Green Valley (Mars)
Encyclopedia
Green Valley is a region on Mars
within Vastitas Borealis
that was chosen as the landing site of NASA
's Phoenix
lander. It is located at 68.35 degrees north, 233 degrees east. The valley is about 50 kilometres wide but only about 250 metres deep; either it was filled in or was never any deeper than that. The edges are not visible from the middle of the valley.
The name "Green Valley" is not officially recognised by the International Astronomical Union
. It came from the decision process by which it was selected as Phoenix's landing site: prospective landing areas were color-coded based on how hazardous they were, with red being most hazardous through yellow to green being the safest. Green Valley has relatively few of the large boulders that could potentially have tipped the lander if it had hit one during touchdown.
The ground within Green Valley is covered with polygonal features several metres across and roughly ten centimetres high, thought to be caused either by repeated freeze-thaw cycles (ice-wedge polygon
s) or by the effects of wind-blown dust (sand-wedge polygons). Water ice is thought to be just below the surface. During the local winter as much as three feet of carbon dioxide ice is expected to appear on the surface.
Shortly before Phoenix's scheduled landing, the Mars Reconnaissance Orbiter
photographed a pair of kilometer-tall dust devil
s in the Green Valley area.
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
within Vastitas Borealis
Vastitas Borealis
Vastitas Borealis is the largest lowland region of Mars. It is in the northerly latitudes of the planet and encircles the northern polar region. Vastitas Borealis is often simply referred to as the Northern plains or Northern lowlands of Mars. The plains lie 4–5 km below the mean radius of...
that was chosen as the landing site of NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
's Phoenix
Phoenix (spacecraft)
Phoenix was a robotic spacecraft on a space exploration mission on Mars under the Mars Scout Program. The Phoenix lander descended on Mars on May 25, 2008...
lander. It is located at 68.35 degrees north, 233 degrees east. The valley is about 50 kilometres wide but only about 250 metres deep; either it was filled in or was never any deeper than that. The edges are not visible from the middle of the valley.
The name "Green Valley" is not officially recognised by the International Astronomical Union
International Astronomical Union
The International Astronomical Union IAU is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy...
. It came from the decision process by which it was selected as Phoenix's landing site: prospective landing areas were color-coded based on how hazardous they were, with red being most hazardous through yellow to green being the safest. Green Valley has relatively few of the large boulders that could potentially have tipped the lander if it had hit one during touchdown.
The ground within Green Valley is covered with polygonal features several metres across and roughly ten centimetres high, thought to be caused either by repeated freeze-thaw cycles (ice-wedge polygon
Patterned ground
Patterned ground is a term used to describe the distinct, and often symmetrical geometric shapes formed by ground material in periglacial regions...
s) or by the effects of wind-blown dust (sand-wedge polygons). Water ice is thought to be just below the surface. During the local winter as much as three feet of carbon dioxide ice is expected to appear on the surface.
Shortly before Phoenix's scheduled landing, the Mars Reconnaissance Orbiter
Mars Reconnaissance Orbiter
Mars Reconnaissance Orbiter is a NASA multipurpose spacecraft designed to conduct reconnaissance and Exploration of Mars from orbit...
photographed a pair of kilometer-tall dust devil
Dust devil
A dust devil is a strong, well-formed, and relatively long-lived whirlwind, ranging from small to large . The primary vertical motion is upward...
s in the Green Valley area.