* Astronomy

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Student Image of the Week: Confluence of Nirgal and Uzboi Valles (PSP_003565_1495) Nirgal and Uzboi Valles are two valleys to the north of the Argyre impact basin in the southern hemisphere.	Proposed MSL Site in North Meridiani (PSP_005581_1815) Image of a proposed landing site the Mars Science Laboratory.	Terraced Fan and Valley in Crater (PSP_005583_1700) Terraced fans are rare deposits on Mars: they have only been seen in a few dozen locations.
Proposed MSL Site in Ariadnes Colles (PSP_005588_1445) A proposed landing site for the Mars Science Laboratory.	Layered Sediments in Tithonium Chasma (PSP_005703_1750) Observations drawn from this image will help understand the history of deposition at this location, and can be compared with nearby related rocks.

New images for 17 October 2007

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FLYOVER MOVIE Nili Fossae Trough 640 x 360, 2MB, 40 sec.

Negative and Positive Relief Valley Feature (PSP_005355_2125)	Slope Streaks within an Impact Crater in Terra Sabaea (PSP_005369_1925)	Scalloped Terrain and Exhumed Crater in Amphitrites Patera (PSP_005421_1215)
Graben in Memnonia Region (PSP_005442_1660)	Radiating Dark Slope Streaks (PSP_005514_1925)	Impact Crater Cut by Ganges Chasma (PSP_005543_1725)

HiRISE RELEASES COLOUR IMAGES, MOVIE OF PROSPECTIVE LANDING SITES ON MARS
The High Resolution Imaging Science Experiment, or HiRISE, on NASA's Mars Reconnaissance Orbiter has added a new dimension to its views of Mars. The dimension is colour.
The University of Arizona-based HiRISE team today released 143 colour images valuable to researchers studying possible landing sites for NASA's Mars Science Laboratory, a mission to deploy a long-distance rover carrying a deck of sophisticated science instruments on Mars in 2010. The colour images are online at the HiRISE Website, and are available through the Planetary Data System, NASA's space mission data archive.
The powerful HiRISE camera has taken more than 3,500 huge, sharp images released in black-and-white since it began science operations in November 2006. The camera carries 10 red-filter detectors, two blue-green filter detectors and 10 infrared detectors that record different colours.
HiRISE is also releasing a colour movie, scrolling over one potential Mars Science Laboratory landing site in Nili Fossae, at 21 degrees north latitude and 74 degrees east latitude. The animation shows a range of enhanced colours that correspond to what Mars Reconnaissance Orbiter's imaging spectrometer, called CRISM, has determined to be hydrated clay minerals and unaltered volcanic rocks.


Movie (640 x 360, 2MB, 40 sec)

"The clay minerals are especially promising in the search for ancient life on Mars" - UA Professor Alfred S. McEwen, HiRISE principal investigator.

Beginning this week, images will be released in colour as well as black-and-white on the HiRISE Website. The colours are false colour, not the way Mars would look to human eyes. The images are processed to maximize colour differences, a technique useful for analysing landscapes.

"Colour data are proving very useful in interpreting geologic processes and history on Mars. The images we're releasing today include views of some of the most exciting and compositionally diverse areas on the planet. They are really interesting" - Alfred S. McEwen.

In a Herculean effort, HiRISE team members developed computer software that automatically process images from the different colour filters into colour images.

"The technical hurdle has been that the sets of different colour detectors are staggered within the camera focal plane array, and the spacecraft isnt perfectly steady as it operates in space" - Eric Eliason, HiRISE operations manager.

The spacecraft has excellent pointing control thanks to superb engineering, but HiRISE pixels cover an extremely small angular diameter, which gives the camera its ability to sample the surface at 30 centimetres per pixel from 300 kilometres above the surface. The slightest spacecraft motion causes shifts in the camera pointing in unpredictable ways.
There's only a split-second time lag between the time each colour filter records the same spot on Mars as the camera view sweeps over the planet, but that's enough time for spacecraft motion to knock the colours out of register by up to a few pixels.

"You can't just take the different colour images and lay them down on each other adjusting only for the slight time lag and get a sharp picture" - Eric Eliason.

HiRISE software developer Guy McArthur and applied mathematics undergraduate student Sarah Mattson put a lot of work into developing code that now successfully correlates the data from the different detectors. McArthur developed software that automates colour correlation processing at HiROC, the HiRISE Operations Centre at the UA.
Colour is a boon to geologists who have been trying to discriminate different surface materials and their relation to the topography.

"Colour clearly identifies basic material distinctions like dust, sand or rocks, light-toned layered material, and frost or ice" - Eric Eliason.

Colour also helps geologists correlate layers in the Martian terrain. And scientists will be able to combine HiRISE data with CRISM data to make detailed maps of minerals and soil types on the planet.
A single HiRISE image will often be a multigigabyte image that measures 20,000 pixels by 50,000 pixels, which includes a 4,000-by-50, 000-pixel region in three colours. It can take a computer up to three hours to process such an image.
McEwen decided to process images that support selection of the Mars Science Laboratory, or MSL, landing site first.

"The MSL is holding a landing site workshop later this month, so the colour images had to be ready a couple of weeks in advance to be useful" - Alfred S. McEwen.

The colour images released today were taken over or near about 30 proposed landing sites for the 2010 mission.
The UA-led Phoenix Scout Mission to Mars was saved from being launched to a dangerous, boulder-strewn landing site when researchers saw HiRISE images taken soon after the camera began taking science images in late 2006.
Images from HiRISE and from Arizona State University's Thermal Emission Imaging System on Mars Odyssey were used in choosing where the Phoenix spacecraft will land on May 25, 2008.
McEwen said the HiRISE camera will try to image the Phoenix spacecraft landing site again in January, although it could be so cloudy the camera might have to wait an extra month or two for a clear view.

New images for 26 September 2007

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Small Channel Winding between Knobs in the Tartarus Colles (PSP_001420_2045)	Student Image of the Week: Debris Apron South of Euripus Mons (PSP_003639_1345)	South Pole Residual Cap Swiss-Cheese Terrain Monitoring (PSP_004976_0940)	South Pole Residual Cap Swiss-Cheese Terrain Monitoring (PSP_005095_0935)
Transected Wrinkle Ridge in Ophir Chasma (PSP_005330_1275)	Small Rayed Crater (PSP_005336_1620)