Moonwards - 2017-11-17

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12:14 AM

btw, i decided to restore the forum databases, now that the actual forum is gone.

that way the posts could still be transferred over to a new forum or some forum-like service, maybe.

Really, the majority of those posts were converted to blog posts, too. They are far down the list now, but they are there.

i don't think the ones that are more recent mattered to the authors very much. they were brief and casual. it's the ones Hoh posted that were mostly worth saving, and essentially they already were, because i converted them into blog posts.

i was just looking again at this one: moonwards.com/2016/07/23/hybrid-ice-shuttles.html

2 hours later…

2:10 AM

>why not simply run water through the reactor when more thrust is needed?
the answer is simple, difference of heat conductivity. One of the thing with hydrogen it is high.
The second part - hydrogen is not an oxidizing agent, which water is not entirely, especially when it might begin to dissociate from high temperatures. One of the ways to mass-produce the hydrogen, or might be one of the first ways to produce it(do not recall atm) was to blow the steam through heated iron shavings.
there is a sense to separate those.

with humans, you will have water on board for different means so you can have enough of it to use afterburner style for such cases

also, TWR of nuclear engines aren't that bad like electric propulsion

2:58 AM

hm, these are quite interesting points

well, maybe the main point here is for something like this i should stick to designs that have been fully analyzed and drawn up by aerospace engineers.

there are just too many things to think about. the things that are hard to anticipate with a skyhook at least aren't things that would cause it to fail.

they are just things that make it hard to stabilize it so the tethers aren't waving around

13 hours later…

4:21 PM

no - hard to stabilize it so they aren't bobbing up and down.

i've been stuck in this confused loop about this for a while. i see khan academy now has practice problems set up for their physics video series. i should go through the course.

i think i can set aside time for that once i have a few more things done.

ask you the question - why you need those sky hooks

wispering -massdriveeerssss...

and the second - and what if they wobble, the thing should just not cross some point in stress distribution and have means to nullify those over time

yes, i know. i think i would need to know more about your whole approach in order to know why you prefer mass drivers. i can see that they have advantages, but depending on what you are doing, they have disadvantages too.

tell me about disadvantages as you see them for yourself

a mass driver it fixed, and unless you make it a lot more fancy, it points in only one direction.

yes, it is kinda fixed, and worse then that, the moon rotates )

they do not have to solve all your problems and be a universal solution(on surface), they have to help you to solve problems in a more general way.

so what is the answer - which main purpose, which main problem is solved by sky hooks in your case

4:38 PM

the provide local transportation on the moon to any point. There is a base at the pole first, from there a shuttle can go anywhere by catching onto a skyhook when it is headed in the right direction, and letting go at the right spot

i also think they are more useful for a sort of launching. a ship has to get from the surface to the foot of the skyhook, but at its tip, it can let go at the right point so that the outward motion the skyhook gives it will throw it to another planet, and it doesn't need to spend any fuel for that

for the equatorial colony, they can still use the skyhooks to get anywhere on the moon, but it would either take a lot more time, or they would need to transfer between skyhooks to do it, which still takes a while and involves a bit more fuel.

i have read that a mass driver can also be used for landing, but it seems more difficult. You have to line up with the exact right point in the exact right direction, and then you can land with it. But unless it is quite long, it is going to put the payload through a lot of g force as it is decelerated.

if you miss, your ship is toast, and possibly the mass driver too.

if you miss a rendezvous with a skyhook, you just need to come around again. It will cost you fuel, but you won't crash.

that's if you are doing a rendezvous with the tip, coming from another planet.

ok, a bit more sofisticated than I expected(which is good ))) ), but seems I can prepare that

i do think about this rather a lot :)

4:56 PM

as usual from the begin, one point at a time.

for one hook to be able to deliver a payload to any place on the moon from polar orbit, it will take about 15 days. for an expense of relatively sophisticated orbital construction of significant mass and size.
and to decrease the time and improve the coverage you need to have let's say 15 of them. not even talking about the need to be delivered to any place(that any place has to have something interesting, and I guess there won't be that many places anytime soon) and the throughput of the system by payload mass(how many you can catch in one go,…

but it is important to take into the account - there should be a system prior hook, which helps at least to build that hook. So there will be some means to solve the transportation problem and locations will be adjusted to capabilities of those means

the first skyhook is built purely with resources from Earth. It actually doesn't need to be that massive at first. And my understanding is that building a mass driver is pretty complex too.

the full skyhook constellation for the moon is only 3 polar skyhooks and 2 equatorial ones. That provides a pretty good alignment with a chosen destination every 4.5 days. By the time that isn't enough, there would be so much infrastructure on the moon it doesn't matter. By that time there are roads.

