SpaceShip One flies - it's official!

[AphelionHellion]

Just keep in mind how huge the Shuttle's external fuel tank is, then remember that one of the primary reasons for
those huge solid rocket boosters is to lift that massive tank and all that fuel.  8o

In a similar vein, Discovery magazine just did a piece on space elevators. And not just a "Wheee wouldn't it be nifty"
article, but one actually discussing the costs of the project, construction techniques, what infrastructure we'd need,
time frames, etc
Yeah, yeah, not another elevator argument, run away!  
I know

[DocHoliday]

Now that's a REALLY cool car!

I have that monstrocity in FS2004 a real bitch to fly

[Simonpro]

I'm not even starting on space elevators, too busy laughing at the idea.

[reekchaa]

An Equal Bitch to fly in X-Plane.  Art Stab is in definite need, if it ever flies.

I was fiddlin' with some quick & dirty SubOrb/Orbital designs in X-P... Fun to play with the Mothership concept. Once
Sub, it took roughly 4x the fuel is required to get mach 25 horizontally, in addition to the mach 3 vertically.  The real
problem is the weight of that extra fuel getting up 100km.  WK only takes SS1 up 13k.. but that still saves a hell of a
lot of fuel.  Hmm... Fuel sounds pretty good right now.

[AphelionHellion]

simonpro: Lets look at this objectively for a moment as if we'd never heard of either rockets or space elevators - what
sounds sillier to you, building what's essentially a simplified tram to lift and lower cargo, or packing it into a flimsy
metal tube full of flammable fuel and blasting it into position with a controlled explosion? Which would you rather stake
your life on?

I believe A. C. Clarke said something to the effect that "The space elevator will be built 100 years after everybody
stops laughing."
Personally I think people are going to be laughing right up until the day the thing is actually completed and they go for
a ride on it


Reekcha: That's a good point - a lot of fuel is burned just lifting the rest of the fuel off the ground (not to mention
through the thickest part of the atmosphere). The WK probably does save a good deal more fuel in the daughtership
than we realize...

Does anyone remember reading about the original plans for the space shuttle? How they wanted to launch it on a sort
of SR-71 looking thing where it would be released at high altitude at a reasonable mach number?
IIRC they figured it'd be too complicated to design two new spacecraft let alone one, and went with the tank
and boosters instead, which was tried and true technology, but made things a lot more expensive in the long run
(assuming the mothership concept had worked).

And I hate to mention this; I don't want to disrespect those fine late astronauts from Challenger and Columbia, but
look at what causes those tragedies were traced to: one of the SRBs in the first case and the external fuel tank
(insulation) in the second

[Simonpro]

I'd still go with the rocket, as i can actually do physics - and a space elevator obviously cant :p

[Shmi]

No I defininitely vote for the space elevator - one with nice soothing music so I dont actually realise how high I
am! Hopefully ,feelings of vertigo stop when you are too far up to see the ground?

NB what about the ideas of getting free power on the electricity generated as the elevator cuts through the earth's
magnetic field?

Of course there's no room to build it in little old england so no risk to my back yard

[AphelionHellion]

Simon: Sure it can't, space elevators don't go to school
Seriously, can you clue us in on what exactly the physics problem is? I've read quite a bit on space elevators, and
granted a lot of it is fanciful what-iffing. But I've also read pieces written by some fairly respected scientists and
physicists, and yes many of them argued that an elevator would never work. However of all the arguments I've
read by NASA et all against a space elevator, physics was never the issue. I've not read any experts condemning the
concept on the basis of it physically not working, but rather other (admittedly very good) arguments regarding, say,
corrosion from micrometeorites and monoatomic oxygen, or lack of power sources for the "crawlers," or insanely
ballooning budgets (look at how much the Space shuttle was supposed to cost compared to how much it wound up
costing, for instance), or vulnerability to terrorism or political problems.
How exactly does the concept not work on paper, though? Most things work on paper even if they're Bad Ideas (tm) in
real life. Like Communism or electricity/utilities deregulation
Again, I'm not arguing that this thing would work at all, let alone on paper, but I'd like to hear your reasoning on the
physics aspect of it

[DocHoliday]

I too have a problem with space elevators.. I didn't really go into it, but something seems wrong or ahead of itself in
the whole concept. Also the whole idea you have such a massive structure makes an inner alert bell go off in my head
and says something like: "gravity polution", can you really predict ALL the effects such an additional mass would have
on the rotation and orbit of Earth... Looks dynamite on paper probably, but so did the Titanic or Tschernobil.

