I was wondering would it make sense/be interesting if you could transport water for terraforming purposes?
Considering how many times you would need to do and repeat this, I think it would soon become tedious.
And eat a lot of fuel stocks.
This is a severe understatement.
We can make a back-of-the-envelope calculation to see how impractical this would be:
Let us assume that volumetric compression can be neglected as a transportation option. Let us also assume that we wish to cover 20% of the surface area of a terraformable body with liquid water to a depth of 10 m---this is a
gross underestimate, but by being so it should more than cancel out the previous assumption to yield a conservative estimate.
Consider a Mars-like world, which has a mean radius of about 3,400 km (3.4e6 m), yielding a surface area of 1.45e14 m^2. To accomplish our stated goal will require (1.45e14 * 0.20 * 10) = 2.9e14 m^3 of water. Now consider a standard 25,000-ton cargo hold: if we neglect compression of the water and use the Walmsley ton (1 t = 14 m^3), we can transport 350,000 m^3 of liquid water per standard cargo hold per round trip. The number of (round trips * standard holds) required to complete this terraforming goal is therefore (2.9e14 / 3.5e5) = 830 million.
In fact, even if we assume a ridiculous Trans-Newtonian compression factor of 100x, we're still looking at over 8 million standard cargo holds worth of water to transport. Now, I've been known on occasion to give a freighter flotilla cycled orders with dozens of cycles and let them run around unsupervised for a few years, but this is well beyond that and probably well beyond the realm of feasibility. And of course, this is ignoring the fact that for a real, sustainable planetary water cycle, bodies much deeper than 10 m are certainly required, increasing the transport throughput required by potentially multiple orders of magnitude still.
A similar analysis could be done for terraforming gases, where the much higher compression achievable with gases is offset by the fact that an atmosphere must be many dozens of kilometers deep rather than 10 meters. This is why in Aurora, our terraformers
magically scientifically produce gases out of nothing through Trans-Newtonian handwaving.
