Moonwards

1:56 AM

@MolbOrg looks like it has some interesting ideas. not my personal cup of tea. i'm not crazy about their moon base design...

MolbOrg

2:14 AM

do see it like an opportunity to improve their models and views.

kim holder

talk to them about it? it doesn't seem you can, that isn't usually the kickstarter way.

also i don't have time...

kim holder

3:12 AM

hey, i was looking at that old tether spreadsheet wrong. that is indeed the problem with spreadsheets, especially when they aren't labelled very well - you look in the wrong place and don't notice your mistake.

the situation is way better than i thought. i see this now thanks to the superior tether tool. :]

with the tether center at 3000 km, and the foot at 250 km, the velocity at the foot is 4.6 km/s. Subtract the rotation of the earth from that speed (which i did with the old spreadsheet) and that is only 4.1 km/s. I had been looking at values for the center and thinking they were for the foot. Sloppy.

so that is a taper ratio of 6.4 with zylon, workable. and the climber car only has to go 2750 km.

MolbOrg

>also i don't have time...
by offering your models and your ideas

kim holder

the center is in the inner van allen belt, but i think it's below the worst of it.

MolbOrg

or might be establishing new connections

kim holder

that takes time... usually quite a bit...

they seem to be very on track for a very specific vision, too. i don't think they would be interested in moonwards right now.

MolbOrg

sure, just noticed the thing, and as there was a discussion about those matters it might turn to be an opportunity with chance 0.1%, but you choose what to do with it.
I saw that one girl on FB has posted the thing, I messaged her about that to get information in which relations she is with the project, let's see if there is something interesting out of that, I'll inform. Do not think it'll get something fruitful, but one little message does not take much time

kim holder

3:25 AM

this is something you do for the project, MolbOrg ;)

i have gotten myself immediately back into a position where i am swamped and will have to manage my time carefully.

i said i'd have a virtual colony that people can walk around and basically interact with by the next time i'm on the space show.

that's nov. 27th - unless david calls on me again to fill in last minute for a cancellation, but that's rare, and anyhow, it doesn't count.

now i have to learn how to build that, and build it, before then.

it might not actually be hugely difficult. actually, i'm almost certain that someone with an introductory knowledge of the software would find not difficult at all. but i have to learn it from scratch and i have no background.

and anyways, if i have extra time, there is plenty to do in terms of filling out the colony models with more details.

but if you have any leads, you can of course direct them to the repo, talk to them about the project, and if you need anything from the rest of us, just let us know.

btw - let me know where i should do a little editing for your blog.

MolbOrg

what is interesting for you in the project is that if it is not a scam, they will do some actual programming, and it could be interesting in terms of connecting some models to some sort of interactive environment. Taste of problems and requirements, implementations(what they did choose as engine and why).
Your position is a bit different than my as an example, you are a public person with some credo, you should have some time in your schedule dedicated to such questions.

In terms of interacting with other projects.

kim holder

they are an established business, they aren't going to give anything away. they aren't doing the same thing, they aren't going to want my models. they've already lined up their experts and look to have most of their designs chosen.

the smart thing to do for the first implementation is use three.js - of that much i'm satisfied.

i don't think i am any more help to them at this point than they'd be to me.

MolbOrg

probably true. As about established business - it looks to me they will look bigger than they are. 50k goal, for a game of that sort, hm ...

kim holder

we're turning in now though. nighty night, MolbOrg.

kk

2:03 PM

LOL

2:25 PM

The taper ratio is still just 1.7 if you extend it all the way to Mars transfer altitude.

The upper part can also take way more mass than the lower part of the tether. This is because their greatest cross section must be equal in order for the tether to be balanced, and loads are subject to a lot less acceleration up there.

At the Mars transfer point it is 0.287 m/s².

kim holder

what would be the approach to preventing it from hitting the planets?

Hohmannfan

The foot?

kim holder

the cable, crossing the orbits of the inner planets

Hohmannfan

Look closer at the image :D

Those are release altitudes for the lunar tether.

kim holder

oooh. see, now you understand the LOL

i thought you were enjoying the mental exercise of imagining just putting a tether through the inner solar system :D

which is sort of a fun idea...

yes, i had wanted to extend the upper tether to 15000 km for a long time. that may still be in the timeline.

oh, look, the planets are also out of order for my fun with cables in the inner solar system

i guess i just liked the idea so much...

