posted
>>> One something starts moving in space it keeps moving in the same way until something hits it. Once the ship is aligned with the position and rotation of the station, it shouldn't need to be held in place by anything. <<<
That would be true in open space, but the situation is quite different in planetary orbit. The linear velocity of an orbit is dependent on the distance from the center of gravity of the object being orbited, and does not correlate to an angular velocity. Objects in lower orbits must travel faster than those in higher orbits.
As an example, to if you are in a ship in orbit at 1000km and wish to catch up with something ahead of you in the same orbit, you do the following: First, fire thrusters *ahead* of you to slow down. This will cancel some of your orbital momentum, and you literally fall into a lower orbit. But your new orbit is lower, so you orbit faster - catching up with the target. Once you're close you fire your *aft* thrusters to speed up, which boosts you into a hire orbit - where you orbit more slowly and can dock with the target.
What does that have to do with these space stations? Well, even a difference of a few meters is significant. The strain on a large object in space - which spans several different orbital velocities - is non-negligible. These are called tidal forces. See "Dragon's Egg" by Robert L. Forward for the more extreme example of orbiting a neutron star, where these tidal force must be compensated for.
(As an aside, this is one of the reasons why shuttle astronauts experience microgravity, not zero-gravity. A shuttle-borne crystal growing experiment will have very different results than a crystal experiment in deep space or in free-fall towards the Earth or the sun.)
In the case of Earth Station McKinley, since its center of mass looks to be offset by tens of meters from the center of mass of the ship, the two objects will tend to diverge, meaning energy (or structure capable of resisting the strain) must be used to keep them together.
A physical contact at a few brief points along the hull might be enough - if both structures are composed of super-resilient materials (which they presumably are). Federation gravity technology or inertial damping fields might be enough to compensate for this, but some magic must be invoked.
It was mentioned as a repair facility in TNG, yet Voyager was built there. We saw the facility in Redemption because of the Sutherland, yet the ship was docked in a different configuration of the drydock we saw the Enterprise-D in.
I think that the Earth Station McKinley facility, as the TNG Tech Manual places it, is a facility with many drydocks and repair facilities.
Okay, you can begin to take my thoughts apart now...
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posted
The Claws probably have some form of docking clamps or another. I will also point out that you can't simply access the ship through one door just to make repairs. Having only one port means that unless the facility starts generating power for Transporters, you're going to get a big bottleneck of personel in that single docking area.
As for Tractor beams, they are probably activated in low power in order to maintain the structural integrity and to make sure the ship is locked in place. Situations may request that the Tractor Beams be set to a higher setting when, say, the Spider Assembly needs to move the ship to a different area to be retrofitted with its Warp Engines.
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posted
Thanks to Joshua Bell for that explanation. I stand corrected. Though this does bring up an interesting point: If it is so hard and presumably energy intensive to keep these two structures together, why not build ship yards in interplanetary spacewhere differences in orbitable speeds would be far less? I suppose building them in planetary orbit is one sure way to make sure that they will move as the solar system moves through the galaxy...
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posted
Re: building ships in places other than planetary orbit
Yes, it would be easier to build them either in solar orbit or a much further orbit than is shown (e.g. geostationary orbit) where the tidal forces are negligible. In those cases, a dropped tool will merely remain in place, rather than quickly moving away in its new and quite different orbit.
Re: planetary orbit so they keep up with the solar system
Not necessary. They can be in solar orbit and will dragged along with the rest of the solar system. Failing that, they can be merely orbiting the galactic core just like the sun is. Of course the sun is also bobbing up and down within the galactic plane and not moving in a simple elliptical orbit, but that's probably too slow to be noticable over the liftime of a space station.
Keeping them in planetary orbit is a good idea, though, if the cost to maintain structural cohesion is less than the cost to transport goods from low orbit to high orbit. If they can only beam materials and personnel to low orbit, the benefits might outweigh the costs.
Also, as I alluded to before, the mere fact that Federation starships, with their gangly nacelles and pylons, aren't pulled apart in low orbit means the Feds are able to compensate for these tidal forces. A low level IDF or SIF may do the trick.
We can turn this around and use it for a reason to have such elaborate spaceframes around vessels under construction. Perhaps they're generating compensatory gravity fields to produce true zero-g conditions within transporter range of the planetary surface?
posted
I thought Voyager was built at Utopia Planitia... ("Relativity")?
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posted
Meaning the Defiant was designed at Utopia Planitia, but the actual construction at Antares, Timo?
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posted
Exactly - or, better still, design work at the big Starfleet design center of UP, but construction work at one of the many facilities of the Antares Fleet Yards corporation, in this case its Bajoran Sector facility.
To further extrapolate on the diversity of dockyard naming:
McKinley Fleet Yards might be named after Earth Station McKinley (it inself named after a guy or gal called McKinley, probably, since why name it after Mt. McKinely when it can't really be synchronized with the location of this off-equator mountain anyway), but would include numerous smaller construction units in the vicinity, or even in other star systems. San Francisco Fleet Yards would be an older corporation named after the city instead of a space station. Utopia Planitia yards would in turn be named after the geological feature, instead of a city or a station, because the surface components would be located in that geological area.
So the naming wouldn't be all that systematic. Instead, there would be various traditions and trade names in use. Most of the "Yards" we hear about wouldn't really be physical locations, but subcontractor corporations for Starfleet, only named after physical locations.
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