if you do the from moon resources alone. And massdriver is basically series of typical elements stack together, not a one-piece construction, which hook is closer too. You need to get some processes going and some mass production going on the moon to build massdriver but once done, you repeat it as much as needed

i don't know. there would be a lot to analyze to compare the infrastructure to build the skyhooks compared to what is needed for the mass drivers. However, you can build other things on the moon, for sale to earn the money to build the skyhooks. And anyhow, the revenue that builds the system comes from selling residence.

the thing that justifies the skyhooks to me is that they provide a wider range of services that become more valuable with time. I supplement them with something sort of like a mass driver eventually, but not until the moon has a lot of infrastructure

the lunar colonies concentrate on development that allows them to build ships, and satellites, and space stations.

shipping such things to space using a skyhook provides a lot more flexibility. there is no need to think about shape and size, or the g force the components can withstand.

>I supplement them with something sort of like a mass driver eventually, but not until the moon has a lot of infrastructure

why not earlier?

5:12 PM

they aren't needed earlier. there isn't enough payload mass to justify them. and they are big, it is a major project.

think about this. If you learn how to build skyhooks around the moon, then you can build one around Earth. You sort of need carbon nanotubes to do it, but still. You are never going to build mass drivers on Earth.

whereas our timeline ends up with a system of skyhooks across the solar system. they can toss payloads back and forth, eliminating almost all need for fuel, from mercury to titan.

>You are never going to build mass drivers on Earth.

Because I do not have to, I'll build orbital mass drivers ))) no this point is 1:1, you master orbital massdrivers, and you do not need carbon tubes for make it be useful

orbital mass drivers don't make it easier to get from the surface of Earth to orbit. A skyhook does, a lot.

and don't tell me your mass drivers don't require any fancy technology development. Carbon nanotube development i think is a modest prediction.

why should they require fancy tech?

you aren't going to use any superconductors?

what about the capacitors needed to provide the extremely precisely timed and high-power energy needed?

they may require a lot of mass to make then sufficiently robust, to have proper stabilization systems and all that, yes they may be sophisticated, but looks in the realm of conventional materials. The spooky thing is probably the size and the length

>you aren't going to use any superconductors?
no. if they are - good, if they aren't - not a big deal. Well cooled aluminum and other metals drop their resistance significantly if one needs.
as for precision/timing - we have a bunch of electronics to solve the problem, and as gauss guns shows(one gauss gun) it is solvable (velocity isn't that high, but if you consider the length timing has to be more precise - and it basically solved by plasma being a switch)

you have energy storages over the length of the construction and discharge happens by means of the projectile flying through

so discharge is there when it is needed

but ok all that build down to us convince each other what is better hooks or mass drivers, so I'll move on, you say your part, I'll read, and move to another point

5:32 PM

i think i've covered all the important points. it is just a matter of looking at what they can do when you put them together. Sure, it requires industrial production of carbon nanotube cable. We have 35 years - from the beginning of the timeline, which isn't tomorrow - to figure that out. That seems plenty to me. My sense is that space manufacturing will make CNT cable easier to make, so it is even more likely.

>launching the ship to another planets

skyhook is also kinda fixed construction. It is fixed by its orbit, and the plane of rotation of those hooks
so they also need right moment to do things. And we do not talk that there should be a right moment to depart from earth orbit in general.
So in that regard hook, isn't that much different from a massdriver on the ground.

really unfortunate that mass-drivers in orbit are considered to being last and not that priority goal for you. I understand it, it is the result of development pace you have chosen.

*I meant points of original starting comments of you

a skyhook orbits around it's primary every few hours. there is a launch opportunity to any planet you choose once per orbit. That's plenty.

>to any planet you choose once per orbit.
it is not, that is the point

if you know as much about the residency program as you know about the skyhook design, i'm not surprised. You've never read the material.

I have read old timeline in full length, but it was quite some time ago )

5:36 PM

it was completely different then. though, the residency program, not so much. anyhow, if there wasn't a political problem, i'm quite convince that nations and other groups would pay the quoted prices to send people to the Moon, considering all that would be happening there.

equatorial skyhooks can launch in any direction, once per orbit. How can that not line up with a trajectory for a planet, once per orbit? Bear in mind that these skyhooks can throw a ship very hard.

I paid attention to it, but it is not my point here, let's focus on technological aspects, financial ones - haven't seen any good points in circulation in notions of general public

>How can that not line up with a trajectory for a planet, once per orbit?
you need to play KSP. Crossing orbit is not sufficient.
the inclination of your orbit is important, phase angle from the orbit location is important.
Think about we have the ability to launch from earth basically at any inclination we would like, but windows to mars are about once in 2 years.

