Space Elevator, What the Hell? Options

[kigmatzomat]

The top speed isn't a problem really as most electromagnetic catapult designs allow for 20km/s or more and 40G aren't really tht much as long as you don't intend to transport personnel that way but then the space elevator, at least in early stages, isn't meant to transport humans as well, the us navy is experimentiung with guided missiles shot from cannons at the moment and there you have thousands of G.

Getting the acceleration isn't the limiting factor, it's the survivability of the cargo. Sure, water and aluminum framing components are fairly durable but most electronics aren't prepared to handle 500G for 4 seconds. And there's a big difference between the components that go into a missile and what you need in orbit. Heck, there's a big difference between a comm sat and a missle.

Some quick and dirty math on Wikipedia's Russian Proton rocket, a common satellite launch vehicle, says that the thrust stays below 15G. The incremental cost for building commsats able to handle significantly increased acceleration is going to be pretty high, possibly exceeding the cost savings of the catapult.

As for the leap in material science *cough* carbone nanotubes may have the tensile strength needed in theory but have yet to be made with such high specs.

*I* never said carbon nanotubes. I said "Unbreakium." The simple fact is that Unbreakium (a super strong material suitable for manufacturing a space elevator) is theoretically plausible. I have no idea what it is, but given we're dealing with fiction, I don't need to, as it doesn't require massive suspension of disbelief.

Also noone has tested a remote power supply at ranges of 10000 or so km so i guess that would need quite a lot of work as well.

Actually SR had Japanese orbital power sats from around 2010, so they are mature tech by 2070.

i've seen a documentary about that once . .
problems with that system arise at the point where you have to keep the propelled rocket exactly above the laser, else it will crash to one side . . and of course, later on there is simply not enough athmosphere to burn to creathe the thrust . . also it would be very uncomfortable to travel in something that's basically getting a big kick into it's ass every some seconds or so . . with rockets you have an ongoing explosion, not many different ones and the vibrations of that are allready tremendous . .

I think you're talking about the rocket that uses a reflector to concentrate a wide beam into a narrow point, which can possible use the atmosphere as the propellant, although I think they generally have a feeder system to provide a propellant better than air.

The alternative is to indirectly cause the propellant to expand, say by heating a containment chamber, and eliminating most of the problems with direct-sublimation rockets.

E.g.: Fill a black metal bottle with dry ice. Fire a laser at the bottle, heating it up but not burning through it. The dry ice sublimates to CO2 and shoots out the mouth of the bottle, generating thrust. If your laser is fired from the side at a sufficiently oblique angle, it never shoots through the exhaust. As it leaves the atmosphere orbital lasers can provide the power, again assuming they hit it on the side at an angle rather than straight down, through the cargo carrier. Preferrably an angle that passes completely through the atmosphere and doesn't hit the surface or flight paths.

If you momentarily miss the bottle, the dry ice continues to provide thrust at a diminishing rate as it vents the stored heat. When the beam reacquires the bottle, there's no explosive jump in power as it takes a bit for the thermal energy to migrate through the chamber. If the lasers fail completely, there's no explosion. 'Kay, there's a massive "thud" when it hits the ground but no "kaboom." The satellite could be saved if the cargo module has an ejection system and 'chutes to carry it to the ground.

I think the technical challenges of firing lasers at a moving target are much easier to overcome than a space gun or elevator.

But the elevator is cooler.

[Stahlseele]

'Kay, there's a massive "thud" when it hits the ground but no "kaboom."

that's the best sentence i've read in a long time ^^

[kigmatzomat]

I'm just tickled that someone bothered to read to the end of my post!

[suppenhuhn]

Actually SR had Japanese orbital power sats from around 2010, so they are mature tech by 2070.

Oh didn't notice that this is about an elevator in sr (IMG:style_emoticons/default/wobble.gif)
Well then its possible ofc but also my mage can take 100G (IMG:style_emoticons/default/nyahnyah.gif)

[kigmatzomat]

Oh didn't notice that this is about an elevator in sr (IMG:style_emoticons/default/wobble.gif)

Actually powersats are relevant to elevators b/c they can provide a means of powering the climber. It's a daunting aspect to run power a couple thousand vertical kilometers via cables/tracks due to wear, flexure, and of course weather exposure (kazot!). Instead you have can antennas mounted along the elevator that are connected to batteries or put the antenna on the climber roof.

I personally like the battery idea b/c a descender should be generating a ton of power through regeneration, and batteries make that energy available to ascenders at various points along the 'vator. It also means the climber can operate without being targeted by a microwave beam. The loss of any individual battery does not mean the climber is stuck since an adequate design would have the climber able to store enough power to climb past two batteries before running dry.

Well then its possible ofc but also my mage can take 100G (IMG:style_emoticons/default/nyahnyah.gif)

I have the utmost confidence your mage can take 100G. I'm also quite sure he'd look like an elephant sat on him since he "weighed" in excess of 5 tons for more than 11 seconds. (100lbs x 100G = 10,000lb = 5 tons)

[Stahlseele]

I'm just tickled that someone bothered to read to the end of my post!

i try, at least . . ok, not so much with frank and his multi page postings and other such monstrosities, but with anything below 0,5 to 0,66 Din A 4 Pages of Text, i mostly read them . . if the general theme of discussion is not relevant to my interests, i just skim over the bits ^^

[kigmatzomat]

Anyone want to talk about the potential risks of an elevator failure?

Best case scenario is it breaks near the ground. The orbital counterweight wants to be in a higher orbit and goes there, with the 'vator hanging down behind it like a giant kite tail. Odds are the broken end of the 'vator is at least a thousand feet higher than it started.

Worst case is probably if it snaps off around the ionosphere, leaving a great cable to slowly topple over across several thousand kilometers of the earth while simultaneously creating a giant "weed-eater" in the sky as the orbital counterweight drags 100km of cable to a higher orbit.

The second-worst case is if it snaps off at the counterweight. The extra 100km of cable is probably not a major change, compared to the potential devastation the "weed eater" might wreak on satellites or orbital structures.

[Herald of Verjig...]

Anyone want to talk about the potential risks of an elevator failure?

Been thought of.
Entertaining though.