> The reason people want to colonize Mars is because it solves the problem of an extinction event on earth wiping out all of humanity (assuming the Mars colony eventually becomes self sustaining).
Life on Earth survived the mass extinction event 66 million years ago, obviously, otherwise we wouldn't be here now. The dinosaurs were wiped out, but the dinosaurs had nowhere to hide and were completely unprepared for the asteroid impact. It's important to keep in mind that the Earth after the asteroid hit was still vastly more livable and conducive to life than Mars is now. Mars is more hostile to life than a big asteroid impact, because Mars has no habitat to start with. Mars has no benefit whatsoever to humans as far as Earth disaster survival is concerned, except for the fact that Mars is not Earth.
A much better plan to avoid extinction is multifold: (1) Stop destroying our own environment, duh. (2) Get rid of nuclear weapons. (3) Stop killing each other in general. (4) Invest in asteroid detection and deflection. (5) Build shelters on Earth capable of surviving disaster, such as underground. It also wouldn't hurt to (6) Stop being afraid of vaccination.
We've got everything we need here already: normal gravity, breathable atmosphere, food, water, raw materials, people. It would be sooooooo much easier to build disaster shelters on Earth than to permanently populate Mars. The difference in difficulty level makes Mars a total joke in comparison.
As a species, if we can't even get our shit together on Earth enough to stop polluting, stop killing, stop the threat of nuclear war, and vaccinate against contagious diseases, then we have no hope of long-term survival anywhere, because of our own stupidity. You can forget living on Mars, a massively hostile environment, if we can't do it right here on Earth, which was practically made for us.
This is tricky. Both because for better or for worse, they do provide a certain military equilibrium, and also because you know, it's probably a good idea to have them around, at least to a certain degree, if the Xel'naga decide that creating us was a bad idea. Not that nuke might not be sort of like throwing rocks at an advanced civilization, but it's not like we'd have anything better...
Not as of now. The outer space treaty[1] forbids nuclear explosions in space. I don’t think this treaty will be revised until it is made obsolete by a total elimination of these weapons of horror (e.g. by another treaty[2]). So if you want to see nuclear explosions used as propellant in space (which honestly isn’t such a bad use for them) then I recommend you petition your government to sign and implement the UN ban on these world ending weapons, if they haven’t already.
I kinda feel this would be worked out one way or another when someone is in possession of a fully fueled Orion space ship with couple thousand nuclear charges on board.
To this day I'm terrified by this concept - so much that I would frankly rather have nukes detonated behind a ship for propulsion. :P But yeah, if it could be made to work, it has some serious benefits!
On a related note, lets also look at the nuclear salt-water rocket - arguably the king of crazy (yet theoretically viable) on the nuclear rocket field right now:
What is so terrifying about that? It could be the middle way between fission as we know it, and fusion as we can't do reliably/practically(as of now). Just need some superconducting magnets to tame and stop the fusing uranium hexaflouride from touching the fused silica walls :-)
The exhaust is clean, because the system is closed.
Also it reminds me of some descriptions of so called 'Vimanas' which occur in old Indian scriptures, and nerdy people from today tried to reconstruct/reverse engineer/remimagine what's described in there.
And this fits, perfectly so.
Edit: I think of this as even more terrifying thant that saltwater thing:
Indeed, this is also very clever and actually sounds quite doable (still I wonder about how much radiation it will give off when running - probably quite a bit! :D) when compared to some of the other concepts.
Actually, I kinda think it demonstrates we really are not done with nuclear engines & even better, more crazy and higher performance propulsion methods will show up. And also, we really need to finally start building some of them them! :)
Like, even some simple NERVA or NEP would be at least a start. :)
It seems easier because Mars proponents often focus on the technological challenges (which are indeed great, if not insurmountable), while ignoring the human challenges. The challenges from human nature are going to exist on Mars just as much as they do on Earth; things like warfare don't suddenly stop existing just by shifting people to Mars. People act like Mars would be a place to keep people safe from nuclear war, but destroying a Mars colony from Earth is trivial compared to creating one.
If one looks at the history of colonies (attempts to colonize the new world, for instance), we see that they often fall apart socially even in situations where they're in a place with much more resources than they had back home. Humans aren't dwarf fortress type automatons that can simply be handed whatever necessary job is needed and mindlessly go about their day for the rest of their lives.
No one has been able to manufacture a functioning mini-society, and every attempt has ended in spectacular failure. It seems crazy to think things will suddenly work if we drop the people in a place devoid of almost all resources and entirely hostile to life from Earth.
