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Photos from NASA's Perseverance rover indicate ancient flash floods on Mars

140 points by el_duderino 5y ago

johnklos 5y ago
We've known about these for decades - this is just confirmation because there were naysayers that insisted otherwise.
- cronix 5y ago
  Or, it's good to confirm what you think you know.
- ChuckMcM 5y ago
  Yes and no right? What I mean is that this is how science works, where someone says "This is the answer to this question" and someone else says "No there is this other answer to the question." And what follows are a series of investigations into why the other person's answer is wrong and your answer is right. Eventually a lot of evidence has been gathered and a lot of theories and predictions have been tested, and then we can say "With everything we know so far, the only possible correct answer is 'A'" which becomes the answer of record. And the longer it holds up against people trying to prove it could also be 'B' or for some reason it could not be 'A' then the more consensus we have that it is the correct answer.
harwoodleon 5y ago
I was watching the ISS live feed going over North West Africa and up to Italy. The landscape was red and arid and it struck me just how ‘Mars like’ it looked. It got me thinking that Earth could be facing the same destiny many aeons from now. It’s hard to imagine with the amount of H2O on the planet right now, but if it can happen to Mars (the atmosphere is stripped away), it could happen here I suppose. But I wonder if a Venus situation is more likely first, because of our proximity to the Sun? This discovery certainly makes me feel that lifecycle of planets is an awesome thing.
- mixmastamyk 5y ago
  The much larger mass, gravity, and magnetic field of Earth prevents large scale atmospheric losses. Whether we have the resources to ignite another Venus remains to be seen.
  - exporectomy 5y ago
    Remains to be seen or is already known to be impossible? All the carbon in fossil fuels originally came from the atmospheric CO2, didn't it? And it was never as hot as Venus. What are the steps we would need to take to make it as hot as Venus in any kind of physically possible scenario?
    - virtue3 5y ago
      You are drastically under-estimating the effects of other compounds in the atmosphere. Methane is a really good example. HFCs were a great bit of disaster for a bit there as well. from: https://en.wikipedia.org/wiki/Greenhouse_gas#Impacts_on_the_overall_greenhouse_effect https://en.wikipedia.org/wiki/Greenhouse_gas#Impacts_on_the_... "The contribution of each gas to the greenhouse effect is determined by the characteristics of that gas, its abundance, and any indirect effects it may cause. For example, the direct radiative effect of a mass of methane is about 84 times stronger than the same mass of carbon dioxide over a 20-year time frame[27] but it is present in much smaller concentrations so that its total direct radiative effect has so far been smaller, in part due to its shorter atmospheric lifetime in the absence of additional carbon sequestration. On the other hand, in addition to its direct radiative impact, methane has a large, indirect radiative effect because it contributes to ozone formation. Shindell et al. (2005)[28] argues that the contribution to climate change from methane is at least double previous estimates as a result of this effect.[29]"
      - deleted 5y ago
        [deleted]
    - mixmastamyk 5y ago
      Too many variables to account for. Didn't mean to imply we could get "as hot as" Venus, which is unlikely due to our distance from the Sun. But hot enough to boil water? Possibly, given a runaway chain reaction. Not sure.
therealdrag0 5y ago
I once saw a clip of Elon saying the fast way to terraform Mars is to nuke the poles. And now that I’m watching The Expanse it got me thinking about that. Except for the possible impact on passive scientific study, it seems like a process worth starting sooner than later right? Any thoughts on this. Or are there other better ways to get a better atmosphere and water on Mars?
- JumpCrisscross 5y ago
  > nuke the poles Nuking asteroids to steer them into the poles would seem like a better solution. (Haven’t run the math on the delta-v for candidate impactors, though. You’d need to manage energy to avoid losing too much to space.)
  - BurningFrog 5y ago
    Anyone who can do that can aim asteroids at Washington or Beijing. This will be technology with more restrictions than nuclear bombs.
    - GekkePrutser 5y ago
      Not really, aiming an asteroid at a pole is easier because it doesn't move around during the day. And on Mars the polar ice caps are huge so they're a big target. I'm also kinda hoping that by the time we get this kind of tech we're evolving a bit away from this war thing. Probably not going to happen but one can hope...
- spfzero 5y ago
  Right now Mars is a pristine snapshot of processes I think we'd like to learn more about. We should propose Terraforming only after we think we've learned pretty much everything we care about. I'm not against terraforming eventually, but I think we need to give exploration a bit of time before considering which early 21st century tech would work best.
- IAmGraydon 5y ago
  I think that comment was tongue in cheek. It would take an utterly massive amount of nuclear weapons to appreciably melt the poles and it would likely poison the environment.
fnord77 5y ago
where did all the martian water/ice go? sublimation into space?
- yborg 5y ago
  In a nutshell, yes. Mars lacks a planetary magnetic field and has probably lacked it for billions of years, and has insufficient gravity to hold its atmosphere against direct impact by the solar wind.
Lendal 5y ago
There are many things in our solar system that can be found in large quantity in liquid form. How do they know it was water, and not some other element or molecule?

