Polar Caps. Carbon Dioxide Ice. The Green Valley.
Some describe Mars as a sister planet to Earth. Like Earth, Mars has Northern and Southern polar regions consisting of water ice. Mars also has carbon dioxide ice within its polar caps, which makes it uniquely distinct from Earth. The changes within the Martian season prompts the carbon dioxide ice to vaporize in the summer; thus, revealing the surface of Mars, and freeze during the Martian winter. During fall, the polar caps grow due to the formation of clouds, and recedes in the spring as the clouds disperse.
Mars’s polar regions also contain vast sand dunes that thaw during springtime and cause dark spots to emerge on its surface. The repetition of the freezing and thawing ultimately form polygon-patterned marks on the Martian soil. These polygon shaped patterns are similar to the polygon structures on Earth’s polar regions.
The observable seasonal changes of Mars played a vital role in the landing site of the Phoenix Mars Lander. Notably, Phoenix landed 68 degrees north and 233 degrees east in Green Valley, Vastitas Borealis, Mars. The Green Valley is an arctic plain within the region of Vastitas Borealis and during May of 2008 the valley experienced a retreat of the Martian polar caps. After a long Martian winter, the polar caps began to recede; thus, allowing the Phoenix to optimize its mission. The receding of the polar caps allowed the Martian soil to gain exposure from the sunlight and created the best opportunity for Phoenix to study Mars’s climate.
The seasonal change also allotted Phoenix more time to operate during the daylight seeing as though the Martian polar summer afforded maximum sunlight. The exposure of the sunlight was an essential energy source for Phoenix’s solar panels and lithium-ion batteries. The sunlight provided energy for Phoenix’s robotic arm in addition to other instruments.
The Martian summer also uncovered the ice-rich soil of Mars which Phoenix sampled for indications of past or present habitability. The unique and distinctive features of the North Pole of Mars aided Phoenix in studying the climate and the potential existence of microbial life. Scientists new that water was present in the polar regions of Mars, but through the success of Phoenix they gained new evidence important to future Martian exploration missions.