How can you bring humans to Mars without also bringing human nature, i.e., human flaws? We'll wreck Mars quicker than Earth, because Mars is already a wreck.
It's not a question of starting or stopping; whether we start or stop seems irrelevant to me. The point is that humanity has been "coddled" by the Earth, because we were born and evolved here, but we won't be coddled by Mars, and thus the Mars project is doomed to failure, since we're already failing on Earth, in a vastly more favorable environment.
What's the point of a "backup plan" when the primary plan isn't even working?
Humans will still be the ones colonizing Mars, the same humans who would theoretically make Earth uninhabitable. If we humans can't stop destroying Earth, we have no chance in making a Mars colony successful.
> A much better plan to avoid extinction is multifold: (1) Stop destroying our own environment, duh. (2) Get rid of nuclear weapons. (3) Stop killing each other in general. (4) Invest in asteroid detection and deflection. (5) Build shelters on Earth capable of surviving disaster, such as underground. It also wouldn't hurt to (6) Stop being afraid of vaccination.
That all sure sounds simple enough if you handwave over all the inherent complexity, but by that standard so does colonizing Mars, and yet colonizing Mars also sounds like a fun adventure.
In particular, (2) and (3) are working at cross purposes here—nuclear deterrent is the primary thing that has prevented a great power war from happening since 1945. Also, (4)—asteroid deflection—could provide a safeguard for earth, but could just as easily be used as a weapon of mass destruction.
(1) is a slogan and not a concrete plan. How do you plan to provide food, energy, housing, and health care to eight billion people? Environmental issues are a question of tradeoffs and cost-benefits. Windmills are a hazard to birds, hydroelectric dams are a hazard to fish, solar and batteries require mining rare earth metals, and so forth.
> That all sure sounds simple enough if you handwave over all the inherent complexity
I didn't say it was simple. I believe what I said: "we have no hope of long-term survival anywhere, because of our own stupidity."
> nuclear deterrent is the primary thing that has prevented a great power war from happening since 1945.
A sad statement about humanity. Which is why I said we need to get our shit together.
Do we bring nationalism and nuclear weapons to Mars? How soon after settlement until the first Martian war starts? Could a Martian colony even survive a war, if the life-sustaining infrastructure is attacked? Or do they do it in the style of Star Trek "A Taste of Armageddon", with simulations and disintegration chambers?
> How do you plan to provide food, energy, housing, and health care to eight billion people?
How do you plan it? Hunger, power outages, homelessness, and lack of access to health care already exist.
> Windmills are a hazard to birds, hydroelectric dams are a hazard to fish
We're already killing birds and fish in many other ways more deadly.
> I didn't say it was simple. I believe what I said: "we have no hope of long-term survival anywhere, because of our own stupidity."
Then give up and cede the floor to the people who are actually trying to do something about the future of humanity. If you're really this defeatist about the whole thing, you aren't contributing anything to the conversation.
Also, you aren't contributing anything to the conversation in general. You've managed to quote almost everything I wrote in my post except for one of the central points, which was: "Environmental issues are a question of tradeoffs and cost-benefits." You ignore that while quoting just about everything else to provide snippy and dismissive comments that aren't really engaging with anything. Of course, why would you contribute anything of value if you're philosophically committed to dismissive doomsaying.
> If you're really this defeatist about the whole thing, you aren't contributing anything to the conversation.
The truth? Are you concerned with truth, or just wishful thinking?
Let's say you have a terminal illness, for example, ALS. Would you lie to everyone, including yourself, and say you're fine, that everything is going to be ok? Or would you admit the truth, and try to come to grips with it?
Of course we would love to have a cure. Nobody welcomes a terminal illness. But the reality and gravity of the situation cannot be honestly denied.
> Environmental issues are a question of tradeoffs and cost-benefits
In the large sense, they're really not, because there's a single planet that supports human life, namely Earth, and if we wreck it, making it inhospitable, then every other tradeoff becomes irrelevant. The livability of the Earth's environment is a precondition for every other human endeavor. You can't have economic activity without ecological activity. And if you aim to convince me to be quiet about that, then the last thing you want to do is claim that we can "trade" the environment for something else. This kind of attitude only reaffirms my pessimism about whether we can, as I put it, get our shit together.
I am dismissive of concern trolling about windmills harming birds and dams harming fish when we're currently facing a period of mass animal species extinction due to human effects on the environment, such as global warming, chemical and physical pollution, deforestation, overfishing, etc.
