If you could build a ladder tall enough
Discussion
CrutyRammers said:
How does a geostationary orbit work then? 
I *think* that orbital velocity is measured relative to the earth's centre of mass; it's certainly not relative to the surface speed.
Difference in altitude and mass between a geostationary and something like the ISS which orbits maybe? I *think* that orbital velocity is measured relative to the earth's centre of mass; it's certainly not relative to the surface speed.
/guesswork
thebraketester said:
A 10mm rope to the ISS would weigh about 20 tons.
Very nearly
Just playing with back of the envelope numbers 400 km is 400,000 metre’s if we took a 220 meter coil of 10 mm rope it would weigh approx. 15 Kilo’s
So 400,000 / 220 metre’s is 1818 (approx. as its .181818 reoccurring) which would mean it would weigh approx. 27 tonnes and this is the giggle factor:
Even if the ISS was geostationary the breaking strength of the 10mm rope is approx…….. 0.63 of a tonne
Eric Mc said:
NASA did try some experiments from the Space Shuttle where they paid out long cables from the Shuttle cargo bay so they could measure the electrostatic charge that built up from contact with the tenuous outer atmosphere. On each occasion the experiment failed either because the cable snapped or jammed.
I think this is a problem for future generations.
This Wiki description of a Shuttle deployment did highlight the tether broke but not before it gains some insightful findings, so was the breakage anticipated......quite probably, was it viewed as a failure probably not because if the data collected (not just electrostatic charge) I think this is a problem for future generations.
Shuttle TSS-1R mission[edit]
Four years later, as a follow-up mission to TSS-1, the TSS-1R satellite was released in latter February 1996 from the Space Shuttle Columbia on the STS-75 mission.[6] The TSS-1R mission objective was to deploy the tether 20.7 km above the orbiter and remain there collecting data. The TSS-1R mission was to conduct exploratory experiments in space plasma physics. Projections indicated that the motion of the long conducting tether through the Earth’s magnetic field would produce an EMF that would drive a current through the tether system.
TSS-1R was deployed to 19.7 km when the tether broke. This extension was long enough to verify numerous scientific speculations. These findings included the measurements of the motional EMF,[7] the satellite potential,[8] the orbiter potential,[9] the current in the tether,[10] the changing resistance in the tether,[11] the charged particle distributions around a highly charged spherical satellite,[12] and the ambient electric field.[7] In addition, a significant finding concerns the current collection at different potentials on a spherical endmass. Measured currents on the tether far exceeded predictions of previous numerical models[13] by up to a factor of three. A more descriptive explanation of these results can be found in Thompson, et al..[14]
Other scientific advancements have resulted from this mission. Improvements have been made in modeling the electron charging of the shuttle and how it affects current collection.[10] In addition, much was learned concerning the interaction of bodies with surrounding plasma, as well as the production of electrical power.[15] For further discussion and analysis of this mission see the referenced documents.[7][9][10][11][12][13][14][16]
Space tether missions
The missions have met with varying degrees of success; a few have been highly successful.
Source https://en.wikipedia.org/wiki/Space_tether_mission...
Toaster said:
thebraketester said:
A 10mm rope to the ISS would weigh about 20 tons.
Very nearly
Just playing with back of the envelope numbers 400 km is 400,000 metre’s if we took a 220 meter coil of 10 mm rope it would weigh approx. 15 Kilo’s
So 400,000 / 220 metre’s is 1818 (approx. as its .181818 reoccurring) which would mean it would weigh approx. 27 tonnes and this is the giggle factor:
Even if the ISS was geostationary the breaking strength of the 10mm rope is approx…….. 0.63 of a tonne
We're nearly there!
Eric Mc said:
Are you measuring a rope to geostationary satellite or the ISS.
Geostationary satellites orbit at around 25,000 miles above the earth. The ISS is at about 250 miles - but it does vary.
The OP stated ISS and if it is irrelevant that the ISS is travelling at 17,000 mph + or not because the of the breaking point of the 10 mm rope Geostationary satellites orbit at around 25,000 miles above the earth. The ISS is at about 250 miles - but it does vary.
CrutyRammers said:
Not that it helps much, but a 10mm climbing rope will be certified to 24Kn or 2.4 tonnes static load, with a breaking strength somewhat above that. If you used something like a dyneema sling, that gives the same strength for only 16g per m, so you'd be looking at 6.4 tonnes for the rope, or only 3 times the breaking strength of it.
We're nearly there!
That is assuming I was using a climbing rope............this was my source http://www.ropesandtwines.com/sizes.asp probably best I don't use the cheap one then We're nearly there!
