First, about fuel part. I thought "why O
2 must mean oxidation, why not oxygen ion thruster?".
Then i googled this paper:
"OXYGEN-PROPELLANT PLASMA THRUSTERS FOR CIS-LUNAR ELECTRIC PROPULSION MISSIONS"
https://deepblue.lib.umich.edu/bitstream/handle/2027.42/76753/AIAA-1998-3994-519.pdf?sequence=1Anyway, it's still discussion about Moon base for space travel facilitation.
Including assumption that humanity
needs to become spacefaring in the long run, all that with supervolcanoes, asteroids and whatnot.
Considering current political dynamics, "long run" may be a teeny bit misleading term - read up on
https://en.wikipedia.org/wiki/Bronze_Age_Collapse, then
http://www.sciencedirect.com/science/article/pii/S0921800914000615?via=ihub
Again, what Moon is and space station isn't - raw materials.
(Also, a point with stationkeeping costs for low mass/high surface area orbital structures like solar, mirror or EM funnels.)
sophiecentaur said:
The Earth has readily available raw materials on or near the surface
Yup, we need products, not raw mats.
So yes - a (business) plan for making usable products out of regolith/craters. Products with a discount of >6km/s deltaV.
https://i.stack.imgur.com/ZLpuN.png - cislunar orbits and deltaV budgets in 1 pic.
>6km/s discount, because fuel used to get to GEO is not wasted, spacecraft within the scope of this discussion is going to NEO and beyond.
>6km/s discount, because getting to LLO from Moon is not just smaller gravity well. It's also no drag = no impulse loss over time.
sophiecentaur said:
People seem to ignore just how totally different every aspect of life would be away from Earth.
We're not talking about "life" - living there, we're talking about industry.
1.25s lag is not significant for remote operation.
Robotic assemby chambers are way beyond prototype phase.
For industry, vacuum is beneficial - no convective heat loss(more problems with cooling but Mr.Stirling may help in more than 1 way), no pesky oxidation for materials and machines.
I also consider vacuum as a "product". Deep vacuum is expensive to make and maintain; it's necessary for quite a number of industrial applications, and desirable but not cost effective for a lot more(including 3D metal printing). Distilling with "free" vacuum and "cheap" heat/insulation would look different. Quotes because deltaV tax.
What products?
Structural materials, shielding, tanks, wiring.
https://www.sawe.org/papers/3662 - "...Most spacecraft structures represent approximately 20% of the total spacecraft mass..."
3D printing is way beyond prototype phase.
And yes, fuel - it needs not be oxygen. No drag = high I
SP low thrust shines.
Ion thrusters are way beyond prototype phase.
Drone ion tug(solar powered), shuttling LEO - EML1.
Modular engineering, 3 drones, 2 teleoperated assembly chamber, 2 3D printers(using lunar dust to print more drone frame parts, for starters).
Hi-tech parts for more drones/printers/chambers.
Plus, almost insignificant moment of power/heat supply infrastructure for all this (:
1 Falcon9 lifts 8300kg to GTO.
Unspecified amount of years and failed attempts later - our first Moonshine distillery/melt separator is up and running!
If we need to lift only hi-tech from Earth - electronics, drives, batteries, sensors, coatings, specialized alloy parts - the price of spacecraft , industrial machinery and drones in situ drops. Mass (relative) abundance would change a number of considerations in design stage.
I am obviously aware of multitude of technical challenges - material properties in vacuum like outgassing and sticking and ablation, moon dust, statics, solar wind, etc. And challenges bring opportunities(ex. sticking = welding things together).
Also I am obviously aware of multitude of technical challenges we're not aware of (: - because we're not there to look.
Huge pile of know-how is needed to make it all feasible and afterwards profitable.
Yet, there is no other way to get this know-how - only testing engineering solutions in practice works.