> if you're philosophically committed to dismissive doomsaying.
I'm not philosophically committed to it, just empirically convinced of it.
I don't know how it's going to go down in the end. What I do know is that humans are essentially less hairy, more talkative apes, and as a group we can't responsibly handle the technology that the cleverest (but not necessarily wisest) among us were able to create. We're like the sorcerer's apprentice, except there's no sorcerer to show up at the last minute to save ourselves from the disaster we created.
We've known about global warming for many decades, yet we've done practically nothing about it, and now hardly anyone can deny that the consequences of it are starting to show. We're already past the point of no return. We allow amoral madmen to control world-threatening nuclear arsenals. We put anything and everything into the water, into the air, into the ground, without any apparent concern for the future. Millions of people are in near total denial of science, believing among other things that the world was literally created a few thousand years ago, and evolution did not occur. And by the way, these people dominate at least one of the two major political parties of the most powerful nation on Earth. I don't know why exactly I should be hopeful about all this. To whom am I supposed to cede the floor? The "pedo guy" guy?
> Let's say you have a terminal illness, for example, ALS. Would you lie to everyone, including yourself, and say you're fine, that everything is going to be ok? Or would you admit the truth, and try to come to grips with it?
In 1963, a graduate student was diagnosed with ALS. Instead of deciding that his life was pointless and meaningless, he completed his doctorate and spent the rest of his life contributing to scientific research and to educating the public. His name was Stephen Hawking and he passed away at age 76, in 2018.
> In the large sense, they're really not, because there's a single planet that supports human life, namely Earth, and if we wreck it, making it inhospitable, then every other tradeoff becomes irrelevant.
Thankfully, nobody is suggesting making the earth uninhabitable. This kind of all-or-nothing thinking about the issue is counterproductive and useless.
> I am dismissive of concern trolling about windmills harming birds and dams harming fish
I'm not saying not to build the windmills and dams. I'm saying that the benefits of doing so outweighs the ecological costs. I'm not concern trolling here; I'm giving an example of a cost/benefit tradeoff that you presumably agree with. You're just so worked up that you missed the point.
> In 1963, a graduate student was diagnosed with ALS. Instead of deciding that his life was pointless and meaningless
1) I didn't say my life is pointless and meaningless. Moreover, I obviously care, otherwise I wouldn't bother to argue about all of this.
2) You're seriously going to pull unusual anecdotal data about a condition that has well known scientific statistics?
3) I think it's fair to say that Hawking's physics talent resulted in greater caretaking effort put into his life than the average case.
> Thankfully, nobody is suggesting making the earth uninhabitable.
Of course nobody suggests it. They're not going to do it on purpose, they're going to do it by accident, due to carelessness and neglect.
> I'm giving an example of a cost/benefit tradeoff that you presumably agree with.
Why? If there's supposed to be a moral to the point about tradeoffs, then why not directly talk about what it's supposed to be, rather than mentioning little tangents that are largely irrelevant?
You asked about my plan to provide the essentials, such as food and housing, but that's a bit of misdirection, because we do vastly more than just provide the essentials. We have rampant, insatiable consumerism, not to mention planned obsolescence, driven by zombie non-human entities called "corporations" that lack ethics and exist for nothing except unfettered growth. We have the military-industrial complex whose appetite for war and weaponry is never ending. And now people want to massively ramp up the space program again and constantly launch (polluting) rockets into space, even littering our orbit with satellites that block our own view of it that we so admire from a distance. I don't think the problem is the essentials. Rather, I want to know what the plan is for cutting back on the non-essentials.
> You're just so worked up
Please refrain from personal comments, which are unnecessary and uninformed. You don't know me, and you're certainly not in the room with me, so you don't have the slightest clue about my present mental or emotional state. At this point, I could probably rattle off my spiel in my sleep.
> I didn't say my life is pointless and meaningless.
No, you said human civilization is doomed, and then you mentioned an ALS diagnosis as an analogy between an individual life and the fate of human civilization.
> If there's supposed to be a moral to the point about tradeoffs, then why not directly talk about what it's supposed to be, rather than mentioning little tangents that are largely irrelevant?
The point is that tradeoffs exist. It's not "tangential" to provide examples of tradeoffs when making the point that tradeoffs exist.
> At this point, I could probably rattle off my spiel in my sleep.
