Essential Lens: Analyzing Photographs Across the Curriculum
Processes of Science: Mars, a Case Study #6008 Barchan Dunes on the Move
Date: November 4, 2013
Source: NASA/JPL-Caltech/Univ. of Arizona
Sand dunes such as those seen in this image have been observed to creep slowly across the surface of Mars through the action of the wind. These are a particular type of dune called a “barchan,” which forms when the wind blows in one direction (here, east to west) for long periods. Barchan dunes are common on Mars and in the desert regions of the Earth.
These barchan dunes are located on the western rim of the Hellas impact basin, in the Southern Hemisphere of Mars. This area is covered by extensive deposits of layered rocks that were initially deposited as loose sediments and, over time, formed these rock layers. Portions of these layered rocks were subsequently eroded away, and the remaining layers now form numerous flat-topped hills called “mesas.” The barchan dunes are forming in the lee (downwind) of the mesas.
Careful comparison of repeat images such as these can reveal the speed and manner by which dunes move across the Martian surface. This information can be used to study the current atmosphere of Mars, the age and mobility of sand deposits on the planet’s surface, and the hazards that sand dunes may pose to landed vehicles such as rovers.
Over the course of its mission, the science instruments on board the Mars Reconnaissance Orbiter (MRO) have returned over 200 terabits of data back to Earth. This image was taken on November 4, 2013, the same day that MRO’s 200-terabit mark was surpassed.
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Supplementary: Essential Lens: Processes of Science - Mars, a Case Study
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Program 1 A Closer Look (video)
This introduction to the course models the process of analyzing photographs with teachers and students. Photography historian Makeda Best discusses the Focus In method with teachers, and educator Julie Keefe employs the method with students at a photography exhibit on "light and dark." Photography curator at the Portland Art Museum, Julia Dolan discusses how she carefully selects a set of photographs to tell a larger story.
Program 2 Witness (video)
Photographs bear witness to world events and help us to learn more about people, places, and situations -- historical and present day. Middle school teacher Donald Rose guides students in analyzing photos from school integration movements of the 1960s. Documentary film producer Ken Burns weaves photographs into historical narratives to bring the past to life. Photojournalist Louie Palu's photos take us deep into mines and war zones, and engage us with the individuals who take on those tasks.
Program 3 Lives (video)
Lives explores the story of human resilience and perseverance. Middle school teacher Donald Rose uses the Migrant Mother photos by Depression-era photographer Dorothea Lange to help students understand what elements a photographer chooses to focus on to create the greatest impact. Historian Linda Gordon, biographer of FSA photographer Dorothea Lange reveals Lange's role in engaging Americans in the plight of those who were most devastated. New Orleans documentary photographers Keith Calhoun and Chandra McCormick talk about the transformation of their photographs after Hurricane Katrina and working with young photographers to preserve the city's cultural heritage.
video 4 Evidence (video)
An image can show us otherwise invisible processes, previously undiscovered life forms, and dramatic change over time. High school teacher Rima Givot engages her students with highly magnified photos of mouse muscle to study genetically modified organisms. Scientist and photomicrographer Dennis Kunkel demonstrates the fascinating process of creating photographs of the microscopic world. Environmental photographer Gary Braasch reports on his worldwide travels to document the state of the planet through repeat photography.
Program 5 Story (video)
Every photograph tells a story: of struggle, of beauty, of community and culture. Social studies teacher Kim Kanof uses photos from the Protests and Politics collection to teach about protests around in the world in 1968. National Geographic photo editor Pamela Chen details the collaborative process of creating photo-based feature stories with design director David Whitmore. Iowa photographer Danny Wilcox Frazier discusses his work documenting the residents and images of marginalized communities across the United States.