i'm redoing the notes on the TESS model on Sketchfab
i looked over the document about the heat losses, and have been thinking about a comment on the space show blog that such a system might be insufficient for power generation
i believe i'd had the idea that after the pit was functional, a trench could be dug around it to limit heat loss, but then i left that
now i'm back at the spot where i wonder if i should return the design to being a huge above-ground tank, or i should model in the trench
or maybe even a little of both. a trench saves on building the tank, which is no small feat, but what do you do about the bottom? i have thought about making it a cone, and inserting supports as the ground is dug away.
complicated... but then again, so is a huge tank...
Do you have some idea about the thermal situation of the base itself? Does it require heating? All the time? Only at night? Or perhaps radiators instead?
the earlier days can be resolved with nuclear reactors, for lalande. the solar thermal could work well if the technical problems have decent solutions proposed for them.
@Hohmannfan with the number of light tubes the galleries have, it takes a large mass of stone to act as a heat sink to keep temps even. i postulated that for most of the gallery length, the floor at least is in contact with rock
and by sinking shafts in that rock to get the surface area and penetration that is adequate, the heat coming in with the sun can be dissipated by that rock so that temperatures stabilize at a point that is comfortable and then it is very hard to shift temps away from that
After modelling most parts of the base now, do you have some estimate on the energy demand? I guess the most power hungry part is the industrial equipment, but that is just spikes when it is active.
that is so complicated and totally above my math abilities i've left it. my hope was to simply size things large enough to have a good margin for error.
i am a bit more concerned about getting the sizing of individual pieces a bit more into proper scale. i have no idea how big the heat reserve and the radiators should be on the solar thermal system
there is so much to do, putting things together all properly sized has to come together slowly.
the TESS is for an advanced colony, and unless it really has problems, it would be nice to keep it.
well, much less. the point on the timeline where a solar thermal system is even possible is advanced
the atriums will be full of plants - reducing need for air scrubbers
the living spaces are far more open, reducing need for fans
heat control should be largely passive, reducing need for pumps
coming up with ways to distribute plants widely, and with bio-processors for human waste - these things would be research priorities, and success would also reduce power needs.
i have been editing these notes, and i am about to simply delete reference to oxygen collection. The temperatures needed are just too high. They create too many materials issues with the heat pipes running through the mirror troughs.
Let us first rule out the chemical batteries. If you have solar power only during the day, you need storage for 330 hours of darkness. That is 330MWh. Good batteries are about 200 Wh/kg, so that is about 1,650,000 kg of batteries. Not gonna happen.
Seriously though, we only have three additional letters. But for some reason they added a ton of other characters as AltGr and AltGr+shift alternatives.
i would star that except i don't want to encourage you ;)
i'm not sure why i didn't think of that before. Maybe i did when i was making the model, but why would we not simply excavate a volume shaped however we want, set up the supports and the insulation, and fill it back in again with the material we excavated?
actually, it would be best to fill the outer areas of the tank with fine grain regolith so it doesn't conduct well
yes. so the chart on page 12 gives us a measure at 300 K, and i'd say it would be fair to take the bottom one, without the phenocrysts, and with no porosity
Approximately doubled over the interval, yeah. The simulation only has to be written once, so we can try many different rock structures as long as we can find data.
I'm working on a graphical simulation and I'd like to get the "look and feel" to seem as realistic as possible. Other than Apollo landing videos (which seem pretty limited and low quality obviously) are there any other good sources of high quality moon photos--specifically at many different altit...
There is also the consideration that the turbines are going to be running, pumping heat out of that store continuously
and i wondered if it would be the best option to place the heat exchange pipes for that around the perimeter of the tank, where they absorb heat that is approaching the exterior of the tank anyhow
David has had him on a few times because he offers some legit and interesting services, but he persists in saying it is possible to use lift to get to the Karman line
he says you can use a giant inflated wing to slowly accelerate as the vehicle rises so its velocity always allows it to have enough lift to remain aloft
and there was a show where someone called in and challenged that, but i felt the argument wasn't all that clear - not wrong, just not that clear
and we have a question about it that was never answered well, in fact the accepted answer claims it is possible.
By one of those weird coincidences, I had been on JP Aerospace's site mere hours before reading this question about space dirigibles here. Their mission plan seems too good to be true.
They are proposing a three part infrastructure
Earth to the top of the atmosphere.
High Altitude airshi...
and a bit above that was the second reply that explained why not, from Mike Murphy, who originally wrote me personally with the explanation, through moonwards.
and he and i got into quite a conversation. i was quite satisfied that the airship doesn't work, but i was happy to have a much better explanation as to why not.
If you can make a wing with a lift-to-drag ratio of 100 (almost impossible), you still need ion engines with a thrust-to-weight ratio of at least 1/100. (assuming the wing does not weight anything).
NSTAR is two orders of magnitude short, but the lighter-than-air lift helps a little, and so does scaling. I can not say this launch system is completely impossible, but it is far fetched.
The required lift is going to be constant (well, decreasing as you approach orbital velocity), and as the lift-to-drag ratio is a ratio, the drag is also slowly shrinking as you always choose an altitude only giving you the lift you need.
The physics behind the concept is fine, the materials and drives probably not.
but you need to constantly overcome that drag to get the lift, and the energy you need to do that, or the wing size to compensate, become so huge due to the squaring, it becomes unmanageable
i'd be interested in your opinion of the responses offered on the blog
As the acceleration happens in air unusable for a jet engine, the only benefit from this method of launch is the Isp of the ion engines. That benefit is somewhat less as most of the work is for the structure to support itself.
As I see it, this is less realistic than for instance a liquid core NTR.
> The remaining lift force must come from aerodynamic lift providing 49,000 Newtons. Ignoring the vehicle configuration needed to provide such lift, the drag is the lift reduced by a factor of 70 or 700 Newtons at sea level. Using the same drag coefficient times area value as in the first scenario, the 700 Newtons of drag at sea level corresponds to an airspeed of about 6 meters/second, so liftoff would occur at that forward airspeed.
> At an altitude of 40 km, the first scenario required thrusts of 757 Newtons at 100 meters/second and 2,639 Newtons at 200 meters per second to overcome drag and provide the 1.32 milliGee net forward acceleration.
"NASA also said that production of Pu-238 was being ramped up to 1.5 kg/yr by the mid-2020s, and by the end of 2015 over $200 million had been spent on this"
it would be nice if mining and refining enough fuel for that from local material was easy.
of course, the fuel doesn't weigh so much that it wouldn't be a lot easier to get it from Earth, unless you are getting it as a by-product of other mining activities
i probably shouldn't be multi-tasking on this. going over the molten regolith heat storage power system paper is hard enough. i think there are figures buried in there that would be useful...
actually, i was mistaken about the whole role beryllium plays. i thought it had to be there for a reactor to work at all. We're building an entire system of tethers in order to make importing and exporting high volumes of cargo cheap
the small amount of mass saved by using plutonium has got to be insignificant
over a series of day/night cycles, the behaviour changes because the assumption here is that this is just a pipe that goes into the ground. No tank.
and at one point i thought, 'adding some more mirrors just to make up for the losses to the ground is simpler than making a tank'
but now i suspect i'm wrong
The author (who, by the way, is Anthony Colozza) figures that 1800 K is the top temperature the system could be expected to withstand with constant use.
By one of those weird coincidences, I had been on JP Aerospace's site mere hours before reading this question about space dirigibles here. Their mission plan seems too good to be true.
They are proposing a three part infrastructure
Earth to the top of the atmosphere.
High Altitude airshi...
Moonwards
Moonwards