I know that. But the skyhooks can throw very hard. They expand the launch windows tremendously. And we were comparing mass drivers to skyhooks. If a skyhook can't launch because the planet is in a difficult spot in its orbit, a mass driver will do even worse.

Alright - orbital mass drivers are different. They can compare, but the scale and complexity is no less than a skyhook. I'd say it's more. And they will subject their payloads to forces that the skyhook doesn't. Skyhook launch is gentle

And they don't need to use fuel to maintain their orbit after a launch

>Skyhook launch is gentle
is gentle because of the length, we still talk about change in the velocity, thus accelerations.
I'm not against hooks as means to do the job when appropriate, and more concerned about moon deals, what happens on the moon, what is first eggs or huns

Gentle is gentle. Of course it's because it's long. The point is a mass driver is not gentle unless it too is quite long. At that point, the difference in mass is not that much - if the skyhooks are made of CNT.

>And they don't need to use fuel to maintain their orbit after a launch
it is correct if you restore the impulse/momentum by delivering payload in another direction.
same for mass drivers, if they are in orbit. But generally, our problem is the electric propulsion is slow and hooks and potentially mass-drivers are the proxies to solve the problem. We are capable to do efficent rocketry, it just takes too much time, so i would not be too much concerned about that particual aspect of the problem

massdriver will be significantly more massive than hooks, I do not say they will be more masseffficient

that is your answer for not having sufficient payload to launch, you mentioned earlier.
More mass, less orbital problems after launch

*after launch of a payload

5:54 PM

the skyhooks can launch plenty of payload, even before the switch to CNT the equatorial skyhooks can launch hundreds of tons, once every 7 hours. That sounds like enough to me.

i am not very inclined to debate economic models. There is so much involved in such decisions, it is really just a matter of opinion. The main thing is i have a model and i've thought it through.

also another aspect of being able to deliver at any point on the surface.

hook has tethers and they rotating with some angular velocity, and the thing is orbiting around the moon at some angular velocity. This result being points on the surface(areas) where the best to launch and land, but those won't be strips of launching and landing as a projection of orbit of the thing.
Multiple tethers will help with the problem, so it not only one once in 15 days for a construction to deliver the payload but a bit more complicated than that.

They don't rotate.

ok ))

you mean like those systems where the whole skyhook rotates around its center so that when the foot comes down it is stationary or close to it relative to the surface, right?

these don't. A shuttle needs to launch and expend fuel to catch up to the foot, but it needs a small fraction of what it would need to do a sub-orbital hop

yes. with nonrotating, there are really more questions. but I do not wish you disappoint to much in one day ))

*by my illiteracy

6:09 PM

believe me, i've thought about this a lot. so far none of your criticisms have caught me by surprise.

remember i do this all day, every day. i know you have a strong physics background and i don't, but i've thought through these things even so.

I mean by me not knowing all the required details to make my points based on your assumptions, not that by catching you off guard in your assumptions.

yes, it would indeed be easier if you were familiar with the plan. This is good practice for me stating my case, though. For the most part, it isn't bothering me that you haven't read the material because i need to learn to explain it well on the spot, and in relation to other ideas instead of just by itself.

for some reason i can't explain, it bothers me more that you discount the residence program. But really, that comes down to a matter of opinion - whether countries would pay the price, or they wouldn't. Anyhow, aside from whether that convinces anybody, Moonwards needs to be based on human settlement. That is the only activity that is interesting in a virtual colony - which is what it is.

also, I hit some limit of easy stuff, which my congrats about.
>A shuttle needs to launch and expend fuel to catch up to the foot
to prepare the thing as an example, it requires a lot of efforts. I can bet half of my lunch, there are somethings to point out.

Also, some arguments just slip through
>>How can that not line up with a trajectory for a planet, once per orbit?
>>a skyhook orbits around it's primary every few hours. there is a launch opportunity to any planet you choose once per orbit.

But this is a case where it genuinely would help if you knew the architecture of the skyhook system. They throw things hard. I mean, really hard. And if a planet still isn't in range, then there is a good chance you can hop to a neighboring skyhook and then get a trajectory that will work from there.

If Venus isn't in range, go to Mercury, and then hop to Venus. If Mars isn't in range, go to Ceres or Venus, if it in range of either of those.

And if none of that works, burn some fuel to get the extra speed. After all, most of the speed you need still comes from the skyhook.

