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Computer Simulations of the Martian Atmosphere Interacting with the Solar Wind
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Mars possesses no significant intrinsic magnetic field. The absence of magnetic
protection allows the supersonic solar wind flow to directly interact with the
Martian ionosphere (an almost fully ionized region of the Mars upper
atmosphere). When the velocity of the solar wind increases,
the Martian ionosphere is compressed and the ionopause (a boundary layer
between the ionosphere and the solar wind) is displaced to lower altitudes.
The ions of planetary origin such as O+ and O2+ escape from the upper
atmosphere of Mars due to solar wind induced scavenging processes. Many more
planetary ions are scavenged when the solar wind velocity increases because a
much larger part of the planetary atmosphere is exposed to the solar wind as
the ionopause is pushed inwards towards the planetary surface.
There are some indications that the solar wind flow, as well as the Sun's x-ray
and extreme ultraviolet radiation, were much more intense early in solar system
history. It is thought that some 3.5 billion years ago, these extreme
interplanetary conditions may have caused a much larger rate of water loss from
the Martian atmosphere. We estimate that the solar wind scavenging pictured
here under the extreme conditions in the early solar system would have caused
the loss of a 10 meter global equivalent ocean layer from Mars over the last
3.5 billion years. This loss is less than one tenth of the 156 m global
equivalent ocean layer estimated to have existed on early Mars using the Mars
Global Surveyor observations.
Arrows represent the flow of the ions of planetary origin. The colors represent the density of the
Martian ionosphere, with red as high and blue as low.
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This movie shows a simulation of the impact of the solar wind on the Martian atmosphere.
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The view of Mars from the opening movie frame.
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In the case of low solar wind pressure, the sunward side of the ionosphere is thick (the red region) and some of the atmosphere can be seen trailing off behind the planet.
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For the faster solar wind, the Martian ionosphere becomes
thinner and many more planetary atmosphere is scavenged by
the solar wind (see text).
View the image:
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TIFF
4 MB
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Studio: SVS
Writer: Bill Steigerwald
Date Completed: July 08, 2004
Duration: 509 frames,
16.97 seconds
Scientist: Naoki Terada (Solar-Terrestrial Environment Laboratory; Nagoya
University; Japan), Hiroyuki Shinagawa (Solar-Terrestrial Environment
Laboratory; Nagoya University; Japan)
Keywords: Mars, Atmosphere, Solar Wind
DLESESubject: Space science
Animation Series: Halloween 2003 Solar Storms
Please give credit for this visualization to NASA/Nagoya University
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