I am vaguely surprised it was not higher rated for a rover mission. 7k meters down should do something interesting to the atmosphere if nothing else.
1. https://trek.nasa.gov/mars/#v=0.1&x=72.07800218650755&y=-42....
2. https://trek.nasa.gov/mars/#v=0.1&x=-116.4913302335018&y=16....
But there's places like the araneiform terrain where you likely get much higher transient pressures, and maybe they create enough of a greenhouse effect to warm up before they burst through the CO2 ice crust. They'd be a great way for life to spread mechanically using those pressurized bursts.
So if you can get 7km down without digging, that's the first place to look!
Though the person you commented on didn't refer to habitation specifically I think, just humans on the surface.
Since Mars atmosphere is 95% CO2 you're pretty much good to go there with a moderate supply of hydrogen. And conveniently enough electrolysis of water yields of course hydrogen and oxygen. And water is shockingly widely available on Mars given the regolith is 2-5% water by volume (giving the unit bastardization of 1 cubic foot of regolith = 1+ liter of water).
Most of the issues people are concerned about like radiation aren't, in reality, that big a deal. I say 'in reality' to mean that the radiation isn't enough to just give you immediate radiation sickness, so the real effect will be a probably reduced life expectancy due to greater rates of cancer. Even that isn't so clear for reason outside the scope of this post, but it's not a show stopper in any case. In general early colonists will have a significantly reduced life expectancy - it's just the nature of colonization, and always has been.
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Beyond that the Moon is a nightmare. Relatively minimal resources, 2 week long days/nights that vary between way beyond boiling hot and something close to absolute zero. No atmosphere at all so no protection against meteorites, somewhat higher radiation than Mars, and so on. There's also gravity very near zero which can pose some issues with various processes (industrial/etc).
And other destinations like Europa not only have dramatically more difficult 'local settings', but also have significantly greater distances. For instance Europa is about 10x as far as Mars and a somewhat more difficult trajectory to manage. In practice you're probably looking at upwards of 5 years for a one-way trip. We probably need to level up the tech tree a few bumps before realistically looking at things like that and Mars is a good way to do that.
Having said that, there would also be the cumulative effects of low/no gravity on astronauts. Even a year on the ISS has profound negative effects on the human body. And humans have cumulatively spent less than a month total on the moon. We have no idea how astronauts would fare on Mars for 18 months, but it would likely be very bad. And then they'd have to successfully get home.
You also have abundant toxic chemicals in the Mars regolith. Whatever technology we'd use to extract drinking water from it would have to filter out perchlorates, which are extremely toxic to both mammal and plant life. AFAIK we've never done this at all on Mars, and now we're talking about having to do it successfully for 18 months (even with water recycling). Not easy!
To be fair, a lot of proponents of human Mars exploration -- particularly here on HN -- see astronauts as essentially disposable. "Who cares if they risk dying of cancer / poisoning / suicide? It's worth it!" But if you prioritize astronauts surviving both the mission to Mars and the return home there are many, many, many unanswered questions, questions which may indeed have no good answers at all.
Before you accuse me of being a hater: I fully support exploration of Mars, and the rest of the solar system. And the best way to do so, by cost and every other conceivable metric, is with robots. Lets spend way more on space exploration, do it with probes of all varieties, and learn more in our lifetime than in all previous human lifetimes put together!
Some misleading articles (or one heinous book) try to count in-transit space weather events as part of the average to bring the numbers to the point of absurdity, but that's plainly lying. Space weather events (like solar flares) are immediately lethal if not shielded against. Fortunately they're easy to shield against since they're predictable and all settlement ships will happen to have one of the best possible radiation shields in large quantities on board - water. Similarly for perchlorates. These can be filtered out with basic water purification tech and trace amounts are even present in much of what we consume on Earth, especially in certain areas.
I'm not accusing you of being a hater, which is quite pointless. But I would say you've probably been misinformed. And I suspect precisely by one book written by a comic book artist. Somebody should probably just make a site 'clarifying' it page by page because it's chock full of misinformation and certainly a contender for the single worst pop-sci book published in modern times. It's the analog of people thinking the Moon landing was a hoax because they read some misleading article about the Van Allen Belts, all of which tend to like suggesting you'd need a radiation shield which would probably have gotten the astronauts killed due to bremsstrahlung, but I digress.
False, at least according to Wikipedia:
"JPL reported that MARIE-measured radiation levels were two to three times greater than that at the International Space Station (which is 100–200 mSv/a).[3] The levels at the Martian surface might be closer to the level at the ISS due to atmospheric shielding – ignoring the effect of thermal neutrons induced by GCR."
So a "typical" 18-22 month mission on Mars will still add up to 60 to 92 YEARS of radiation exposure on Earth -- assuming 100% perfect shielding to and from Mars, which seems exceedingly unlikely.