As far as I can tell, you are rattling this off in your sleep, because you aren't constructively responding to my points in any way. It was a charitable assumption on my part that you're just worked up, as opposed to having poor reading comprehension or some sort of apocalyptic monomania. At this point I'm content just dismissing you as a fanatical doomsayer with no interest in what anyone else has to say, because that's how you've conducted yourself thus far.
> No, you said human civilization is doomed, and then you mentioned an ALS diagnosis as an analogy between an individual life and the fate of human civilization.
Yes. That doesn't mean human life isn't worth living. After all, the Earth itself is ultimately doomed, billions of years in the future. And it should go without saying that each of us is mortal. You and I are both going to die someday. Everyone acknowledges that, scientifically. What we do with that knowledge is a different matter.
If there's a way for humanity to avoid its sorry fate, I believe that the solution is not inherently technological. Technology may be needed, but the solution has to start with our acknowledging the truth, acknowledging reality, and becoming self-aware, self-reflective, especially of our own human flaws. We can't attempt to overcome our flaws if we don't even admit that we have those flaws.
The first step is to look inward, to human nature, not look outward to Mars. We'll never be able to govern the space outside of Earth unless we can govern the space between our ears. Rationality, ethics, cooperation, these are the keys to long-term survival of the species. And perhaps biological evolution would bring us to that eventually. But evolution works painfully slowly, so I fear that the combination of technology and self-destructiveness will get us first.
If humans even need something like "nuclear deterrence", for example, that's an inherently unstable and extremely dangerous situation. It's no way to live. Which is why I keep asking if we're going to bring that crap to Mars with us. Setting aside basic survivability problems — which are huge problem — whatever social problems we have here on Earth would just be magnified in the extremely hostile Mars environment. There's little or no margin for error (or stupidity) there.
> The point is that tradeoffs exist.
Ok. And 1+1=2. You really need to elaborate to explain how this basic point illuminates the current discussion in any way.
> It was a charitable assumption on my part that you're just worked up
No, it wasn't. Try coming up with something other than your two uncharitable interpretations, the second of which isn't even worth repeating.
> If there's a way for humanity to avoid its sorry fate
You don't think there is, though. You've admitted as much. So why are you wasting your time?
> Setting aside basic survivability problems — which are huge problem — whatever social problems we have here on Earth would just be magnified in the extremely hostile Mars environment. There's little or no margin for error (or stupidity) there.
That's always been one of the benefits of settling a frontier--any hard and dangerous undertaking has a way of forging people and cultures into a healthier and more functional form.
> Ok. And 1+1=2.
So you agree with my point that "environmental issues are a question of tradeoffs and cost-benefits"; you just want to express that agreement in a belligerent tone.
> You really need to elaborate to explain how this basic point illuminates the current discussion in any way.
It's certainly more nuanced than the statement of yours I was responding to, which was "stop destroying our own environment, duh". It doesn't take very much light to illuminate the bottom of the Marianas Trench.
Because I've got time to waste? And because I'm not happy about the situation.
Honestly, aren't most HN commenters mostly just wasting time here?
> any hard and dangerous undertaking has a way of forging people and cultures into a healthier and more functional form
This does not seem true to me.
> So you agree with my point that "environmental issues are a question of tradeoffs and cost-benefits"; you just want to express that agreement in a belligerent tone.
No, I'm still waiting for the nuance that you mention. There are some obvious, massive environmental problems in the world, such as global warming, air pollution, water pollution, ground pollution, etc. I'm not seeing a serious global effort to stop, undo, or prevent these problems. In that respect, I'm not interested in "tradeoffs", which sound to me like a justification or excuse to continue to destroy our one planet for the sake of short-term profit. But if there's some nuance that I'm missing here, then please explain. The only thing you ever mentioned was windmills hurting birds and dams hurting fish, which as you can probably guess, doesn't impress me or justify doing nothing about the environment.
> In that respect, I'm not interested in "tradeoffs", which sound to me like a justification or excuse to continue to destroy our one planet for the sake of short-term profit. But if there's some nuance that I'm missing here, then please explain. The only thing you ever mentioned was windmills hurting birds and dams hurting fish, which as you can probably guess, doesn't impress me or justify doing nothing about the environment.
I mentioned those things as examples of tradeoffs where the benefit outweighs the ecological impact. “Doing nothing about the environment” is a complete strawman that you made up for some reason, it certainly has nothing to do with anything I mentioned.
I don’t think I’m making a particularly nuanced point either, but you’re still not really grasping it or coherently responding to it, so I have no reason to think you’re willing and capable of engaging with anything more nuanced.
