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We are talking about battle station with a hyperdrive. And there we have to wait till it orbits around Yavin to get a shot at the moon.

We know why they didn't blast the gas giant with the superlaser out of the way.

But why didn't they navigate DS1 so that it had a clear shot at the rebel moon in the first place?

And why couldn't it orbit faster?

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(Source: Irregular Webcomic Strip #507)

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I would prefer canon answers (any level of canon) or real physics/astronomy logic asnwers as opposed to random guessing. – DVK Jun 9 '12 at 15:35
Because luke needed time to line up his run... if he needed 16 minutes it would have taken a minute longer to round the planet... Besides it was a moon... and they were in an practically indestructable space station... what could go wrong with a slow burn around the planet? The moon wasnt going anywhere. – Chad Jun 17 '13 at 20:27

5 Answers 5

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They didn't make a microjump because Hyperdrive doesn't work in a gravity well. They probably didn't jump directly to a spot where they could target the moon immediately because they didn't know the precise location of the moon within Yavin's orbit, and they happened to come out of hyperspace on the wrong side of the planet. Besides, they were (at least Tarkin was) very overconfident, so what if it takes them a little bit to get around the planet?

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+1. Who would assume that a supposedly indestructible battle station would be destroyed before 30 minutes were up? – Gabe Willard Jun 9 '12 at 16:54
@GabeWillard - Constant Vigilance!!! </Moody> – DVK Jun 9 '12 at 21:16
Pretty sure there's a reference in the novelisation (and other EU sources) to back this up... repulsors for moving in gravity wells, and hyperdrive once you're free of that well. – HorusKol Jan 2 '14 at 2:44
Besides, it's well established that Tarkin is a sadistic bully. "It'll take thirty minutes for the station to clear the planet? Excellent. Thirty minutes for those Rebels to slowly watch their doom approaching and knowing there's nothing they can do but scurry like ants trying to get out from under a boot." I bet the mental image give him a huge stiffy under his uniform. – Shadur Sep 4 '14 at 9:02
i would also doubt they'd want to rush in considering the sheer number of moons our gas giants have, rushing in might have resulted in the discovery on Yavin's 16th moon in a very spectacular fashion – IG_42 Sep 8 '14 at 0:57

I believe that Han Solo said it best:

Traveling through hyperspace ain't like dusting crops, boy! Without precise calculations we could fly right through a star or bounce too close to a supernova, and that'd end your trip real quick, wouldn't it?

From this we can infer a number of things:

  • Hyperspace is dangerous, and even more so if you get your calculations wrong.
  • You need to be real careful about where you come out.
  • Flying through or near objects with large gravity wells is really not a smart thing to do.

If Han, as one of the better pilots in the galaxy and with a specially modified ship, exhibits this kind of caution, then of course Imperial pilots of a larger ship are going to be even more cautious.

Common sense would therefore seem to dictate that you come out some distance from your objective and make a normal flight from there.

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Yup. And DS is slooooooooooow. – Petersaber Jul 24 at 6:18

With the computing power they have it seems unlikely that they wouldn't know the position of the planet when they arrived. However, it would be silly to go out of their way in hyperspace just so that they could come in to the system with the moon already in range.

Their arrival in the system would have been based on a most-direct hyperspace jump, which would be standard practice for hyperspace navigation under all but the most unusual circumstances.

Considering the balance of forces, the destruction of the Death Star would have been inconceivable and certainly wouldn't have sweated the 30 minutes it took to orbit the planet.

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And yes, I do know what the word "inconceivable" means. :-) – Donald.McLean Jun 18 '13 at 14:58
Why would computational power be a limitation here? We can compute the times of solar and lunar eclipses a thousand years from now down to the second, surely they're not that far behind us? – Charles Jan 2 at 15:59
Perhaps I wasn't clear. The point I was trying to make was that they could certainly have calculated any course they wanted to with reasonable ease. However, the roundabout course would have taken longer. And since the empire didn't believe that the Death Star could be destroyed, what would be the point of taking the longer course? – Donald.McLean Jan 3 at 5:40
But surely "longer" would have been much less than the 30 minutes, since they would be traveling at > c? – Charles Jan 4 at 3:51
Well, it depends, you would have to make a "dog leg" journey, minimum of two jumps. Depending upon the angles, you might wind up having to take a journey that was 5 times longer in distance. And hyperdrive is not instantaneous, just faster. – Thorin Schmidt Jul 24 at 17:48

As per the comic, you can't orbit faster without increasing the orbital altitude. You can't just stay at the same altitude and "go faster". Orbital motion doesn't work like that. Also, moving large ships is very often a slow and imprecise task.

To give a nautical example, it's not unusual for a fully loaded modern supertanker to take 3~8 km to complete a braking maneuver from its normal cruising speed. This means if you're cruising along and decide you need to stop, and you throw your engines in full reverse, it's going to take 14 minutes or more to stop.

And while some large ships have maneuvering thrusters or bow/stern thrusters that help it turn without moving forward, they're mainly used for docking. For normal turns out at sea, a large tanker usually has a turn radius of over 3km.

A space station like the Death Star is going to have a lot more momentum and even less agility. Plus, it's much harder (takes more energy and time) to brake in space. So simply waiting for the orbit of the Death Star to put itself in position for the shot does make sense.

Even in space, there are gains and tradeoffs when it comes to size.

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Why orbit at all? Just use the thrusters to get a clear shot and don't worry about being on escape trajectory after. You're hyping out in a few hours anyway. – Joshua Nov 19 at 2:30
It might make sense for the Death Star to use vertical thrusters to supplement gravity, allowing it to orbit around the planet faster at the same altitude (or at least maintain an irregular orbit), but you can't move in a straight line to get on the other side of the planet unless you plan to pass through the planet. Otherwise, if you want to get on the other side of the planet, you'd have to accelerate, use reverse thrust to stop, adjust your attitude and repeat. – Lèse majesté Nov 19 at 6:31
I plan to move in a nearly streight line until I have a clear shot. The range is pretty good; the problem is Yavin is in the way. – Joshua Nov 19 at 16:11

Pseudo-scientific explanation:

The strong, complex tidal forces near Yavin IV present a significant hyperspatial navigational hazard to a vessel as large as the Death Star. To mitigate this, the Death Star dropped out of hyperspace at a point where Yavin, Yavin IV and Yavin's sun were all roughly in alignment, and then orbited the planet to reach Yavin IV. This is a standard manoeuvre for ultra-large vessels.

The real reason:

George Lucas thought it would be more exciting that way.

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What's the origin of the first explanation? – DVK Jan 1 '14 at 19:37

protected by Richard Sep 7 '14 at 10:32

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