This global map of Mars shows the estimated radiation
dosages from cosmic rays reaching the surface, a serious
health concern for any future human exploration of the planet.
The estimates are based on cosmic-radiation measurements by
the Mars radiation environment experiment, an instrument on
NASA's Mars 2001 Odyssey spacecraft, plus information about
Mars' surface elevations from the laser altimeter instrument
on NASA's Mars Global Surveyor. The areas of Mars expected to
have the lowest levels of cosmic radiation are where the
elevation is lowest, because those areas have more atmosphere
above them to block out some of the radiation. Earth's thick
atmosphere shields us from most cosmic radiation, but Mars has
a much thinner atmosphere than we have on Earth.
The colors in the map refer to the estimated annual dose
equivalent in rems, a unit of radiation dose. The range is
generally from 10 rems (color-coded dark blue) to 20 rems
(color coded dark red). Radiation exposure for astronauts on
the International Space Station in Earth orbit is typically
equivalent to an annualized rate of 20 to 40 rems.
NASA's Jet Propulsion Laboratory, Pasadena, Calif. manages
the 2001 Mars Odyssey and Mars Global Surveyor missions for
NASA's Office of Space Science, Washington D.C. The Mars
radiation environment experiment was developed by NASA's
Johnson Space Center, Houston. Lockheed Martin Astronautics,
Denver, is the prime contractor for Odyssey, and developed and
built the orbiter. Mission operations are conducted jointly
from Lockheed Martin and from JPL, a division of the
California Institute of Technology in Pasadena.
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