8 ms·

Space Elevators Are Possible

79 points by cyphersanctus 13y ago

kornork 13y ago
Great! What does the paper say about overcoming some of the problems that seem to make it tough, like the radiation that humans will receive riding up, or avoiding space debris? I'm assuming problems like building a rope strong enough to hold its own weight will be overcome, as well as developing the technology to climb the elevator.
- aunty_helen 13y ago
  The fragile humans could still hitch a ride on a (reusable) rocket and extraplanetary garbage collection is something that is currently being proposed and could be a good source of materials too.
- eru 13y ago
  Why should radiation be much more of a concern than for rockets? (Couldn't you just add shielding?)
  - mullingitover 13y ago
    The rocket ride is shorter.
    - lutorm 13y ago
      That just means you get to the high-radiation regions faster...
      - briandw 13y ago
        No, you will spend more time in the http://en.wikipedia.org/wiki/Van_Allen_radiation_belt http://en.wikipedia.org/wiki/Van_Allen_radiation_belt with a space elevator.
        eru 13y ago
        There's an interesting proposal for reming that radiation belt (https://en.wikipedia.org/wiki/Van_Allen_radiation_belt#Proposed_removal https://en.wikipedia.org/wiki/Van_Allen_radiation_belt#Propo...). But shielding seems to be doable with pretty thin layers of metal.
- mahranch 13y ago
  Radiation is only a minor concern, astronauts in the space station experience similar radiation doses. I assume if it's cheaper to get things into orbit [with the elevator], it's also cheaper to shield the entire contraption. Climbing isn't much of a concern either, they've already run a bunch of tests and NASA has already awarded their prizes out for the challenge. The real issue is mass producing the carbon nanotubes. It's like saying "Warp drive is possible" then saying all you need to do is build a ship that can manipulate the fabric of spacetime. Well of course that's all you need to do. Sure, producing carbon nanotubes is easy. I've seen them make the it in a lab. It's making the tubes to spec and making thousands of miles of the stuff that is the hurdle. It's the equivalent of asking computer engineers in the 60s to mass produce 22nm CPUs with billions of transistors. Can it be done? Sure. In about 50 years.
  - mcv 13y ago
    > Radiation is only a minor concern, astronauts in the space station experience similar radiation doses. Why would they be similar? The space station is only in LEO. That's not remotely comparable to geostationary orbit, or the Van Allen belts. Fortunately, shielding is a lot cheaper than on anything a rocket carries.
- cgrubb 13y ago
  Early in the book: The first few years will enable 20ton payloads without humans [radiation tolerance an issue for the two week trip]... From Finding 7-5: Radiation is not a problem for tether climbers, as the designers will incorporate this threat into the design requirements and ensure operational success through any radiation environment. Historic precedence supports this conclusion as the space community runs spacecraft in all regions where the space elevator will be operating. However, when people are included in the tether climb [after some years of robotic success], the radiation problem becomes an order of magnitude more difficult. There are many ways to reduce the radiation and shorten the trip, which will have to be incorporated when the human element is added. Although the authors envision eventually using the elevator for transporting humans, I don't see any discussion about how to speed up the trip or increase the shielding. There is a fairly long section on debris. The authors note that significant debris only exists in low earth orbit. They think the chance of collision is small, but large enough that the situation needs to be monitored. They think debris can be tracked and that if a collision were forecast, the cable could be moved. Also, they think space faring nations should be tasked with removing some of their junk from orbit.
elktea 13y ago
The animated icon on this site is terrible
- thrownaway2424 13y ago
  The writing isn't too hot, either.
  - frozenport 13y ago
    This HN needs a downvote button or an embargo on upvotes. For example, you can only upvote 5 minutes after you have read the link. Having been away for a year I am shocked by the number of upvotes everything is getting.
mehwoot 13y ago
What happens if something hits the cable and it breaks? Does the whole thing drift off into space?
- ars 13y ago
  Depends where it hits. On the tether there is a "zero" point. Below that point things fall toward the Earth, above that point things "fall" away from the Earth. So it depends on where it broke and how much weight there is above vs below that point. (To keep the tether in the air they put lots of weight above the point, which falls away from the Earth and pulls the tether taught.) If I were making one of these I'd make several tethers, spaced such that a single object can not break more than one at once. Then tie the tethers together periodically. This object is about max: https://en.wikipedia.org/wiki/Tunguska_event https://en.wikipedia.org/wiki/Tunguska_event so I'd make the multiple tethers at least 200m apart. That's pretty far apart, so I'd invest in better detection technology to reduce the size maximum undetected object. (Although that raises the question of what to do if you do find a big one and it's headed right toward you.)
  - atgm 13y ago
    > If I were making one of these I'd make several tethers, spaced such that a single object can not break more than one at once. What I'd worry about is security, honestly. What if some nation decides that the space elevator existing isn't in the best interest of their national security, or some paramilitary group wants to make a point? Bombing the base station would hurt the elevator. But of course, we should expect that to be secured. That still leaves the entire length of cable running up and down the elevator -- that's a huge volume of space to secure against anything explosive or fragmentary.
    - manicdee 13y ago
      And indeed the scenario of "terrorists sever the tether from its geostationary anchor" was part of the story in Red Mars. https://en.wikipedia.org/wiki/Mars_trilogy https://en.wikipedia.org/wiki/Mars_trilogy
- 13y ago
ars 13y ago
This kinda glosses over the hard part: Making that tether!
deleted 13y ago
[deleted]
ericd 13y ago