Also I'd prefer to build a Vespucci type vessel or more than one for only a fraction of the space elevators cost and
resources...

But that's just because I'm ignorant on the subject, so I'm really interested what you guys know.

[Simonpro]

Biggest problem is what goes up must come down. The same amount of mass must go back to earth as go up to
orbit,and where the heck do you find this mass to come back down?

[DocHoliday]

mm. not sure I understand. You're saying that if you lift say a dg into orbit using the elevator and then bring the
elevator back down empty, that's a problem?

Hm, I THINK I get it.. when you move the mass up... the whole system remains balanced.. but then you "detach" a
certain albeit insignificant amount of mass from the system, and you do not do it at the barycenter (which you
probably won't, prefering the Geosync altitude instead), you induce new forces into the system's extreme points. The
Earth's opposite side and the "theoretical" Toutatis balancing mass at the top of the elevator. You keep repeating
that and don't make sure to cancel out the effects, you are "polluting" the Earth's orbital path? did I get it right?

[Simonpro]

Havnt got the foggyest idea what you are talking about, im afriad.
If you bring up.down uuneven amounts of mass then you will upset the orbit of the space elevator - eventually it will
fall from orbit as it will lose energy.

The other problem with a space elevator is all orbits under GEO will become nigh on imopssible, as all orbits cross the
equator and you run a VERY high risk of smahing into the cable sooner or later, so no more ISS, no more LEO
anything.

[DocHoliday]

Hm... I was using Kulch's Space Elevator addon as the example in the previous post if that helps, but I think I will
have to read more about the subject, because I am obviously making some faulty assupmtions. Hence making
meaningless statements I was assuming a space elevator is not on a cable and up in GEO actually doing it's own
orbiting, but on a solid structure and reaching higher up than GEO, as Kulch did it in his addon with asteroid Toutatis
as some sort of countermass. So basically a big long stick between Earth and that asteroid. Is his version than only
fictional?

I do agree about the orbits tho.

[AphelionHellion]

Simon: That makes sense to me if the counterweight is at or not very far from geostationary orbit, but what if it's
well beyond that? How is hoisting cargo to that point going to de-orbit the counterweight?
I admit it sounds like "something for nothing" at first glance, but if I'm not mistaken, the energy balance is paid by the
earth's rotation - in the same way that an orbital slingshot maneuver "steals" a tiny portion of the planet's inertia, the
elevator uses the earth's rotational momentum. If you hoisted a trully massive and impossible amount of weight, the
earth's rotation would slow measurably.
Am I right?

I'm thinking there must be some small scale way to experiment with these principles, the way gyroscopes and marbles
and such can be used to simulate certain simplified aspects of planetary motion.
Bungie cords and ceiling fans, anyone?
*ducks*

IMHO the problem with other orbiting structures may be the best argument against the whole idea. Even objects in
orbits nowhere near the plane of the equator would precess signifigantly and pass near the elevator every few days.
It wouldn't take very much propellant to "dodge" the ribbon, but yeah, can we honestly expect every single satellite in
sub-GSO to have RCS systems, not to mention use them every few days?
I may be mistaken but I think most survey and communications satellites just have reaction control wheels or are spin
stabilized anyway?

[Simonpro]

The reason for the couterbalance is so that the centre of mass is in geostationary orbit. The entire structure will lose
energy if more goes up than down, and that will eventually cause the structure to deorbit due to the fact that it is no
longer carrying sufficient energy to remain in geostationary orbit with its centre of mass. Kulches model only uses a
fixed structure due to the internals of programming it for orbiter, and the fact that the orbiter physics engine aint
stupid, having a free floating cable would deorbit quickly.

