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TOPIC: Mars


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Mars Cave
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Title: THEMIS OBSERVES POSSIBLE CAVE SKYLIGHTS ON MARS.
Authors: G. E. Cushing, T. N. Titus, J. J. Wynne, P. R. Christensen,

Introduction: Here we report the discovery of seven candidate skylight entrances into subterranean caverns. All seven are located on the flanks of Arsia Mons (southernmost of the massive Tharsisridge shield volcanoes), a region with widespread collapse pits and grabens which may indicate an abundance of subsurface void spaces.
Motivation: Subterranean void spaces may be the only natural structures on Mars capable of protecting life from a range of significant environmental hazards. With an atmospheric density less than 1% of the Earthís and practically no magnetic field, the Martian surface is essentially unprotected from micrometeoroid bombardment, solar flares, UV radiation and high-energy particles from space. Additionally, intense dust storms occur planet wide, and some regions exhibit temperature ranges that can double over each diurnal cycle. Besides general geological interest, there is a strong motivation to find and explore Martian caves to determine what advantages these structures may provide future explorers. Furthermore, Martian caves are of great interest for their biological possibilities because they may have provided habitat for past (or even current) life. Preserved evidence of past or present life on Mars might only be found in caves, and such a discovery would be of unparalleled biological significance. Cave deep zones on Earth generally maintain constant climate conditions which are ideal for the preservation of organic material. Accordingly, Martian caves are among the most desirable targets for astrobiological exploration.

Marscaves
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Seven proposed cave skylights. Clockwise from upper-left: Dena, ChloŽ, Wendy, Annie, Abbey, Nikki and Jeanne. Arrows signify direction of solar illumination (I) and direction of North (N). Respective image IDs are: 18053001, 13448001, 17716001, 18340001, 14334002 and 18315002. To facilitate our photoclinometry routine, each candidate has been map-projected with the sun coming from the 9 oíclock direction.

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Martian caves
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Scientists studying pictures from Nasa's Odyssey spacecraft have spotted what they think may be seven caves on the surface of Mars.
The candidate caves are on the flanks of the Arsia Mons volcano and are of sufficient depth their floors mostly cannot be seen through the opening.
Details were presented here at the Lunar and Planetary Science Conference in Houston, Texas.
Temperature data from Mars Odyssey's Themis instrument support the idea.
The authors say that the possible discovery of caves on the Red Planet is significant.

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Some underground martian caves may have been spotted, thanks to 'skylight' holes into the caverns that have been photographed from above.
Glen Cushing, from the US Geological Survey (USGS) in Flagstaff, Arizona, got his first hint of the underground cave system from THEMIS (Mars Odyssey's Thermal Emission Imaging System) images of the Arsia Mons region near the equator of Mars. He spotted a system of pit craters, indicative of collapsed areas, and nestled among them half a dozen dark spots ranging in diameter from 100 to 252 metres.
Two of the seven possible openings found by Cushing have been probed using thermal infrared imaging, which shows that their temperature is pretty constant at any time of day: in daylight, the spots are cooler than the rest of the surface, but not as cool as shadowed areas, and at night the spots are warmer than their surroundings.

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Mars
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Dramatic virtual flyovers of NASA's two Mars rover landing sites have been made using 3D imagery from the agency's Mars Reconnaissance Orbiter (MRO). The flyovers give a first taste of the probe's astoundingly precise 3D mapping abilities and may help the Opportunity rover find a safe path into the yawning chasm of Victoria crater.
The images were made using the most powerful camera ever sent to another planet, MRO's High Resolution Imaging Science Experiment (HiRISE).
The three-dimensional information is obtained by taking pairs of images from slightly different vantage points as the spacecraft orbits the Red Planet.
This data is used to create 3D models of the planet, allowing virtual flyover animations to be produced.

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This image of Mars was taken by Rosetta's Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS). It shows planet Mars in the pre-close-approach phase (updated with additional spectral information).

ROSettaMars1
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Credit ESA

An orange (red), green and near-UV colour filter composite image of Mars; the UV channel (the blue colour) has been enhanced. The enhanced UV signal clearly shows the presence of the cloud system covering most of the Martian disk.
The image was acquired on 24 February at 19:28 CET from a distance of about 240 000 km; image resolution is about 5 km/pixel. Higher resolution images of Mars will be made available later.