The longest stay aboard the ISS was 437 days. The round trip to Mars alone would be between 360 and 540 days. Between the trip and the stay, astronauts will be exposed to conditions that, to the extent that they have been explored, are incredibly harmful to the human body: low/no gravity, elevated levels of CO2, etc. And they'll spend the bulk of that time on a planet that is months, at best, away from any support on Earth.
They're also going to be exhausted due to the rigors and harsh environment of space, while also bored due to the absence of anything to do for fun besides consuming media; after all, there'll be no humans to talk to synchronously besides the same, small number of fellow crew members. (It's my pet theory that they'll all have LLMs and get way deep into AI psychosis.)
If you see the lives of astronauts as being essentially disposable, then these are not concerns of yours. But when you consider that sending humans to Mars to do research is the least cost effective approach imaginable, even a bit of concern for their safety should give you pause.
https://en.wikipedia.org/wiki/Mars_Radiation_Environment_Exp...
So that's where out friend Valeri Polyakov [2] comes in. His first words after landing following his initial 240 day stay in space were "We can fly to Mars." He then made an even stronger point of it by spending more than a year (continuously) in space, landing, and then immediately briefly walking after landing on Earth. As Mars is around 0.4g and the trip there wouldn't take anywhere near a year, it was a pretty clear demo that we can definitely get to and start working on Mars. Also, he spent another even longer stay in space later on. And would go on to die aged 80.
As for your concern about astronauts being bored. Well, let's just say I think they'll find a few ways to keep themselves busy - turns out there's quite a lot to do when starting a civilization. And disposable stuff is a bit off the mark. Nobody's sending anybody to do anything - everything is about personal choice. Would you rather have a life expectancy of let's say 10% less than average but filled with a life lived to the absolute extreme, or a life expectancy of let's say 10% longer than average, but where somebody lives in a bubble and avoids doing basically anything just to try to eek out a few more years? I think almost everybody would pick the former option. A good chunk of astronauts come from backgrounds like military test pilot, which means you certainly already know their answer.
[1] - https://www.scienceintheclassroom.org/research-papers/curios...
Your own source disagrees with you. According to the paper, you cited:
"Combining our measurements with those obtained during the cruise phase (22), we estimate a total mission dose equivalent of ~1.01 Sv for a round trip Mars surface mission with 180 days (each way) cruise, and 500 days on the martian surface for this current solar cycle (Table 2)."
As a reminder, 1.01 Sv is about 275 YEARS of radiation. Not good!
And the fact that a single astronaut is bullish about astronaut stuff should not determine out space exploration policy. Who cares if he wants to go back to space again?
> Well, let's just say I think they'll find a few ways to keep themselves busy - turns out there's quite a lot to do when starting a civilization.
There's no doubt our hypothetical Mars explorers (settlers, now?) will be busy. There will be tons of measurements to take, repairs to make, construction, maintenance, etc. But it will doubtless be tedious to be so far from the slightest bit of nature as we know it on Earth, or synchronous communication with anyone but each other, stuck in low gravity and inside the same small habitats (or space suits). And that will be their reward after 180 days of space travel!
I did some light research into the perchlorate-in-water issue, and you're correct that there exist industrial processes on Earth to filter them out. But at this point we're not just shipping pilots and engineers and scientists to Mars, but also perchlorate removal specialists to operate these machines.
What's the point? If it's to explore Mars, then we're wasting untold hundreds of billions of dollars to send humans to do a job infinitely better suited to robots. If it's to explore Mars (2), then why are we setting up industrial machines to extract water from its surface and do permanent harm to the place we're supposedly interesting in learning about?
The only credible answer left is, "We should explore Mars because the idea is cool." That's fine if Elon Musk wants to pay for it. But that money is infinitely better spent on Earth -- even if, or especially if, we invest it in building robots to do that exploration for us.
Let me start with the last thing you said. Is 'the idea is cool' a valid reason to go to Mars? First I think achieving great things is good for humanity - period, but there's even a purely pragmatic motivation as well. After we landed on the Moon the number of people wanting to (and who would) go into sciences, become astronauts, and other such things skyrocketed. The exact same thing is happening in China today where the majority of kids want to become astronauts or teachers. Whereas in America and the UK the plurality want to become streamers, with seemingly the majority having no direction for their life whatsoever. [1] Which next generation do you think will 'win' the 21st century? Even outside of competitive aspects, which generation is going to create a better country?
As for the radiation, you're again primarily referring to space radiation. Table 2 on the study shows their measured Martian surface level radiation level, which is less than the ISS. The space radiation is something that needs to be dealt with. Fortunately the current estimated trip length is 50% of their estimates - around 3 months, space weather events can be more effectively shielded against, and so forth.