> I mentioned those things as examples of tradeoffs where the benefit outweighs the ecological impact. “Doing nothing about the environment” is a complete strawman that you made up for some reason, it certainly has nothing to do with anything I mentioned.
I keep asking, over and over, for you to give examples of tradeoffs where the cost/benefit goes the other way, but you steadfastly refuse to elaborate. All you do is complain that I'm misunderstanding you, while never elaborating on your view. If doing nothing about the environment is a strawman, then why don't you go ahead and explain your non-strawman position?
> I don’t think I’m making a particularly nuanced point either
You're not making any point. That's my point. You apparently just want me to say "You were right, Phil, and I was wrong", despite my not even knowing what the heck you're supposed to be right about, except the totally vague, handwavey "tradeoffs exists".
Ok, fine. Tradeoffs exists. Are you happy now? But that doesn't really get us anywhere or change anything in the argument.
You asked, "How do you plan to provide food, energy, housing, and health care to eight billion people?" Can we feed and house an unlimited number of humans? No. Can we feed and house the current number of humans? Yes, I believe so. We already produce vastly more consumer goods than is necessary for this basic purpose, but we refuse to distribute them equitably. In any case, if for some reason we can't adequately feed and house the current number of humans, the answer is certainly not Mars, which doesn't support human life at all and wouldn't help even a tiny bit to feed or house current Earth humans. The cost of feeding and housing a human on Mars is, as it were, astronomically greater than the cost of feeding and housing a human on Earth.
One answer would be population control, strictly limiting new births. There's a tradeoff for you. But as I already said, I don't think the basics are really our biggest problem: "We have rampant, insatiable consumerism..."
> I keep asking, over and over, for you to give examples of tradeoffs where the cost/benefit goes the other way, but you steadfastly refuse to elaborate.
You haven't, actually. But now that you finally have, I think the use of coal to generate electricity would be an example that goes the other way.
More generally, carbon taxes and similar measures, like the cap-and-trade systems used for other emissions, are IMO a good policy mechanism for controlling ecological costs according to cost-benefit tradeoffs. I don't think anyone is smart enough to centrally plan these kinds of economic decisions, so it's good to use these policies to make the market work for us in these instances.
> All you do is complain that I'm misunderstanding you, while never elaborating on your view.
When you keep misrepresenting what I've already said, I'm going to go back and try and clarify the points that you missed instead of moving on. If you're going to continue making the same misunderstandings, I'm going to get frustrated and give up.
> Ok, fine. Tradeoffs exists. Are you happy now? But that doesn't really get us anywhere or change anything in the argument.
You've spent the past three days disingenuously arguing against the point that tradeoffs exist. Now you've conceded the point. I'd say that's progress, and I'm going to leave it at that because I don't think you're engaging in good faith here, and I suspect that if we continue, you're just going to circle back to claiming that I was "concern trolling" about renewable energy again even though I've clarified that point more than once.
Me: "How do you plan it?" "If there's supposed to be a moral to the point about tradeoffs, then why not directly talk about what it's supposed to be, rather than mentioning little tangents that are largely irrelevant?" "You really need to elaborate to explain how this basic point illuminates the current discussion in any way." "I'm still waiting for the nuance that you mention." "But if there's some nuance that I'm missing here, then please explain. The only thing you ever mentioned was windmills hurting birds and dams hurting fish"
> But now that you finally have, I think the use of coal to generate electricity would be an example that goes the other way.
> You've spent the past three days disingenuously arguing against the point that tradeoffs exist. Now you've conceded the point.
From my perspective, you've spent the past three days hiding your real views in order to get me to get me to concede a point that in most circumstances would not be worth even mentioning, like 1+1=2. Why? Why did you place so much importance on that, on the (purposely?) vague "tradeoffs exist", unless you believed that my conceding the point commits me to other things that are favorable to your own argument and views? There's a rather simple and obvious reason why I've been resisting what you called "one of the central points, which was Environmental issues are a question of tradeoffs and cost-benefits." The reason I've resisted is that I want to know exactly what I'm agreeing to by conceding that point, and you've refused to say until now. And guess what, I do not agree about coal. So I think I was justified in resisting your point. I definitely don't agree with a laissez-faire market-based approach that always leads to the tragedy of the commons. I think "carbon offsets" are a joke and nothing more than a system to pay to pollute, as usual allowing the wealthiest to do nothing and get away with murder.
