Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Mars likely to have enough oxygen to support life: study

phys.org

Post reply on HN
Print view View original

131–140 of 217 posts

Re: Mars likely to have enough oxygen to support life: study

#131

Post by bryanrasmussen »

rohit2412 wrote: post #63
bryanrasmussen wrote: post #39

Earlier quoted context omitted.

Well people often argue that part of the reason we're making this planet inhabitable is because there are too many people on it, so they have a fanciful notion of moving some of those excess people to another planet. which is sort of nonsensical. However spreading your species across two self-supporting planets makes a planet ending catastrophe less likely to destroy your species. The knowledge gained from any large…

I doubt outside of gamma ray bursts if anything can actually wipe out all humanity. And even then, a nuclear bunker on the Earth is far more habitable than any non settlement. In fact, I'll argue that any money spent on vanity Mars settlements is going to save more lives in a calamity if it is spent helping developing countries lift people out of poverty. > although I have to think it should be easy enough to see how…

Just because I outline reasons why people might want to have a Mars terraforming project or similar does not mean that I am interested in a Mars settlement.

Re: Mars likely to have enough oxygen to support life: study

#132

Post by jamesrcole »

worldsayshi wrote: post #107
jamesrcole wrote: post #20

Earlier quoted context omitted.

Despite what we hear in the media, the world has gotten so much better in many ways in the last couple of hundred years. That's not to say there aren't big issues, or no things that have gotten worse, but there's a clear and very strong overall trend. See for example The Better Angels of Our Nature: A History of Violence and Humanity, by Steven Pinker https://www.amazon.com/Better-Angels-Our-Nature-Violence/dp/... Or…

The world has gotten much much better in some ways (health, longevity, child-mortality, education, economy, violence). But it has also gotten much much worse in others (environmental destruction, military capability). We can't just focus on one aspect and neglect the other. One doesn't take away the magnitude of the other. The magnitudes of the bad as well as the good are both enormous.

> We can't just focus on one aspect and neglect the other

Who is doing that? I said "That's not to say there aren't big issues, or no things that have gotten worse, but there's a clear and very strong overall trend."

When you look at the magnitudes it's clear that overall the direction is overwhelmingly in the positive direction.

You say it has "gotten much much worse in others (environmental destruction, military capability)". I agree in the case of environmental issues. But if you're talking about wars and violence (and in what other sense could military capabilities be bad?) things have gotten much better not worse.

Re: Mars likely to have enough oxygen to support life: study

#133

Post by cbkeller »

richardknop wrote: post #97
cbkeller wrote: post #75

Earlier quoted context omitted.

Geologist here. I would tend to agree, considering that present-day oxidizing conditions on mars are generally thought to be due to photolysis and hydrogen loss, not life/photosynthesis, e.g.: https://www.liebertpub.com/doi/abs/10.1089/ast.2013.0999 https://www.sciencedirect.com/science/article/pii/S001910350... Heck, Mars is so oxidized it has soils that are 0.5% perchorate: https://en.wikipedia.org/wiki/Perchlorate…

What are the current thoughts on what caused oceans on Mars to disappear (with some remainder concentrating in ice caps)? Was it some impact of a really big meteor/comet? It is accepted that Mars used to have liquid water oceans and rivers in the past, correct? You can see geological remains of rivers and oceans, for example, quite clearly on Mars.

It seems increasingly likely that there was originally quite a bit of liquid water on Mars during the Noachian (https://en.wikipedia.org/wiki/Noachian) and Hesperian (https://en.wikipedia.org/wiki/Hesperian) -- the Martian geological time periods more or less contemporaneous with what we call the Archean Eon on Earth. It's not clear that this would have been quite as extensive as "oceans" yet, but it's definitely possible.

As to why the water was lost, it basically all boils down to "Mars is too small". Too small to have a strong gravitational field that makes escape velocity hard for gas molecules to achieve, too small to have enough primordial+radiogenic heat driving a magnetic field to protect from solar wind, and too small to have primordial+radiogenic heat to drive plate tectonics and the silicate weathering feedback (https://doi.org/10.1029/JC086iC10p09776) that stabilizes liquid water on Earth on billion year timescales

As for how: ions and molecules reaching escape velocity. For water in particular, a lot of this would have been through hydrogen escape, which actually happens on Earth too (just slower). If you photolyze H2O, it's very easy to lose the H because it's so light, thermally or by solar wind, etc. There's more info on the how here: https://en.wikipedia.org/wiki/Atmospheric_escape

Re: Mars likely to have enough oxygen to support life: study

#134

Post by utopcell »

fuscy wrote: post #99

I never understood why colonizing Mars is needed. Even if a meteorite hits Earth or Yellowstone erupts, Earth would be more "hospitable" to life than any other planet in our solar system because Earth has a lot of resources that are right under our noses: breathable atmosphere, radiation shielding, easily mined metals and organic matter. It's much easier to build and maintain a bio-dome in the Sahara desert, Arctic r…

Much like the space program [1], colonizing Mars will be a focal point for developing technologies for improving life on Earth.

