What does water on Mars really mean?

The announcement that scientists have discovered evidence of liquid water flowing on Mars has stirred up excitement around the world.

Scientists from NASA’s Mars Reconnaissance Orbiter (MRO) mission have taken part in an Ask Me Anything (AMA) session on Reddit to elaborate on the discovery.

Questions ranged from why the “average Joe” should care about possible water on Mars, to whether the discovery meant Martians might see rainbows.

Answers were given by NASA Mars Program Office chief scientist, MRO project scientist Rich Zurek and MRO deputy project scientist Leslie Tamppari.

Q: How much liquid water are we talking about? Like tap water leaking when you don’t close the valve tight enough, or Niagara falls?

A: Tap water leaking. – Rich Zurek

Q: I read that the rover can’t approach specific areas (including where the streaks are located) due to risk of infection by Earth microbes. What are some examples of microbes that could be living on the rover that you are concerned with infecting the surface of Mars?

A: These features are on steep slopes, so our present rovers would not be able to climb up to them. Because liquid water appears to be present, these regions are considered special regions where we have to take extra precautions to prevent contamination by Earth life.

Our current rovers have not been sterilised to the degree needed to go to an area where liquid water may be present. – Rich Zurek

Click through the gallery below for images of the water discovered on Mars. Post continues after gallery.

Q: Given the seasonal nature of today’s discovery, does this suggest that their is a hydrologic cycle on Mars?

A: There is a hydrologic cycle on Mars, but typically it involves vapor going to ice (frost) or ice going to vapor.

There is no rain in Mars today, but there may have been very early in its history. – Rich Zurek

Q: In the articles I’ve read so far, the water is referred to as “briny” and that it’s more fluid than it is water. What does that mean?

Would this be something theoretically possible to drink or grow things with? Or would this be the kind of thing that would need purification before it could be used?

A: The salts in the water appear to be perchlorates, so I wouldn’t want to drink the water. To be a future resource for humans, you would want to remove the salts. – Rich Zurek

Q: It was shown back in 2011 that salt water flows may be a seasonal occurrence. What was the final proof for the team that this was happening?

A: With MRO, we were able to observe a few of these sites at various points within the Mars year, and again the next year.

Over time, we saw that the streaks darkened and lengthened during the warm season and faded during the cold season.

A benefit of having MRO lasting so long is that we’re able to see changes and patterns over time. – Leslie Tamppari

Q: Is there any evidence of evaporation happening on Mars? And do you know where this water came from?

A: New impact craters on Mars sometimes have bright ice exposed in the bottom of the crater. This goes away over a few months.

The ice, when exposed, is going from solid to vapor. Evaporation of a briny flow will also occur, so the water needs to be resupplied. We don’t know how. – Rich Zurek

Q: Why should the average Joe care about this? What does this mean for science and space exploration?

A: Liquid water, even if very salty, is still a good place to look for life forms. We don't know how robust Martian life (if it exists) could be.

Also, water in any form is a resource that future missions could exploit. - Rich Zurek

Q: With the discovery of water on Mars does that mean there could be rainbows on Mars?

A: Not quite rainbows, because there is no rain, but we have seen icebows with the Pathfinder mission. - Rich Zurek

Q: Is NASA now considering putting a man on Mars to get more data on this or can we find all the information without having a man/woman on Mars?

A: The basic answer is yes, NASA is planning to send humans to Mars in the 2030s. It's always helpful to have more information before sending them, and that's why our robotic explorers are so important. - Leslie Tamppari

Q: What's the next step?

A: The next step is to look for more locations where brine flows may occur. We have covered 3 per cent of Mars at resolutions high enough to see these features. - Rich Zurek

This post originally appeared on the ABC and was republished here with full permission. 

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