October 18th, 2006 11:26 EST
NASA Orbiter Reveals New Details of Mars
Washington -- During its first week of observations from low orbit, NASA's newest Mars spacecraft already is revealing new clues about recent and ancient environments on the Red Planet.
Scientists hope the Mars Reconnaissance Orbiter will answer questions about the history and distribution of Mars' water by combining data from the orbiter's high-resolution camera, imaging spectrometer, context camera, ground-penetrating radar, atmospheric sounder, global color camera, radio and accelerometers.
Between September 29 and October 6, science instruments on the spacecraft viewed dozens of sites that reflect different episodes in Mars' history. The sites provide a good test for the spacecraft instruments, according to an October 16 NASA press release.
The orbiter begins its primary science mission in early November, when Mars emerges from behind the sun.
DATA FROM MARS
The instruments are seeing details in the shapes and icy composition of geologically young layering in the planet’s surface near the Martian north pole. Other views offer details of a mid-latitude valley whose upper layers were eroded away, revealing an underlying clay layer that formed a few billion years ago, when wet conditions produced the clay.
Observations of a southern-hemisphere crater show fine-scale details of more recent gullies, adding evidence that they were carved by flowing water.
"The teams are getting amazing science data,” said Steve Saunders, Mars Reconnaissance Orbiter program scientist at NASA headquarters in Washington. “They are ready to fulfill the mission's science objectives and to support other Mars missions.”
One image already is helping the Mars Exploration Rover team choose a route to explore Victoria crater, now being visited by the Mars rover Opportunity. (See related article.)
Others images will help guide the selection of a safe site for the Phoenix Mars Lander, scheduled to launch in August 2007 and designed to measure gases and liquids (especially water) and complex organic molecules in the arctic plains of Mars.
Phoenix was so named because, like the mythical bird, it is rising from the remains of a predecessor, a 2001 Mars Lander that was never flown. Many parts are being reused and some newer pieces are being substituted for older parts to meet current engineering standards and to prepare this lander for its 2007 mission goals.
LIFE ON THE RED PLANET?
In Chasma Boreale, a vast valley that juts into the north polar ice cap, the orbiter's spectrometer sees layers that vary in soil composition and in how much ice is mixed with the soil. The spectrometer takes pictures in visible-light and infrared wavelengths useful for identifying the composition of the picture’s subject. A dark underlying layer contains little ice, but just beneath it is ice-rich material resembling higher layers.
"You see more-ice-rich and less-ice-rich layers, which tells you that conditions changed from the time one layer was deposited to the time another layer was deposited," said Scott Murchie of the Johns Hopkins University Applied Physics Laboratory in Maryland, principal investigator for the spectrometer.
"These layers are geologically young,” he added, “on the order of thousands or millions of years -- and may hold clues about climate cycles."
A lower-latitude target was Mawrth Vallis. The European Mars Express spacecraft previously discovered ancient deposits of clay minerals that could form only if water were present for a long time at Mawrth Vallis.
The Mars Reconnaissance Orbiter's spectrometer has resolved smaller-scale compositional features and detected differing clay mineral content. The clay-rich areas show some of the best evidence for conditions possibly favorable for life on ancient Mars, Murchie said.
The mission's High Resolution Imaging Science Experiment camera has shown unprecedented detail in orbital images of Mars. An example was released recently showing the Opportunity rover at Victoria crater. The camera imaged 64 areas on Mars during the testing week.
"These images are truly beautiful, and since they resolve features the size of people, you can visualize yourself hiking around in these diverse terrains," said Alfred McEwen, of the University of Arizona-Tucson and the camera's principal investigator.
The high-resolution camera, the imaging spectrometer and the orbiter's wider-looking context camera all observed Mawrth Vallis. Details visible in the new observations, such as small channels, are consistent with past wet conditions, McEwen added.
Another observation of an unnamed southern crater shows relatively young gullies. Braided channels characteristic of sediment-rich streams are visible in the new observations.
This reinforces the interpretation that these geologically young gullies formed at least in part from erosion by flowing water.
More information about the Mars obiter is available at the NASA Web site.
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