Terraforming of Mars Ideas (and questions!)

[Twark_Main]

I've yet to read a single terraforming idea that is at the same time simpler, faster, cheaper, and more permanent than dropping large wet rocks onto the planet.

Water isn't the problem. Heat is the problem.

A large asteroid impact produces a lot of heat on a human scale, but it's tiny compared to solar radiation. Blanketing dry ice snow polar caps with dust also won't work, because the dry ice already sublimates away and switches poles twice a year.

[Phil Stooke]

I'm surprised that you think finding large wet rocks, getting them to Mars and making them hit it will be simple, fast and cheap. 

[Vultur]

A strong greenhouse effect could probably give Mars a reasonable temperature.

It's more a question of:

- hitting Mars with comets will mess up anything people are already doing on Mars

- if you can move comets on that scale, you can probably build space habitats, which would likely show results quicker than terraforming

I am not sure what the *point* is since you need large-scale asteroid-mining type tech/infrastructure anyway.

OTOH terraforming Mars may be a good vision to *sell* developing that infrastructure for someone like Elon Musk (like the big mural at SpaceX). But if that infrastructure ever actually exists, I don't think terraforming Mars is what it'll be used for -- at least not through

(IF it ever does happen, I'd expect something less disruptive like highly engineered microbes/nanobots [if there's even a difference] cracking atmosphere out of rock.)

[Twark_Main]

Hurling sulfur hexafluoride tanks at Mars is one possibility.

At 230 K and 6 bar the density of SF₆ is 1.83 g/ml. A 200 tonne spherical tank would be 6 meters in diameter.

That 200 tonne tank would have the equivalent greenhouse gas impact as 200 t x 23,900 x r_Earth²/r_Mars² = 17 million tonnes of CO2. So "only" 4,420 tanks per synod would need to be launched to match the current warming rate due to terrestrial CO2e emissions.

I presume the tanks would be designed to break up on reentry to release the SF₆. Nice and simple. A small Starlink-derived cruise stage would ensure the tanks remain on course for Mars.

The tanks would be jettisoned after TMI by a "launcher" Starship, which would immediately retro-burn to remain in the Earth SOI. This way a single Starship can deliver multiple tanks per cycle.

If we assume that Earth is experiencing 1 degree of warming per century, then it would take "only" 884,000 tanks to achieve 2 K of warming.

This works out to about 118x as much mass as Casey Handmer's reflector proposal. But...

  • Sulfur hexafluoride has an atmospheric lifetime of 800-3,200 years (caveat: on Earth), vs optimistically a 30 year failure half-life for satellites

  • Sulfur hexafluoride is 80¢/kg, which compares favorably to $200/kg for satellites

  • There exists mixtures of greenhouse gases that offer roughly twice the specific warming of pure SF₆

  • In real life you would almost certainly simply make the sulfur hexafluoride in-situ on Mars and vent it, eliminating tank and launch costs. 



One of the first steps would be to better constrain the atmospheric lifetime of SF₆ (and friends) on Mars.

[mike robel]

Does not contribute to the scientific discussion here, but a fun game to play for 1 to 5 players is https://boardgamegeek.com/boardgame/167791/terraforming-mars available from Sweden, various game stores, amazon, and even Target.  This is one of my favorite games to play and there are several expansions to include additional Mars maps, Venus, a prelude (to make games go faster), colonies, and Turmoil which adds trials and tribulations.

It can also be played in various digital forms.

There is also a card game version which I have not played.    https://www.fryxgames.se/produkt/terraforming-mars-ares-expedition/

[KelvinZero]

You could make nanoballoon robots that replicate themselves from carbon and construct nanodiamonds they drop to the surface.

I had wondered about nano-balloon robots quite recently, or more specifically a " lighter than air liquid".
Im not sure if my logic is correct, but I think instead of having an atmosphere that gradually thins to nothing you could fill a crater or canyon with a lighter than air liquid and trap an atmosphere beneath it. The compressed air beneath is denser than the liquid but above could be pure vacuum.
..or maybe it would just form a whirlpool hole and the air would gush through it.

If the balloon-layer is "lighter than air", then it's not significantly compressing the atmosphere. So the air beneath would expand up and out (pushing up the "liquid") until it matches the density of the balloon-layer. At that point, the balloons and top-most air would mix freely, and the air would be able to disperse, further lowering the pressure of the air beneath; rinse and repeat until there's nothing left but the nano-balloons sitting on the ground.

The only way to prevent it would be if the nano-bots secured the balloons together into a coherent, air-tight layer. Which is just a membrane again.

So the question just becomes "could we use nanobots to make a membrane of arbitrarily large size?"

Im not convinced of my own idea, but your intuition might not be strictly correct either. It may not do much to hold in pressure but it could reduce the height at which a wall in needed to hold the atmosphere in by hundreds of kilometers.

Just using the example of earth pressure where we have 10 tons of atmosphere sitting above every square meter. Maybe the first 9 tons fits into the first 20km or so (thats a guess) but then it just goes on and on. Your lighter than air liquid could still be lighter at that height. If this layer is thick enough to provide one ton of pressure its weight could equal what the hundreds of km of ever thinning atmosphere would have produced. I don't think there is any particular reason for the atmosphere to push through it, because it is lighter at the boundary and that is all that matters

(apart from all sorts of whether effects and whirlpools forming etc. Im only arguing at a spherical cow level)

edit: and sure, it could have some sort of surface-tension or other sort of clingyness. It has to be at least non-permeable to gasses, not with many gaps like a ball pit.