If the Empire can make a shield around the entire planet of Scarif, why not make a shield around the entire moon of Endor?

Question

In Return on the Jedi, the Empire made a shield around just the Death Star and a small part of the moon of Endor.

In Rogue One, the Empire made a shield around the entire planet, Scarif.

If it can shield an entire planet, it can also surely shield a moon (plus nearby space station).

Why not make a shield around the entire moon of Endor?

One possible out-of-universe explanation is that the producers of Star Wars had not considered a planet-wide shield when they wrote Return of the Jedi. I don't want an out-of-universe explanation. Is there an in-universe explanation? Please provide answers from canon sources.

Answer 1

There is a shield around Endor.

When the Tydirum shuttle arrives to land on Endor, Han asks for the shield to be deactivated.

Here's the quotes from the Return of the Jedi script:

CONTROLLER (over radio)

We have you on our screen now. Please identify.

HAN

Shuttle Tydirium requesting deactivation of the deflector shield.

CONTROLLER (over radio)

Shuttle Tydirium, transmit the clearance code for shield passage.

HAN

Transmission commencing.

After Vader allows the shuttle to land:

CONTROLLER (filtered)

Shuttle Tydirium, deactivation of the shield will commence immediately. Follow your present course.

Answer 2

Why bother?

Well, first of all, it does cover a portion of the moon (though probably not close to the whole thing). There’s some suggestion in (now not particularly canon) novelizations that it might encompass the whole moon, but the film image does look pretty clear.

More importantly, though, the Empire is not known for their concern for collateral damage. As long as the Death Star is shielded, and as long as their shield generator is protected (which it is; it’s covered by its own shields), why do they care what damage is sustained by the moon of Endor? The Emperor basically wants the moon to get damaged:

The shield generator could have been built in any of thousands of desolate, lifeless planetary systems. But the Emperor himself picked this spot from several suggested by Imperial engineers.

The engineers liked the idea of burning up the moon’s resources to fuel the shield.

And the Emperor liked the idea of crushing something beautiful.

_{Beware the Power of the Dark Side!}

Presumably the shield generator over Scarif is more resource-intensive, but necessary because the whole planet must be protected. However, when it comes to some useless forest moon? Who cares.

Not to mention, the whole thing is a setup:

All the secrecy, all the comlink jamming, all the biker scout chasing—it’s all been pointless. The whole thing is pointless.

When Han Solo and his strike team reach the shield generator, they will find a large force of troops waiting for them. They’ll be captured or killed and the shield will remain in place. The rebel fleet’s attack—and the Rebellion itself—will be equally doomed.

_{Beware the Power of the Dark Side!}

If the goal is to set a trap for our intrepid heroes, Palpatine doesn’t want to make it too hard.

Answer 3

The film's official novelisation states that the Endor Moon has its own planetary shield, also projected from the Shield Station.

At the center of the briefing room was a large, circular light-table, projected above which a holographic image of the unfinished Imperial Death Star hovered beside the Moon of Endor, whose scintillating protective deflector shield encompassed them both.

_{^{Return of the Jedi - Official Novelisation}}