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Science Instruments: MARSIS |
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What is MARSIS?
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An artists drawing of Mars Express
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MARSIS is a subsurface radar sounder with a 40-meter (130-foot) antenna on the Mars Express orbiter that will search for water and study the atmosphere.
Once Mars Express is in orbit around Mars, the MARSIS antenna will
unfurl and begin its radar analysis. The main objective of MARSIS is to look
for water from the martian surface down to about 5 kilometers (3 miles)
below. It will provide the first opportunity to detect liquid water directly.
It will also be able to characterize the surface elevation, roughness, and
radar reflectivity of the planet and to study the interaction of the
atmosphere and solar wind in the red planet's ionosphere. During the
lifetime of the mission, the instrument will be able to conduct
ground-penetrating studies over the entire planet. [More on MARSIS:
Searching for Water and Studying the Atmosphere]
How MARSIS Works
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An artists drawing of Mars Express
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The technique used by this radar instrument has been used before on
Earth. Similar instruments have been flown on low-flying aircraft to probe
deep into the ice sheets of Antarctica and Greenland. At Mars, the
instrument with its long antenna will fly over the planet, bouncing radio
waves over a selected area and then receiving and analyzing the "echoes."
Any near-surface liquid water should send a strong signal, while ice would
be more difficult to detect since its electrical radar signal would be about the
same as rock. The echoes will also help characterize the materials and
roughness of the surface.
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