Huge area of debate right now. The entire border between the northern plains of Mars and the southern highlands appears like an eroded dried coastline, but at the same time, it could be the effect of some other cause. It’s odd how the entire northern plains has very little impact craters, while the rest of Mars has many more impact craters, so some people suspect that the impacted areas had been land since Mars’s creation, and the desolate northern plains is the remnants of a dried up water ocean (which would’ve soaked up the impact energy from any asteroid without it leaving a mark on Mars’s surface).
Well on that note, I think we should remember that there are mountains starting at the bottom of our Earthly oceans that, from top to bottom, are much taller than Everest, Everest is the highest above sea level. Many of them are caused by volcanic activity. From this photo Olympus almost looks like a continent or a large island. Those look like cliffs surrounding it which you tend to see on Earth as a result of water erosion.
Oftentimes, the actual study of Martian topography is “look at mars, look for Earth similarities”, and for the time being, a continental ocean seems like the most plausible answer. But, there is an extreme scarcity of carbonates on Mars, and carbonates form when carbonic minerals react with other minerals when dissolved in water, where it would then precipitate out during the drying of the ocean. But, we see nearly nothing, so the likelihood of an ocean is still up for debate.
Btw, all this info comes from Caltech professor John Brown, planetary astronomer. His course on Coursera is amazing.
Yup. All I’m doing is supplying both sides. That’s why it’s debated among the scientific community, and also why we continue to send probes to Mars. It’s one of many reasons why we sent Perseverance to the Jezero Crater: it is on that border, and has inflow and outflow channels that would either be resulting from a period of heavy precipitation (thought to have happened between the Noachian, warm and wet, period, and the Hesparian, beginning to dry, period), or a river delta.
Well I value people who are able to argue for a side they don’t necessarily agree with. I think it shows objectivity, which is essential in the search for knowledge
I mean it could be water but a slightly different chemistry ocean, meaning it doesn't producer carbonates. Or the remnants disappear over time under harsh conditions after the ocean dries up.
I’m pretty sure it’s either water or no liquid for Mars. I’m not a chemist or a geologist but I think that any other liquids have been ruled out. some moons around gas giants contain oceans of liquids like ammonia.
So it couldn't be liquid CO2 pr anything like that? With the prior volcanic activity and already present CO2 levels in the Mars atmosphere, I thought there would be a slight chance.
Carbon dioxide requires significant pressures to liquefy, otherwise it just bounces back and forth between solid and gas. Pretty sure that rules out CO2.
Yep. Ever play with dry ice? It doesn’t melt, you just see the smoky look, no liquid at all. If you take a container with carbon dioxide in it and cool it, it will eventually start to deposit as solid on the inside of the container, but it won’t condense as liquid first.
Only way to get it liquid is with significant pressure.
The very basic tl;dr is that any state (solid, liquid, gaseous) depends on two parameters, temperature and pressure.
The sCO2 phase diagram shows that the liquid state (dark blue) of carbon dioxide only exists within a specific temperature and high pressure range, meaning conditions would have to be just right to have CO2 oceans long enough (millions of years) for erosion to even take place in a significant manner.
Hydrogen and Oxygen are the second and third most common elements in the universe and therefore water is an extremely common compound, its the most common multi element compound in the universe. Water is always a good go to when evidence of the presence of a liquid is found.
Definitely not. The conditions required for something like that would require too high of pressures to be reasonable on a body with as little mass as Mars.
Might sound like a pedantic question but how certain are we of the conditions necessary for carbonic
mineral formation? My understanding is that they require dissolved CO2 to form. And the solubility of
CO2 is dependent on many factors like acidity of the water, pressure (and atmospheric pressure on mars would be far lower than on earth), and temperature, in addition to CO2 concentration in the atmosphere.
I mean, I’m not an expert in it, but there is a segment of the course on solely the mineralogy of Mars, taught by not Brown but instead another Caltech professor who literally studies exactly that. Her name is Bethany Ehlmann, and if you’d like to shoot her an email about it, I’m sure she’d be receptive. Afaik, professors love sharing their knowledge.
My knowledge on carbonates just goes far enough to say “not enough carbonates present to discern abundance of water,” but I could be missing other pieces. There is a great source that the course opened me up to, called the Mars Global Data Sets from ASU, with interactive maps of almost all things Martian. I encourage you to scroll to the mineral distribution maps.
Although, there is a place on Mars with what people call “blueberries”, which are small spherical concretions of hematite (blueberry because the first images had a blue tint, so they looked like little blueberries). It is only found in this one place, Sinus Meridiani, where it is suspected there was a groundwater hot spring that managed to create hematite, and precipitate them out over extended periods of time (like hundreds to thousands of years, nothing on the geologic and astronomic timescales) as little spheres. The way we know to form these is with spring water as found on Earth, so their very presence implicates water on Mars during the Noachian or early Hesparian period. Now, Sinus Meridiani is not in those northern plains where the ocean is fabled to be, but the presence of there once being water at all anywhere on Mars could hint towards the ocean’s existence.
