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Comment by misja111 | Hacker News Reader

The title says TerraForm Mars but the article itself only proposes a solution for directing more sunlight to the planet's surface. That is a very, very long way from terraforming.

To really terraform Mars, it would for instance need an atmosphere with a decent amount of oxygen in it. And there's a slight problem with that: Mars doesn't have a strong magnetic field like Earth does. Which is the reason that Mars' atmosphere was blown away in the first place*. How to solve that? Nobody knows, and this article doesn't even attempt to come up with a solution.

* https://eos.org/research-spotlights/how-marss-magnetic-field...

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Some folks at NASA think we can just park an MRI machine's worth of magnetic shield a million miles in front of Mars to fix the issue.

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

Yes - exactly this. A very large RTG or even fission powered electromagnet parked at L1.

Wouldn't the solar wind continuously impart some momentum on the field generating station, eventually pushing it out of L1? I don't doubt we could generate a good enough field, but the continuous station keeping might be tricky.

Probably, but I can imagine a converted starship being useful here - just keep refueling it every 5 years or whatever.

In a world... Where the entire survival of the planet is dependent on one shield ship... One man... Must save it... From the mad scientist who wants to destroy it!

I would see this sci fi movie!

Losing atmosphere due to solar wind is very slow process. If you spent 10 millions years building the atmosphere, you can afford few millions years to build a replacement for that ship.

That’s one hell of an institutional memory!

Yeah, but because of McGuffin it will happen in like 15 minutes if the super-villain gets his will. And then billions of Martians will needlessly die of suffocation and sun-burns. But our HERO John McLane III is there to valiantly save the day by employing fast one-liners and walking bare-footed on broken glass!!1

How much mass would you need for ion thrusters to offset that momentum?

It wouldn't be a problem for a species with an active space economy to keep a few satellites at L1. Should the species no longer have active space travel then eventually the planet would be screwed though, but how long is "eventually", and how long would the satellite have to be in place before the goal is met.

As a species we struggle do 5 years projects, let alone 500 or 5000 year projects.

You can park the magnet a little bit closer to the sun than a stable orbit would be and use the push to compensate for that. Make it a ring and you can even focus the protons around the middle of the disk and help Mars regain some hydrogen.

Yup, I'm a huge fan of this idea, and I think this is the obvious Step 1. After that, we can figure out how to genetically modify plants and other advanced terraforming techniques with automation.

Terraforming would be a very long-term thing, but we better get started now.

On topic: Yeah, teraforming is probably a pipe (ha! pun!) dream. Do we even have enough o2? n2? Imagine wasting our "solar system inheritance" and losing the atmosphere.

Off topic: My space friends tell me we should first land on Phobos and tele-operate the Mars robots.

But why bother with the landing? Phobos is just 14km, has no atmosphere or gravity. You have to bring a fully shielded habitat anyway. Why not just park in orbit?

you can dig in, that should give you some protection (both against radiation and meteorite strikes)

Ignoring the distance (which is a big thing, I admit) might Venus be a better choice to try and make livable compared to Mars?

Really hot, ACID rain. Not really

The wonderful pop science channel Kurzgesagt has a video on this:

https://youtu.be/G-WO-z-QuWI

Venus is close too but not quite tidally locked. Even if you could solve the considerable other problems, a planet with a day/night cycle nearly 6 months long isn't usable anywhere except the poles, and "spinning up" a planet is an absolutely enormous challenge compared to building a biosphere.

It's possible to live on floating platforms, because O2 is lighter than CO2. By capturing of sunlight (or strong winds), platform can generate a lot of energy to split CO2 into O2 and carbon, to keep platform flying forever, even with moderate leaks.

Isn't the main problem with Venus mainly an excess of carbon ? Is there any way to use (say) solar power to extract it and mass drivers to fling it off-planet ? It would have to scale. Megamegamega-ly.

Before anything else, you’ll need to cool it down. We could use solar sails for that as well, but to make shade instead of extra sunlight. It’d require a lot more sails (but they could be less efficient at producing thrust) than heating Mars. They’d need to be parked closer to the Sun than Sun-Venus L1 to compensate for the push they’ll get from the Sun.

According to my napkin math, a sunshade capable of completely obstructing sunlight to Venus would require at least 450 million sails of 1 square kilometre each. Seems doable for a civilisation slightly more advanced than ours.

Atmosphere is the least of the concern with the lack of a magnetosphere. Lethal solar radiation is the real problem.

The amount of atmosphere it loses is very small, the amount of generation can be much larger and the atmosphere would stay for quite a long time after it was created.

I don't know the exact math, but eventually humanity would have to find a way to top it off.

Mars is cold enough for a superconductor, so just dig two wires around the Mars poles and power them. Mars equator will be almost habitable, like in Arctic.

You solve it the same way you keep a tire inflated: Add more gas as needed.

Mars loses an atmosphere in about 10 million years, which seems a very reasonable time scale.

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