Photos from NASA's Perseverance rover indicate ancient flash floods on Mars
science.org
science.org
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.
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_...
"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]"
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.
When I learned about this I got kinda scarred. If the climate of an area can change this drastically all of a sudden that means to me that the climate system is a lot less stable than I previously have thougt.
IIRC one of the causes might be orbital precession, which could lead to a re-greening in a few millenia.
Mars' atmosphere isn't protected by a strong magnetic field because the planet isn't geologically active, unlike the Earth. Gasses escape from the Earth into space constantly, but not at a rate that will leave the Earth like Mars before the sun becomes a red giant.
In billions of years, the sun will expand and probably blast away the Earth's atmosphere before possibly engulfing it later.
It may be safe to say that both factors are at play, here.
https://phys.org/news/2021-03-simulations-earth-oxygen-rich-...
(the summary there is inaccurate; CO2 will be increasingly absorbed by weathering of rocks as the Earth heats, until photosynthesis fails and oxygen levels collapse.)
Eventually (~4-5B years) the Sun will expand while in its dying stages and probably swallow the Earth.
What can we do? That's actually quite "easy". I mean "easy" in the essence that no weird new physics is required, it's just an engineering problem, albeit a massive one. Then again, we have a lot of time. So there are essentially three things we can do:
1. Reduce the amount of light and heat hitting the Earth. Example: large arrays of solar power collectors at the L1 Lagrange point. If the Sun is 10% hotter in 1B years and you reduce the light hitting the Earth by ~10% it about evens out. The captured energy can be put to use and I expect it wouldn't even be noticeable from Earth. The Sun will just be slightly dimmer;
2. You can move the Earth. Many people are familiar with gravity assists for spacecraft. Obviously gravity affects both bodies but the spacecraft is so low-mass it has no discernable effect on the larger body. Imagine taking large rocks and flying them past the Earth. The net interaction can be that the Earth moves slightly faster. Do this over a long enough time frame and you can move the Earth's orbit outwards.
3. The Sun itself can be manipulated to remove mass from it, particularly Helium.
A lot can be done in a billion+ years.
I'd imagine evolution is possible but only under collapse of civilization as we know it.
But we'll have other challenges first like finite resources and our self-destructive tendencies. We'll have made bigger fish to fry before we can even make it a billion years
The idea is simple: there's little evolutionary pressure to adapt because technology and society can deal with issues that once would've been fatal.
There are a bunch of issues that still affect survivability though: recklessness, propensity for violence, inability to survive in modern society, addiction issues, mental health issues, etc. We can expect all of these to improve but go away entirely? That's less certain.
Even if you ignore mortality issues, the other side of natural selection is how many offspring you have and how many of them survive to have their own offspring. If a group with trait A has an average of 2 children each but trait B have an average of 3, it's not too many generations before B becomes dominant.
Evolution is also relatively slow and not smooth. We only identified DNA ~50 years ago and mapped the human genome in the last 10-15. It's a bit early to refute observational evidence.
Remember too that certain traits that were once advantageous can become a disadvantage or they only become a disadvantage in certain circumstances. Take the modern abundance of food. Some people have genes that predispose them to storing excess, others less so. 1000 years ago, that was probably an advantage. Now? Less so, both in terms of health effects related to, say, obesity, but also in terms of finding a mate and having offspring given changing societal standards for beauty (not universal of course).
Lack of recycling comes down to it mostly being uneconomic to do so. There can be a labor component to this too but the energy cost matters. A lot of labor can be automated, which then also becomes an energy problem.
It's highly likely that in 1B years, we'll have access to energy many orders of magnitude higher than we do now and it'll probably be much cheaper. My personal prediction is the space-based solar power collection is likely to be dominant. The big unknown is fusion. Personally I'm not yet convinced fusion will ever be economical, but that's a whole other topic.
We live in hot, dry climates now (eg the Middle East). What makes that possible is simply energy for food and water production, climate control and so on.
