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Part of the problem is having too much atmosphere. In the original Cosmos Carl Sagan talked about a hypothetical solution where we capture asteroids, and throw

Part of the problem is having too much atmosphere. In the original Cosmos Carl Sagan talked about a hypothetical solution where we capture asteroids, and throw them at Venus in such a way that they just nick the atmosphere and knock large quantities of atmosphere out into space. One you reduce atmospheric pressure to a certain level, things could become habitable. Then throw in iron form the atseroid belt to react with it to form carbonates. Venus is dry so brining in hydrogen form the outer planets would be necessary anyway to form wate r and thta will account for a good bit. Garden the surface so subsurface rocks which might react with the atmosphere cna absorb some. (Assumign the subsurface rocks are thta reactive.) Scoop it off with smaller versions of the same scoops used to harvets hydrogen from the gas giants.

dylan604 1y ago
Couldn't we just build a MegaMaid and suck the atmosphere out? If we're going to go sci-fi, it seem easier to hoover it out than capture an asteroid and nick the atmosphere just right.
- shepardrtc 1y ago
  Something like a solar powered space elevator that just blows atmosphere into the sun
  - bdamm 1y ago
    That would require a lot of energy to ensure the gasses escape Venus' gravitational pull, which would in turn effectively be a rocket. So then we'd be adjusting to ensure we don't mess with Venus' orbit too much.
    - p1mrx 1y ago
      We can avoid orbital drift through the magic of building two of them.
    - gcanyon 1y ago
      Venus outweighs its atmosphere by about 10,000 times. This is actually less than I thought -- for comparison Earth outweighs its atmosphere by over 1,000,000 times, which is still far less than I would have guessed. Venus's escape velocity is less than 1/3rd of its orbital velocity. According to google, Venus's orbit, despite being very circular, causes its velocity to vary by a KM/s from aphelion to perihelion. So I believe you could send all of Venus's atmosphere off permanently into space at the cost of about 1/30,000th of Venus's orbital velocity, meaning you could very slightly circularize its orbit further.
      - hinkley 1y ago
        Spinning it up would be handy.
- BuyMyBitcoins 1y ago
  Then, move the MegaMaid into an orbit around Mars and go from suck to blow. Venus has too much atmosphere, Mars has too little. Win Win.
  - moron4hire 1y ago
    It wouldn't do Mars any good. Lacking a magnetosphere, any atmosphere you add will get stripped away by the Sun.
    - adrianN 1y ago
      The atmosphere will be stripped away over a time period of millions of years though.
    - irrational 1y ago
      I’ve read that a large asteroid could be positioned at a particular Mars L point and it would protect the planets atmosphere from being stripped by the sun.
      - andrewflnr 1y ago
        I've read something similar, but I believe it has to be an asteroid with a magnetic field, whether permanent or electromagnet.
    - hinkley 1y ago
      The estimate I heard is it would take 100,000 years for the atmosphere to be stripped off. That’s a long long time.
andrewflnr 1y ago
I recall one of the plans being to use the sun shield to entirely freeze out the atmosphere, then use a mass driver to chuck most of the CO2 into space. I don't recall exactly where that was supposed to be on the feasible to scifi spectrum. I'd rather try to keep the carbon around for organic molecules. Are we sure we can't get in enough H2O and N to balance it out and build a nice thick biosphere?
- pfdietz 1y ago
  You'd have to shoot it out of the solar system, otherwise much of it would reaccrete onto Venus... or onto Earth!
  - andrewflnr 1y ago
    I guess I'll count that as another reason to prefer managing it in situ. But it might be fine, actually? Slow re-accretion can probably be managed by whatever terraforming process we've kickstarted while most of it was gone. Oh wait, I remember the plan, ship it to Mars so they can have some decent atmospheric pressure.
    - pfdietz 1y ago
      Mars could use only a small fraction of it. If the entire atmosphere of Venus were moved to Mars, the surface pressure there would be 120 bars (more at the lowest point).
- hinkley 1y ago
  There’s a book where they freeze the atmosphere then cover the ice with a thick layer of dirt. But I cannot recall which.
somat 1y ago
"Venus is dry" I thought the Venus theory was runaway greenhouse driven initially by water vapor. Going off memory, H2O is roughly 10 times as effective a greenhouse gas as CO2, with Venus being closer to the sun A larger percentage of water ended up in vapor form, leading to a feed back loop where the increased heat pushes more water to vapor leading to more heat, eventually liberating the co2 from the rock, making everything worse, ending up with the current situation where venus has way too much atmosphere. Which is the long way to say, I think there is a lot of water on venus. https://en.wikipedia.org/wiki/Atmosphere_of_Venus https://en.wikipedia.org/wiki/Atmosphere_of_Venus
- andrewflnr 1y ago
  From your link: > Lighter gases, including water vapour, are continuously blown away by the solar wind through the induced magnetotail. There used to be a lot of water on Venus.
  - wahern 1y ago
    Moreover, I think Venus has lost most of its hydrogen to space, so you can't even make water anymore. Hydrogen escapes the atmosphere relatively easily for Earth- and Venus-sized planets[1], and the vaporization of all the water and subsequent disassociation[2] of H2O allowed the hydrogen to escape into space. [1] See https://en.wikipedia.org/wiki/Atmosphere#/media/File:Solar_system_escape_velocity_vs_surface_temperature.svg https://en.wikipedia.org/wiki/Atmosphere#/media/File:Solar_s... [2] See https://en.wikipedia.org/wiki/Atmospheric_escape https://en.wikipedia.org/wiki/Atmospheric_escape
    - saalweachter 1y ago
      Earth's oxygen rich atmosphere is really important here-- any free hydrogen can readily combine with the free hydrogen, decreasing the chance of any being loss.
      - andrewflnr 1y ago
        According to that wiki article, the hydrogen was mostly lost in the form of water vapor. The hydrogen and oxygen in the magnetotail are in almost a perfect 2:1 ratio. At least, > Currently the main ion types being lost are O+, H+ and He+. The ratio of hydrogen to oxygen losses is around 2 (i.e. almost stoichiometric for water) indicating the ongoing loss of water. Also Earth didn't have an oxygenated atmosphere until relatively late, a couple billion years in, so I didn't know if that could be the thing that saved it.

