Space Elevator
- Thread starter Rahnd
- Start date
M
Malenfant
Guest
I just did. By the time the war ended, the administration and the general populace had got bored with sending people to the moon. Apollo/Soyuz was an earth-orbit mission. The US government felt that scientific return from the moon was not worth it (which is annoying since the last couple of Apollos were where it was getting good and actual *exploration* and scientific discovery were being done on the moon's surface), and cancelled the manned moon missions.
That's it. The reason we didn't keep the momentum going was a combination of a lot of factors - the Vietnam War being a more pressing concern for people, general apathy and lack of interest after Apollo 11, and short-sighted politicians. That, historically, is why we didn't follow through, and that is what the general consensus is on the matter. Believe differently if you want, but if you do then realise that you are in the minority that refuses to believe the facts of the matter.
IMHO the key for Humanity's exapnsion into space lies in the industrialization of space. As long as we keep using earthbound infrastructure for the manufacture and construction of all materials used in spaceflight, we are going to be stuck down here with extreme launch costs for anything and with an inability to construct anything big in space without it being very modular.
What we need is infrastructure in space - that is, on the moon and in LaGrange points, using materials mined from the moon and from near-earth asteroids to construct factories in orbit. Remember - the highest cost of spaceflight is the cost to launch from earth. With enough infrastructure, we will only have to send the Humans up with enough life-support and fuel to reach the orbital facilities; and even this cost could be minimized by aerodynamically-assited launch-craft (X-33 IIRC, but the program was cancelled by the government during budget cuts
).
The initial investment would be staggering, but otherwise we're going to continue to pay massive launch costs for every unmanned sattelite of manned spacecraft.
The Apollo Project was basically a single-goal mission, aiming at landing an American on the moon for PR and propaganda purposes, with military applications, technological development and pure science coming a distant second. No infrastructure was built off earth, and once the goal was reached the entire prospect for further Apollo-style moonflights got less and less appealing from nearly any POV, especially due to the facts that robots could easily return moonrocks back to earth at far lower costs as Humans. To return to the moon a more systematic approach is needed.
See this site for ideas about what I'm talking about.
The overall problem is IMHO political in nature rather than technical - we COULD colonize space; those in power simply choose not to as their current interests lie in other places. So either we remove the ones in power and take control of our destinies, or we could wait for their interests to shift and hope that they'll change their minds early enough to get us out of here before all of our non-renewable resources burn out and our ecosystem dies.
What we need is infrastructure in space - that is, on the moon and in LaGrange points, using materials mined from the moon and from near-earth asteroids to construct factories in orbit. Remember - the highest cost of spaceflight is the cost to launch from earth. With enough infrastructure, we will only have to send the Humans up with enough life-support and fuel to reach the orbital facilities; and even this cost could be minimized by aerodynamically-assited launch-craft (X-33 IIRC, but the program was cancelled by the government during budget cuts
).The initial investment would be staggering, but otherwise we're going to continue to pay massive launch costs for every unmanned sattelite of manned spacecraft.
The Apollo Project was basically a single-goal mission, aiming at landing an American on the moon for PR and propaganda purposes, with military applications, technological development and pure science coming a distant second. No infrastructure was built off earth, and once the goal was reached the entire prospect for further Apollo-style moonflights got less and less appealing from nearly any POV, especially due to the facts that robots could easily return moonrocks back to earth at far lower costs as Humans. To return to the moon a more systematic approach is needed.
See this site for ideas about what I'm talking about.
The overall problem is IMHO political in nature rather than technical - we COULD colonize space; those in power simply choose not to as their current interests lie in other places. So either we remove the ones in power and take control of our destinies, or we could wait for their interests to shift and hope that they'll change their minds early enough to get us out of here before all of our non-renewable resources burn out and our ecosystem dies.
Okay, guys. Here part of what happened.
In 1969, NASA's manned space program plans after Apollo were: </font>
Shuttle was commissioned for </font>
In fact, shuttle failed. At most 12 launches per year and the 2001 cost per launch was $780M. See
2001 GAO report on ISS Costs
Every President going back to Nixon was a part of this, Democrat or Republican. So we are all - to one degree or another - responsible. And since rewriting time is only possible in SF, the only thing we can do is to get things going now. And this is all way off-topic.
