The Southwest Research Institute team has uncovered evidence of an ice age via polar deposits on Mars. NASA’s Mars Reconnaissance Orbiter was used during observations to collect the data. Ice ages on Mars are caused by a variety of processes, such as long-term cyclical changed in both the tilt and orbit of the planet. These adjustments affect the amount of solar radiation exposure within each latitude. Planet Earth works in very much the same way during ice ages.
Dr. Isaac Smith, lead author of the paper that was published in Science journal on May 27th says the team found an accelerated accumulation rate of ice in the highest 100 to 300 meters of the polar cap. Both the volume and the thickness of the ice matched models which predicted the event in the early 2000s. Radars were used to observe the ice cap, and their findings included a detailed history of both ice accumulation and erosion that were directly associated to climate changes.
Mars has annual rotation and seasonal cycles much in the way planet Earth does. Mars however, also has an increased number of noticeably longer cycles that influence ice distribution on the surface of the planet due to the fact that the tilt of the planet changes drastically (as much as 60 degrees) within timescales of hundreds of thousands to millions of years. During the same timeframe, Earth tilts an average of 2 degrees. Due to its larger variability, the amount of sunlight that touches any given spot on Mars creates dramatic stability fluctuations.
Smith says that the climate on Mars fluctuates with larger swings in axial tilt, causing ice to distribute differently during each swing. Because of this the planet looks far different today than it did in the past. Since Mars does not have any oceans, it works as a laboratory of sorts for better understanding the science behind the climate of Earth.
In depth measurements of the thickness of ice on Mars show that around 87,000 cubic kilometers of ice have compiled at the poles since the end of the last ice age which was around 370,000 years ago. Most of that ice went to the martian north pole. If spread out evenly across the surface, the accumulation adds up to a layer of just over 60 centimeters. This latest data helps researchers understand how ice accumulates in relation to the movements of the planet, including its orbital eccentricity, axial tilt and rotation surrounding the Sun. The new research will help create models for a more in depth understanding of martian climate and how ice moves from poles to mid-latitudes during climate cycles.
Smith explains that by learning more about the ice on Mars, we will have a much better handle on effective human exploration of the planet as water will be a very important resource for a martian outpost. The complete study was entitled “An ice age recorded in the polar deposits of Mars” and can be read in full in Science journal.