[1] https://en.wikipedia.org/wiki/NASA_spinoff_technologies

Re: Mars likely to have enough oxygen to support life: study

#135

Post by MaxBarraclough »

biffq wrote: post #103
MaxBarraclough wrote: post #95

Earlier quoted context omitted.

We can put that another way: the odds of a populated Mars being an anarchist utopia are nil. Politics and power dynamics would remain. Moving planets doesn't let you escape power-structures, and anarchism is still stupid - you still have to hope you get a good power-structure.

It appears you are setting yourself up to a series of sound disproofs, such as having to point out how communities with purpose without the damaging effects of power dynamics are more efficient, intelligent and effective.

Even in a frontier society there are power structures, and they are better off that way, no?

Re: Mars likely to have enough oxygen to support life: study

#136

Post by robotomir »

dagw wrote: post #106
skzo wrote: post #102

Earlier quoted context omitted.

Indeed, but you are forgetting that Earth also has the biggest threat of them all... Humans

but you are forgetting that Earth also has the biggest threat of them all... Humans So will any place we colonize.

Well in the absence of government regulations you could populate the new place with clones of yourself and institute a personal theocracy.

Re: Mars likely to have enough oxygen to support life: study

#137

Post by richardknop »

coldtea wrote: post #113
richardknop wrote: post #93

Earlier quoted context omitted.

It's easier and much more efficient to get resources such as raw materials and metals from the ground. Being in the air without option of landing means you are completely dependent on import of raw materials to repair/expand your habitat. Very inefficient as well as not economical. It might be cheaper to get to Venus than to Mars but on Mars you can actually start mining and building factories on the ground. At some…

> It's easier and much more efficient to get resources such as raw materials and metals from the ground. Being in the air without option of landing means you are completely dependent on import of raw materials to repair/expand your habitat. Very inefficient as well as not economical. Assuming you overcome all the other difficulties and have a colony on Venus' skies, what prevents you from having ships that can go to…

It was my understanding that the surface of Venus is infernal, with super high temperature (hotter than Mercury which is closer to sun), rains of sulphuric acid and very high density. Building machines capable of landing there and being able to return seems like a tall order.

Since for humans it is inconceivable to go down to Venus ground (they'd die immediately from the heat), mining materials and then lifting again and returning back to the habitat in the upper atmosphere, then you'd need to automate the whole process.

The automated machine would have to be incredibly durable to survive the hellish ground environment and be able to fly away again. Also drones that would do the mining work would need to be made from incredibly strong materials. There's a reason we only send suicide probes to Venus that live maybe for couple hours before dying.

Also for humans, cold temperature is easier to survive compared to very high temperature. We can generate heating for astronauts (batteries in space suites can generate heat, we can recharge batteries from solar panels brought by the mothership or on previous automated mission, or from RTG). I'm not sure how would a cooling system for astronauts to be able to survive in 700 degrees Celsius for longer than few minutes even work.

Re: Mars likely to have enough oxygen to support life: study

#138

Post by cbkeller »

raducu wrote: post #125
adrianN wrote: post #116

Earlier quoted context omitted.

Mars gravitiy is not strong enough causing it to very slowly lose gases to the solar wind. Water vapor included.

I wonder if it's the solar wind or just the escape velocity vs. the termal escape. I'm sure in a couple of centuries humans would be able to build superconducting magnets powerful enough to shield Mars from the solar wind (those would double as energy storage as well), but we can't do anything about the fundamental properties of gases and escape velocity.

There's a bit of comparison of the two (thermal vs. non-thermal escape) here: https://en.wikipedia.org/wiki/Atmospheric_escape#Thermal_esc... but I don't know the relative proportions on Mars. There have been some recent studies of the xenon isotopic composition of the paleo-Martian atmosphere that might provide a bit more insight, and in particular suggest most of the loss happened early: https://www.sciencedirect.com/science/article/pii/S0012821X1...

Re: Mars likely to have enough oxygen to support life: study

#139

Post by richardknop »

adrianN wrote: post #116
richardknop wrote: post #97

Earlier quoted context omitted.

What are the current thoughts on what caused oceans on Mars to disappear (with some remainder concentrating in ice caps)? Was it some impact of a really big meteor/comet? It is accepted that Mars used to have liquid water oceans and rivers in the past, correct? You can see geological remains of rivers and oceans, for example, quite clearly on Mars.

Mars gravitiy is not strong enough causing it to very slowly lose gases to the solar wind. Water vapor included.

So how can we Terraform Mars to make it like Earth then? It seems impossible due to the gravity being so small. Even if we melt ice caps and get liquid water running again, it will slowly evaporate to space? How could a colony on Mars then be self sustaining with this problem?

Re: Mars likely to have enough oxygen to support life: study

#140

Post by cbkeller »

richardknop wrote: post #139
adrianN wrote: post #116

Earlier quoted context omitted.

Mars gravitiy is not strong enough causing it to very slowly lose gases to the solar wind. Water vapor included.

So how can we Terraform Mars to make it like Earth then? It seems impossible due to the gravity being so small. Even if we melt ice caps and get liquid water running again, it will slowly evaporate to space? How could a colony on Mars then be self sustaining with this problem?

Definitely a problem long-term, but we'd be talking in millions of years at least
Post reply on HN