Martian polar ice caps revealed in 3-D
Three-dimensional subsurface images are revealing unprecedented new insights into the structure of the Martian polar ice caps. The 3-D images were produced by data from the Shallow Radar (SHARAD) instrument on board NASA’s Mars Reconnaissance Orbiter (MRO) over the course of more than 2,000 orbital passes over each Martian pole.
The images reveal previously obscured layering that points to a larger volume of carbon dioxide than originally thought, as well as bowl-shaped features within both polar ice caps that may be buried impact craters.
Nathaniel E. Putzig, a senior scientist at the Planetary Science Institute in Tucson, Arizona, is a co-author of the study “3-D Imaging of Mars’ Polar Ice Caps Using Orbital Radar Data” that is being published in a special section on remote sensing in the January issue of The Leading Edge.
“We have applied industry-developed techniques in a very novel fashion to a Martian dataset, producing 3-D volumes that are each over 600 times larger than any terrestrial or planetary dataset of this kind,” Putzig said.
“This work literally adds another dimension to the SHARAD data beyond what has been available to planetary scientists in the past,” said Frederick Foss of Freestyle Analytical & Quantitative Services and the lead author on the paper. “While 3-D seismic and ground penetrating radar have become routine tools in terrestrial geophysical exploration, our 3-D treatment of the SHARAD data is a first in planetary geophysical exploration.”
Layering has been observed in the ice at the Martian poles for decades and has long been thought to represent climatic changes, much in the same way as layers seen in the ice at Earth’s poles. The climatic record retained in the ice at Earth’s poles has been studied by way of core samples or by ground penetrating radar techniques; however, until radar-sounding equipment arrived at Mars, the internal extent of this layering in the Martian poles remained a mystery.
Single-orbit profiles of SHARAD data had previously been used to help make many important discoveries, but the new study represents one of the first uses of the comprehensive volume of 3-D data products that exist for both polar caps in their entirety.
In addition to providing increased estimates for the amount of carbon dioxide ice at the south pole, suspected craters have been observed at both poles as well. Known impact craters that are partially filled with ice have distinctive bowl-shaped signatures on radar data. Similar bowl-shaped signatures have been found elsewhere within the polar caps but without any surface expression.
If these features are determined to be impact craters, then revised ages of the polar caps via crater counting could be calculated. The extent to which these relate to previous estimates generated via climate modeling could have implications for understanding how the Martian climate and polar caps have evolved.
“It is gratifying to see so plainly in the SHARAD volumes structures that took years of effort to characterize with the single-orbit profiles,” Putzig said. “I’m excited about what we will learn from newly revealed features such as the probable impact craters.”
Paul is currently a graduate student in Space and Planetary Sciences at the University of Akransas in Fayetteville. He grew up in the Kansas City area and developed an interest in space at a young age at the start of the twin Mars Exploration Rover missions in 2003. He began his studies in aerospace engineering before switching over to geology at Wichita State University where he earned a Bachelor of Science in 2013. After working as an environmental geologist for a civil engineering firm, he began his graduate studies in 2016 and is actively working towards a PhD that will focus on the surficial processes of Mars. He also participated in a 2-week simluation at The Mars Society's Mars Desert Research Station in 2014 and remains involved in analogue mission studies today. Paul has been interested in science outreach and communication over the years which in the past included maintaining a personal blog on space exploration from high school through his undergraduate career and in recent years he has given talks at schools and other organizations over the topics of geology and space. He is excited to bring his experience as a geologist and scientist to the Spaceflight Insider team writing primarily on space science topics.