Mars Reconnaissance Orbiter sends photographic clues of water flowing on Mars
By Amanda Jermyn

We’ve long known that water once flowed on Mars, and it is currently abundant on the Red Planet in the form of ice. Water ice covers its north pole. It also lies beneath carbon dioxide ice at its south pole and below the surface elsewhere in warmer latitudes. In fact, enough ice has been identified on Mars to cover the planet to a depth of about 115 feet, and there is probably even more deeper down.

While ancient Mars had warmer temperatures and higher atmospheric pressures that allowed for liquid water, its current temperatures and pressures were thought to be far too low. Recently, however, NASA’s Mars Reconnaissance Orbiter and Odyssey Orbiter have been taking photographs that reveal strange dark streaks. These are intriguing researchers with their mysterious features, and may be evidence of water flowing on Mars today.

Lujendra Ojha, a graduate student at the Georgia Institute of Technology, first identified the streaks as potential saltwater flows while an undergraduate at the University of Arizona in Tucson. He is the lead author of two recent reports on these features in the journals Icarus and Geophysical Research Letters. The recurring slope lineae, as they are known, appear to flow downhill. They are visible only during the late Martian spring and summer, and then disappear as the weather cools. The thin streaks, located around the equator, cover long distances and branch out as if they were rivers.

This is not the first time that dark materials have been observed on Mars. In the 1970’s the Viking Orbiter recorded evidence of such matter that appeared from time to time on crater walls and other steep slopes on Mars. Researchers determined that they were caused by avalanches disturbing the surface layer of dust. However, these were very different from the recently discovered dark streaks. They were much wider, and appeared at random times throughout the Martian year.

The recently discovered recurring slope lineae are now thought to be the result of ice in the soil heating up, becoming liquid and flowing downhill. But how could this be, given that the temperatures on Mars are too cold for liquid water, even in the summer? Researchers suggest that the flows are brines containing iron-rich minerals, such as ferric sulfate, that act as a kind of antifreeze, letting the water remain liquid despite temperatures below freezing. These iron-rich minerals have, in fact, been found to be more abundant in recurring slope lineae than elsewhere on Mars. They are also more abundant in warmer weather when water is more likely to flow. Lujendra Ojha maintains that while no definitive proof currently exists of water flowing on Mars, there is no other likely explanation for these features.

According to Richard Zurek, the Jet Propulsion Laboratory’s Mars Reconnaissance Orbiter project scientist, “The flow of water, even briny water, anywhere on Mars today would be a major discovery, impacting our understanding of present climate change on Mars and possibly indicating potential habitats for life near the surface on modern Mars.” While the rover Curiosity currently exploring Mars is not equipped to detect life, NASA plans to send another rover to the Red Planet in 2020 to look for signs of past life and collect samples for future return to Earth. With the recent discovery of potential water flows, that search might just possibly reveal signs of life on Mars today.

Join the Springfield Stars Club on Tuesday, March 25th at 7:30pm at the Springfield Science Museum for a talk by Dr. David Wexler on “Space and Time.” Dr. Wexler will discuss concepts of space, time and energy, and provide insights into Einstein’s Theory of Relativity. A Stars Club board member, Dr. Wexler studied neuroscience and engineering at Case Western Reserve University, and completed medical studies at Stanford University. He works as an ear, nose and throat specialist at Wing Memorial Hospital in Palmer. Dr. Wexler has a Master’s degree in astronomy and is currently a distance-learning student in astronomy-physics with Open University, UK. Refreshments will be served, and the public is welcome. The meeting is free of charge for members, with a suggested donation of $2 per non-member.