A new documentary is coming out. Should be interesting, whatever you think about the feasibility.
22 thoughts on “Space Elevators”
Comments are closed.
A new documentary is coming out. Should be interesting, whatever you think about the feasibility.
Comments are closed.
I like the picture, sort of. And seems it might be worth watching the show.
But I would put the craft inside the pipe.
They never mention how slow the climb or the real problem is not going vertical but getting horizontal speed.
If you have a material for an elevator, you have it for a SSTO which takes 3 minutes to orbit.
All else being equal, I’d prefer the scenic route.
I haven’t seen it anywhere else, but couldn’t the electrodynamic tether effect provide horizontal velocity for a space elevator? Otherwise an ascending of descending elevator will deflect the tether and tension will provide for horizontal velocity.
–They never mention how slow the climb or the real problem is not going vertical but getting horizontal speed.–
I wrote a longer post but severely shortened it above. But one of the things was that one would have get the payload to a speed of about 1000 kph [600 mph] or more. And explained it’s better to get this speed near the beginning of the +36,000 km journey. And also if returning to Earth surface decelerating in last 10 or 20 km. And such acceleration and deceleration could supported from Earth surface rather from a cable from Space.
But if one could do this then you don’t really need the cable.
Or at least you don’t need to start with having a cable- you build this part and do cable to GEO at some later date [if ever].
Or a problem with space elevator is how fast one can go and the payload size a solution to this problem is accelerating/decelerating relatively near the the earth surface and cable keeping the payload at constant [high] speed- though of course even maintaining a fast velocity
along the cable is problematic.
So problem with space elevator how much payload can lifted over year period in comparison to infrastructure cost of say, somewhere around 10 billion.
The another near term problem is no one needs this much payload lifted.
If something cost 10 billion as infrastructure cost and you charge 1 million per usage, then 10,000 usages equals 10 billion.
Pick a number Say, it’s 1/2 million for 1 ton [$500 per kg] and $100 per kg for each kg than 1 ton.
Or 1 million per 6000 kg. But this rate 20,000 kg of payload is 2.4 million.
But it could cost more to ship 3 6000 kg as compared to 1 20,000 kg or two 10,000 kg as space elevator
is limited by trips and mass. So might charge 2 million for 2 10,000 kg if can lift 20,000 in one trip, less than 2 million for 20,000 kg [$100 per kg].
Or if somehow in one trip one lift 200,000 kg, it could be $10 per kg.
Now if payload was rocket which carried a payload, say 1/2 payload and 1/2 rocket and it’s
fuel, one getting more volume of traffic [something space elevator needs badly]. And can be “better” if 1/4 is payload and 3/4 rocket and it’s fuel. Or rocket weighs 150,000 kg and payload
is 50,000 kg and paying $10 per kg, or 2 million per launch or $40 per kg of it’s payload.
So such rocket accelerated to 10 km and 600 mph, can’t make orbit, but it can do suborbital.
For orbital destination, it need to be around 1/8th payload and 7/8 rocket. Or $80 per kg of the payload.
But going back to 1/4 payload, one could do suborbit trajectory which could dock with bottom of a cable [well above LEO].
So have base of space elevator lifting max of 200,000 kg, and a gap then the cable lifting 25000 kg. With base charging 2 million for 200,000 kg lifted and cable charging 2 million to lift 25,000 kg to GEO. And to make simple rocket cost 2 million, so 40 + 40 + 40 is $120 per kg to lift payload to GEO.
Advantage is one can build base before the cable. If cable built should add volume to base, and with the base already operating, provide predictable market for cable. Or say mechanical tether.
Or both.
–If you have a material for an elevator, you have it for a SSTO which takes 3 minutes to orbit.–
I would say if you have the traffic needed for elevator, you would have already have the traffic needed for SSTO.
But if chemical rocket from stationary launch pad, SSTO will have limit in low price due to cost of Earth rocket fuel.
But if chemical rocket from stationary launch pad, SSTO will have limit in low price due to cost of Earth rocket fuel.
