Artemis 2

billvon said:
I think you can realistically have space elevators or LEO satellites. Not both.
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But. But. Dave said they can swing the beanstalks. Have you forgotten Mister Roger's Law? "The greatest nation in the world is Imagi-Nation."
 
TheVat said:
Oh those SU carbs were elegant things - variable venturi throat. LOL running a Mini on a big LA battery - we heard stories about stranded Beetles which played off that idea....engine was dead, so guy just kept turning the starter motor, flat terrain, he limps to the next town on his battery. Good luck finding any factory EV without the screen. Some of the first generation ones, like a Nissan Leaf, are a more stripped-down car, relatively. (If you go that route, you can upgrade to a newer battery pack, iirc)
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Had twin SUs on my next car - an MGB. Balancing them was a bit of a pain.

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This is a pic of a K reg one. Mine was J reg but same colour. Lot of fun.

B-series engine 1.8l. But not that different from the Minor really.

But I’m off topic. Apologies.
 
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DaveC426913 said:
Apparently it's not a big deal to swing the beanstalks out of the way of any satellites. They looked into this.
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I think "swinging" a 10 million ton cable out of the way of 15,000 satellites passing by once every 90 minutes (a little more than 2 a second) might be optimistic. Sure, most satellites won't intersect on every orbit. But they just keep launching the things, and once we have a million satellites in orbit - going to be a bit of a problem.

I agree it's theoretically possible. But it's like saying "hurricanes aren't a problem. Apparently it's not a big deal to move Kauai out of the way of any hurricanes."
 
billvon said:
agree it's theoretically possible. But it's like saying "hurricanes aren't a problem. Apparently it's not a big deal to move Kauai out of the way of any hurricanes."
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Fine, then skyhooks. Artemis 14 can park in orbit and the next crew comes up in an X-plane which docks with a skyhook tether and gets flung up into orbit.

en.wikipedia.org

Skyhook (structure) - Wikipedia

en.wikipedia.org en.wikipedia.org

A skyhook is a proposed momentum exchange tether that aims to reduce the cost of placing payloads into low Earth orbit. A heavy orbiting station is connected to a cable which extends down towards the upper atmosphere. Payloads, which are much lighter than the station, are hooked to the end of the cable as it passes, and are then flung into orbit by rotation of the cable around the center of mass. The station can then be reboosted to its original altitude by electromagnetic propulsion, rocket propulsion, or by deorbiting another object with the same kinetic energy as transferred to the payload.
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Geez. You pilots are so picky about safety.
 
billvon said:
I think "swinging" a 10 million ton cable out of the way of 15,000 satellites passing by once every 90 minutes (a little more than 2 a second) might be optimistic.
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Well its also 30,000 km long. You putcattitudecjeyscwt various heights.

billvon said:
Sure, most satellites won't intersect on every orbit. But they just keep launching the things, and once we have a million satellites in orbit - going to be a bit of a problem.
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I suspect that, should a beanstalk ever get funding, a plan to deal with the satellites will go hand-in-hand.
billvon said:
I agree it's theoretically possible. But it's like saying "hurricanes aren't a problem. Apparently it's not a big deal to move Kauai out of the way of any hurricanes."
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Well except Kauai doesn't have attitude jets.
 
Apologies to Peter Dow - didn't mean to overlook his contribution (new thread) on skyhooks when I posted on them. His simulator may be worth a look, here:

Skyhook Equator. Orbiting Rotating Launcher Animator-Calculator.

Skyhook Equator Skyhook space megastructures for launching from equatorial skies to Earth orbits. Orbiting Rotating Launcher Animator-Calculator. Skyhook (structure) – Wikipedia I was inspired to author my “Skyhook Equator” animator-calculator webpage by NASA’s Artemis II mission around the...
www.sciforums.com www.sciforums.com
 
billvon said:
But it has boats. How hard can it be?
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They don't need attitude jets, just attitude. And...cooperative plate tectonics.

I guess the sky elevator does somewhat violate the KISS rule of good engineering. So again, the skyhook concept steps up with more feasible....wait, damn....it needs attitude jets, too. But still, way easier in many respects.
 
DaveC426913 said:
Seriously though, don't take my word for it, and no need to speculate in an absence of information.

There's lots of engineering documentation on beanstalks going back decades. Lots to read.
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OK let's assume the "dodge the satellites" problem can be solved.

Now we hit the next problem - cost. Estimates of cost-to-orbit have ranged from $100 to $400 per pound for current (preliminary) space elevator designs. Current launches on Falcon Heavy (fully reusable mode) are under $1000 a pound - call it $900 per pound. That's a little more than 2x. Estimates for early operational use of Starship (fully reusable mode) are $200 to $450 per pound, almost identical to that of a space elevator.

And of course rockets can be launched almost anywhere and recovered almost anywhere - you are not restricted to the equator.

I think the idea behind space elevators is cool. I just don't see them being practical or possible any time soon.
 
And how a Skyhook (not a space elevator) will make getting to LEO much easier for later Artemis missions. :biggrin:

I can see the practical obstacles to the space elevator, which are more than just anfgkidugjdde jets, but the sling thing with a skyhook seems far more achievable and within the budget of a consortium.
 
billvon said:
OK let's assume the "dodge the satellites" problem can be solved.

Now we hit the next problem - cost. Estimates of cost-to-orbit have ranged from $100 to $400 per pound for current (preliminary) space elevator designs. Current launches on Falcon Heavy (fully reusable mode) are under $1000 a pound - call it $900 per pound. That's a little more than 2x. Estimates for early operational use of Starship (fully reusable mode) are $200 to $450 per pound, almost identical to that of a space elevator.
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Why would it cost more than a pittance to get anything into orbit via beanstalk?


billvon said:
And of course rockets can be launched almost anywhere and recovered almost anywhere - you are not restricted to the equator.
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That's benefit is rendered moot with a beanstalk.

You can always change your inclination from equatorial. Beanstalk-lofted satellites don't have to carry any fuel just to get to orbit, so they'll have all they need for inclination adjustment.


billvon said:
I think the idea behind space elevators is cool. I just don't see them being practical or possible any time soon.
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Well "anytime soon" is doing a lot of heavy lifting there. That's a question of when the long-term cost savings outweigh the upfront construction cost.
 
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DaveC426913 said:
Why would it cost more than a pittance to get anything into orbit via beanstalk?
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Energy/maintenance/construction costs. Even the most optimistic designs have constant cable replacement as a requirement.

You can always change your inclination from equatorial.
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The base has to be equatorial.

Well "anytime soon" is doing a lot of heavy lifting there.
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Sure. If we someday get staze (ref - https://www.goodreads.com/book/show/49214833-a-pause-in-space-time) it becomes pretty trivial. But that's a long way off.
 
Not for those who get seasick.

I think this is a good clip of the opening of the capsule’s hatch, it’s almost as if you are sitting in the inflatable boat.
BBC
 
foghorn said:
Not for those who get seasick.

I think this is a good clip of the opening of the capsule’s hatch, it’s almost as if you are sitting in the inflatable boat.
BBC
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Look how little it is!

I love the comment, "We have four greens, four greens!"

Presumably a traffic light system?
 
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