Hohmannfan

2:37 PM

Hehe, if I place a tether like that in the tether tool it gives me stuff like "centre-top taper ratio: 7.562437427654154e+29"

kim holder

heheheh, i'm impressed it can handle it

i guess it's just putting in exponent notation - javascript is pretty cool that way

don't mind me.... i'm having my first tea of the day...

Hohmannfan

I think javascript is ok with numbers up to ~e317. After that it starts to return "Infinity" and every thing stops working.

kim holder

so the release points marked are to get to the transfer points?

Hohmannfan

Yes. If you release something from there at the right time it can reach those destinations.

kim holder

i thought it took more energy to get to venus than it does to get to mars

Hohmannfan

2:43 PM

EML1/EML2: 6750km
Earth: 9300km
Venus: 14200km
Mars: 17020km

No, Venus is slightly less expensive.

Not mine, but I found it very useful.

kim holder

yes, i have it, from when you last posted it. an excellent version.

Hohmannfan

Sadly it just covers the routes from Earth.

kim holder

:)

maybe that is the kind of thing you'd like to make, that map from the moon.

Hohmannfan

I started to create an universal one a long time ago, but I became tired of it. Perhaps I should complete it in vector one time:

kim holder

:D

yes, the upper cable of the equatorial tether goes to 20 000 km in what's written right now. And i put that it will also get you to Vesta or Ceres.

i may need to ask a question on the site about the inner van allen belt. i'd like to put the anchor station for the eventual earth orbiting tether complex well below the worst of it, but the typical altitude of the core of it is something i can't find.

Hohmannfan

3:13 PM

One thing I like about the Earth tethers:
1. Release something from the tether.
2. Let it fly by the Moon (must be carefully timed)
3. Re-catch it at a higher point of the tether
4. Climb down to original release point
Free momentum!!

kim holder

yeah, i am still working on the mother ship post, and i am doing that with the cycler ship. Which isn't really a cycler any more if it is caught at both ends...

oh - but you are talking about boosting the tether?

heh, neat

i may continue to be a bit slow today...

Hohmannfan

Also, if you boost the Earth tethers like that, you can send something to the Moon tether from them and send it back from a lower/higher altitude, boosting the Moon tether. So free momentum is something to consider.

The source of the momentum is of course the Moon's orbit, but I doubt it does much harm

kim holder

we can stop it from escaping that way :)

> High Voltage Orbiting Long Tether, or HiVOLT, is a concept proposed by Russian physicist V. V. Danilov and further refined by Robert P. Hoyt and Robert L. Forward for draining and removing the radiation fields of the Van Allen radiation belts[34] that surround the Earth.[35] A proposed configuration consists of a system of five 100 km long conducting tethers deployed from satellites, and charged to a large voltage. This would cause charged particles that encounter the tethers to have their pitch angle changed, thus over time dissolving the inner belts.

heh - i like it.

let me just put the Earth tether anchor at whatever altitude we like and drain the surrounding radiation, instead of trying to figure out if the flux of protons there is enough to make it necessary to shield the climber car so much it would be prohibitively heavy.

i wonder if this is the kind of thing that is probably going to have unintended consequences...

Hohmannfan

3:31 PM

Robert L. Forward again. He shows up everywhere.

kim holder

i wish i could have met that guy. died rather young.

uhoh

@Hohmannfan where is the transfer delta-v map from?

kim holder

3:51 PM

it's actually sort of curious they didn't put a credit on it anywhere.

yumonstudios.deviantart.com/gallery

uhoh

hmmm..... the source is an anime character?

kim holder

best ref i could find, from a google image search

MolbOrg

the anume character says
>My edit to the Ultimate Delta-V Map of the Solar System (created by CuriousMetaphor from Reddit), but now with even MOAR ORBITS!!!
so it is reddit as usual

kim holder

ah, nice work

Hohmannfan

6:24 PM

@kimholder Another way to manage the tether balance and momentum: dropping stuff. A dummy mass would enter a stable orbit if dropped between altitude 3600km and 6750km. Then they can be caught later.

kim holder

on the lunar tether? would they be hard to catch?

tethers seem to be really fun things to think about, if you have the knowledge :P

Hohmannfan

The acceleration is much lower there, so they should be easy to catch. And if you miss you can just wait until it comes back.