Which is a minor cost, if not trivial. Fuel and oxidizer currently account for less than 1% of launch costs. Capital costs predominate. Space-elevator proponents obsess over the ability to reduce those minor propellent costs, in exchange for a huge increase in the already-dominant capital costs.
That makes about as much sense as Keith Henson’s obsession with developing a laser-powered Skylon.
— But if chemical rocket from stationary launch pad, SSTO will have limit in low price due to cost of Earth rocket fuel.
Which is a minor cost, if not trivial. Fuel and oxidizer currently account for less than 1% of launch costs.–
With SpaceX Falcon-9 at around 60 million per launch it’s slightly more than 1%, and Falcon Heavy will be about 2%. And if SpaceX gets to the point of reusing it’s first stage [and this lower SpaceX cost or price for a launch it then becomes a higher
percentage. Or if SpaceX lower a launch to 6 million, it’s more than 10%. And once it’s 10% or more it’s a significant cost.
What not included is the integration of satellite to rocket and the launching of a rocket from some spaceport. That is much more significant cost than cost of LOX at 10 cents a kg from some supplier of LOX. So for example have additional costs of rocket fuel being the infrastructure needed to put the rocket fuel into the rocket.
One also has the cost of launching tower. I believe SpaceX did not pay much for such infrastructure, but heard some launch towers costing well over 100 million. So if that tower is used 100 times- it’s at least 1 million per use. And it needs maintance and security, and perhaps it’s scrap value pays for it’s demolition.
Now it might work out that so a launch company or even the satellite maker is not paying for this, but someone is paying for it.
Also Russia is renting it’s launch facilities at about +100 million per year. And Russia probably getting a good deal as compared to cost of KSC.
And Sea Launch is paying some hideous cost for it’s private launch capability- it’s ships, their docks and infrastructure in long Beach. And oil platform was bought used at about 25 million- or it’s strap value was probably more than 1 million, and spend lots of money remodeling it- a fixing it after blowing up a rocket on it.
Etc.
So the general use a launch site is much larger cost, than buying LOX and kerosene from a supplier.
I believe lowering the cost of the use launch site [and stop thinking of it as free] is important to lower the cost of getting into space.
Though using motherships “could be” a way to lower this cost- because the cost of airport can mostly supported by other traffic
than traffic going into space. Or one using infrastructure of commercially supported airport- you just another customer.
Of course even if KSC had more rocket launches per year, it could lowers it’s unit cost- though it increases the yearly bill as more work [total manhours] is done in the year.
Rockets don’t always have to launch from KSC or its Russian equivalent. That assumption comes from the “New Space” addiction to NASA crew and cargo, not from the laws of physics.
Go back and look at programs such as DC-X, for example.
**…Go back and look at programs such as DC-X, for example.**
https://www.youtube.com/watch?v=wv9n9Casp1o
White sand missile range?
And SpaceX’s falcon 1 began by launching from another US military missile range in Pacific.
While on topic where does grasshopper and Blue Origin launch from? Ok,Wiki: “SpaceX McGregor, Texas”
And blue Origin: ” Shepard rocket being erected on a launch platform at Blue Origin’s west Texas development facility ”
http://spaceflightnow.com/2015/04/30/bezos-blue-origin-completes-first-test-flight-of-new-shepard-spacecraft/
Hmm I would guess the sub-orbital and FAA thing made it easier to launch experimental craft from non-governmental locations. And also it seems Texas seems more on top of things.
[though Arizona has Virgin Galactic spaceport, and Mojave, CA from airport, and in east coast, wallop island and then some from Alaska, somewhere:) though imagine it’s military missile range, also. Oh here, Poker Flats, “Welcome to Poker Flat Research Range – the largest land-based rocket research range in the world and the only high-latitude rocket range in the United States.”
http://www.pfrr.alaska.edu/
Somewhere around Fairbanks ]
But I suppose what you mean is DC-X didn’t need a launch
tower?
But I would say it was experimental and it had a test range, so not getting your point. Unless your point is the New Space seems to have changed it, in some ways,
If you get to the geo-synchronous level on a space elevator, your orbital velocity is exactly the same as that of a geosync satellite. Below that level you’d have to add deltaV to maintain orbit, but if you carried your payload all the way to the counterweight end of the tether, just letting go will fling it off at quite a bit higher speed. The counterweight serves not just to hold the weight of the elevator (break it off near ground level and it all goes flying off into space, so little threat to those on the ground), but also to hold enough tension to keep the elevator vertical.
