Rock Slide in Ophir
Summary (May 07, 2004): Today's images from Mars include: Rock Slide in Ophir and Cut Crater in Reull Vallis (Released 6 May 2004), from the Mars Global Surveyor and 2001 Mars Odyssey spacecrafts.

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Rock Slide in Ophir

Images released by the orbiting instruments around Mars.

Cut Crater in Reull Vallis (Released 6 May 2004)

Cut Crater in Reull Vallis (Released 6 May 2004) Image Credit: NASA/JPL/Arizona State University

Parameter Value Parameter Value Latitude -40.1 Instrument VIS Longitude 99.1E (260.9W) Resolution (m) 19 Image Size (pixels) 1347x663 Image Size (km) 25.6x12.6 This image is part of the following themes: Best Craters Channels Color Full data on this image has now been released via the THEMIS Data Releases website. This daytime visible color image was collected on May 24, 2002 during the Southern Fall season in Reull Vallis. The THEMIS VIS camera is capable of capturing color images of the martian surface using its five different color filters. In this mode of operation, the spatial resolution and coverage of the image must be reduced to accommodate the additional data volume produced from the use of multiple filters. To make a color image, three of the five filter images (each in grayscale) are selected. Each is contrast enhanced and then converted to a red, green, or blue intensity image. These three images are then combined to produce a full color, single image. Because the THEMIS color filters don't span the full range of colors seen by the human eye, a color THEMIS image does not represent true color. Also, because each single-filter image is contrast enhanced before inclusion in the three-color image, the apparent color variation of the scene is exaggerated. Nevertheless, the color variation that does appear is representative of some change in color, however subtle, in the actual scene. Note that the long edges of THEMIS color images typically contain color artifacts that do not represent surface variation.

Left: Latitude -40.1 Longitude 99.1E (260.9W) Image Size (km) 25.6x12.6 Mars 2001 Odyssey, Thermal Emission Imaging System (THEMIS), Mars Orbital Laser Altimeter (MOLA) Team

Rock Slide in Ophir

Rock Slide in Ophir MGS MOC Release No. MOC2-719, 7 May 2004 Image Credit: Mars Global Surveyor, Malin Space Systems

The dark streaks, just left of center, on the steep slope in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image were formed by a relatively recent rock slide. The streak closest to the center of the image resolves into a series of small depressions, indicating the path of a large, rolling boulder. The rock slide is inferred to have been recent (i.e., within the past several Mars years) because it is so much darker than its surroundings---there has not been sufficient time for the streak surfaces to become mantled by dust. The other talus accumulations on this slope are most likely lighter in tone because they are older and coated with dust. These features are located in Ophir Chasma, part of the Valles Marineris trough system, near 4.2 degrees S, 74.0 degrees W. The picture is illuminated by sunlight from the lower left and covers an area about 3 km (1.9 mi) across.

About the Missions

By launching the Mars Global Surveyor (MGS) spacecraft in November 1996, NASA and the Jet Propulsion Laboratory began America's return to Mars after a 20-year absence. The Surveyor spacecraft is a rectangular-shaped box with wing-like projections extending from opposite sides. When fully loaded with propellant at the time of launch, the spacecraft weighed only 1,060-kilograms (2,342 pounds). The spacecraft travelled nearly 750 million kilometers (466 million miles) over the course of a 300-day cruise to reach Mars on September 11, 1997. During mapping operations, the spacecraft circled Mars once every 118 minutes at an average altitude of 378 kilometers (235 miles). After mapping finishes, the spacecraft will function as a communications satellite to relay data back to Earth from surface landers launched as part of future Mars missions.

2001 Mars Odyssey launched on April 7, 2001, and arrived at Mars on October 24, 2001. The mission is mapping the amount and distribution of chemical elements and minerals that make up the Martian surface. The spacecraft especially looks for hydrogen, most likely in the form of water ice, in the shallow subsurface of Mars. One of its three primary instruments is called THEMIS (Thermal Emission Imaging System), for determining the distribution of minerals, particularly those that can only form in the presence of water. It also provides the communications relay for U.S. and international landers, including missions in NASA's Mars Program, the Mars Exploration Rovers. The name "2001 Mars Odyssey" was selected as a tribute to the vision and spirit of space exploration as embodied in the works of renowned science fiction author Arthur C. Clarke.

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Related Web Pages

NASA
Jet Propulsion Laboratory
Malin Space Systems
Mars Global Surveyor
Arizona State THEMIS
Mars 2001 Odyssey

Note: Imagery: [2004-05-07]

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Friday, May 07, 2004