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Comment by robbles | Hacker News Reader

I remember reading that Mars doesn't have a magnetic field like Earth's to protect it from solar wind, therefore the atmosphere mostly gets swept away. Is that not the more difficult problem here? This debate seems to center on generating enough CO2, but that seems a bit irrelevant if it would just blow away. How would you even go about fixing the magnetic field of a planet?

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We can create a magnetosphere at Lagrange point between Mars and Sun that has a tail that would protected Mars from solar radiation. Radiation from other stars is still a problem I think? https://phys.org/news/2017-03-nasa-magnetic-shield-mars-atmo...

True, but at least the magnetic field could redirect solar wind (or, at least, its protons) to impact head-on and replenish Martian hydrogen instead of pushing the atmosphere away.

https://phys.org/news/2017-03-nasa-magnetic-shield-mars-atmo....

> In answer to this challenge, Dr. Jim Green – the Director of NASA's Planetary Science Division – and a panel of researchers presented an ambitious idea. In essence, they suggested that by positioning a magnetic dipole shield at the Mars L1 Lagrange Point, an artificial magnetosphere could be formed that would encompass the entire planet, thus shielding it from solar wind and radiation.

It's all about the rate of loss. If it's 1% per year, that's probably not going to work; if it's 0.0001%, that's a different matter altogether.

Everything is temporary in the long run.

From the paper in the article:

>"MAVEN has observed the Martian upper atmosphere for a full Martian year, and has determined the rate of loss of gas to space and the driving processes; 1–2 kg/s of gas are being lost."

https://www.sciencedirect.com/science/article/pii/S001910351...

Oh, I was thinking in terms of the cost benefit of terraforming. If you magically make the planet's atmosphere 1 bar of co2, how long would that last at a usable level - say at or above 0.5 bar - assuming no replacement?

If that's 10k years it's less appealing, but 1m years might be worth it.

Build a worldhouse instead of full terraformation ?

https://www.orionsarm.com/eg-article/484746e824a3a

No need to worry about atmosphere loss & you can start incrementally and get usable land almost at only, not only after long years of terraformation.

Agreed. Para-terraforming is a criminally underrated concept.

With "terraforming" you'd have the problem that dozens of generations would have to work their proverbial asses off without ever experiencing the fruits of their labour. Not exactly a strong suit of the human race.

Another advantage of the world-house approach is the possibility to leave sites of interest as-is by not including them. With terraforming it's impossible to preserve select areas for scientific or cultural reasons.

No problem - we just need to melt the outer core to get the dynamo effect - will only require 1 trillion nuclear bombs once we figure the technology to drill down to that depth.

Perhaps that's the end-game for lord Musk's Boring Company

That's probably a problem on billion year scales. I wonder what the annual loss would be.

Its estimated Mars had at atmosphere for the first billion years. But loss is not linear. The less you have, the faster it's eroded.

So to rebuild it, might want to quickly get to a sustainable value before its blown away again? I favor crashing Saturn's icy asteroids into Mars to release gigatons of water vapor.

Isn't it the reverse? The more atmosphere is present the faster it erodes away?

Not according to the papers.

Which papers? That's really counter intuitive to me. I'd expect that a higher atmosphere concentration would have a higher rate of loss because the solar wind would grab more of it.

Does this mean that mars is losing atmosphere faster today than it did 500million years ago? That's really fascinating!

Can't find it now. Curiosity has an instrument to measure isotopes, which tells how its air chemistry changed over the aeons. It showed disparity in heavy vs light gasses trapped in rocks of different ages. Light gasses are lost first, so that gave a clock on atmosphere loss. And a profile of that loss over time.

Here's a sunday-supplement summary I did find: https://science.time.com/2013/07/23/revealed-how-mars-lost-i...

From the paper in the article:

>"MAVEN has observed the Martian upper atmosphere for a full Martian year, and has determined the rate of loss of gas to space and the driving processes; 1–2 kg/s of gas are being lost."

https://www.sciencedirect.com/science/article/pii/S001910351...

The math is clear. A new atmosphere would take millions of years to get swept away.

Last math I saw suggested 100,000 years, but if we're still on Mars for that long and dealing with atmospheric bleed-off, we done fucked up already.

Even if it’s only a hundred thousand years, we can set up a magnetic field in Mars orbit that would substantially reduce losses far easier than actually making the new atmosphere.

Earth’s magnetic field comes from consisting of a massive ball of molten iron surrounded by layers of rock, soil, and, ultimately, monkeys.

The critical component for the magnetic field (the molten iron ball) is hard to replicate.

The necessary magnetic field is actually easy to replicate.

By that logic it's pointless to pump a tire, since the air will eventually leak out.

Terraforming will in part be a permanent process. The atmosphere lost will have to be continually replaced. And that's fine.

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