6:28 PM

>because i need to learn to explain it well on the spot
nice then, I won't fee that much guild then. Also, you might be used to throw links at me from the timeline, to see if I can get the required information from it.

>would help if you knew the architecture of the skyhook system.
I have no doubts it can be potentially done, good coverage, all requirements met. For me it is just underestimating the problem.
They throw hard, they have to catch hard.

>If Venus isn't in range, go to Mercury, and then hop to Venus. If Mars isn't in range, go to Ceres or Venus, if it in range of either of those.

with inertial trajectories, which is the point do not spend the fuel for delta-v, you need to respect those

the skyhooks throw things hard. this is the key point.

and those hops will take years. you better off to launch when appropriate.

They can throw a ship out of orbit with far more velocity than is needed for a Hohmann transfer. Far more.

For cargo, years isn't a problem, but the extra speed they get shaves off a lot of that time.

hard is not enough, on time and in a proper direction. When you miss a planet by a few million km ...

well, it isn't like either an orbital mass driver or a skyhook could make it unnecessary for a ship to burn any fuel at all.

6:35 PM

ok let's say they throw at 100km/s, or 1000km/s - does not matter, and capable to catch at those velocities, it does not mean you can throw the thing in any direction - right? It does not mean you can trow the thing at any time it "intersects" the target orbit - is that correct?

>well, it isn't like either an orbital mass driver or a skyhook could make it unnecessary for a ship to burn any fuel at all.
that's correct.

and i wasn't saying they wouldn't have any other source of delta v. i just said that most of it could be eliminated

i think, the vast majority

the extra speed expands launch windows a lot, combined with the other things, i think most destinations would be in range most of the time.

moonwards.com//timeline.html#sith

there, i'm testing the use of a link. Though, that section is long.

6:58 PM

actually, that one is more relevant

oops, wrong one

moonwards.com//timeline.html#tossShips

and that one doesn't work.... crap....

>i think, the vast majority
correct, it is the potential.
but before you throw thing left and right, probably more important would be to deliver required fuel

>the extra speed expands launch windows a lot, combined with the other things
correct it is, but it does not negate the requirements to throw at a proper time in the proper direction. And I remember, it is smore about "fixed position" and the problems of the thing which makes the launch, and that orbit of the thing is a parameter which is kinda "fixed".

>"Also, to go from Venus to Earth or vice versa, it's often faster to launch to Mercury, and then go from Mercury to either planet." - this one you need to think more about it

however i can't right now to say something super smart about it, again needs calculations and etc
or be smarter in making the argument, than I'm capable right now

ok, seems the best strategy not to distract you from doing things )))

The thing about mercury was a simplification, the timeline expands on that, considering mercury's inclination and its proximity to the sun

i don't know why that links isn't working...

Most of this came from playing with the tether tool Hoh built

the hard throw thing is also considered in terms of catching. The tips of the skyhooks on the receiving end are also moving much faster than orbital velocity. But the toss ships don't come in and dock all by themselves, they are helped in. That means fuel use, but it has been optimized as much as possible

>is also considered in terms of catching
yes, sure I assumed that

7:18 PM

`for(var i=0;i<detailsToLink.length;i++){
if(detailsToLink[i].id){
var detailsSummary = detailsToLink[i].getElementsByTagName('summary')[0];
var linkingNode = document.createElement("span");
linkingNode.innerHTML = " 🔗";
linkingNode.setAttribute("class","permalink");
linkingNode.title = "permalink";
var linkingLocation = window.location.protocol + "//" + window.location.host + "/" + window.location.pathname + "#" + detailsToLink[i].id;
linkingNode.setAttribute("onclick","var linkingText = document.createElement(\"textarea\");linkingText.setAttribute(\"rows\",\"1\");linkingText.setAt…

it seems the extra slashes generated for those permalinks are not so simple to understand

there are some that have even more than the rest, and those ones don't work

or, no, that's not it... i don't understand.

but it mostly works

7:52 PM

window.location.pathname == "/timeline.html"
so this part "window.location.host + "/" + window.location.pathname"
has to be - "window.location.host + window.location.pathname"

oh okay - i was looking further down. i missed that. though actually, i think i noticed that the other day...

Something interesting - if you use a permalink to open that section in a new tab, and then copy a permalink from that page, the address now has 2 extra slashes, not just one.

and they will continue to multiply like that

i'll try removing that slash

yep. that worked. thanks.

8:48 PM

>and they will continue to multiply like that
it continues because URL get screwed, and when yone used that //time..# he gets window.location.pathname == "//timeline.html" - pathname, which it is.
so they did procreate

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Nov '1717

Moonwards

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