locations, perhaps due to disturbing a thin dust coating. North is about 7 degrees to the right of straight up in this image and illumination is from the lower left.

Something new June 2, 2008

Posted by jtintle in Space Fotos.
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I think I will be posting more, from now on. I know you all have heard that numerous times but I’ll really try this time. Also I set up a twitter account that will post just the links to the images. the url for the twitter page is: http://twitter.com/Spacephotos

W28: A Mixed Bag June 2, 2008

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W28
Credit: Chandra X-ray: NASA/CXC/HSC/J. Keohane et al; ROSAT X-ray: NASA/ROSAT; Optical: NOAO/CTIO/P.F. Winkler et al; Radio: NSF/NRAO/VLA/G. Dubner et al.
JPEG (594 kb) Tiff (14.8 MB) PS (1012.8 kb)

Description:

When some stars die, they explode as supernovas and their debris fields (aka, “supernova remnants”) expand into the surrounding environments. There are several different types, or categories, of supernova remnants. One of these is known as a mixed-morphology supernova remnant. This type gets its name because it shares several characteristics from other types of supernova remnants. More specifically, particles that have been superheated are seen in X-rays in the center of the remnant. This inner region is enclosed by shell structure detected in radio emission.

This composite shows a classic example of mixed-morphology supernova remnant known as W28. Each wavelength shows detailed structure of how the supernova shock wave is interacting, or has interacted, with the complex cloudy environment which surrounded its parent star. In this image, the stars and fine structure in the background are seen in optical light (grey and white) by the Cerro Tololo Inter-American Observatory in Chile. The radio (orange) data was obtained by the Very Large Array in New Mexico, while the blue in the wide-field view comes from the ROSAT satellite (X-rays). Data from NASA’s Chandra X-ray Observatory give new detail into the heart of W28 as seen in the inset. In this close-up view of the center, low-energy X-rays are colored red, the medium are green, and the highest found by Chandra are blue. The Chandra data show the shape and extent of the high-energy emission in the central region. By studying W28 and others like it, astronomers hope to better understand the complexities involved when a star explodes in a crowded neighborhood.

Involved in this W28 study were Jonathan Keohane (Hampden-Sydney College), Jeonghee Rho (Spitzer Science Center), Thomas Pannuti (Morehead State University), Kazik Borkowski (North Carolina State University) and Frank Winkler (Middlebury College).

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