And don’t ever think your questions are pedantic. Questions are questions are questions, and hopefully they can be answered! Being specific is what forces us to come up with in-depth conclusions, instead of glossing over the surface and missing key information.
Sadly no, it’s $50, but totally worth it, considering it’s basically the overview of an entire course at one of the most prestigious tech schools in the world.
It’s difficult to stall a meteor and leave no trace, as well as have coastline-looking and ocean bed-looking geography, plus knowledge that there are outflow channels and glacier valleys all over Mars, and not owe up the only possibility of all this to the presence of water.
The tallest mountain from base to peak, including underwater, is Mauna Kea. It's about 10.2km tall, so 1.5km taller than Everest but still less than half the height of Olympus. Some people like to bring up Chimborazo, because it's near the equator and thus gets a boost from the Earth's bulge, but I don't think measuring from the Earth's center is very appropriate for this.
Assuming there was indeed oceans, when it dried up, where did it end up? Underground? Or, and this is harder for me to imagine being likely, did it get blown away from, idk, solar(?) winds or something? Like, is that even possible? Could water on a planet without any atmosphere get pushed to other nearby celestial bodies? Like even a miniscule amount over an incredible period of time?
We have like 5 different ways that water left Mars, and im sure this isn’t all:
Jeans escape. This is the natural slow escape of atmospheric particles, where they cross that threshold high up in the atmosphere where they are gravitationally bound. It is slow, and not enough to account for all the water figured to exist on Mars, but definitely not negligible.
Chemical reactions. Some reactions require water to occur, and when the water dries up into the atmosphere, it leaves behind minerals that required water to form, and incorporate water into their structure, either by chemical reactions, or hydrated salts.
Magnetic field disappearance + solar winds. Mars’s magnetic field is very weak presently. It is suspected that it was once stronger, but progressively weakened. But there is a threshold to pass where the strength of the magnetic field is not enough to protect from the onslaught of solar wind, and then solar wind begins to strip the Martian atmosphere of particles, some of which would be water.
Martian ice caps. The ice caps on Mars’ northern and southern hemispheres are water-ice and CO2 ice, but mainly water ice. But, there isn’t enough present to account for an entire goddamned ocean, so there’s probably more than this as well.
Underground ice. When we launch probes to Mars, they leave behind areas where they hit Mars where the dust is wiped away. These areas tend to be much more reflective and bright than the normal Martian surface, and it is confirmed that this increase in brightness is due to subsurface water ice. Perhaps the water sunk into the ground and froze when temperatures dropped far enough, then got covered by a global layer of dust.
and then solar wind begins to strip the Martian atmosphere of particles, some of which would be water.
If you've got no atmosphere (or minuscule atmosphere) you can't have liquid water right? Not enough pressure would cause it all to turn to gas? Then yeah it leaves with the rest of the atmosphere as you mentioned.
But the theory is that Mars did used to have a prevalent atmosphere capable of maintaining liquid water, and possibly even precipitation. Evident by the outflow channels from the Hesparian period.
For sure. I was just trying to possibly add some clarity as to where the water could have gone (maybe I did, maybe I was wrong idk). The end part of #3 was a bit ambiguously worded for me. I don't really know what would happen, just was trying to apply my understanding of physics.
I’m not an expert so I can’t answer that with any credibility, but perhaps if the entire planet was exposed to extreme heat it could have burned off the atmosphere and the ocean. Possibly from a massive meteor?
Very little chance. If by “giant impact crater” you mean the northern plains (the de-elevated part), you would most likely see striation lines (stress marks) across the entire circumference of Mars, similarly as found on some other rocky planetary bodies (I wish I could remember its name!), with no active volcanism and plate tectonics, that have survived massive impacts.
Global glacier, impact crater (yes the entire thing) followed by volcanism, active volcanism but only in a selective area (known to happen, it did on the Moon, hence the basaltic regions), and other phenomena people haven’t known to be existent yet.
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u/AidanGe Oct 07 '22
Huge area of debate right now. The entire border between the northern plains of Mars and the southern highlands appears like an eroded dried coastline, but at the same time, it could be the effect of some other cause. It’s odd how the entire northern plains has very little impact craters, while the rest of Mars has many more impact craters, so some people suspect that the impacted areas had been land since Mars’s creation, and the desolate northern plains is the remnants of a dried up water ocean (which would’ve soaked up the impact energy from any asteroid without it leaving a mark on Mars’s surface).