What did Mars look like when it had water?

Four billion years ago, Mars was covered in water and had a thicker atmosphere that kept temperatures warm enough to maintain liquid water on the surface. Mars lost its magnetic field 3.7 billion years ago, and this could be one reason it also lost most of its atmosphere.



This video by NASA shows what Mars could have looked like in the past. The video flies over a fictional past surface of Mars, and as the video goes on, time passes, until Mars looks like it does today.

With an atmosphere, Mars was able to maintain heat on its surface, and thus maintain flowing rivers and the like, and had clouds. As the atmosphere gradually went away, the water evaporated or became frozen. The planet also became ice cold.

Source

Judging from Mars' current atmosphere, which has a high carbon dioxide content and low oxygen content, we could assume that the atmosphere in the past would have been similar. This would have been fine for plant life and the like.

The Martian atmosphere consists of approximately 96% carbon dioxide, 1.9% argon, 1.9% nitrogen, and traces of free oxygen, carbon monoxide, water and methane, among other gases, for a mean molar mass of 43.34 g/mol.

However, some scientists have declared that the atmosphere could have been "oxygen rich" in the past! So what caused the atmosphere to become too thin?

Possible causes for the depletion of a previously thicker Martian atmosphere include:

Gradual erosion of the atmosphere by solar wind,[71] possibly helped by Mars's magnetic-field irregularities;[72]

Catastrophic collision by a body large enough to blow away a significant percentage of the atmosphere;[72]

Mars's low gravity allowing the atmosphere to "blow off" into space by Jeans escape.[73]

Wikipedia: Atmosphere on Mars

There is evidence that earth once went through a stage of extremely low oxygen, but once plants came into the scene oxygen started pouring into the atmosphere to the point where some scientists are baffled how things didn't just burst into flames.

Cool find and read. When I get home I'm gonna read more on this.

originally posted by: strongfp
There is evidence that earth once went through a stage of extremely low oxygen,

Of course. When the Earth formed it was mostly devoid of oxygen and it was that way until about 2.5 years ago when photosynthesis took off.

but once plants came into the scene oxygen started pouring into the atmosphere to the point where some scientists are baffled how things didn't just burst into flames.

Cool find and read. When I get home I'm gonna read more on this.

Actually there was a mass die off due to mass forrest fires.

What no plants or animals? Surly if it had water there would have been grasses or moss at least? That vid just seems to show rocks and water, nothing else, that couldn't be, could it?

originally posted by: seanridesajones
What no plants or animals? Surly if it had water there would have been grasses or moss at least? That vid just seems to show rocks and water, nothing else, that couldn't be, could it?

No plants no life. Water is not a guarantee of life. There is plenty of sterile water around, even on Earth.

originally posted by: seanridesajones
What no plants or animals? Surly if it had water there would have been grasses or moss at least? That vid just seems to show rocks and water, nothing else, that couldn't be, could it?

I wouldn't say "that couldn't be, could it?". I mean, it certainly "could be" the case that it only had rocks and water.

Sure -- it could also be that it had plants, but science only has solid evidence of water, so that's what the video shows. Anything else would be speculation that is for the most part baseless.

originally posted by: seanridesajones
What no plants or animals? Surly if it had water there would have been grasses or moss at least? That vid just seems to show rocks and water, nothing else, that couldn't be, could it?

Water is not a guarantee of life. So yes, Mars could have been "just rocks and water."

Even if it did have life, and it originated and evolved in a similar way as on Earth, there wouldn't have been enough time for plants and mosses to appear. You see, on Earth, primitive single-celled organisms appeared about 3.6 billion years ago, and it took them about 2.6 billion years to evolve into multi-celled organisms. Land plants here appeared only 475 million years ago.

Mars (which formed around the same time as Earth) lost its magnetosphere 4 billion years ago, which led to the loss of most of its atmosphere and liquid water. Even if there was some basic single-celled life on Mars (and even if we give it a stretch to include some _very_ basic multi-celled organisms), it simply didn't have enough time for plants and mosses to evolve. At best, there could have been some green (or other colours) microbial goo and slime in the water and on wet rocks. But no grassy plains and forests, sorry.

en.wikipedia.org...

originally posted by: JadeStar
Of course. When the Earth formed it was mostly devoid of oxygen and it was that way until about 2.5 years ago when photosynthesis took off.

I may be dating myself here but I was around 2.5 years ago and photosynthesis didn't change much.

Of course i know you forgot the billion, and I wasn't around then. Some people apparently think 3 billion years ago but by 2.5 billion years ago for sure it had taken off.

a reply to: wildespace
Yes, if evolution on Mars existed and followed a remotely similar path to Earth, multicelled evolution would have taken a long time. But if Mars had evolution it could have followed a much different path. When our sample size of life-bearing planets like the Earth is one, it's hard to extrapolate from such a small sample what the range of possibilities might be on other planets. So Mars could have had faster evolution of life, or for all we know, it had perfect conditions for life but maybe life never developed there before the perfect conditions disappeared.

a reply to: seanridesajones

It very well could, it is our current understanding that water is necessary for life to exist, how ever it's presence does not mean that life will in fact have evolved or came to be on that world. There are plenty of bodies in our solar system that have ice as well as sub surface lakes or oceans... this does not mean there will be life, it's simply more probable.

At this time we can not critically say there was or wasn't life on mars, how ever we can say based on the evidence we have at this time that mars at one time had large flowing bodies of water. Thus the video represents this fact and this fact alone.