dylan604 1y ago

Couldn't we just build a MegaMaid and suck the atmosphere out? If we're going to go sci-fi, it seem easier to hoover it out than capture an asteroid and nick the atmosphere just right.

shepardrtc 1y ago
Something like a solar powered space elevator that just blows atmosphere into the sun
- bdamm 1y ago
  That would require a lot of energy to ensure the gasses escape Venus' gravitational pull, which would in turn effectively be a rocket. So then we'd be adjusting to ensure we don't mess with Venus' orbit too much.
  - p1mrx 1y ago
    We can avoid orbital drift through the magic of building two of them.
  - gcanyon 1y ago
    Venus outweighs its atmosphere by about 10,000 times. This is actually less than I thought -- for comparison Earth outweighs its atmosphere by over 1,000,000 times, which is still far less than I would have guessed. Venus's escape velocity is less than 1/3rd of its orbital velocity. According to google, Venus's orbit, despite being very circular, causes its velocity to vary by a KM/s from aphelion to perihelion. So I believe you could send all of Venus's atmosphere off permanently into space at the cost of about 1/30,000th of Venus's orbital velocity, meaning you could very slightly circularize its orbit further.
    - hinkley 1y ago
      Spinning it up would be handy.
BuyMyBitcoins 1y ago
Then, move the MegaMaid into an orbit around Mars and go from suck to blow. Venus has too much atmosphere, Mars has too little. Win Win.
- moron4hire 1y ago
  It wouldn't do Mars any good. Lacking a magnetosphere, any atmosphere you add will get stripped away by the Sun.
  - adrianN 1y ago
    The atmosphere will be stripped away over a time period of millions of years though.
  - irrational 1y ago
    I’ve read that a large asteroid could be positioned at a particular Mars L point and it would protect the planets atmosphere from being stripped by the sun.
    - andrewflnr 1y ago
      I've read something similar, but I believe it has to be an asteroid with a magnetic field, whether permanent or electromagnet.
  - hinkley 1y ago
    The estimate I heard is it would take 100,000 years for the atmosphere to be stripped off. That’s a long long time.

