Mars, the red planet, wasn’t always the rusty wasteland we see it as today. The scientific community believes there was once liquid water on Mars, possibly even while there were humans roaming around the Earth, but are unsure how much water existed and for how long. While the history of Mars is becoming more explicit, we still don’t know most of the details of the ancient Martian surface, but due to the work of UW graduate student Elena Amador, we now have evidence to believe that there was water on Mars much later than previously believed, and a lot of it.
Amador, a graduate student in the UW department of Earth and space sciences (ESS) in the astrobiology program, recently published her first scholarly article as the lead author, titled “Elevated bulk-silica exposures and evidence for multiple aqueous alteration episodes in Nili Fossae, Mars.” Her article, co-authored by Joshua Bandfield of the Space Science Institute, examined spectral data collected by the Mars Reconnaissance Orbiter, one of the satellites that currently collects images of the Martian surface.
Amador focused on the Nili Fossae region of Mars, an area with distinct stratigraphy, visible rock layers that developed over long periods of time, making it an ideal site to study the geologic history of the planet.
In her article, Amador describes the three distinct layers: the deepest and oldest clay-rich layer; an intermediate layer characterized by the mineral olivine; and the youngest layer of rock, which is the layer analyzed by orbiters and the Mars rovers, known as the capping layer. Amador’s analysis of data from the Thermal Emission Imaging System data and Compact Reconnaissance Imaging Spectrometer for Mars revealed areas of silica abundance in the Nili Fossae region, which Amador then used to produce technicolor maps of the Martian surface.
Amador suggests that this silica abundance in the capping layer of Mars may be due to an aqueous alteration, meaning that a large volume of water washed out certain minerals from the capping layer, leaving the more stable silicate minerals behind as geologic evidence.
The capping layer was commonly believed to be the relatively uninteresting top layer of rock, due to a lack of evidence of aqueous alteration. However, Amador’s analysis suggests otherwise.
“This capping unit that people previously thought was not altered, is altered, which extends the time period, in Nili Fossae specifically, where you had sustained aqueous activity to its stratigraphically youngest unit,” Amador said.
While this kind of geologic evidence doesn’t provide a definitive answer on the history of water on Mars, it does bring the scientific community a step closer to revealing Mars’ past.
Steven Sholes, a graduate student in ESS, said that Amador’s work contributes to the broader knowledge of the Martian surface and how it was formed.
“It falls under the whole idea of understanding the geological history of Mars, which over the past three or four decades we’ve been piecing it together since the Mariner Missions,” Sholes said.
Sholes studies the habitability of Mars and cites liquid water as one of the most basic elements of a potentially habitable Mars. However, it has to be present in large quantities and sustained long enough for life to develop and evolve.
“All three main stratigraphic units of Nili Fossae show evidence for having water flowed through it and altered the composition,” Amador said.
This suggests that throughout the history of this region of Mars, liquid water was present for long enough periods to leave mineralogical evidence in the rock layers, Amador said.
Whether or not that’s long enough for life to begin on Mars has yet to be proven, but as one of just two astrobiology programs in the nation, the UW is sure to be at the center of space exploration and the piecing together the multibillion-year-old story of our next-door neighbor.
Amador’s contributions to the collective knowledge of Martian history are happening in an exciting era of space exploration, one that involves missions to Mars and beyond, as well as a continuous collection of data that is available to researchers and the general public.
“The cool thing about Mars is that there’s all this data out there,” Amador said. “You have to think of new ways to look at it to try and tease out what the important, or interesting, or new information may be.”
Reach contributing writer Mallory Culbertson at email@example.com. Twitter: @malculbertson