Star Trek: Enterprise Rewatch: “Marauders”

 @krad: I tend to agree that this episode is passable, inoffensive and rather uninspiring (with the exception of a pre-credits sequence pitiably limp even by the mostly-unimpressive standards of ENTERPRISE); my best guess as to why the Klingons completely fail to do anything tactical is that they’re not actually Space Pirates, just Space Truckers who’ve gotten a little too used to driving a harder deal at the expense of the locals whenever they roll into town.

 It also bears considering that wiping this colony off the map means wiping out all hope of further profit – if the Klingons could run the place themselves they’d probably have taken the place over lock, stock and barrel by now (and probably wouldn’t be trucking about the space lanes, as opposed to wildcatting); if they had backers willing to cut them in on a juicy share of the profits (as opposed to cutting them out of the deal) they would probably have wiped the miners off the planet the first time those roughnecks attempted to throw them off it and then brought in more tractable experts.

 So in other words these Klingons are exactly the sort of Houseless wastes of space you’d expect to be nickel-and-diming a frontier mining colony to death; too ignorant and unimaginative to even avenge their own humiliations properly!

 Put another way – how do we know these ‘Marauders’ are even Warrior Caste, as opposed to the sort of less-belligerent souls one might expect to be driven to the margins by the latter’s ‘corporate takeover’ of the Empire?

There were at least a couple of moments during the episode where it seemed like they were setting something up with Q’ell: both his interest in the shuttlepod (and fiddling with the controls) at the beginning, and Tessic’s admonition that Q’ell was to stay out of the fight. One might have expected Q’ell to commandeer the shuttlepod and attempt to use it in the battle, with potentially tragic results. But as KRad points out, that story went absolutely nowhere. I wonder if the original intention was to go in that direction, but it got cut for time or for being too dark.

Nobody throws me my phase pistol and says run. Nobody!

Yes Deuterium is a gas at standard temperature and pressure. My guess is that this planet is somehow richer in Deuterium (in Water, Brines, Hydrocarbon deposits etc) than is typical for rocky planets. The “miners” are probably using processes similar to how we extract Deuterium from seawater. From there they probably use pumps and compressors to chill the Deuterium to the point that it liquifies to make transportation of large quantities practical.

Q’ell was definitely a wasted plot point. At least Florida Man wasn’t being creepy, but given how Q’ell was interested in the Shuttlepod, why didn’t Mayweather interact with him? Boomer who grew up on a freighter talking spacecraft with kid interested in them might have resonated better than Engineer talking to said kid.

@krad in 3:
What does it take to deliver a targeted kinetic bombardment from orbit? At the very least aerodynamic, guided projectiles, unless we’re into ‘dinosaur killer’ territory — and there was no indication that the Klingons have a tractor that capable.

Anything that pays homage to Seven Samurai  is okay in my boo

@29: That’s largely because the Shuttle orbiter has a nice handy atmosphere to do all the braking for it, which isn’t really a desirable thing when your objective is to have something slam into the ground as fast possible. Contrariwise, you can go look at the LMs, and pretty quickly spot that the descent stage is by far the larger of the two. A deltaV comparison, which cancels out the differing masses the two stages needed to move, shows that the descent stage still had approximately 10% more deltaV available than the ascent stage, which I believe owes to the larger potential need for manouvering on landing approach as compared to the relatively simple launch trajectory.

Your example’s not really applicable.

Oh and also, @33:

“The reason it’s large is because you don’t want it to hit fast and hard (and because there’s no atmosphere for deceleration, so I don’t know why you’re even bringing it up in this context). It just proves my point that a hard landing is comparatively easier to achieve than either a soft landing or a launch into orbit, because it’s what gravity is trying to make you do anyway.”

There not being any atmosphere is the whole reason I brought it up, because it illustrates an important thing: Going down in space *is not easier* than going up. Orbits are reversible. “Gravity is trying to make you go down, so going down is easier than going up” is a fundamental misunderstanding of the situation.

@37: You’re correct in your conclusion — well, sort of — but your first statement contains an error: If you’re doing a landing on an airless world, most of your thrust is *not* spent against the force of gravity, as that’s a wildly inefficient way to do things. Instead, it is directed laterally, perpendicular to gravity’s influence and consequently not reduced by it. This is also true of liftoffs, which are significantly easier on airless bodies than on Earth because you needn’t spend energy gaining altitude to avoid air drag, but can instead devote every particle of thrust not currently being used to support your weight into going sideways faster, which in turn means you need to spend less thrust fighting gravity and do so for less time.

@36: As I mentioned earlier it is not true of every rocket ever, but that’s beside the point here: I accept the Shuttle as a stand in for any given Earth-return-to-Earth rocket. The point is that your analogy is based on a major misunderstanding of orbital physics. It is, and I will stress this again, *not easier* to go down than to go up once you are in orbit. That little tiny tap that can put the Shuttle into an atmospheric intercept could — if it weren’t for the interference of the atmosphere — put it right back into its original orbit, too. This was in fact one of the abort modes for the Shuttle descent if there were problems — the Shuttle would pop itself right back into orbit and do another go-round.

More broadly, gravity does not add energy into a system, nor remove it, and orbital altitude changes are, functionally, changes in energy. It is precisely, and exactly, as easy in terms of deltaV, to go from an Earth orbit to a Moon orbit as it is to go from a Moon orbit to an Earth one. Exactly the same energy must be supplied in either direction, either to add to the orbital energy if you’re going up, or remove it if you’re going down.

