Gallery: Rover Recon: Mars Images Track Changes and Landing Sites
01dune-channel
A fresh collection of Martian portraits from NASA's prolific HiRISE camera captures new views of dunes and gullies, ice caps and craters. The [225 new images](http://www.uahirise.org/releases/jun_11.php?page=1), taken between April 6 and April 30 and released June 1, include new images of potential [landing sites for Curiosity](http://stag-komodo.wired.com/wiredscience/2010/09/mars-landing-gallery/), the next Mars rover, which will be increasingly important as scientists decide where to send the rover this November. [HiRISE](http://www.uahirise.org/) (High Resolution Imaging Science Experiment) has been circling the red planet on the Mars Reconnaissance Orbiter for [more than five years](http://stag-komodo.wired.com/wiredscience/2011/03/happy-birthday-mro/), taking nearly 19,000 dramatic photos with a camera that can focus on objects the size of a beach ball from more than 180 miles away. These are some of our favorites from the new set. You can help point the camera toward its next targets using the HiRISE team's "[HiWish](http://hirise.lpl.arizona.edu/releases/hiwish.php)" feature. __Above:__ Dune Channel ------------ Dark dunes and sand streaks lie trapped in a valley in a region called Lobo Vallis. Winds funneled through the valley could reach speeds high enough to pick up and redistribute sand. Note, however, that this isn't what Mars actually looks like. HiRISE images are presented in false color to highlight interesting features and assign color to wavelengths of light that are invisible to human eyes. Infrared wavelengths of light are shown in red, regions that would look red to human eyes are shown in green, and green through blue wavelengths are shown in blue.
02next-steps
Next Steps ---------- Mawrth Vallis, one of the suggested landing sites for the next Mars rover, takes center stage in this image taken April 29. Mawrth is one of the oldest valleys on Mars, and is full of clay minerals that, on Earth, form only in the presence of liquid water. Images like this one could become increasingly important as the Martian community zeroes in on the best spot to land Curiosity. Planetary scientists met in Monrovia, California for a week in May to debate the merits of the [final four landing sites](http://stag-komodo.wired.com/wiredscience/2010/09/mars-landing-gallery/), but still haven't decided. NASA will choose a landing site in June or July.
03find-the-river
Find the River -------------- This image features Eberswalde Crater, another of the top four contenders for the next Mars rover's landing site. Spectral observations of the 40-mile-wide crater revealed the presence of clays called phyllosilicates, which on Earth form in the presence of water. A wide, meandering delta to the crater's left suggests that Eberswalde may be a dry river delta or lake bed — the perfect conditions for preserving signs of life.
04tracing-tendrils
Tracing Tendrils ---------------- These gullies are traced into Mars's Hellas Basin, one of the largest impact craters in the solar system. On Earth, the basin would stretch from New York to Houston, or about 1,400 miles. Small valleys like these suggest the crater at one point hosted running water. Other observations suggest that Hellas hides great glaciers of water ice buried beneath soil and rock.
05heaps-of-hematite
Heaps of Hematite ----------------- The reddish-gold flecks in this false-color image are hematite, an iron-rich mineral that forms in the presence of water on Earth. In 2004, the Mars rover Opportunity landed in an area full of small hematite lumps that astronomers dubbed "blueberries." The plains in this image, part of a region called Capri Chasma, are similar to Opportunity's landing site, and suggest that hematite-rich particles cluster at the top of Martian soils.
06crater-and-bedrock
Crater and Bedrock ------------------ This slice of an unnamed crater in Mars's southern hemisphere is ringed with ripples and pockmarked with smaller craters. These craters could be secondary craters formed from material knocked aside by the initial impact, or from other small meteorites that hit more recently. The crater's central peak could expose bedrock beneath layers of Martian soil.
07frozen-fingerprints
Frozen Fingerprints ------------------- This image shows a portion of Mars's south polar ice cap. Every spring, frozen carbon dioxide shifts directly from solid to gas, carving bizarre patterns into the ice. Usually, these patterns are almost perfectly circular, because the pole gets equal amounts of sunlight from all directions. But here, the ice arranges itself in lines that planetary scientists have dubbed "fingerprint terrain." The features could be sand dunes covered by a thin layer of frost, or loose ice crystals that bounce like sand grains and collect in ripples. HiRISE has been watching sites like these since 2007 to check for changes and figure out what's going on at these weird sites.
08spider-maps
Spider Maps ----------- Receding carbon dioxide ice can also give rise to the vein-like texture in this image, which planetary scientists call "spider terrain." Scientists think these features form when gases built up by sublimating dry ice break through the surface and scatter dark dust in the wind.
09bands
Bands ----- These alternating bands of light and dark soil line Darwin Crater, a 110-mile-wide crater in Mars's southern hemisphere. Scientists aren't sure how these multicolored stripes formed, but they could be layers of sediment laid down under a long-ago lake or shallow sea.
10gouged-gullies
Gouged Gullies -------------- Gullies like the ones in this image may have been carved in an earlier epoch when Mars was warmer and wetter, but they may also still be changing today. HiRISE regularly monitors such sites for evidence of new geologic activity.
