Norbert Schorghofer of the University of Hawaii's Astrobiology Institute has claimed that the wobble of Mars could be the answer to the mysterious patches of ice on the mid-latitudes of Mars. Various spacecraft have revealed evidence of multiple ice ages on Mars. The only visible ice on Mars has been on the polar caps in the past (as shown in the above picture of the North Polar Ice Cap). However, orbiting probes have recently found evidence for vast sheets of underground ice near the planet's equator (as seen in the picture below of Kasei Vallis, one of the largest outflow channels on Mars).
The Earth's rotation axis is tilted by about 23.5 degrees, which is fairly fixed due to the Moon's gravitational influence. However, the tilt of Mars can vary as much as 10 degrees from its current 25-degree angle. These wobbles can cause vast amounts of ice to shift every 120,000 years. When the planet's axis sways one way, sunlight vanishes from some areas and increased in others. The areas in direct sunlight became warmer, causing the ice to recede. When the ice receded, it provided plenty of water vapor for new ice to form in the areas where there was less sunlight (this can be seen in the model below). Schorghofer believes that when the Phoenix lander arrives on the surface in 2008, it will see the abundant and layered ice forms.
No comments:
Post a Comment