andrewflnr 1y ago

I recall one of the plans being to use the sun shield to entirely freeze out the atmosphere, then use a mass driver to chuck most of the CO2 into space. I don't recall exactly where that was supposed to be on the feasible to scifi spectrum. I'd rather try to keep the carbon around for organic molecules. Are we sure we can't get in enough H2O and N to balance it out and build a nice thick biosphere?

pfdietz 1y ago
You'd have to shoot it out of the solar system, otherwise much of it would reaccrete onto Venus... or onto Earth!
- andrewflnr 1y ago
  I guess I'll count that as another reason to prefer managing it in situ. But it might be fine, actually? Slow re-accretion can probably be managed by whatever terraforming process we've kickstarted while most of it was gone. Oh wait, I remember the plan, ship it to Mars so they can have some decent atmospheric pressure.
  - pfdietz 1y ago
    Mars could use only a small fraction of it. If the entire atmosphere of Venus were moved to Mars, the surface pressure there would be 120 bars (more at the lowest point).
hinkley 1y ago
There’s a book where they freeze the atmosphere then cover the ice with a thick layer of dirt. But I cannot recall which.

somat 1y ago

"Venus is dry" I thought the Venus theory was runaway greenhouse driven initially by water vapor. Going off memory, H2O is roughly 10 times as effective a greenhouse gas as CO2, with Venus being closer to the sun A larger percentage of water ended up in vapor form, leading to a feed back loop where the increased heat pushes more water to vapor leading to more heat, eventually liberating the co2 from the rock, making everything worse, ending up with the current situation where venus has way too much atmosphere. Which is the long way to say, I think there is a lot of water on venus. https://en.wikipedia.org/wiki/Atmosphere_of_Venus https://en.wikipedia.org/wiki/Atmosphere_of_Venus

andrewflnr 1y ago
From your link: > Lighter gases, including water vapour, are continuously blown away by the solar wind through the induced magnetotail. There used to be a lot of water on Venus.
- wahern 1y ago
  Moreover, I think Venus has lost most of its hydrogen to space, so you can't even make water anymore. Hydrogen escapes the atmosphere relatively easily for Earth- and Venus-sized planets[1], and the vaporization of all the water and subsequent disassociation[2] of H2O allowed the hydrogen to escape into space. [1] See https://en.wikipedia.org/wiki/Atmosphere#/media/File:Solar_system_escape_velocity_vs_surface_temperature.svg https://en.wikipedia.org/wiki/Atmosphere#/media/File:Solar_s... [2] See https://en.wikipedia.org/wiki/Atmospheric_escape https://en.wikipedia.org/wiki/Atmospheric_escape
  - saalweachter 1y ago
    Earth's oxygen rich atmosphere is really important here-- any free hydrogen can readily combine with the free hydrogen, decreasing the chance of any being loss.
    - andrewflnr 1y ago
      According to that wiki article, the hydrogen was mostly lost in the form of water vapor. The hydrogen and oxygen in the magnetotail are in almost a perfect 2:1 ratio. At least, > Currently the main ion types being lost are O+, H+ and He+. The ratio of hydrogen to oxygen losses is around 2 (i.e. almost stoichiometric for water) indicating the ongoing loss of water. Also Earth didn't have an oxygenated atmosphere until relatively late, a couple billion years in, so I didn't know if that could be the thing that saved it.