In 1969, NASA's manned space program plans after Apollo were: </font>
- Post-Apollo program with 15 CSM/Saturn V missions, including Skylab as a precursor to</font>
- a 55-man space station at 600nm orbit; not the 250 of the current station</font>
- and finally, a reusable space shuttles to eventually take over as the lifting system.</font>
Shuttle was commissioned for </font>
- $5.25M development with first launch by '79</font>
- 40 launches per year from Kennedy Space Center</font>
- 20 launches per year from Vandenburg AFB</font>
- Per launch cost no more than $43.1M (~$196M FY 99 dollars)</font>
In fact, shuttle failed. At most 12 launches per year and the 2001 cost per launch was $780M. See
2001 GAO report on ISS Costs
Every President going back to Nixon was a part of this, Democrat or Republican. So we are all - to one degree or another - responsible. And since rewriting time is only possible in SF, the only thing we can do is to get things going now. And this is all way off-topic.
P
Pickles
Guest
Ooo-kay ... back on topic, everyone! 
I don't want to keep harping back to Kim Stanley Robinson, here, but so far his approach to the space elevator makes (Science Fiction) sense to me in most ways.
One of these is that the cable should be manufactured in orbit, using raw materials mined from a suitable rock manoeuvred into position above the 'landing' spot on the planet. It would make more sense than shooting material up from the bottom of the gravity well.
Lowering the cable as it is produced would be almost energy-free, apart from the boost needed to move the rock into higher orbit to compensate for the change in C-of-G.
Whatever's left of the rock could then be transformed into the highport.
I don't want to keep harping back to Kim Stanley Robinson, here, but so far his approach to the space elevator makes (Science Fiction) sense to me in most ways.
One of these is that the cable should be manufactured in orbit, using raw materials mined from a suitable rock manoeuvred into position above the 'landing' spot on the planet. It would make more sense than shooting material up from the bottom of the gravity well.
Lowering the cable as it is produced would be almost energy-free, apart from the boost needed to move the rock into higher orbit to compensate for the change in C-of-G.
Whatever's left of the rock could then be transformed into the highport.
The fundamental problem for a space elevator is that we can't build the cable required. Not currently, and possibly not ever. Overcome that problem, and you can build it either up or down -- you start by lowering a very thin cable from orbit, then you can enlarge it from whichever end it's easier to make cable at.
TheEngineer
SOC-14 1K
Hi !
The theoretical strength of a perfect nanotube material is given around 100 GPa. Sadly actual production reduce it down to 30 GPa.
Refering to NASA sources it would need a 63 GPa tension proof material to do the cable job.
Well, thats under earth conditions.
We could assume planets with a bit lower gravity (0,7 g) and increased nanotube production skill.
IMHO the solution of the material problem could be in reach here (around 40 PGa ?).
I made a little speadsheet for that. At least here the numbers could be tuned to a working theoretical model.
Regards,
Mert
The theoretical strength of a perfect nanotube material is given around 100 GPa. Sadly actual production reduce it down to 30 GPa.
Refering to NASA sources it would need a 63 GPa tension proof material to do the cable job.
Well, thats under earth conditions.
We could assume planets with a bit lower gravity (0,7 g) and increased nanotube production skill.
IMHO the solution of the material problem could be in reach here (around 40 PGa ?).
I made a little speadsheet for that. At least here the numbers could be tuned to a working theoretical model.
Regards,
Mert
P
Pickles
Guest
I can live with handwaving production accuracy and material advances in Traveller. IMTU, beanstalk cables work. I know it's not based on rational thinking or scientific probability, but disbelief in better materials is just more intutively suspended by my (ex)players and I than in gravitics.
TheEngineer
SOC-14 1K
After checking the NASA pages and crunching some numbers the beanstalk appears to be far more realistic as many other Traveller technologies
Perhaps its more important to give some convincing arguments, why a Beanstalk is used. (We noted some possible reasons at the top of the thread).
Perhaps its more important to give some convincing arguments, why a Beanstalk is used. (We noted some possible reasons at the top of the thread).
Exactly. Under Lunar or Martian gravity, beanstalk become quite possible. So Mars might end up as Sol's most important world as it'll have a beanstalk and thus massive traffic capacities as opposed to Earth with its need for lift-assisted launch vehicles and big gravity-well.
The sheer amount of surface-to-orbit and orbit-to-surface traffic at relatively ultra-cheap costs allowed by a beanstalk seems to justify this for me - the reduction in launch costs will probably cover the enourmous construction cost within a reasonable amount of time.
Think of a beanstalk as a gateway to the stars.
The beanstalk is probably the single most important change in thought in Sci-Fi in the last 3 decades. Skyhooks are pretty darned close.
Skyhook: a rotating several KM bar, (or disk, or ring) which reaches down far enough to catch high altitude airbreathers and fling them into LPO.
