Neutron Mars
Explanation:
Looking for water on Mars, researchers using detectors
on board the
orbiting Mars Odyssey spacecraft have
created this
false-color global map
of energetic neutrons from the otherwise
Red Planet.
What do
neutrons have to do
with water?
As
cosmic rays
from interplanetary space penetrate the thin martian
atmosphere and reach the surface they
interact with elements in
the upper layer of soil, scattering neutrons back into space.
But if the martian soil contains hydrogen, it seriously absorbs
energetic scattered neutrons.
Tracking variations in absorption,
neutron
detectors can map changes in surface hydrogen content
from orbit.
Hydrogen content is taken as a surrogate measure of
frozen water (
H20),
the most likely
form of hydrogen
close to the martian surface.
Thus, bluer shades in the above map correspond to larger presumed
concentrations of near-surface water ice.
Water ice at the
martian poles came
as no surprise, but significant concentrations also seem to be
present at lower latitudes.
The melting of such near-surface
ice could be responsible for the formation
of martian gullies.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.