With an elevator, the basic economic idea is to amortize the cost of it by lifting many thousands of trips over decades or even centuries. There’s quite a few sci-fi books that have explored the technical concept pretty well, but I think there’s room for more discussion of the political and security aspects. For example how would you cope with low orbit activity that might conflict with the elevator’s footprint?
Who was it wrote the book about the rotating beams that dip down into the atmosphere to pick up payloads? Fascinating concept.
–With an elevator, the basic economic idea is to amortize the cost of it by lifting many thousands of trips over decades or even centuries. —
Only way that makes sense to me, is to make GEO a nation, and the nation of GEO as the loan of the space elevator. Though I suppose one could also make a nation in the chunk of ocean the space elevator is on the earth surface.
–If you get to the geo-synchronous level on a space elevator, your orbital velocity is exactly the same as that of a geosync satellite. Below that level you’d have to add deltaV to maintain orbit, but if you carried your payload all the way to the counterweight end of the tether, just letting go will fling it off at quite a bit higher speed. The counterweight serves not just to hold the weight of the elevator (break it off near ground level and it all goes flying off into space, so little threat to those on the ground), but also to hold enough tension to keep the elevator vertical.–
It seems this is same thing as say a 1 km long pipe in LEO. And it’s most stable position would be vertical to Earth’s surface. One could spin it, but it would become tidally lock in vertical postion. And if one end has more mass, that mass will be nearest the Earth surface. Or it has gravity gradient.
Now, were one to have 1 km length pipe in LEO, and one were to saw off 10 meter from the bottom, this could little effect upon the 10 meter chunk or the 990 meter chunk. If you were to rip off the 10 meter chuck somehow [shoot a cannon shell at it] this could have greater effect- depending on how it was torn off. If torn off at fast enough speed, it could like sawing it off- except the 10 meter chunk “appears” to disappear “somewhere” or like the trick of pulling off the table cloth away from dishes resting on it, a chunk say 10 cm long between 10 and 990 meters, could appear to disappear.
The difference with space elevator and 1 km pipe, is a load could stretching the cable, though ultra strong material might/probably doesn’t stretch too much, but if was stretching 1 cm per km, thousands of km can be tens of meters, and if it breaks one has near instant acceleration.
So it seems like that could be complicated [varying depending upon how precisely this thing is made and the circumstances]. So one could some kind of whipping action, and the stuff of cable could brittle, and shattering might more descriptive than whipping. Though diamond isn’t generally regarded as very brittle and the cable might like a diamond.
As said it could be complicated, but it seem unlikely that cable flies off in space, or it’s seems less romantic than that- perhaps more interesting than that, and maybe it makes some kind of sound.
With an elevator, the basic economic idea is to amortize the cost of it by lifting many thousands of trips over decades or even centuries.
That only works if you ignore the cost of money. Otherwise the interest (at the real interest rate which high-risk projects command) will eat you alive.
Indeed, for a space elevator to make economic sense, even ignoring the finite lifetime of the cable, the launch rate must be enough to pay the interest on the construction loan.
Well assume a 50 year Amortize loan at 5% flat rate:
http://www.money-zine.com/calculators/loan-calculators/loan-amortization-table-calculator/
This uncommon, but since over long period it work out to be about same as interest only loan or balloon payment type loan. One could have construction loan but that assume someone buys the house so the balloon payment makes sense, since home buyer will get mortgage and bank pays it off. So could be construction loan which is followed by 50 year loan.
And like said, probably best to create a Nation and it’s a National debt and means to make a nation, and the nation could worth more than space elevator:)
But anyhow for 10 million at 5% and 50 years:
Monthly Payment ($ / Month) : 45,413.88
Total Payments ($) 27,248,326.15
Total Interest Paid ($) 17,248,326.15
So if 10 billion times it by 1000
If was business, one want to have option of paying it off sooner
without much penalty. If a nation, you don’t need that option as long terms debts to nations are useful to a nation- in terms of nation having it’s own currency.