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A spacecraft that aims to land on a comet may also establish whether there is a thin ring of debris around the Red Planet this week.
The Rosetta probe will use Mars' gravity to pick up speed on a mission that will reach its climax in 2014.
But during a very close flyby, Rosetta will look for a scattering of dust from Mars' two moons, Phobos and Deimos.
In seven years' time, the probe will enter orbit around a comet, releasing a small lander on to its icy nucleus.
Rosetta scientist Horst Ewe Keller said a number of different observations would be made of Mars from a distance of only 250km, using high resolution cameras and instruments.
The spacecraft would be in position at about 1800 GMT on Saturday, 24 February, to observe the martian moon Phobos appearing from behind the planet.

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Scientists using data from the HRSC experiment onboard ESA's Mars Express spacecraft have produced the first 'hiker's maps' of Mars. Giving detailed height contours and names of geological features in the Iani Chaos region, the maps could become a standard reference for future Martian research.

The maps are known as topographic maps because they use contour lines to show the heights of the landscape. The contour lines are superimposed upon high-resolution images of Mars, taken by the High-Resolution Stereo Camera (HRSC) onboard Mars Express. On Earth, such maps are used by hikers and planning authorities.
They are known in the UK as ordinance survey maps. Every country has its own equivalent. The contour lines themselves were determined using data from the HRSC.
This data has been transformed into three-dimensional computer models of Mars, known as the HRSC Digital Terrain Models (DTMs).
The new maps have been produced under the leadership of the Principal Investigator (PI) G. Neukum (Freie Universitšt Berlin), as part of the effort of the science and experiment team of the HRSC experiment, by J. Albertz and S. Gehrke of the Institute for Geodesy and Geoinformation Science, Technische Universitšt Berlin, in cooperation with the German Aerospace Centre (DLR), Institute of Planetary Research, Berlin.
They used the HRSC DTMs of the Iani Chaos region to produce a series of topographic maps at different scales, from 1:200 000 down to 1:50 000.
The researchers chose the Iani Chaos region because of its major topographical interest. It is covered in individual blocks and hills that form a chaotic pattern across the landscape.
These 'islands' of rocks are likely all that remains of a previous surface of Mars. The areas in between the islands collapsed when cavities formed below the surface. Initially these cavities may have been supported by the presence of ice, which melted due to volcanic heat. As the water flowed out into Ares Vallis, towards the northern lowlands of Mars, the landscape collapsed and formed the Iani Chaos region we see today.
The contour lines help the eye to understand the morphology of the surface shown in the images. On most of the maps, each line represents a difference of 250 metres in height. The maps also display the names of geographical features and the lines of Martian longitude and latitude.
The maps are a demonstration of the kind of products that can be derived from the HRSC experiment. The HRSC is on the way to providing enough data to create such maps for the whole of Mars. This would generate 10 372 particular map sheets, each covering an equal area of the Martian surface. The maps would be to a scale of 1:200 000.

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Night clouds warm surface of Mars
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Temperature anomaly picked up by now-lost Mars Global Surveyor
Nighttime clouds detected for the first time on Mars help to keep the planetís surface warm after sunset when temperatures drop, a new study suggests.
The nocturnal clouds are five times thicker than their daytime counterparts and hover close to the ground, almost like a fog.
The study, conducted by researchers at NASA and the National Oceanic and Atmospheric Administration (NOAA), is detailed in the Feb. 1 issue of Geophysical Research Letters.

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RE: Mars
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The seasons here on Earth roll by at a regular clip -- about three months for each one. Right now, we're just more than half way through winter in the northern hemisphere. In fact, we marked the halfway point last week with Groundhog Day.
But the seasons on other planets aren't always as regular. Consider Mars, where autumn begins in the northern hemisphere this week. The season will last about 146 Earth days. That's about two weeks longer than northern winter, and five weeks longer than summer.

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Martian rayed craters
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Large rayed craters on Mars, not immediately obvious in visible light, have been identified in thermal infrared data obtained from the Thermal Emission Imaging System (THEMIS) onboard Mars Odyssey. Livio Tornabene (previously at the University of Tennessee, Knoxville and now at the University of Arizona, Tucson) and colleagues have mapped rayed craters primarily within young (Amazonian) volcanic plains in or near Elysium Planitia. They found that rays consist of numerous chains of secondary craters, their overlapping ejecta, and possibly primary ejecta from the source crater. Their work also suggests rayed craters may have formed preferentially in volatile-rich targets by oblique impacts. The physical details of the rayed craters and the target surfaces combined with current models of Martian meteorite delivery and cosmochemical analyses of Martian meteorites lead Tornabene and coauthors to conclude that these large rayed craters are plausible source regions for Martian meteorites. in these extreme environments, similar technology could be used to live on the Moon or Mars.

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