In the search for life outside of Earth, a key indicator of its presence has long thought to be liquid water. Yesterday, NASA confirmed findings that liquid water may presently flow on Mars, but with two large caveats: the flow appears to be intermittent, and it is salty.
This new development comes from NASA’s Mars Reconnaissance Orbiter (MRO) – a satellite launched in 2005 with the express purpose of exploring the possibility of water on Mars. Using a spectrometer (a machine that measures light), researchers found streaks of light on several locations on Mars that change in intensity over time.
The behaviour of these streaks (known as recurring slope lineae, or RSL) seem to point towards briny water: they darken and flow down slopes during warmer seasons, and then fade during cooler times; just as liquid water does. The temperatures that cause the changes in the streaks point towards hydrated salts being present in the apparent liquid water.
In the header image above, the RSL is visible on the slopes of Mars in the Hale crater. The narrow, dark streaks are what NASA thinks is water. To give some scale: the streaks are said to be (about) four to five meters wide and 200 to 300 meters long.
To try and elaborate on the findings and give them some meaning, several scientists from NASA took to Reddit in an open forum to take questions from users. The most poignant question was, of course, can the water support life? Leslie K. Tamppari, Deputy Project Scientist at the Mars Program Office answered the question:
So, in the end, it’s a big, fat “maybe, we don’t know yet”.
Other important questions asked include the amount of water and the next step for NASA to further explore the findings. The water was estimated to be just enough to wet the top layer of the planet, and the next step is to look for more locations where the water may flow. Currently, NASA has only covered 3% of Mars at a high enough resolution to find what they’re looking for.
The take away here is that there are new developments that point towards life being present on Mars, but we know nothing for sure yet. We’ll just have to wait for more of the mysterious, red planet to be explored and for NASA to let us know what they find.
Here is a simulation of what the seasonal flows in the Hale creator may look like:
We spoke to Professor Hartmut Winkler, head of the Physics Department at the University of Johannesburg, who has a doctorate in astronomy, about the findings:
The discovery announced by NASA is very significant in that it provides us with important knowledge about the geology and physical processes taking place on Mars. It is also a crucial development in unravelling how the present Martian environment evolved. One should however not read too much into this announcement. The existence of water molecules on Mars was already well known. These are generally in the form of ice due to the much lower temperatures on that planet – it is the evidence of liquid water that had not yet been conclusively demonstrated. While the presence of water is critical for the development of practically all life forms that we know, conditions on Mars are in many ways very different to what we are familiar with (e.g. Mars has a carbon dioxide atmosphere, much lower surface gravity and is significantly colder). The discovery should therefore not be interpreted as a sign that the Martian environment could host advanced life comparable to Earth.