October 20, 2015
When news broke in September that a team of scientists and researchers had found evidence of liquid water on Mars, Georgia Tech assistant professor and Hertz Fellow James Wray had never seen a reaction quite like it.
Heralded by many as a breakthrough that could transform long-held perceptions of the Red Planet as a dry, arid wasteland, Wray’s team analyzed strange dark streaks that formed during warm seasons, trickling down the planet’s hills before disappearing in colder seasons, using hardware aboard NASA’s Mars Reconnaissance Orbiter (MRO).
With the orbiter’s Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), the researchers determined the streaks, known as recurring slope lineae (RSL), contained hydrated salts—magnesium perchlorate, magnesium chlorate and sodium perchlorate—strongly indicating the presence of flowing water on Mars. When the discovery was made in January, Wray could barely contain his glee.
“I thought we were just testing out this new spectrometer, and lo and behold the (perchlorate) spectrum matched exactly what we were seeing on Mars,” Wray said. “Having done infrared spectral analysis on Mars for years, it’s rare that you find something that matches quite that well, let alone on the first day of looking for it. It was really exciting.”
These dark, narrow, 100 meter-long streaks called recurring slope lineae flowing downhill on Mars are inferred to have been formed by contemporary flowing water. Recently, planetary scientists detected hydrated salts on these slopes at Hale crater, corroborating their original hypothesis that the streaks are indeed formed by liquid water. The blue color seen upslope of the dark streaks are thought not to be related to their formation, but instead are from the presence of the mineral pyroxene. The image is produced by draping an orthorectified (Infrared-Red-Blue/Green(IRB)) false color image (ESP_030570_1440) on a Digital Terrain Model (DTM) of the same site produced by High Resolution Imaging Science Experiment (University of Arizona). Vertical exaggeration is 1.5. Image credit: NASA/JPL/University of Arizona.
The paper describing the team’s findings, published in the September 28 issue of Nature Geoscience, included researchers from the NASA Ames Research Center, the University of Arizona, the Applied Physics Laboratory, and Southwest Research Institute.
Wray, an assistant professor of earth and atmospheric sciences at Georgia Tech, advised the paper’s lead co-authors Lujendra Ojha and Mary Beth Wilhelm. The discovery, he said, is encouraging news for the future of human exploration of Mars and for the potential for life on the Red Planet.
“Getting the spectral fingerprint that only the H2O molecule could reproduce is reassuring and changes the game,” he said. “If Mars does have life today, these (recurring slope lineae) are the best place to look.”
Wray’s moment in the spotlight was a long time coming. Born in New York City and raised near Princeton University, science was always his favorite school subject — he eventually decided on planetary science as a way to incorporate “all of the sciences.” Seeing the film adaptation of Carl Sagan’s book, Contact; in high school solidified his interest in the search for extraterrestrial life.
“It came at a formative time for me,” Wray said. “Something having to do with the question ‘is there life elsewhere?’ was appealing early on.”
Wray obtained a Hertz Fellowship in 2006, which he credited with giving him the freedom to find a path that suited his goals. After graduating from Princeton with a degree in astrophysical sciences, he moved on to Cornell to work with Steve Squyres, the lead investigator on the Mars Exploration Rover project.
Despite initially thinking he would work on rovers at Cornell, Wray shifted over to the High-Resolution Imaging Science Experiment (HiRISE) on the Mars orbiter, and CRISM, which provided an infrared spectral analysis of the planet that images alone couldn’t do.
“The real boon for me was that (rovers) Spirit and Opportunity outlived their originally planned lifespans for years,” Wray said. “Squyres didn’t have the time, so he needed a student to look at the orbital images from Mars.”
Motivated by the quest for finding life in places that have or have had liquid water, such as Mars or the moons of Jupiter and Saturn, Wray received his master's and PhD in astronomy from Cornell, gaining expertise in planetary surface processes, climate history and aqueous environments on Mars, oceans in the outer solar system, and spacecraft remote sensing.
Wray is currently serving in several capacities for NASA, including principal investigator for a project funded under NASA’s Outer Planets Research program and co-investigator for HiRISE and CRISM.
The latest Mars breakthrough is only provoking more questions, Wray said. Where is the water coming from? Is it springing from an underground aquifer, is it a result of melting ice? Are salts sucking the water vapor out of the atmosphere? If we send humans to Mars, will this mean they won’t have to bring their own water?
To better answer those questions, Wray wants the scheduled multi-agency ExoMars mission to look specifically at recurring slope lineae at certain times of the day when they might be most active, and eventually, more rovers that can sniff around the RSL for evidence of biological organisms.
“Now that we know there’s this salty water there, I’d want to be more ambitious; not just to see, but to touch,” Wray said.
And, if a manned mission to Mars becomes reality within the next 20 years, as NASA has proposed, Wray wants to be a part of it.
“If you give me the chance to go and explore this world that so fascinates me, I would certainly want to be involved, at least in a supporting role,” he said.