Global Flood on Mars: Where Did the Water Go?

News of evidence that Mars was once host to a volume of water equivalent of the Arctic ocean on Earth has been hitting the newswires.  This might sound like new news but this is really just a more comprehensive analysis of work that has been ongoing for several years.  Preliminary analysis had already suggested that there was much more water on Mars than had previously been assumed.  This new analysis simply nails down the volume of that water a bit more precisely.

What prompted my interest in this story is how the evidence of vast amount of water present on Mars in the past challenges young universe creationists who need to compress the entire history of Mars into a time span of not much more than 6000 years.  Many  young earth creationists now accept the evidence that water once flowed on Mars.  They can see that there are massive deposits of sedimentary rock, there are erosion patterns that suggest large rivers and there are shallow areas that have rock types that point to their formation in shallow oceans or lakes. For example here is Answer in Genesis’ Andrew Snelling in 2007:

“There is no longer any doubt that the surface of Mars has in the past been covered by huge volumes of water which spread over vast areas. These resulted from cataclysmic outflows, which were also responsible for catastrophic erosion of channels and valleys, on a scale far greater than anything comparable on Earth, and deposition of sedimentary strata.”  Water activity on Mars: Landscapes and Sedimentary Strata.

I especially like the part about catastrophic erosion of valleys far greater than on Earth.  It seems that Snelling believes that Mars experienced an even more violent Flood than Earth experience just 4500 years ago according to young earth creationists.  Even though a global Flood on Mars makes little sense Biblically (why should God feel he needs to destroy Mars for the sin of man on Earth?), Snelling and other Young Mars Creationists  (YMCs) seem to be driven by the physical evidence despite no one being there to witness the event or having any Biblical support to believe that there was cataclysmic flooding on Mars in the past.  There is no “I have a book” reason for believing this to be true.  I find this acceptance of historical science for past events on Mars by YMCs rather ironic given their insistence that conclusions of historical science are untrustworthy.

Astrogeologists, or exogeologists if you prefer, have concluded that Mars was wetter in the distant past – 4 billion years ago!  That time when liquid water flowed was so long ago that the erosion and dust deposition has made it difficult to interpret the water-produced geological features which are billions of years old.  Young earth creationists, most of whom also believe the entire universe is also 10,000 years old or less, believe that Mars is as young as the Earth. Therefore this wet period happened very recently.

So what happened to the water?

Creationists have speculated that there may be connection of the Flood on Earth and changes to the climate and possibly even a flood on Mars at the same time.  But the water on Earth is still here – at least most of it – and on Mars most of the water is gone.  There is some water in the polar caps on Mars and certainly some in the sediments but it is hard to hide an entire oceans worth of water.

Astrogeologists and chemists have been studying the history of Mars atmosphere and water and have concluded that Mars had a much thicker atmosphere in the past.   This is not surprising given that a more substantial atmosphere would be necessary to allow liquid water to be sustained on the surface. And they now agree that there was much more water.

So where did the water and the atmosphere go?

It escaped into outer space.

This latest research on Mars water provides us with even more evidence that this is what happened.  Satellites and numerous models of the interface of the atmosphere with space tell us that gasses are escaping from Mars today just as they are escaping from the Earth’s atmosphere.

One difference between Earth and Mars is that water can escape from Mars far more easily than it can from Earth which may explain why, if both began with water and thick atmospheres, that Mars is so different from Earth today.  But what is really cool is that we can do more than speculate about the past history of Mars. We can test our hypothesis about water on early Mars.

One way scientists can do this is by looking closely at the water itself.  There are two forms of water.  You can read more about the specifics of these water types here but for simplicity I will simply call them heavy and light water molecules.  As you might guess heavy water molecules are less likely to escape the upper atmosphere and so one would expect that as more light molecules escape the ratio of heavy to light should increase over time.

Very precise measurements now available for the Mars atmosphere allow us to compare the ratios of heavy to light versions of water for Mars and Earth.  Knowing those ratios the original amount of water can be calculated.  What those measurements reveal is that in the polar caps of Mars water for every 1 heavy water molecule there are 400 light ones but on Earth the ratio is 1 heavy water for every 3200 light water molecules. That is eight times as much heavy water on Mars. Therefore if Mars started with similar amounts of heavy water as the Earth then Mars must have had far more light water in the past.The calculations reveal that Mars has lost an arctic oceans worth of water to space.

You might object and say: but how do we know that Mars ever had the same ratio of heavy and light water?  Maybe God simply made Mars with a different ratio of water.   We weren’t there so how could we ever know?

No person was there to measure and record the ratio of water molecules four billion years ago. That is true, but there was something that was there and recorded it for us:  rocks that formed on Mars when water was present on the surface.  Rocks that formed and trapped water molecules should retain the original ratio of water on Mars.  We can measure the water ratios in these rocks today. This has been done with martian meteorites and may also be done with the help  of the drill that is found on the Mars Curiosity rover.

Water measured in ancient martian meteorites reveal ratios of heavy and light water that is similar to Earth’s current ratio. This is direct evidence that the original water on Mars was similar to water on Earth and therefore the very different ratio observed today is best explained by a dramatic loss of water from Mars into space.

The escape rate of water from Mars today suggests that such large volumes of water could have been lost to space over a billion years or more.  This data is very problematic to Young Mars Creationists who believe that this water existed less than 10,000 years ago.  Not only is there the ratio of heavy to light water problem but regardless of the type of water the loss of water to space is not a viable explanation given rather strict physical limits on the rate of water loss given the gravitational constraints of a body the size of Mars.  How could a trillion tons of water be lost to space in just a few thousand years!?  YMCs like Snelling will assert that the water is still on Mars but he can only do so by suggesting that much of that water remains hidden from our sight and that still would not account for the observed ratio of heavy to light water.

The simplest explanation for our measurements of  water on Mars and its atmosphere point us to an ancient watery origin followed by billions of years of loss of its atmosphere and water.  The young mars creationists must appeal to unknown mechanisms of loss, supernatural intervention, or assert missing data to provide any explanation for what we observe.  Mars hardly provides support for a young universe. Rather Mars has diverse geological features and an atmosphere that is most readily explained as the result of a lengthy process of geological and environmental changes.