If we can make one, it seems pretty obvious from the studies I've seen that it will be the major enabling technology for getting into space in a large way. Unfortunately, I don't think we've hit the carbon nanotube lengths that we'd need (on the order of meters). Here's a great book that came out of a NASA funded study that breaks the issues down well, including costs, necessary tech, and methods for dealing with potential issues like cable breakage: http://www.amazon.com/Space-Elevator-Earth-Space-Transportation/dp/0974651710 http://www.amazon.com/Space-Elevator-Earth-Space-Transportat... Their conclusion was that it would be much more cost effective than most people think, and that it would enable an incredible reduction in cost to orbit due to not needing to use a pyramid of fuel to carry other fuel for later, or enormous one-time-use precision machinery, and instead using simple containers with electric motors and transmitted electricity.
deleted 13y ago
[deleted]
avmich 13y ago
The main problem with the elevator, in my opinion, for many years already is not in the strength of the material. After all, nanotubes are known for many years, and their properties are sufficient for the tether, so in principle it can be done. No, the main problem is with satellites. In fact, asking many times - what to do with existing or future satellites - I never heard a workable answer, even in principle. Just a reminder - every satellite crosses the equatorial plane twice for every rotation around the Earth. Majority of satellites are below the geostationary orbit. So, given enough time every satellite will hit the tether - and even if tether is near-zero width, the satellite isn't. One of ideas was to dynamically move the tether - from the Earth, making propagating wave along the tether, which would avoid the satellites. This means we need the good means of watching the space and predicting satellites movements - even small satellites can bring trouble. But that's not enough, we might get a situation when we need to perform conflicting movements, considering the current state of the wave. This problem is well known for decades. Attempts to launch satellites from the elevator - and the elevator makes it tantalizingly cheap, so we'll want to launch many - will exacerbate the problem. The whole world astronautics will have to adjust to accomodate the elevator - and nobody knows how it is going to look like.
- grecy 13y ago
  Would a satellite/tether collision damage the tether, or just destroy the satellite? If it just destroys the satellite, I'm kind of tempted to say "who cares", because by then we will have other solutions, or satellites out past the counterweight, or we can easily launch more now that we have the fancy elevator, or whatever... but then we'd have the problem of an unimaginable amount of space junk orbiting the earth.
  - Tuna-Fish 13y ago
    Everything in low earth orbit has 30MJ/kg worth of kinetic energy. TNT has 4.6MJ/kg worth of chemical energy. A rule of thumb: when the kinetic energy of things goes above the chemical energy of high explosives, you can assume that nothing survives.
- ChuckMcM 13y ago
placeybordeaux 13y ago
This article did almost nothing to aleviate the real concerns.
maxharris 13y ago
How do you keep space junk (which can include larger objects as well as small as bolts and the like, all of which may have considerable momentum) from tearing through the cable?
sgt 13y ago
"The rotation keeps the cable taut, to counter the gravitational pull as robotic, electric “climbers” ride the line up into space carrying the payload. Boom." Let's just hope he didn't mean that literally. But early attempts may include some disasters, as often is the case.
SlowButEffectiv 13y ago
That's an awful long way to have to stare uncomfortably at the doors.
kamaal 13y ago
At the risk of appearing stupid, I just have few simple questions 1. What exactly holds the counter weight in position? 2. Such a long rope, which the article says is around 62000 miles, won't it function more like rubber band than function like a rope? Due to mere stretching/elastic effect? 3. I'm sure traveling 62000 miles is nothing like fuel efficient especially when you travel in the direction of highest friction(Up). So how do you store the fuel and of what weight that would be? Will such a vehicle be even practical?
- jccooper 13y ago
  1. The counterweight is in geosynchronous orbit. It is "held up" by its absurd speed like any other satellite. 2. One of the reasons you need a very strong material. The tether will be in tension, but probably will have quite a bit of movement to it. The tether dynamics are not a solved problem. 3. Most plans suggest that power will be beamed from the ground to the climber, either as microwaves or visible light. Some plans might use a paired tether to carry electricity. In either case, no onboard fuel is needed, which us pretty nice, as that's a lot of weight you don't have to pull against gravity. There have been several competitions in this area already.
  - kamaal 13y ago
    Yes, sorry the centripetal-centrifugal force balance thing was completely off my mind when I asked that question. But with all the remaining two points look in the domain of SciFi to me. I'm sure tether dynamics are going to a materials engineering problem like never seen in history of mankind. Plus the energy problem is still by and large a very problem. Sending electricity down the tether looks very inefficient give the article says it will 62K miles long. In short we are still may be what, say 50 years away from this?
    - Sharlin 13y ago
      Solar power satellites would most likely beam the power to Earth using microwaves.
    - jccooper 13y ago
frozenport 13y ago
First build the hyperloop, then we will talk.
panacea 13y ago
No they're not.
nmc 13y ago
Why does this seem like a shamelessly unacknowledged copy-paste from [1]? Is it the other way around? Where is the original post? [1] http://motherboard.vice.com/blog/space-elevators-are-totally-possible-and-will-make-rockets-seem-dumb http://motherboard.vice.com/blog/space-elevators-are-totally...
- vesinisa 13y ago
  To me, it seems like this site Techblog copied Vice without giving any credit. Vice credits the original story to their in-house journalist, while Techblog.co seems like a news aggregation service. I am cool with news aggregation (think Google News), but they should definitely always credit the original source.
oldmantaiter 13y ago
All these comments about space junk, Spaceballs had it right with the giant cleaning lady in orbit. I think we should switch our focus to that instead.

