NASA just announced that Mars Reconnaissance Orbiter data showing recurring slope lineae (RSL) are formed by water flowing at the surface of Mars today. This is big news. No, let me rephrase that: This is huge news … but not necessarily for the reasons emphasized by most headlines.
Here’s why:
We have known for years that brines are flowing in gullies every spring and summer. The big news is not really that.
The big news is first about the fact that the RSLs are a scientific mystery that has vexed scientists for years. We can now say, “mystery solved”! And solving that mystery has taken years of not only collecting images and looking for changes. On their own, these would not be enough to close that case. It was also about collecting spectra and mineralogical data, and thinking about converging evidence. It is about the resilience of a team that has used to its best science by testing hypotheses over thousands of observations. Reward after frustration.
But where the news becomes really huge is when we realize what it really means is that, indeed, water also forms the RSLs, and this is the real importance of this discovery. It means that water is more abundant and flowing more freely in more places on Mars than we had ever anticipated!
For all of us passionate about the search for life on Mars, this news is beyond exciting. Water is one of the key ingredients for life – not the only one, but one that is essential for life’s chemistry and metabolic activity. That gives one more chance for life to still be on Mars, if it had ever appeared early on.
Once again, water alone could not do it, but we also know that there was volcanic activity recently on Mars (in geologic terms ~ 500,000 years to a few million years ago.) This means that energy was there not long ago and, sheltered from cosmic rays and ultraviolet under the surface, life might just have found a way to survive. This makes the upcoming Mars 2020 and ExoMars missions all the more exciting. It also makes it a bit of more complicated to select landing sites for our landers.
As I mentioned, the presence of water increases the chances that life might have survived, and those regions where water is flowing today have become special regions overnight. It is now in the hands of the planetary protection folks to think about how to explore them.
Looking a bit farther into the future, more water on Mars is also very positive news for human exploration as it promises more resources for humans to produce their own fuel and other needs on Mars.
Yes, today’s announcement was huge.
