Martian Landform Observations Fill Special Journal Issue
Martian landforms shaped by winds, water, lava flow, seasonal icing and other forces are analysed in 21 journal reports based on data from a camera orbiting Mars. The research in a January special issue of Icarus testifies to the diversity of the planet being examined by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. Examples of the findings include:
-- Valleys associated with light-toned layered deposits in several locations along the plateaus adjacent to the largest canyon system on Mars suggest low-temperature alteration of volcanic rocks by acidic water both before and after formation of the canyons.
-- The youngest flood-lava flow on Mars, found in the Elysium Planitia region and covering an area the size of Oregon, is the product of a single eruption and was put in place turbulently over a span of several weeks at most.
-- New details are observed in how seasonal vanishing of carbon-dioxide ice sheets in far-southern latitudes imprints the ground with fan-shaped and spider-shaped patterns via venting of carbon-dioxide gas from the undersurface of the ice.
Spectacular satellite images suggest that Mars was warm enough to sustain lakes three billion years ago, a period that was previously thought to be too cold and arid to sustain water on the surface, according to research published today in the journal Geology. The research, by a team from Imperial College London and University College London (UCL), suggests that during the Hesperian Epoch, approximately 3 billion years ago, Mars had lakes made of melted ice, each around 20km wide, along parts of the equator. Read more
The surface of Mars is littered with channels that appear to be the work of ancient water flows. Indeed, some of these channels meander back and forth like slow-moving streams on our planet. Channels can be carved by lava, wind and glaciers, but these processes can't explain all the features on Mars. Read more
This image from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter shows a sample of the variety and complexity of processes that may occur on the walls of Martian craters, well after the impact crater formed. At the very top of the image is the high crater rim. At the bottom of the image is the crater's central peak, a dome of material rising above the surrounding crater floor. The central peak was uplifted during the impact event.
Expand (647kb, 1200 x 2844) Credit: NASA/JPL-Caltech/University of Arizona
Distal Rampart of Crater in Chryse Planitia Impact craters on Mars are kind of neat. Many of them look very different than impact craters seen on Earth's moon or Mercury. Fresh lunar and Mercurian craters have ejecta blankets that look a bit rough near the crater rims; around larger craters, long rays or chains of secondary craters radiate away from the crater rims. Some Martian craters are similar to these craters, but Mars also has a high proportion of craters with forms not found on the moon or Mercury: rampart craters.
Chaotic terrain between Kasei Valles and Sacra Fossae
Kasei Valles and Sacra Fossae. North is to the right
Mars Express flew over the boundary between Kasei Valles and Sacra Fossae and imaged the region, acquiring spectacular views of the chaotic terrain in the area. The images, obtained by the High Resolution Stereo Camera (HRSC), are centred at 12°N / 285°E and have a ground resolution of about 21 m/pixel. They cover 225 x 95 km or 21.375 sq km, an area roughly half the size of the Netherlands.
This image from NASA's Mars Reconnaissance Orbiter shows channels to the southeast of Hale crater on southern Mars. Taken by the orbiter's High Resolution Imaging Science Experiment (HiRISE) camera, this view covers an area about 3 kilometres wide. Channels associated with impact craters were once thought to be quite rare. Scientists proposed a variety of unusual circumstances to explain them, such as impacts by comets or precipitation caused by the impact event. As more of Mars is photographed with high-resolution imagery, more craters surrounded by channel systems are being discovered. See more
This image shows gullies near the edge of Hale crater in southern Mars. The image was captured by the High Resolution Imaging Science Experiment (HiRISE) camera on the Mars Reconnaissance Orbiter. The view covers an area about 1 kilometre across and was taken on Aug. 3, 2009. The terrain in this image is at 36.5 degrees south latitude, 322.7 degrees east longitude.
Expand (567kb, 1347 x 4170) Credit NASA/JPL-Caltech/University of Arizona
Scientists See Water Ice in Fresh Meteorite Craters on Mars Scientists are seeing sub-surface water ice that may be 99 percent pure halfway between the north pole and the equator on Mars, thanks to quick-turnaround observations from orbit of fresh meteorite impact craters on the planet.
"We knew there was ice below the surface at high latitudes of Mars, but we find that it extends far closer to the equator than you would think, based on Mars' climate today" - Shane Byrne of the University of Arizona, a member of the High Resolution Imaging Science Experiment, or HiRISE, which runs the high-resolution camera on NASA's Mars Reconnaissance Orbiter.