It'll likely be worse for other life on Earth but that too is an energy problem. Also, we have no real idea of what life will look like in 1B years since we'll likely have gone through several mass extinction events between now and then.
And of course, in the last 1B years we've largely gone from single-celled and early multi-cellular organisms to what we have now.
A billion years is a long time. I feel like this or extinction are the only two real scenarios.
Indeed, to the point that talking about it in terms of what "we" could do about it in ordinary engineering terms becomes pointless.
A billion years ago, the first multicellular plants were beginning to move onto land; animals were still water-bound single cells who would have to wait another couple hundred million years to discover sex. Whatever life still exists on Earth a billion years from now will presumably be as far removed from us as we are from those ancient ancestors.
https://en.wikipedia.org/wiki/Timeline_of_the_evolutionary_h...
In ~1 billion years, "we" won't be inhabiting anything in our current form. If humanity/primates haven't gone extinct by then, they will have evolved completely beyond our current form.
Any thoughts on this. Or are there other better ways to get a better atmosphere and water on Mars?
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.)
This will be technology with more restrictions than nuclear bombs.
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...
Second of all, nuking obviously (1) produces far too little energy for terraforming, and (2) produces large amounts of dust and radioactive fallout. It's also very doubtful that melting Mars's poles would do much to help with the habitability of Mars - it will still be extremely cold, extremely lacking in Oxygen, extremely lacking in atmospheric pressure, and extremely radioactive on the surface.
We also don't know how much water is left on Mars after the atmosphere was washed away - water may have frozen, but a good amount may have simply boiled away in the low pressure and been long carried away by the solar winds. Until we know for sure, boiling away more water would be extremely irresponsible.
Also, given humanity's current total energy output, there is simply no way to terraform Mars. If in the future we will discover some way of using orders of magnitude more energy, we could visit this, but given current scientific knowledge, any energy used to start terraforming Mars is as wasted as trying to terraform the Sun.
They have nuclear designs which are 98% fusion. The radioactive fallout for these is much more limited.
For example, atomic lake (which was terraformed with nuclear bombs), has radiation levels of 9 µSv vs 3 from background per week
What's even weirder about the "pro-science" folks - they don't seem to understand radiation exposure ranges in space. Surface of mars is going to have radiation levels on the order of 20 uSv per HOUR - we are talking RADS/year (not mili rads).
That said, impactors or nuclear power on the surface are likely more feasible.
> For example, atomic lake (which was terraformed with nuclear bombs), has radiation levels of 9 µSv vs 3 from background per week
It's kind of weird to take an authoritative stance with that example. "atomic lake" was from an underground detonation of a moderate-yield fission device 50 years ago and largely just moved dirt around while still sending up detectable radioactive waste. OK, you can go near the lake now without ill effect but you've accomplished...what exactly?
So scale it up to what is actually needed to vaporize a meaningful amount of the ice caps and look at how effective that would be at making a dent in the Martian atmosphere and the GP has a very good point. It's not a workable idea.
Sure, but there is a difference between solar radiation coming from a clear source that you can shield against, versus potentially coating the planet in fine radioactive dust that would get into every nook and cranny it finds. Radiation from the sky is bad, but radiation inside our lungs is many times more deadly.
To be fair, martian dust is already extremely toxic, so mixing in radioactive fallout may not significantly increase the need for scrubbing everything down.
“ (2) produces large amounts of dust…”
The purpose would be to produce dust to spark a warming feedback loop…
That's like spiking Earth’s atmosphere with greenhouse gases to promote global cooling.
He is a businessman with an undergraduate degree in physics. It is literally true that he has some training, but less so than any junior engineer working in the field for a year or two.
Not that I disagree that Musk is selling bullshit a lot of the time. But that is completely separate from his academic career.
Also, money opens many doors even in the top universities in the USA, so being accepted for a PhD you don't even start is not an iron-tight guarantee of that much (if he had finished his PhD, I would not say this).
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.