A team of scientists recently discovered that water was once present in a region of Mars called Arabia Terra. The team includes scientists from Northern Arizona University and Johns Hopkins University.
Arabia Terra is a large upland region in the north of Mars. This region covers an area slightly larger than the European continent, contains craters, volcanic calderas, canyons, and beautiful bands of rock reminiscent of sedimentary rock layers in the Painted Desert or the Badlands.
These rock layers and their formation fascinated scientists.
NAU Ph.D. candidate Ari Koeppel said, “We were specifically interested in using rocks on the surface of Mars to get a better understanding of past environments three to four billion years ago and whether there could have been climatic conditions that were suitable for life on the surface.”
“We were interested in whether there was stable water, how long there could have been stable water, what the atmosphere might have been like and what the temperature on the surface might have been like.”
Scientists especially focused on thermal inertia to determine what happened to create the rock layers. Thermal inertia defines the ability of a material to change temperature. Sand, with small and loose particles, gains and loses heat quickly, while a solid boulder will remain warm long after dark.
Scientists determined the physical properties of rocks in their study area. Doing so, they could tell if the material was loose and eroding when it otherwise looked like it was solid.
Associate professor Christopher Edwards of NAU’s Department of Astronomy and Planetary Science said, “No one had done an in-depth thermal inertia investigation of these exciting deposits that cover a large portion of the surface of Mars.”
For this study, scientists also used remote sensing instruments on orbiting satellites.
Koeppel said, “Just like geologists on Earth, we look at rocks to try to tell stories about past environments. On Mars, we’re a little bit more limited. We can’t just go to a rock outcrop and collect samples — we’re pretty reliant on satellite data. So, there are a handful of satellites orbiting Mars, and each satellite hosts a collection of instruments. Each instrument plays its role in helping us describe the rocks that are on the surface.”
“We figured out these deposits are much less cohesive than everyone previously thought they were, indicating that this setting could only have had water for only a brief period of time.”
“For some people, that kind of sucks the air out of the story because we often think that having more water for more time means there’s a greater chance of life has been there at one point. But for us, it’s actually really interesting because it brings up a whole set of new questions. What are the conditions that could have allowed there to be water there for a brief amount of time? Could there have been glaciers that melted quickly with outbursts of huge floods? Could there have been a groundwater system that percolated up out of the ground for only a brief period of time only to sink back down?”
- Ari H.D. Koeppel, Christopher S. Edwards, Andrew M. Annex, Kevin W. Lewis, Gabriel J. Carrillo. A fragile record of fleeting water on Mars. Geology, 2021; DOI: 10.1130/G49285.1