Anyway if 10 billion then monthly payment of 45.4 million, or yearly amount totaling 544 million and change.
But if I had the nation, Equatora Pacifica I focus on just building the base of possible future Space elevator. So start with have spaceport, in the pacific ocean at equator as the first step. Work alliances/treaties with neighboring nations and with US. And have as part of spaceport something which is a launch pad but adds velocity to the launch. So something which assists the rocket launch. This would not cost much, what would cost more is a “deepwater” port and having electrical power and water, and place to live, etc.
Of course a existing nation with a island in good location might be easier. And give it the deepwater port, electrical power, and etc.
Now if wanted to start from GEO, the nation of GEO Prime, would need to work with existing owners of satellites slots in GEO. And generally seems rather difficult but perhaps within 10 to 20 years in the future it might be more viable. Or at moment it seems easier to start the master plan by collecting dead GEO satellites.
Well assume a 50 year Amortize loan at 5% flat rate: This uncommon
Yes, it is. No one in his right mind loans money for a high-risk project at 5% interest rates.
Commercial space won’t take off until we replace wishful thinking with realistic assumptions.
Edward Wright
November 21, 2015 at 4:30 PM
–Well assume a 50 year Amortize loan at 5% flat rate: This uncommon
Yes, it is. No one in his right mind loans money for a high-risk project at 5% interest rates.–
Why I said starting a new nation would be easier.
And starting a new nation is not easy.
I merely saying 50 year Amortize loan is more realistic than construction loan and it’s payments are close to the same as as interest only loan.
–Commercial space won’t take off until we replace wishful thinking with realistic assumptions.–
I think new president might help.
And I blame Obama for SLS. Or I think SLS was the direct result of leading from behind. Though at this point, I favor getting SLS launched so as to prove it’s a bad idea [the sooner the better]. But if don’t care what NASA does, then SLS or not, does not matter.
Nor does matter whether NASA explores the Moon or Mars or whatever.
In terms of Commercial space and realistic assumptions. I believe sub-orbital travel is rather important.
I also think assisted boost is important regarding suborbital and orbital spaceflight. I also think launching from Equator is important in terms of the satellite market.
So generally I think using motherships is a fairly good direction but also think there other ways of providing an assisted rocket boost- better because cheaper and more flexible ways of doing this.
So to clear I don’t think space elevator are needed. I don’t even think SSTO is needed.
I think what needed is suborbital flight business.
And I think what needed is market for rocket fuel in space.
And in terms of NASA, it should explore the Moon to determine if and where there might be commercially minable lunar water at the lunar poles. And then for NASA to stop exploring the Moon and do something else- like explore Mars or something. If NASA explores Mars it’s focus should be if and where could be best location for commercial settlement. Though “commercial settlements” is a redundant term, as settlements are commercial. Towns are market places.
What particular expertise does NASA have in identifying commercially valuable resources? That’s like going to a mining company and asking them to find signs of extraterrestrial life.
–Edward Wright
November 22, 2015 at 7:18 AM
What particular expertise does NASA have in identifying commercially valuable resources? That’s like going to a mining company and asking them to find signs of extraterrestrial life.–
They search with robotic exploration, to help select locations to send crew, and the crew would bring back lunar samples.
So large part of the exploration by robotic missions will be available to those who want to examine it, and return sample can tested back it earth- and with published results.
One is basically looking at new environment, and expertise has a lot to do being familiar with something- or I would expect that unexpected things will be found, or that there to various differences as compared to the Apollo sites.
But mining experts should be involved with the immediate exploration process.
Or as I said I think the purpose of the exploration is to find commercial minable water, and those who could considering such commercial ventures give input in terms of what they would be looking for. And this includes makers of mining equipment and other products which might used on the Moon.
But NASA could do a lousy job of exploration, and also I would expect more refined method of exploration to be developed by the private sector.
My assumption is one of hardest aspect of lunar water mining will be getting cheapest electrical power on the Moon. Another aspect will be to develop lunar landers which can reused with little maintenance. A very critical aspect is getting customer for lunar rocket fuel. It seem to me the expertise required to be successful would be CEOs.