79 points by cyphersanctus 13y ago

Great! What does the paper say about overcoming some of the problems that seem to make it tough, like the radiation that humans will receive riding up, or avoiding space debris? I'm assuming problems like building a rope strong enough to hold its own weight will be overcome, as well as developing the technology to climb the elevator.

aunty_helen 13y ago
The fragile humans could still hitch a ride on a (reusable) rocket and extraplanetary garbage collection is something that is currently being proposed and could be a good source of materials too.
eru 13y ago
Why should radiation be much more of a concern than for rockets? (Couldn't you just add shielding?)
- mullingitover 13y ago
  The rocket ride is shorter.
  - lutorm 13y ago
    That just means you get to the high-radiation regions faster...
    - briandw 13y ago
      No, you will spend more time in the http://en.wikipedia.org/wiki/Van_Allen_radiation_belt http://en.wikipedia.org/wiki/Van_Allen_radiation_belt with a space elevator.
      - eru 13y ago
        There's an interesting proposal for reming that radiation belt (https://en.wikipedia.org/wiki/Van_Allen_radiation_belt#Proposed_removal https://en.wikipedia.org/wiki/Van_Allen_radiation_belt#Propo...). But shielding seems to be doable with pretty thin layers of metal.
mahranch 13y ago
Radiation is only a minor concern, astronauts in the space station experience similar radiation doses. I assume if it's cheaper to get things into orbit [with the elevator], it's also cheaper to shield the entire contraption. Climbing isn't much of a concern either, they've already run a bunch of tests and NASA has already awarded their prizes out for the challenge. The real issue is mass producing the carbon nanotubes. It's like saying "Warp drive is possible" then saying all you need to do is build a ship that can manipulate the fabric of spacetime. Well of course that's all you need to do. Sure, producing carbon nanotubes is easy. I've seen them make the it in a lab. It's making the tubes to spec and making thousands of miles of the stuff that is the hurdle. It's the equivalent of asking computer engineers in the 60s to mass produce 22nm CPUs with billions of transistors. Can it be done? Sure. In about 50 years.
- mcv 13y ago
  > Radiation is only a minor concern, astronauts in the space station experience similar radiation doses. Why would they be similar? The space station is only in LEO. That's not remotely comparable to geostationary orbit, or the Van Allen belts. Fortunately, shielding is a lot cheaper than on anything a rocket carries.
cgrubb 13y ago
Early in the book: The first few years will enable 20ton payloads without humans [radiation tolerance an issue for the two week trip]... From Finding 7-5: Radiation is not a problem for tether climbers, as the designers will incorporate this threat into the design requirements and ensure operational success through any radiation environment. Historic precedence supports this conclusion as the space community runs spacecraft in all regions where the space elevator will be operating. However, when people are included in the tether climb [after some years of robotic success], the radiation problem becomes an order of magnitude more difficult. There are many ways to reduce the radiation and shorten the trip, which will have to be incorporated when the human element is added. Although the authors envision eventually using the elevator for transporting humans, I don't see any discussion about how to speed up the trip or increase the shielding. There is a fairly long section on debris. The authors note that significant debris only exists in low earth orbit. They think the chance of collision is small, but large enough that the situation needs to be monitored. They think debris can be tracked and that if a collision were forecast, the cable could be moved. Also, they think space faring nations should be tasked with removing some of their junk from orbit.