Edited to say, I assume it will melt/burn shred at 17,000 MPH? in the atmosphere
Edited by Toaster on Tuesday 8th December 12:08
Toaster said:
The OP stated ISS and if it is irrelevant that the ISS is travelling at 17,000 mph + or not because the of the breaking point of the 10 mm rope
Toaster - why do you love commenting on my posts? Is this your main hobby in life?If it is, I am so glad that I am providing you with a purpose to your existence. It gives me a warm glow.
CrutyRammers said:
V8LM said:
The bottom of the ladder has a velocity of just over 1000 mph. The ladder would only be of use to reach a geostationary object 22,000 miles above the Earth's surface, where its top will be travelling at just under 7000 mph.
Relative to....?Eric Mc said:
Toaster - why do you love commenting on my posts? Is this your main hobby in life?If it is, I am so glad that I am providing you with a purpose to your existence. It gives me a warm glow.
Bit weird that comment Eric you asked a question........'Are you measuring ........' and I responded with an answer so whats wrong with that?You mentioned the space shuttle I just added a little more detail around how successful one of the flights was rather than a view of failure, if we were in a pub it would be a natural ebb and flow of a conversation you will notice you are not the only person I have engaged with on this thread, there is at least three others.
Edited by Toaster on Tuesday 8th December 22:10
Is escape velocity & geostationary orbit really relevant to a space ladder?
They're not connected to anything and only need the speed because otherwise they'll hit the ground as they're always "falling" to earth, or that is my understanding.
Rather than a space rope, is there a material of such strength under compression:mass ratio that we could build the Tower of Babel? Or would the top bricks be torn off/structure be broken in two by the differences in velocity?
They're not connected to anything and only need the speed because otherwise they'll hit the ground as they're always "falling" to earth, or that is my understanding.
Rather than a space rope, is there a material of such strength under compression:mass ratio that we could build the Tower of Babel? Or would the top bricks be torn off/structure be broken in two by the differences in velocity?
Edited by glazbagun on Thursday 10th December 14:12
In theory either a tower or a rope would work if you had strong enough materials and it didn't get blown down by high winds. The critical bit is the geostationary orbit though.
Basic bit of orbital mechanics:
Basic bit of orbital mechanics:
- Everything falls towards the earth at 1g (9.81m/s/s) [ish, it actually decreases a bit the further way you get]
- If you throw a ball and fire a bullet horizontally from the same height they'll both hit the ground at the same time because they fall at the same acceleration, but the bullet will have travelled further obviously.
- Because the earth curves, if fire your bullet fast enough you can match the speed it falls towards earth with the rate the earth falls away from you and you never hit the ground. This only works without atmospheric drag though, but you've now reached orbital velocity.
- Because the earth rotates, if you stand at the equator you're already doing about 1000 mph relative to the earth's mass (this is why space rockets always launch heading east, and the closer to the equator the better, ESA's facilities in French Guiana are moving about 100mph faster than NASA's launch sites in Florida)
- Basic geometry means if you had a massive tower on the equator, the top would be moving faster than the base (the greater the radius the faster the speed)
- As you build your tower higher eventually you'll reach a point where the top reaches your orbital velocity. This is a geostationary orbit at occurs at about 22k miles.
- If you throw a ball forwards from your geostationary tower it will have a higher speed, so won't fall back to earth quite as quickly as the earth falls away, meaning it will end up in a higher orbit, where the distance it has to travel is now further than the distance you're travelling, and it will go backwards relative to you.
- If you throw a ball backwards from your tower it will fall in to a lower orbit, which is shorter and it will go forwards relative to you.
- If you let a rope down from the top of your tower it will a) be very heavy (it's 22k miles long!), and b )just fall to the ground (it's a flexible rope)
- If you threw a ball straight up, but kept hold of a bit of string attached to it, it should be able to remain above you, a bit like swinging a conker round on a string.
- If you threw a really big weight up in the air it could theoretically be tethered by the rope you let down to the ground, but would need to be heavy and high enough that it was being flung out from the earth with enough force to hold up the weight of the 22k miles of rope.
- If you have followed the above steps correctly you now have a space elevator, someone could climb the rope from the bottom all the way to a geostationary orbit at 22k miles, or climb out further towards the counterweight, where if they let go they'd be flung in to a higher orbit.
- If you've stuck with it to this point I strongly recommend you play Kerbal Space Program
Edited by RizzoTheRat on Friday 11th December 14:25
OP here, glad to see this thread is going strong and has not dissolved into the vitriol and abuse that most threads seem to do nowadays. All very interesting reading and helping with my research. I am planning on starting to build my ladder in the new and should be completed just before Donald Trump comes to power in the USA. I can then begin my escape.
I have one other question, does anyone know what the depreciation will look like over a 3 year PCP on the base materials and should I have maybe waited for the Spyder version as I believe these will be more limited numbers?
I have one other question, does anyone know what the depreciation will look like over a 3 year PCP on the base materials and should I have maybe waited for the Spyder version as I believe these will be more limited numbers?
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