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There’s a heck of a lot more CO2 in Venus’ atmosphere than there is in Mars’.
by jscipione 4y ago
There’s a heck of a lot more CO2 in Venus’ atmosphere than there is in Mars’.
- ncmncm 4y agoAnd, more importantly, hydrogen. For those wondering, the gravity, temperature, and air pressure in the cloud tops of Venus are all near Earth-normal. And, breathing air is buoyant. Mars is a frozen, dry dump. There is really no value in sending live people there. They would take one trot around the lander and want to go home.
- metadat 4y agoWhat about the sulfuric acid in the atmosphere of Venus? Can we transform that away, too?
- ncmncm 4y agoThat would all be outside. Polypropylene is proof against sulfuric acid. But you will need that sulfuric acid for the hydrogen it carries. Carbon from CO2 for structural members, hydrocarbon for plastics and fabric for gas bags, oxygen to breathe. There is thin gaseous silicides, in case you need any silicon. It will be hard to keep the concentration of CO2 in the breathing air thin enough not to make everyone stupid, with so much of it outside.
- jscipione 4y agoSabatier reaction plus ordinary rain will solve that problem away but nothing will solve the slow rotation rate and lack of a molten core and resulting magnetosphere. Still Venus is a better candidate than Mars for terraforming.
- mahkeiro 4y agoVenus lacks a magnetic field too…
- Teever 4y agoWhat if we terraformed Venus by shipping the CO2 to Mars? That way we'd be terraforming both planets. I've been wondering about the feasibility of self-replicating floating comet factories that make dry ice comets that could be launched to mars. You could even wrap them in some sort of carbon based exterior to prevent them from boiling off too much in transit.
- XorNot 4y agoIt would be more efficient just to redirect some comets. There is more then enough of everything floating around the inner solar system, and the Oort cloud has even more. The composition of Mars' atmosphere is less important then getting the pressure right - at 1 atmosphere, humans don't need suits just respirators, and Earth-microbes will be more then happy to normalize things to suit them (they did it here, after all). For Venus the big problem is water: Venus is dry. The reason it's in run-away greenhouse is because all that CO2 just will not precipitate into carbonate minerals, which to do so needs water. Again: something comets have plenty of. The difference between the two in suitability though is the tidal lock: Mars has a day-night cycle. Venus has a day-night cycle but it's 116 Earth-days long - half the planet, if you got the atmosphere under control, would be in a freezing night for 3 and half months. You could settle it, but life would only really survive at the polls. While we can process a planetary atmosphere with plausible near-future technology and local resources, there's no known way we could "spin up" Venus (ironically a fully-tidally locked planet would have much more usable surface area as an oculus-world).
- mr_toad 4y agoThe clouds (and presumably anything floating in them) ‘orbit’ the planet much faster than the planet rotates. It only takes about 4 days for the upper cloud decks to circle the planet.
- Teever 4y agoBut you still have to vent the excess CO2 from Venus to terraform Venus, so where would you put it if not somewhere like Mars?
- JKCalhoun 4y agoWould the gravity of Mars even hold on to an oxygen atmosphere?
- _joel 4y agoDepends how dense the oxygen is ;) It wouldn't, but there are methods to retain it. If we had the capability, which we definitely don't, currently. On earth we have a magnetosphere that protects our atmosphere from erosion from the deluge the sun gives us (hello Auroras!) but Mars doesn't have that. It's size is an issue too plus it's distance and orbit around the sun now. It didn't used to be so barren, it had massive lakes and oceans and possibly life once upon a time. To terraform it now would take a level of engineering that we don't have, but could, if we manage to not nullify ourselves in the next 200 years.
- retrac 4y agoNo, particularly in combination with the lack of an active magnetic field to shield the atmosphere from the solar wind. It's thought Mars had a much thicker atmosphere in the far past, now mostly bled off into space. Though if a new atmosphere were created, it would be lost again on a very, very long time-scale -- hundreds of millions of years. It might work to just "top up" once in a while.
- bee_rider 4y agoHow near Earth normal is the gravity around Venus?
- midoridensha 4y agoAbout 0.9g.
- elihu 4y agoIt's almost 10% less. It's either a really weird coincidence or it says something interesting about planet formation that Earth, Venus, Saturn, Uranus, and Neptune all have almost the same gravity at the surface. (Of those five, Neptune has the highest gravity at 1.137g and Uranus is the least at 0.886g.)
- bee_rider 4y agoHuh, Mars is interestingly outside the norm there.
- ncmncm 4y agoIt is also unique, among those, in being wholly unable to sustain a buoyant aerial unshielded nuclear reactor. Titan can. But its surface gravity is less than a seventh of Earth's. It seems unlikely people can live on Titan or the Moon for long without fatal loss of skeletal tone. (Mars might be possible, but why bother?)