Depending on where they are released the re-docking opportunities should range from a couple of days to some weeks (multiples of 13.8 hours).

kim holder

let me see if i can think this through. 3600 km is 1400 km below the center point, and so is moving slower than orbital speed. If you drop something, it will descend, speed up, and move into an eccentric orbit with a perilune i guess a little further along in its orbit than where you dropped it.

Hohmannfan

Perilune on the exact opposite site.

The 3600-anchor zone is a place where it is good to drop a mass during shuttle docking with the foot.

kim holder

oh, that is very interesting indeed.

Hohmannfan

6:39 PM

That means we can keep a nice circular orbit before and after docking.

kim holder

that's beautiful...

Hohmannfan

Not that eccentric tether orbits are necessarily bad.

they are just harder to calculate.

like, they are not ellipses. They have oscillating elements.

And the node line moves.

kim holder

no... i guess during that part where the center mass is pretty light, and we are adding to it from the surface, an eccentric orbit could help with managing the orbit...

Hohmannfan

And the foot must be high enough to not perform uncontrolled lithobraking.

kim holder

:]

dropping from that higher point, the apolune would be on the opposite side from where you dropped it?

releasing from 6750 km?

Hohmannfan

6:42 PM

Yes. The tether tool can give you the appolune if you set the top to the desired dropping altitude.

(it also gives you the perilune instead if you set the top below the anchor, just ignore the warnings)

kim holder

21 million km apolune??

yeah, that isn't coming back for a few weeks...

Hohmannfan

6750km is basically an escape. So anything below that.

kim holder

i guess this has to be done so it loops away from Earth and isn't really affected by it?

Hohmannfan

Yes. Well within the SOL

kim holder

saying eccentric tether orbits are harder to calculate i suppose is an understatement.

you've reminded me i still haven't emailed Arthur

Hohmannfan

6:48 PM

Very yes.

Calculating it while a climber is ascending or descending is even harder.

5670km is a nice drop altitude. Then there is a re-docking chance every day.

kim holder

so, when it comes back, it will be higher than when it was released right? and it will be moving slower than the cable at that altitude?

Hohmannfan

No, exactly the same height and speed. No propulsion cost besides trajectory corrections.

5925km for once every one and a half days

kim holder

man, one day i will get used to thinking about this...

at the moment, my excuse is i'm digging into the NASA cancer prediction model to put in good data on CGRs for my blog post on mother ships

Hohmannfan

pfft. Radiation scare.

kim holder

:} this is why i want to do a good job...

Hohmannfan

6:57 PM

Why move though? Isn't the regolith a nice place to hide below?

kim holder

the small amount of research done so far on embryos in microgravity shows it is a really bad thing.

Hohmannfan

Centrifuge?

kim holder

and in the opinion of the doctors who have talked about it on TSS - who are pretty senior experts and so i'm taking their word for this - that is probably also true for low gravity places like the Moon.

centrifuge for how long? she can't stay there through her pregnancy. and then there is the question of child development in low gravity.

Hohmannfan

1. Why not? 2. So no kids in space then?

kim holder

if she is to spend her whole pregnancy there, and also the first years of the child's life, what that really amount to is 'put her on an O'Neill cylinder at one of the tether stations'.

which is an option... but pretty disruptive to family life...

and the basis of the whole argument we should forget about the Moon and stick to orbital colonies.

Hohmannfan

7:03 PM

Sounds like having kids in space is impractical. So then that should not be done.

kim holder

so my pitch right now - because personally i would really not want to live in an O'Neill cylinder - is that because we know so little right now, there is a method, we just have to figure it out.

if we can't have kids in space, we can't settle space.

stay tuned for the post on this. it says the whole thing a lot better.

it has just taken a while to sort out the data i want to include.

Hohmannfan

Space is a good place to dispose healthy people above 20 so they can get cancer.

kim holder

that is the image i had been searching for since late yesterday afternoon.

Hohmannfan

congrats

kim holder

: /

Hohmannfan

7:10 PM

Found a hard science fiction manga Planetes. It was ok (not quite strict enough sci-fi for my taste). I am going to check out the anime adaptation later.

kim holder

7:21 PM

enjoy. i'll try to finish that post.

MolbOrg

8:37 PM

funny service thunderclap.it/howitworks

for promotion

kim holder

9:51 PM

that's a really great idea. i'd never heard of it.

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