02.08.2017 Mars Reconnaissance Orbiter Observes Changes
01.26.2017 Mono Lake
01.25.2017 'Wing' Dike of Hardened Lava in New Mexico
01.25.2017 Blade-Like Martian Walls Outline Polygons
01.23.2017 Spirit And Opportunity By The Numbers
01.10.2017 Mars 2020 Rover - Artist's Concept
01.06.2017 Earth and Its Moon, as Seen From Mars
12.13.2016 Now and Long Ago at Gale Crater, Mars
12.13.2016 Where's Boron? Mars Rover Detects It
11.15.2016 Schiaparelli Impact Site on Mars, Stereo
11.03.2016 Schiaparelli Impact Site on Mars, in Color
10.17.2016 MAVEN Captures Rapid Cloud Formation
10.17.2016 Mars' Nightside Atmosphere
10.17.2016 Ultraviolet Image Near Mars' South Pole
10.17.2016 Ultraviolet Mars Reveals Cloud Formation
10.05.2016 Dust Haze Hiding the Martian Surface in 2001
10.04.2016 Test of Lander Vision System for Mars 2020
10.03.2016 A Sharpened Ultraviolet View of Mars
10.03.2016 Curiosity Self-Portrait at 'Murray Buttes'
10.03.2016 Butte 'M9a' in 'Murray Buttes' on Mars
09.19.2016 Ribbon Cutting
09.09.2016 Farewell to Murray Buttes (Image 5)
09.09.2016 Farewell to Murray Buttes (Image 4)
09.09.2016 Farewell to Murray Buttes (Image 3)
09.09.2016 Farewell to Murray Buttes (Image 2)
09.09.2016 Farewell to Murray Buttes (Image 1)
08.26.2016 Out-of-this-World Records
08.04.2016 Mars Rover Is New Social Media Game
08.04.2016 Mars Rover Social Media Game
08.02.2016 Artist Concept for RIMFAX
07.20.2016 Viking 40 Year Anniversary Artwork: Medal
07.18.2016 Mars 2020 Range Trigger
07.14.2016 NASA to Launch Mars Rover in 2020
Martian Features Formed When Material Moves DownslopeAs on the Earth, many processes can move material down a Martian slope. This graphic compares seven different types of features observed on Mars that appear to result from material flowing or sliding or rolling down slopes.
Processes that explain one type of downslope feature may be irrelevant to another type. Some processes depend on the presence of a fluid, some are driven by seasonal changes in the environment, and others occur randomly when gravity is able to pull down unstable slope material.
These different processes can generate a wide range of feature shapes, though sometimes different processes can yield similar-looking results. Thus, to figure out how a feature may have formed, more must be considered than its shape. For example, researchers examining images from Mars orbiters have found differences in 1. the season when the features are formed or are active (e.g., the features called "recurring slope lineae" or RSLs appear during late spring and summer, but linear gullies are active only during early spring); 2. the features' sizes (e.g., slope streaks can extend for miles or kilometers, but dark frost streaks on dunes extend only up to 100 yards, or meters); and 3. the types of terrain on which a feature is found (e.g., gullies with an alcove-channel-apron shape are found both on rocky slopes and on sandy slopes, but linear gullies are only found on sandy slopes; dark frost streaks are formed on frozen dune slopes, but RSLs are formed on dark, warm slopes).
Scientists consider all of these factors -- and more -- when trying to form a complete picture about a feature's formation history and in figuring out what the presence of that feature means about the environment.
The seven images of different types of downslope features come from three different NASA Mars orbiters. The image of a landslide comes from the Thermal Emission Imaging System (THEMIS) on NASA's Mars Odyssey. The images of alcove-channel-apron gullies and of slope streaks come from the Mars Orbiter Camera (MOC) in NASA's Mars Global Surveyor. The other images come from the High Resolution Imaging Science Experiment (HiRISE) on NASA's Mars Reconnaissance Orbiter.
The University of Arizona, Tucson, operates THEMIS. Malin Space Science Systems, San Diego, operated MOC. The University of Arizona, Tucson, operates HiRISE. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, has managed the Mars orbiter projects for NASA's Science Mission Directorate, Washington.
Image Credit: NASA/JPL-Caltech/ASA/MSSS/UA