Quote from: Robotbeat on 05/24/2016 05:57 pmCO/O2 What about for the MTV voyage home?
CO/O2
My point was about propellantless launch of ISRU propellant from the Moon, where a) propellantless launch is *much* easier than for Earth or Mars due to the much lower orbital velocity and the lack of atmosphere you have to deal with, b) can be less infrastructure intensive than even setting up the ISRU system to feed it payloads, and c) makes a big economic difference to the cost of propellant from the lunar surface.
Propellantless launch, when practical (it's tons more practical on the moon than either Mars or Earth) dramatically cuts down on the amount of mining and infrastructure you need in order to support a given rate of propellant export. For the Moon, there are options for propellantless launch that could be landed in a single ACES/Xeus landing that could cut the amount of prop you'd need to produce on the moon by nearly half. Half the required infrastructure, half the required landings.
Quote from: jongoff on 05/24/2016 06:12 pmMy point was about propellantless launch of ISRU propellant from the Moon, where a) propellantless launch is *much* easier than for Earth or Mars due to the much lower orbital velocity and the lack of atmosphere you have to deal with, b) can be less infrastructure intensive than even setting up the ISRU system to feed it payloads, and c) makes a big economic difference to the cost of propellant from the lunar surface. OTOH, if you have enough activity in cis-lunar space to justify the construction of any form of propellantless launch from the lunar surface, it implies you've already solved whatever problem you are trying to solve with propellantless launch.
I want to follow up on this... is there a paper somewhere I should go read? To me propellantless means magnetic catapult. Even at reeealllllly high acceleration I'd assumed you need quite a lot of mass in a launcher. When you say "could be landed" what do you mean? As a kit that someone has to put together? With some ISRU components? Or self contained? Or do you mean something that unrolls/unfurls self deploys? Does the kit include the solar cells or NTU to power it and the batteries or is that assuming an existing ISRU plant that powers this for a bit?
Nothing is free, things have varying levels of difficulty to obtain so whether it's worth it to use one thing or another depends on the situation.
This technology is essentially a land based train that takes excess electrical energy and stores it through potential energy gained in large train masses. In rudimentary terms, it’s the equivalent of pushing a large rock up a hill when you have the energy so you can push it down later when you need more energy.
Bumphttp://interestingengineering.com/concrete-gravity-trains-may-solve-energy-storage-problem/QuoteThis technology is essentially a land based train that takes excess electrical energy and stores it through potential energy gained in large train masses. In rudimentary terms, it’s the equivalent of pushing a large rock up a hill when you have the energy so you can push it down later when you need more energy.
Quote from: Lar on 05/24/2016 10:02 pmI want to follow up on this... is there a paper somewhere I should go read? To me propellantless means magnetic catapult. Even at reeealllllly high acceleration I'd assumed you need quite a lot of mass in a launcher. When you say "could be landed" what do you mean? As a kit that someone has to put together? With some ISRU components? Or self contained? Or do you mean something that unrolls/unfurls self deploys? Does the kit include the solar cells or NTU to power it and the batteries or is that assuming an existing ISRU plant that powers this for a bit?I've been meaning to do a blog post on this, but it's been a previous topic on this forum (hint, hint). But yeah, I think a single ACES/Xeus lander could land the main system and the rest of the "kit" to setup a specific type of propellantless launch system that could put 1mT payloads into lunar orbit on a regular basis.~Jon
Yeahhhhh... wildly inefficient from a volume: power perspective and on the Moon, six times less efficient than *that.*
Quote from: Lampyridae on 08/16/2017 11:16 amYeahhhhh... wildly inefficient from a volume: power perspective and on the Moon, six times less efficient than *that.*Unless .. you are using local materials.
this would be to prove that the notion of glass domes would or would not have been a viable on the moon.
Energy storage tends to be heavy any way you slice it. Using local materials would obviously be beneficial, question is at what stage do you try to do that, and how high tech can you get.
Minor aside:Quote from: NIVbV-O77OdV-VSVN-Op-SLE7 on 08/16/2017 06:13 amthis would be to prove that the notion of glass domes would or would not have been a viable on the moon.Domes are compression structures, they are rarely viable when containing a higher pressure (such as air, in a vacuum.) If you are containing pressure, it is, by definition, a pressure vessel and hence should be shaped like a pressure vessel.(Even if you pile mass on top of the dome to artificially outweigh the force from the contained gas, that gas is still trying to blow out the sides, particularly where the floor joins the side (and that's assuming a gas-tight floor.) Hence the optimal shape would still be a classic pressure-vessel, but "squashed" by the top mass. A low, oblate spheroid, or elongated, ellipsoidal equivalent.)[Nothing to do with energy storage, just one of those SF tropes that annoys me.]
When comes to surviving 14 day lunar night here 3 options 1) Nuclear.2) Space Based Solar power beamed to surface.3) LH/LOX. Can generate 2kW/hr per kg, but takes lot more than that to convert it back from water to LH/LOX.