- elihu 4y agoI forgot to link the page with a big table of planets/moons and their gravities: https://en.wikipedia.org/wiki/Surface_gravity https://en.wikipedia.org/wiki/Surface_gravity Anyways, Mars is an outlier with respect to the "about 1G" crowd, but it's almost identical to Mercury. 0.379g vs 0.377g respectively. Jupiter is a true outlier at 2.528g.
- WalterBright 4y agoI've often thought that, too. It's difficult to see what would make Mars worthwhile to colonize. The moon, on the other hand, has many advantages: 1. shallow gravity well 2. only a couple days away 3. interactive radio Since you'll need a spacesuit anyway on Mars, what's the point over the moon?
- somenameforme 4y agoNear identical axial tilt to Earth, meaning a similar seasonal cycle (none on the moon). Day/night cycles near identical to Earth differing by less than an hour (2 week long day/nights on moon). A land surface area near identical to Earth's land area, which means room for vast expansion. (moon is a bit more than 2x Russia) Somewhat more tolerable gravity at 0.38g compared to .17g on the moon. Vastly more tolerable temperature ranges. A day on the equator in summer can get up to around 70 degrees F, though nights hit -100 F. The large difference owing to no atmosphere. The moon ranges from nearly absolute zero at night, to greater than boiling during the day. And many more. These are just a handful off the top of my head. --- And some would consider the distance to be a feature, not a bug. It creates a necessity for a large degree of self sustainability which is ultimately a prerequisite to becoming a multiplanetary species. On the Moon, self sustainability not only more challenging, but ultimately not really necessary given it's just a stone's throw away from a resupply. And necessity really is the mother of invention. Ultimately I also don't even view Mars as a goal (though it may be able to over millennia developed into an amazing place, and I would be the first to sign on for a mission to such), so much as a stepping stone. By the time the first human settlement is established on Mars, we should be looking outward from there as well. Titan being a possible next destination.
- andrew_lvov 4y agoCould you do the same comparison with Venus please ?
- ceejayoz 4y agoVenusian days are 116 Earth days long, and land surface area is functionally zero.
- CrazyStat 4y agoIn absolute terms, yes. Venus is larger and has a much denser atmosphere. In relative terms they're similar. Unfortunately nobody wants to live on Venus, in part because of that much denser atmosphere, so there's not much interest in making oxygen there.
- ncmncm 4y agoYet, for all that, it is way more appealing than Mars.
- CrazyStat 4y agoAs a tourist destination, perhaps. As a self sustaining colony absolutely not. Since you have to float in the atmosphere to survive, mass is at an enormous premium. On-world industry would be nearly impossible. If your goal is to build an exotic resort for billionaires go to Venus. If you're trying to ensure the survival of humanity in the event of a planet-scale catastrophe go to Mars.
- ncmncm 4y agoGoing to Mars would contribute exactly nothing to the survival of humanity, because everybody on Mars would remain absolutely dependent upon frequent shipments from Earth. Any attempted Mars colony would die out not long after the last shipment, as materials necessary to its continued survival remain unobtainable there. Furthermore, Starship is anyway wholly inadequate to establish a continued presence on Mars. If it works fully l as well as promised, it might suffice to maintain a Lunar outpost. Anyone who hopes to establish a sustainable presence off-Earth must look to O'Neill Cans.
- exq 4y agoThe same could've been said about the ISS when it was planned, but we've learned a heck of a lot from that.
- 4y ago
- zoba 4y agoAny ideas on how to get Venus’s rotation speed more similar to Earth’s?
- ncmncm 4y agoThe cloud tops go around in 4-5 days, depending on latitude. That is pretty high winds already. For solar power, you need storage for the long night. A heavy weight on a cable could be played out at night to spin a generator, and then wound back up in the daytime. A nuke power plant, if you would rather, could be as simple as a naked pile hung inside a big fabric tube with a wind turbine at the top. No need for shielding, cooling, or containment.
- TaylorAlexander 4y agoThe clouds rotate around Venus once every few earth days I believe. It’s actually pretty earth like if you’re floating in the clouds.
- dhosek 4y agoDeflect a comet to glance against Venus and increase the spin. As an added bonus, you might create an equatorial ocean in the process.
- hansvm 4y agoDunno that I'd want to be anywhere near Sol if an impact imparted enough energy to Venus to sufficiently increase its spin.
- deleted 4y ago[deleted]
- wolfgang000 4y agoonly one small problem with that idea, the lack of a magnetic field, mars also has this problem but you atlest can bury your self in the ground to protect yourself agains the solar radiation
- bee_rider 4y agoIf you've already figured out how to live in space for the many months required to get to Mars, why would you want to abandon your (presumably shielded) ship to live underground at the bottom of a massive gravity well? Stay in orbit. The view is better and you're halfway to anywhere.
- solarengineer 4y agoThere's a Kurzgesagt video on terraforming Venus https://www.youtube.com/watch?v=G-WO-z-QuWI https://www.youtube.com/watch?v=G-WO-z-QuWI
- _joel 4y agoIt's a bit warmer too