Note that this, so far, simply talks about altitude changes, which are by far the simplest and least-energy cost operation to do in spaceflight. Potentially germane to ‘dropping rocks’ are other aspects of those transfers, so let’s talk inclination and timing.

If you’re trying to hit a specific, precise target with an unguided projectile, a ‘rock’, you need to have a ground track that crosses over it as soon as you’re done applying thrust. Unless you’re trying to bombard somebody on the equator, that means your timing becomes extremely restricted, since in order for dropping rocks to make any sense as a value proposition you can’t be expending significant amounts of energy getting them into the right place. That means you’re going to have to wait, very patiently, for the target to rotate its way underneath your current ground track. And if your inclination is wrong, you might not *ever* actually cross over that target in the first place. Changing an inclination is not energy-efficient because, suddenly, all the energy you’ve invested in going fast in one particular path is a liability.

For example, if you were on the ISS and, for some reason, wanted to bomb the North Pole, your rock would need to execute almost a 40 degree inclination change. The ISS’s orbital speed’s approximately 7.7km/s; this means that the dV required to perform that manouver is approximately five and a half kilometres per second. That’s a non-trivial fraction of the actual orbital velocity and would, in fact, require some pretty large fuel tanks to accomplish. Even much smaller inclination changes, such as you might want if your track didn’t take you precisely over your desired target for another ten weeks, rapidly become non-trivial.

The need for your track to pass over the target causes other timing issues as well. You have a very limited window in which you can fire your rock, because both you and the ground are moving. In particular, again using the ISS as an example, you are moving at over seven kilometres per second relative to your ground target. If your timing is off by even a tenth of a second for a given trajectory, your rock is going to miss by substantial amounts as a result.

Further, let’s talk about what can actually happen to those rocks. The results of it hitting the atmosphere can fall into one of the following categories:

1. The rock incinerates itself in the atmosphere from shock heating.

2. The rock survives passage, but has a trajectory such that it does not impact the Earth — if it retains escape velocity, that’s that; if it does not, it will at some point re-intersect the atmosphere and we repeat the process.

3. The rock survives passage, and has a trajectory that impacts the Earth, but does not have exceed its standard terminal velocity on impact. This is not particularly useful as a weapon as, while having something hit you at a few hundred kilometres an hour is obviously not fun, you can get that in ways much less complex than going into space. Note that this is the kind of trajectory most returning capsules follow, which is part of why ‘but they don’t need big engines to get back’ isn’t useful reasoning in considering a weaponized scenario. They don’t need big engines because they are, specifically, trying to *not* be going fast when they hit the ground.

4. The rock survives passage, and has a trajectory that impacts the Earth with a greater-than-terminal velocity. In other words, it is going so fast that the air can’t slow it down in time. *This* is the category that people think about when they talk about ‘dropping rocks’, and it’s the one to which Tunguska belongs aside from the fact that it actually exploded midair (which for weaponry purposes is probably sufficient). This is not, in fact, a cheap thing to arrange in energetic terms. The sharper your impact angle, the less time the air has to slow the projectile down, but to get a sharp angle impact *from Earth orbit* you not only need to remove the projectile’s existing orbital velocity you need to supply most of it all over again in order for any of it to survive the braking forces.

Consider HARP. It achieved an altitude of ~180km on a muzzle velocity of 2100m/s with an 85kg projectile. That means of its launch energy only about half survived the atmospheric friction, and that was in a vertical launch, where those losses would be absolutely minimized. The trouble there is that achieving a vertical trajectory back down *from* orbit is, in energy terms, basically about as hard as getting there in the first place. So it doesn’t really get you anywhere to do that, either. There’s some bang-for-buck optimum where you get the most impact energy per orbit change energy in between that and a harmless landing, but the math for that is not something I’m proficient enough at to give you in a comment on a Star Trek episode.

But of course, we’re *are* talking about a Star Trek episode. In Trek the energy costs of local spaceflight are, basically, completely irrelevant. Even in Enterprise, the NX-01’s dinky little shuttle is perfectly happy toodling up and down from ground to orbit and back with Space Magic. So while now dropping rocks is really easy, whatever energy advantage might exist in doing so versus working from the ground is also made completely irrelevant — it doesn’t *matter* if you’re in space because I can get there too just as easily! It’s like saying, I dunno, that you should crew a Trek ship entirely with the smallest people you can, because that way it’s more manouverable. It’d be technically true, but it’s also, obviously, pointless.

Moreover, there’s usually a simpler way to attack someone. Someone else said this a lot better than I ever will: Rocks Are Not Free, Citizen!

@38: Oh, certainly there’s lots of things the Klingons could potentially do given they have a ship, but like, they have a *Star Trek* ship, dropping rocks is just a waste of everybody’s time.

@foamy in 37, consider this:

The rock survives passage, and has a trajectory that impacts the planet with a greater-than-terminal velocity, yet some parts break off and change the aerodynamics. It hits with significant energy, call it a few kilotons, in the next valley over. That might be sufficient to coerce the government of a densely populated planet, but in this example the next valley over was probably considered expendable.

Hence my suggestion to use aerodynamic, guided projectiles, which add to the cost and required preparation.