Computer Simulations of the Martian Atmosphere Interacting with the Solar Wind
Tom Bridgman, Marte Newcombe, Cindy Starr, Naoki Terada, Hiroyuki Shinagawa, NASA GSFC Scientific Visualization Studio, NASA GSFC Scientific Visualization Studio, NASA GSFC Scientific Visualization Studio, Solar-Terrestrial Environment Laboratory; Nagoya
University; Japan, Solar-Terrestrial Environment
Laboratory; Nagoya University; Japan
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 Suns 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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