And if minable water lunar not apparent on the near surface, it seem it would not minable in the near future
So my view is the NASA exploration program would take less than 10 years and would require less than 40 billion, and would spend about 20 billion or 40 billion budget on robotic missions [or 20 billion on crewed part], and after beginning robotic part to finish exploration with crew landing at small regions which has been narrowed down from from the robotic exploration.
So starts by exploring both poles, and perhaps crew landing on both poles, though one of poles could more crewed landings, than the other. And crew landing could occur with a period of about 2 years. And around time of crewed lunar landing, ISS should be handed off to parties other than NASA- so NASA doesn’t need to spend 3 billion of it’s budget on ISS, and having enough budget to explore Mars.
It could be that commercial lunar mining starts quickly, or it might take 5 or more years after NASA has finished it’s lunar exploration program, before commercial water mining begins.
An obvious point is were some party to start mining the Moon, NASA at that point in could determine whether to terminate or curtail it’s lunar exploration- as purpose of exploration of the Moon is to enable commercial lunar water mining, and that would become a box to check off. And if towns have started on Mars, it’s same thing- NASA should find something else to explore.
Specifically, normal business requires that it pay for itself in 5 years, at least on paper. Most projects will fail, but by always planning for a 5 year payback we keep GDP growth mostly positive…
One serious issue with a space elevator is the safety system needed for the passengers in case their vehicles comes off (or the cable breaks above them.)
The vehicle will need to be able to reenter the atmosphere, but there’s a limit to how high it can fall vertically from before reentry deceleration kills the passengers. At sufficiently high altitude it will go into orbit if it falls off, but there’s a large black zone in between. So, the vehicle will need propulsion — either to brake before hitting the atmosphere, or to boost sideways so the atmosphere can be entered at a sufficiently shallow angle. The crossover point can be computed where the delta-V in the two cases is equal, and IIRC is greater than 4 km/s. The vehicle will have a substantial amount of propellant on it.
–Paul D.
November 22, 2015 at 1:34 PM
One serious issue with a space elevator is the safety system needed for the passengers in case their vehicles comes off (or the cable breaks above them.)–
Related to this.
Say you had a pipe 10 meter in diameter with pipe wall made of 3/4rd
of inch ship steel. And pipe was 1000 meter long [1 km].
And one one of the pipe was sealed by 1 inch thick ship steel.
The total weight of this would be about 3775 tonnes. Similar to mass of a ship’s hull and you make the pipe in a shipyard, and launch it like a ship. To float like a boat, one would temporary seal the other end- say, inflate a large balloon in it.
Then tow it to a location [which had deep water]. Then remove temporary end. Then it will sink and end up floating vertical.
To float with end above the water one needs about 48 meter of air in the top end of it, and for the air to be about 69 psig
And by adding enough air one could have end of the pipe floating say 100 meter above the water. And were it floating above the water and you put about 500 tons on it, it would sink about 10 meter lower in the water and it will support more than 1000 tons [add 20 meter worth of air to inside pipe and returns to the level before putting 1000 tons on it.
So this is something one could attach a space elevator to. One moor it in deep ocean and it could have the end 100 meter above the water. And have say 100 meter tower on top of it. Elevators and/or crane attached to it, which takes stuff off ships and bringing it up and down.
Anyways from the point one gets into some elevator car one could more that couple hundred meter above the ocean. Or one could jump from 200 meters and deploy a parachute. So elevator likewise with emergency can deploy a parachute [though one want get far enough away from the structure before deploying parachute]. So this kind of thing could work below 50 to 100 km, or existing velocity does carry much higher than 100 km. Or above 100 km what I am talking can’t apply and it seems one would need something like rocket power and probably fair amount of it, like + 1 km/sec, or more than say 1/4 of entire mass of the car. And is another argument for using rocket power as part of using a space elevator. And if start of rocket burn is say 20 km, if fails near start of burn, one could then use parachutes as abort option.
But anyhow space elevators are not in any way a near term solution, but the long road to possible use of space elevators could begin by focusing on an ocean launch site and assisted boost as part of the launch site.