[AphelionHellion]

Doc: Well if I understand correctly a space elevator really isn't in GS orbit (or any normal orbit) at all. The
counterweight, being well past the altitude of a geostationary orbit, is "tied down" to the earth so that it's moving
faster than it would if it were orbiting by itself at that altitude and that's what keeps the cable taut.
How the thing would be built is a bit puzzling - if you have something in orbit and run a cable down to earth and pull
on it, yeah, you will screw up the object's orbit. It seems to me that the key is that a space elevator actually doesn't
rely on an orbit at all.

[DocHoliday]

eventually cause the structure to deorbit due to the fact that it is no longer carrying sufficient energy to
remain in geostationary orbit with its centre of mass

Duh, of course it makes sense now.. But can you compensate for it, by increasing velocity of the counterweight
periodically, some economic type of engine, like ion?

[AphelionHellion]

Even if the center of mass is higher than GSO??

Wait a minute... Ohhhhhhhh... Conservation of momentum!
So what you're saying, Simon, isn't that the counterweight would be yanked down, but that it'd be slowed by the
mass moving up it (and away from the axis of the earth's rotation). The angular momentum of the counterweight
would be lost increasing the momentum of the load that's being lifted.
Methinx I get it now

I like Doc's ion engine idea. Of course, as long as we're thinking big, how about a massive solar sail that's opened on
the retrograde half of the orbit and closed on the prograde side?  
Heh, just kidding. That'd need to be a sail the size of the friggin' moon.

But still, it does seem like hoisting fuel to rockets on the counterweight would be more economical in the long run than
using rockets, no?
That'd eat into the profit margin, though, for sure

Anyway I'm off to bed. Thanks for the "lightbulb-going-on moment"

[AphelionHellion]

Yeah I get it now

How'd that be for a job, though? Sitting up there in some utility station priming the big engines on the end of the
sucker every day.

Kinda reminds me of those guys who had to shovel coal continuously into the boilers of those old steam locomotives

[DocHoliday]

That'd need to be a sail the size of the friggin' moon.

Well, less need for an countermass of actual asteroid proportions

That'd eat into the profit margin, though, for sure

Well at the end of the day, the atmosphere and ozone layer will be all that will count as profit if it is as preserved as
possible

[AphelionHellion]

Doc: True
I haven't read much, if anything, about the effects of rockets on the upper atmosphere, but I do seem to recall hearing
that the current findings were turning out to be a little disturbing...

This is sorta off the topic, but I read somewhere that it's thought that there's a signifigant charge differential between
the ionosphere and the earth's surface, caused by charged particles from the sun interacting with the air up there. I
wonder if closing that gap could generate electricity? IIRC Tesla wrote something about that, but I may just have my
memories discombobulated.

I just wanted to say ahead of time that I'm not thinking about the geomagnetic induction experiments where they
dragged a tether behind the shuttle. That obviously is a whole different mechanism. The other day I read something
about some people suggesting that that sort of tether be used to de-orbit old satelites, though

[Simonpro]

Yeah, it would be a good way to deorbit satellite in theory.

Most current rocket launch systems are fairly large polluters, airship1 is a rather less pollutant one, the shuttle is one
of the most pollutin machines on the planet - there are entire areas of the atmosphere that have been put there by
the shuttle!

[DocHoliday]

About electroinduction. Shmi may know more on the subject, she mentioned before the cable could be used to
generate power...

NB what about the ideas of getting free power on the electricity generated as the elevator cuts through the
earth's magnetic field?

Shmi?

[Simonpro]

You could run a cable up the inside of the elevator to gain some power, but the actual amount of power gained would
be tiny.
Ill try to drag out some formulae from my first year physics textbook

[reekchaa]

So, Simon, you're saying the fuel cost/amount to accelerate the counterweight to stay in GEO sync with each 'slowing'
lift would be greater/same as the amount of fuel to boost a ship up directly ?

I gotta spin some weights on strings and twirl in my chair for a little while.