Geography professor receives
NASA grant to study
Martian valley networks

by Tom Parisi

Wei Luo, an NIU professor of geography, is leading a new study that aims to shed light on whether cold, desolate Mars has a wet, warm history that might have been more hospitable to life.

Luo’s team is examining the Red Planet’s extensive dry river valley networks to determine whether they were shaped predominantly by flowing rivers or by the action of groundwater, a process of erosion known as groundwater sapping. The valley networks are located throughout the southern highlands of Mars.

“The topography of Mars holds secrets to the planet’s climate history dating back billions of years,” Luo said. “Determining how the valleys formed on the Martian surface will begin to unlock those secrets and have important implications in the study of whether the planet ever could have supported life.

“If surface runoff is the dominant erosion style on Mars, then it must point to an early warmer and wetter climate with an Earth-like hydrologic cycle, including rainfall,” Luo added. “On the other hand, if groundwater sapping is the dominant erosion style, the valley networks could have been formed under current climatic conditions, perhaps under a thick ice cover.”

NASA is funding Luo’s three-year, $187,000 research project, which begins this spring.

In a preliminary report two years ago, Luo concluded that the Martian topography in an area called Margaritifer Sinus displays features of groundwater sapping and to a lesser extent surface-water runoff.

“The different processes generally leave different shapes on the landscape,” Luo said. “The key question I want to answer this time is the relative importance of each process in forming the valley networks. My gut feeling is that Mars at one time had a climate that was Earth-like. If you look at images of Mars and the patterns of the valley networks, they look just like the dendritic drainage systems found on Earth.”

Luo, of DeKalb, earned his Ph.D. at Washington University in St. Louis nine years ago. His dissertation on landforms in Egypt ultimately led to his current project. “Many aspects of landforms on Mars are remarkably similar to the landforms found in Egypt’s western desert,” Luo said. “That’s how I got interested in Mars.”

Raymond Arvidson, Luo’s adviser at Washington University, also encouraged Luo’s study of the Red Planet. Arvidson has had a role in nearly every NASA Mars mission since the 1970s, and is deputy principal investigator for the current Mars rover mission.

He and Alan Howard of the University of Virginia are collaborating with Luo in the study of Mars’ valley networks.

Under current atmospheric and climatic conditions, liquid water is unstable on the Martian surface, meaning that it either would freeze or evaporate almost immediately. NASA discovered ice at the planet’s south pole in 2002. This year, the rover mission has confirmed that water existed in a liquid form at one time on the Martian surface.

Luo’s research project will use Geographic Information Systems (GIS), high-resolution satellite imagery and computer simulations to examine valley network basins located in a wide range of latitudes and elevations. The relative importance of surface water, groundwater and impact cratering (from large meteoroids, asteroids or comets) in forming each basin will be determined. The study also will attempt to measure the secondary effects of wind, gravity and volcanic lava flow in modifying the valley network forms.

“My preliminary study didn’t consider impact cratering, which is another important process on Mars,” Luo said. “This time around, we’re using information from the topography of the moon to get the landform signature resulting from that specific process. The lunar landscape is pure craters. Our planet also was impacted by cratering, but because of rapid recycling of the crust through plate tectonics, most of Earth’s craters have been destroyed.”

By quantifying the surface characteristics, coupled with the computer simulation and image analyses, the researchers can infer past processes and thus past climatic conditions. Their study also could be useful to NASA for the selection of future landing sites, because the results will suggest where deposits generated by surface water or groundwater will most likely be found.

If the scientists conclude that surface water was plentiful on the Red Planet, then that does not necessarily mean that life existed there. “The presence of water is one necessary condition, but it’s not sufficient to say there was life,” Luo said. “That’s one of the motivations for sending astronauts to Mars.”

4-5-04