APOD: 2007 August 5- The Dotted Dunes of Mars
Explanation:
What causes the black dots on dunes on Mars?
As spring dawned on the Northern Hemisphere of
Mars in 2004, dunes of sand near the poles begin to defrost.
Thinner regions of ice typically thaw first
revealing sand whose darkness soaks in sunlight and accelerates the thaw.
The process might involve
sandy jets exploding through the thinning ice.
By summer, the
spots expanded to encompass the entire
dunes that were then completely thawed and dark.
The
carbon dioxide and water ice actually
sublime
in the
thin atmosphere
directly to gas.
Taken in mid-July, the
above image shows a field of
spotted polar dunes spanning about 3 kilometers near the Martian North Pole.
Today, the future of
Mars rovers
Spirit and
Opportunity remains
unknown
windy dust storms continue to starve them of needed sunlight.
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.