And filtering out perchlorates isn't some advanced industrial process. It's literally just filtering water in a normal way. Plain old cartridges (specialized for perchlorates) like you might use in an at-home filter would work just fine. The reason I mentioned astronauts being enthusiastic about going to Mars because you have the most qualified people on Earth enthusiastic about it, some of the richest people on Earth enthusiastic about it, and billions of others. So it's obviously going to happen. There's no coercion or sacrificing people or whatever. It's a free world, and hopefully in the future we can make worlds plural.
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Robots are an interesting topic because people don't seem to understand how limited they are, though it's self evident if you think a bit more deeply about it. The most fundamental problem (among many) is that moving parts break. So for instance Curiosity's drill, as underpowered as it is (able to dig a narrow hole to about 6cm) broke after about a dozen light activations. It took a team of scientists almost 2 years to come up with a work-around that still left it crippled, but at least kind of workable.
And the drill is just one aspect. The more obvious one is moving. You have to be extremely cautious when doing such meaning major human oversight, and with an average round-trip latency to Mars of around 25 minutes, well - you don't move much. On average Curiosity travels about 1 mile per year. Try to imagine digging into the secrets of Earth by using a drill you can use a few times for holes up to 6cm deep, while traveling at mile per year. We're not even scratching the surface of Mars, quite literally.
And this is isn't just a technological problem that can be hand-waved away, because the reason things are in this state is because moving parts break. A human on site could have likely easily fixed the rover's drill in about 30 seconds, or just did a way better job of 'drilling' with a spoon. Humans will discover more about Mars in a week or two than the past 60 years of probes and rovers have, and likely even more than another century of such would achieve.
[1] - https://www.statista.com/chart/28802/childhood-aspirations-i...
And even then, again there's just something about a trained geologist being there, immersed in the thing, thinking on the spot, using a shovel that just can't be matched with robots.
Then you have all the ISRU (in situ resource utilisation) that you can take advantage of on Mars vs. in orbit around Mars. There have been experiments already demonstrating obtaining useful stuff (MOXIE got oxygen). And theoretically you can also make methane, you can melt water, etc.
Our existing method of moving between planets (heck, even the Earth & Moon) will take 9 months to get from Earth to Mars (or back). And the launch window is every 22 months. The return to Earth is either 4 weeks after you get to Mars, or 23 months later (so any fault that prevents a prompt return means you better have almost 3 years of food/water/air onboard).
Without some magical SF technology being invented, no, we're not going to see humans travelling to Mars in our lifetimes.
If folks are serious about human trips to Mars, there would be an effort to send supply ships ahead of time and stockpiling fuel/food/water/air in orbit around Mars. This would solve 2½ problems:
1 - Carrying supplies for both directions would require building spaceships bigger than we can currently build.
2 - If there is any failure on the way or at Mars, there will be stuff to let the astronauts survive until they can fix things or any sort of rescue mission could be sent.
And "that half" - Currently, the US has had a 70% success rate sending stuff to Mars (the Soviets had 50% success). Some of those supply ships won't reach Mars orbit. Some will break on the way there and drift past Mars. Some will smash into the surface of Mars.
Why send stuff? Supplying the astronauts on ISS requires sending 1000 pounds of stuff per person per month. And that's only 300 miles from Earth. And the ISS has water recycling, yet they still need water sent up.
My estimates for a successful "manned" trip to Mars (and return them safely to Earth again) would start around $200 billion.
https://en.wikipedia.org/wiki/Hohmann_transfer_orbit
https://en.wikipedia.org/wiki/Launch_window
This page claims Earth/Mars launch windows are every 26 months:
https://en.wikipedia.org/wiki/Exploration_of_Mars#Launch_win...
So you are telling me we could have gone to Mars and back a few times instead..
Sounds like the Martian mantle is (or was) organized as a single giant convection cell, with the upwelling under the volcanoes and sinking at Hellis Planitia.
Effects of 7km upon the atmosphere seem easily predictable. Ditto the benefits of 7km for exploration - improved aerobraking, drone performance, etc. But not so predictable would be effects on the subsurface.
An obvious downside of 7km would be "better" air cooling of equipment that needs to stay warm during Martian nights.
Also, whatever caused the Noctis Labyrinthus (west side of the valley in the article south east of the volcanoes) is a wild geologic process I don't think I have seen anywhere else. The large valley looks sort of like a rift valley, and erosion canyons are obvious, but Noctis Labyrinthus with it's fragmented plate look is weird, my best guess is a rift valley where three plates are separating, but that is a weak guess.
Really the fact that the jpl was able to fly a helicopter at all in mars's weak excuse for a atmosphere was an engineering flex like I have never seen.