Both are ways to reduce the launch energies to something manageable for commercial traffic without resorting to gravitics. My first encounter with a beanstalk was in A Tour of the Galaxy in the late 70's.
But in Traveller, with gravitics and Cheap fusion, they are not essential. 2300, which was missing gravitics, needed them. Mainnstream traveller doesn't need them for TL10+ worlds, and they look to need TL10 materials.
Skyhook: a rotating several KM bar, (or disk, or ring) which reaches down far enough to catch high altitude airbreathers and fling them into LPO.
Both are ways to reduce the launch energies to something manageable for commercial traffic without resorting to gravitics. My first encounter with a beanstalk was in A Tour of the Galaxy in the late 70's.
But in Traveller, with gravitics and Cheap fusion, they are not essential. 2300, which was missing gravitics, needed them. Mainnstream traveller doesn't need them for TL10+ worlds, and they look to need TL10 materials.
i think anti-grav vehicles will
be the key to space exploration
much easier to get things to orbit...
the beanstalk or regular lift
veh. are just too expensive or
cumbersome for long term viabilty
at least from my limited knowledge,
for mars or the moon it might be
more possible..
a beanstalk would be neat for a
traveller mission dont you think?
protect or destroy?
be the key to space exploration
much easier to get things to orbit...
the beanstalk or regular lift
veh. are just too expensive or
cumbersome for long term viabilty
at least from my limited knowledge,
for mars or the moon it might be
more possible..
a beanstalk would be neat for a
traveller mission dont you think?
protect or destroy?
Yeah, but as Aramis has said, in a gravitics-less TU these things will be the norm. And even with gravitics, some of the more developed (but low-G) TL9 worlds will have them as their gravitics will be quite primitive but their material sciences could be well-developed.
Exactly. Under Lunar or Martian gravity, beanstalk become quite possible. So Mars might end up as Sol's most important world as it'll have a beanstalk and thus massive traffic capacities as opposed to Earth with its need for lift-assisted launch vehicles and big gravity-well.
The sheer amount of surface-to-orbit and orbit-to-surface traffic at relatively ultra-cheap costs allowed by a beanstalk seems to justify this for me - the reduction in launch costs will probably cover the enourmous construction cost within a reasonable amount of time.
Think of a beanstalk as a gateway to the stars. </font>[/QUOTE]Talking about a Martian Beanstalk only, if there are no Martians to build it, what's the point? If we can't get people off Earth, there's no point in building a Martian Space Elevator as there will be no one there to build it. Besides assuming we can get people of of Earth there's marvelous things we can build out of asteroids without even going near Mars.
Much much easier. A martian beanstalk needs to be only about 20% as strong as a terrestrial beanstalk. The moon is something like 5% and might be doable with current materials, though the beanstalk would need to be enormously long because of the moon's slow rotation (I think it needs to be anchored at one of the lagrange points).
I didn't say we couldn't get off earth - we can now, and with lift-assisted vehicles (for eaxmple X-33 if it wasn't cancelled
) it won't be THAT difficult; Mars could be settled from Earth (with significant industrialization of the near-earth space to reduce Earth-to-Orbit launch weights to a bare minimum), but once it'll be settled the economical advantage will go to it as it'll probably have a beanstalk.And yes, we could and should colonize near-earth planetoids - in fact, industrializing near-earth space (using Luna and near-eath planetoids for raw materials) would probably be a prequisit to any serious colonization effort of any further bodies in the Sol System.
The X-33 was just an example; I am not aware of any spaceplane currently under development. However, the fact that something was cancelled once doesn't meant that it cannot be restarted later on - we could go the DYNA-SOAR way, the Hermes way, the 1969 Shuttle way, the X-33 way - only willingness of the decision-makers is needed. or their replacement by ones who are willing.
Scarecrow
SOC-14 1K
As an aside, there was an old issue of White Dwarf (whilst it was still an RPG mag), that had a Traveller scenario that revolved around a heist job on a Beanstalk. Can't remember which issue now, but it had a beanstalk rooted on Mt Kilimanjaro with a huge city built around it. The stalk itself was a solid structure 10-20 metres across with two tunnels running through it, along which the shuttles (sort of vertical train carriages) ran between Earth and orbit. The job (and scenario) was set on the 16,000 km half way relay station; a small single deck structure some 40-50 metres square. I never ran it, but it looked like great fun. I believe it used Clarke's Fountain's of Paradise as inspiration, not sure about the science behind it.
Crow
Crow
Andrew Boulton
The Adminator
Ah, the classic "Tower Trouble". Issue 71.