140 points by el_duderino 5y ago

johnklos 5y ago

We've known about these for decades - this is just confirmation because there were naysayers that insisted otherwise.

cronix 5y ago
Or, it's good to confirm what you think you know.
ChuckMcM 5y ago
Yes and no right? What I mean is that this is how science works, where someone says "This is the answer to this question" and someone else says "No there is this other answer to the question." And what follows are a series of investigations into why the other person's answer is wrong and your answer is right. Eventually a lot of evidence has been gathered and a lot of theories and predictions have been tested, and then we can say "With everything we know so far, the only possible correct answer is 'A'" which becomes the answer of record. And the longer it holds up against people trying to prove it could also be 'B' or for some reason it could not be 'A' then the more consensus we have that it is the correct answer.

harwoodleon 5y ago

I was watching the ISS live feed going over North West Africa and up to Italy. The landscape was red and arid and it struck me just how ‘Mars like’ it looked. It got me thinking that Earth could be facing the same destiny many aeons from now. It’s hard to imagine with the amount of H2O on the planet right now, but if it can happen to Mars (the atmosphere is stripped away), it could happen here I suppose. But I wonder if a Venus situation is more likely first, because of our proximity to the Sun? This discovery certainly makes me feel that lifecycle of planets is an awesome thing.

mixmastamyk 5y ago
The much larger mass, gravity, and magnetic field of Earth prevents large scale atmospheric losses. Whether we have the resources to ignite another Venus remains to be seen.
- exporectomy 5y ago
  Remains to be seen or is already known to be impossible? All the carbon in fossil fuels originally came from the atmospheric CO2, didn't it? And it was never as hot as Venus. What are the steps we would need to take to make it as hot as Venus in any kind of physically possible scenario?
  - virtue3 5y ago
    You are drastically under-estimating the effects of other compounds in the atmosphere. Methane is a really good example. HFCs were a great bit of disaster for a bit there as well. from: https://en.wikipedia.org/wiki/Greenhouse_gas#Impacts_on_the_overall_greenhouse_effect https://en.wikipedia.org/wiki/Greenhouse_gas#Impacts_on_the_... "The contribution of each gas to the greenhouse effect is determined by the characteristics of that gas, its abundance, and any indirect effects it may cause. For example, the direct radiative effect of a mass of methane is about 84 times stronger than the same mass of carbon dioxide over a 20-year time frame[27] but it is present in much smaller concentrations so that its total direct radiative effect has so far been smaller, in part due to its shorter atmospheric lifetime in the absence of additional carbon sequestration. On the other hand, in addition to its direct radiative impact, methane has a large, indirect radiative effect because it contributes to ozone formation. Shindell et al. (2005)[28] argues that the contribution to climate change from methane is at least double previous estimates as a result of this effect.[29]"
    - deleted 5y ago
      [deleted]
  - mixmastamyk 5y ago
    Too many variables to account for. Didn't mean to imply we could get "as hot as" Venus, which is unlikely due to our distance from the Sun. But hot enough to boil water? Possibly, given a runaway chain reaction. Not sure.

therealdrag0 5y ago

I once saw a clip of Elon saying the fast way to terraform Mars is to nuke the poles. And now that I’m watching The Expanse it got me thinking about that. Except for the possible impact on passive scientific study, it seems like a process worth starting sooner than later right? Any thoughts on this. Or are there other better ways to get a better atmosphere and water on Mars?

JumpCrisscross 5y ago
> nuke the poles Nuking asteroids to steer them into the poles would seem like a better solution. (Haven’t run the math on the delta-v for candidate impactors, though. You’d need to manage energy to avoid losing too much to space.)
- BurningFrog 5y ago
  Anyone who can do that can aim asteroids at Washington or Beijing. This will be technology with more restrictions than nuclear bombs.
  - GekkePrutser 5y ago
    Not really, aiming an asteroid at a pole is easier because it doesn't move around during the day. And on Mars the polar ice caps are huge so they're a big target. I'm also kinda hoping that by the time we get this kind of tech we're evolving a bit away from this war thing. Probably not going to happen but one can hope...
spfzero 5y ago
Right now Mars is a pristine snapshot of processes I think we'd like to learn more about. We should propose Terraforming only after we think we've learned pretty much everything we care about. I'm not against terraforming eventually, but I think we need to give exploration a bit of time before considering which early 21st century tech would work best.
IAmGraydon 5y ago
I think that comment was tongue in cheek. It would take an utterly massive amount of nuclear weapons to appreciably melt the poles and it would likely poison the environment.

fnord77 5y ago

where did all the martian water/ice go? sublimation into space?

yborg 5y ago
In a nutshell, yes. Mars lacks a planetary magnetic field and has probably lacked it for billions of years, and has insufficient gravity to hold its atmosphere against direct impact by the solar wind.

Lendal 5y ago

There are many things in our solar system that can be found in large quantity in liquid form. How do they know it was water, and not some other element or molecule?