> Me: "How do you plan it?" "If there's supposed to be a moral to the point about tradeoffs, then why not directly talk about what it's supposed to be, rather than mentioning little tangents that are largely irrelevant?" "You really need to elaborate to explain how this basic point illuminates the current discussion in any way." "I'm still waiting for the nuance that you mention." "But if there's some nuance that I'm missing here, then please explain. The only thing you ever mentioned was windmills hurting birds and dams hurting fish"
None of these quotes actually contain the question, “what are some tradeoffs that would go the other way?”.
> Why? Why did you place so much importance on that, on the (purposely?) vague "tradeoffs exist"
Because your apocalyptic rants are very, very absolutist and seem to exclude the very possibility of tradeoffs. You are right that it’s a 1+1=2 type point, but you were passionately ranting that 1+1=11. I was trying to introduce some nuance into the conversation, and then you freaked out.
> And guess what, I do not agree about coal.
You don’t agree with me that we should phase out coal power plants? That makes absolutely no sense given your doomsday ranting.
Oh, I think I see what happened here. We agreed, I think, on hydroelectric dams as a case where the tradeoff favors building or maintaining the power plant. You asked for a tradeoff that went the other way, and that’s when I mentioned coal. See, hydroelectric goes the way of “let’s keep the power plant running” while coal goes the other way—i.e. not keeping that power plant operational. Or do you think we should phase out hydroelectric? You’re not making any sense here.
>Do we bring nationalism and nuclear weapons to Mars? How soon after settlement until the first Martian war starts? Could a Martian colony even survive a war, if the life-sustaining infrastructure is attacked?
Would a small Mars colony survive a single jilted lover aiming for the ultimate murder-suicide?
> A much better plan to avoid extinction is multifold
I don't think going extinct from the effects of any human capability is much of a concern. Humans have lived in stone age for tens of thousands of years. It's more that we wouldn't have nice things like houses, cars, and computers.
It is flippant. "Net zero" has already been an ally to the Russian government in their war on Ukraine.
Energiewende was the renewable transition that primarily offshored responsibility to Russian natural gas and coal when plants weren't running, assuming that the renewables would grow and balance out.
That didn't work so well, and now a European heat wave is saving European lives.
People need heat, and light, and to compute.
The developing world cannot wait for net zero carbon energy, and the developed world cannot just stop all useful human activity to pursue climate goals.
The rhetoric around this is if we "just" had better politics, if the oil and gas lobby weren't such villains, if conservatives weren't sticking their heads in the sand we would be able to make it to net zero while "only" sacrificing things we don't care about, like big gas guzzling pickup trucks.
We are finding out that no, we can't.
Continuing down this line of rhetoric is flippant, or perhaps glib.
There's hope though, even if you believe that climate change will end humanity (it won't) - the status symbol cars are electric, more consumer cars are electric, renewable deployment is proceeding apace and we even have developments in fusion and SMRs.
That's how we win - not with the Extinction Rebellion, but with new people doing diligent work to produce higher and higher standards of living at less and less cost.
Fuel costs money, and nobody wants to use it if they don't have to - economics will eventually win, because the best low or no carbon energy sources require almost no operational cost due to lack of constant fuel input.
Life on Earth survived the mass extinction event 66 million years ago, obviously, otherwise we wouldn't be here now. The dinosaurs were wiped out, but the dinosaurs had nowhere to hide and were completely unprepared for the asteroid impact. It's important to keep in mind that the Earth after the asteroid hit was still vastly more livable and conducive to life than Mars is now. Mars is more hostile to life than a big asteroid impact, because Mars has no habitat to start with. Mars has no benefit whatsoever to humans as far as Earth disaster survival is concerned, except for the fact that Mars is not Earth.
A much better plan to avoid extinction is multifold: (1) Stop destroying our own environment, duh. (2) Get rid of nuclear weapons. (3) Stop killing each other in general. (4) Invest in asteroid detection and deflection. (5) Build shelters on Earth capable of surviving disaster, such as underground. It also wouldn't hurt to (6) Stop being afraid of vaccination.
We've got everything we need here already: normal gravity, breathable atmosphere, food, water, raw materials, people. It would be sooooooo much easier to build disaster shelters on Earth than to permanently populate Mars. The difference in difficulty level makes Mars a total joke in comparison.
As a species, if we can't even get our shit together on Earth enough to stop polluting, stop killing, stop the threat of nuclear war, and vaccinate against contagious diseases, then we have no hope of long-term survival anywhere, because of our own stupidity. You can forget living on Mars, a massively hostile environment, if we can't do it right here on Earth, which was practically made for us.