elktea 13y ago

The animated icon on this site is terrible

thrownaway2424 13y ago
The writing isn't too hot, either.
- frozenport 13y ago
  This HN needs a downvote button or an embargo on upvotes. For example, you can only upvote 5 minutes after you have read the link. Having been away for a year I am shocked by the number of upvotes everything is getting.

mehwoot 13y ago

What happens if something hits the cable and it breaks? Does the whole thing drift off into space?

ars 13y ago
Depends where it hits. On the tether there is a "zero" point. Below that point things fall toward the Earth, above that point things "fall" away from the Earth. So it depends on where it broke and how much weight there is above vs below that point. (To keep the tether in the air they put lots of weight above the point, which falls away from the Earth and pulls the tether taught.) If I were making one of these I'd make several tethers, spaced such that a single object can not break more than one at once. Then tie the tethers together periodically. This object is about max: https://en.wikipedia.org/wiki/Tunguska_event https://en.wikipedia.org/wiki/Tunguska_event so I'd make the multiple tethers at least 200m apart. That's pretty far apart, so I'd invest in better detection technology to reduce the size maximum undetected object. (Although that raises the question of what to do if you do find a big one and it's headed right toward you.)
- atgm 13y ago
  > If I were making one of these I'd make several tethers, spaced such that a single object can not break more than one at once. What I'd worry about is security, honestly. What if some nation decides that the space elevator existing isn't in the best interest of their national security, or some paramilitary group wants to make a point? Bombing the base station would hurt the elevator. But of course, we should expect that to be secured. That still leaves the entire length of cable running up and down the elevator -- that's a huge volume of space to secure against anything explosive or fragmentary.
  - manicdee 13y ago
    And indeed the scenario of "terrorists sever the tether from its geostationary anchor" was part of the story in Red Mars. https://en.wikipedia.org/wiki/Mars_trilogy https://en.wikipedia.org/wiki/Mars_trilogy
13y ago

ars 13y ago

This kinda glosses over the hard part: Making that tether!

deleted 13y ago

[deleted]

ericd 13y ago

If we can make one, it seems pretty obvious from the studies I've seen that it will be the major enabling technology for getting into space in a large way. Unfortunately, I don't think we've hit the carbon nanotube lengths that we'd need (on the order of meters). Here's a great book that came out of a NASA funded study that breaks the issues down well, including costs, necessary tech, and methods for dealing with potential issues like cable breakage: http://www.amazon.com/Space-Elevator-Earth-Space-Transportation/dp/0974651710 http://www.amazon.com/Space-Elevator-Earth-Space-Transportat... Their conclusion was that it would be much more cost effective than most people think, and that it would enable an incredible reduction in cost to orbit due to not needing to use a pyramid of fuel to carry other fuel for later, or enormous one-time-use precision machinery, and instead using simple containers with electric motors and transmitted electricity.

deleted 13y ago

[deleted]

avmich 13y ago

The main problem with the elevator, in my opinion, for many years already is not in the strength of the material. After all, nanotubes are known for many years, and their properties are sufficient for the tether, so in principle it can be done. No, the main problem is with satellites. In fact, asking many times - what to do with existing or future satellites - I never heard a workable answer, even in principle. Just a reminder - every satellite crosses the equatorial plane twice for every rotation around the Earth. Majority of satellites are below the geostationary orbit. So, given enough time every satellite will hit the tether - and even if tether is near-zero width, the satellite isn't. One of ideas was to dynamically move the tether - from the Earth, making propagating wave along the tether, which would avoid the satellites. This means we need the good means of watching the space and predicting satellites movements - even small satellites can bring trouble. But that's not enough, we might get a situation when we need to perform conflicting movements, considering the current state of the wave. This problem is well known for decades. Attempts to launch satellites from the elevator - and the elevator makes it tantalizingly cheap, so we'll want to launch many - will exacerbate the problem. The whole world astronautics will have to adjust to accomodate the elevator - and nobody knows how it is going to look like.

grecy 13y ago
Would a satellite/tether collision damage the tether, or just destroy the satellite? If it just destroys the satellite, I'm kind of tempted to say "who cares", because by then we will have other solutions, or satellites out past the counterweight, or we can easily launch more now that we have the fancy elevator, or whatever... but then we'd have the problem of an unimaginable amount of space junk orbiting the earth.
- Tuna-Fish 13y ago
  Everything in low earth orbit has 30MJ/kg worth of kinetic energy. TNT has 4.6MJ/kg worth of chemical energy. A rule of thumb: when the kinetic energy of things goes above the chemical energy of high explosives, you can assume that nothing survives.
ChuckMcM 13y ago

placeybordeaux 13y ago

This article did almost nothing to aleviate the real concerns.

maxharris 13y ago

How do you keep space junk (which can include larger objects as well as small as bolts and the like, all of which may have considerable momentum) from tearing through the cable?

sgt 13y ago

"The rotation keeps the cable taut, to counter the gravitational pull as robotic, electric “climbers” ride the line up into space carrying the payload. Boom." Let's just hope he didn't mean that literally. But early attempts may include some disasters, as often is the case.

SlowButEffectiv 13y ago

That's an awful long way to have to stare uncomfortably at the doors.

kamaal 13y ago

At the risk of appearing stupid, I just have few simple questions 1. What exactly holds the counter weight in position? 2. Such a long rope, which the article says is around 62000 miles, won't it function more like rubber band than function like a rope? Due to mere stretching/elastic effect? 3. I'm sure traveling 62000 miles is nothing like fuel efficient especially when you travel in the direction of highest friction(Up). So how do you store the fuel and of what weight that would be? Will such a vehicle be even practical?

jccooper 13y ago
1. The counterweight is in geosynchronous orbit. It is "held up" by its absurd speed like any other satellite. 2. One of the reasons you need a very strong material. The tether will be in tension, but probably will have quite a bit of movement to it. The tether dynamics are not a solved problem. 3. Most plans suggest that power will be beamed from the ground to the climber, either as microwaves or visible light. Some plans might use a paired tether to carry electricity. In either case, no onboard fuel is needed, which us pretty nice, as that's a lot of weight you don't have to pull against gravity. There have been several competitions in this area already.
- kamaal 13y ago
  Yes, sorry the centripetal-centrifugal force balance thing was completely off my mind when I asked that question. But with all the remaining two points look in the domain of SciFi to me. I'm sure tether dynamics are going to a materials engineering problem like never seen in history of mankind. Plus the energy problem is still by and large a very problem. Sending electricity down the tether looks very inefficient give the article says it will 62K miles long. In short we are still may be what, say 50 years away from this?
  - Sharlin 13y ago
    Solar power satellites would most likely beam the power to Earth using microwaves.
  - jccooper 13y ago

frozenport 13y ago

First build the hyperloop, then we will talk.

panacea 13y ago

No they're not.

nmc 13y ago

Why does this seem like a shamelessly unacknowledged copy-paste from [1]? Is it the other way around? Where is the original post? [1] http://motherboard.vice.com/blog/space-elevators-are-totally-possible-and-will-make-rockets-seem-dumb http://motherboard.vice.com/blog/space-elevators-are-totally...

vesinisa 13y ago
To me, it seems like this site Techblog copied Vice without giving any credit. Vice credits the original story to their in-house journalist, while Techblog.co seems like a news aggregation service. I am cool with news aggregation (think Google News), but they should definitely always credit the original source.

oldmantaiter 13y ago

All these comments about space junk, Spaceballs had it right with the giant cleaning lady in orbit. I think we should switch our focus to that instead.