Resource Asteroid?

[Mafty]

So it has been explained that the asteroids are mined for minerals(and perhaps) water for the construction of colonies in Gundam, so then why are asteroids attached to a Space Colony? You can see this most obviously in ZZ with Cicero and Core 3, Frontier 1 and its mining asteroid, as well as Heliopolis in SEED. Aside from Frontier 1 the other Colonies had been long completed (Heliopolis in particular was stated to be 50 years old), so why do they still have the asteroid attached? Is it just for colony repair, or are they using the metals to build MS?

[Seto Kaiba]

Why not still have the asteroid attached?

Raw and processed materials are worth money. Extracting and processing those materials creates jobs, which drive a colony's economy. Even if they're not using it themselves, they have excellent reasons to want to mine those asteroids hollow.

[SonicSP]

Would be easier and cheaper to just attach and mine it locally than transporting people and product back and forth multiple times. Just transport the asteroid once then mine it for all it's worth.

[Mafty]

Makes sense really. We do see alot of different colony types in the Gundam series. There are agricultural colonies (like Texas and Junius 7 in fact ZAFT specializes in sorting the colonies into different types ), Industrial and Heavy Industry Colonies (like Industrial 7, Shangri-La, and Gryps 2, and Possibly Frontier 1) . And there are Asteroids people live on(Axis, Palau, and Cicero), so it makes sense that they'd probably have colonies that specialize in mining.

[SonicSP]

Maybe can also serve as an extra shield againts meteorites as a secondary function.

[Arsarcana]

Maybe can also serve as an extra shield againts meteorites as a secondary function.

Could be, assuming the colony is oriented properly. Something similar happens in the novel Seveneves when an asteroid (originally intended for mining) was used to protect the ISS-turned-ark.

[Mafty]

Frontier I in F91 had an actual asteroid built in to the colony itself, the rear half of the colony is actual a mountainous mining range. Considering SNRI had a large facility there , the minerals probably helped in the development of the Mobile Suits, as well as in general making it a resource center for the Frontier Side. Plus it is probably why Crossbone Vanguard chose to invade it. Side 4 has (at least) 4 Colonies; I is chose as the capital due to the Ronah family living there , while IV seems to get a lot of attention, probably due to its mining resource and a SNRI branch that makes Mobile Suits.

[MythSearcher]

Two sides of the debate.
Balancing the angular momentum will be hellish. A little bit of shift in the centre of gravity and you start wobbling, or just change the mass distribution will make it spin at a different speed. You can kinda have the asteroid not spin and only the colony spin, but that is pretty hard to do if you consider space have no anchor to hold the asteroid in place.
Or simply not spin it until you finish building, but that is not what they show in Unicorn.

The depiction in Unicorn is just so...strange.
Where did they get the material for building? The rate of material usage should keep up with the building speed, In the show we see them laying at a visible speed, I don't recall the exact speed but say you are laying 1m^2 of board per 10 seconds. The walls of an Island 3 colony is about 2m thick, so you spend around 12m^3 of wall material every minute.(I am not counting the 10~20m deep of soil or whatever building they will be building afterwards) So in a day you will have spent 17,280m^3 or 134,784tons(iron) of material. Thus they will need to keep moving materials equivalent to 2 Magellan class battleship(65000t@) everyday.
Having an asteroid attached and just mine it makes sense, but having it spin while building really isn't.

[Mafty]

So what happens after the asteroid is completely mined? If it's built on to the colony it would be harder to move. That being said however it could be transformed into a bigger port facility or even a Federation base. Also I agree with Myth Searcher in questioning how exactly The Snail works , once it completes the colony , how exactly is it removed, and how do they attach the back of the colony anyway?

[MythSearcher]

So what happens after the asteroid is completely mined? If it's built on to the colony it would be harder to move. That being said however it could be transformed into a bigger port facility or even a Federation base. Also I agree with Myth Searcher in questioning how exactly The Snail works , once it completes the colony , how exactly is it removed, and how do they attach the back of the colony anyway?

The only mention about completely minded asteroids seems to be Solomon and ABQ, both are made into bases.
I'd say in a more real life situation, you won't have a completely mined asteroid, usually asteroids are fairly consistent in composition. You don't have an S type or C type asteroid with a lot of metal in it that you can just mine the metal leaving a siliceous or carbonaceous shell. Same goes for M type asteroid. Most of those are nickel-iron with small amount of stone. You simply won't have a shell of another type of useless material. Lunar II is Juno, which means it is an S type asteroid, I have no idea why they need so much stone but that might also be why it was not depleted.
Anyway, you simply have pebbles left after you mined an asteroid if you decided keeping the pebbles is a good idea and not just release them in space randomly(which will create debris problem unless you spend extra energy either shooting them to escape velocity of the Sun or slow it down enough to let it fall to the Sun. Both really energy intense and not really good ideas.)

On the other hand, the snail isn't really a big problem. It is probably just like Lavie en Rose where it got its own thrusters and can simply move to another location.(something that size likely uses nuclear pulse) Notice they can simply build new colonies in other locations and move them into position(as seen in 0083) so moving the snail isn't really that big of a deal.
Consider how much they like to have transformable mecha, it might just be able to just collapse and become much smaller, at least I won't be surprised if they decided it can turn into a colony tossing humanoid.

[SonicSP]

A little bit different than the topic question but in 00 world they seemed to be a lot of asteroids near Earth. I seem to remember hearing in discussions that they (humanity/governments/corporations/etc) moved them there for easy access to mining but not sure whether that's stated in an in-universe profile somewhere or just speculation.

And if they did move them there, would it economically make sense theoretically? There are a few colonies functioning on 00 and more being constructed but they also can bring material up fairly cheaply with the Orbital Elevator presumably (assuming Earth mines haven't run dry or anything like that)? Compared to just grabbing them and transporting them from wheverever it is they got it from.

[Mafty]

So what was the status of colonies in the AD Era anyway? We only saw a few colonies, and more focus was placed on the Orbital Elevators. There didn't seem to be as much of a push to get people into colonies, and toward the end of the series colonies seem to stop being mentioned. Then again its been awhile since I watched 00, so I think it was the early days of colonization, so they probably needed the minerals to aide in construction of future colonies, ships and elevators, or even turn the old mines into Army Bases.

[SonicSP]

There's a few working colonies and more in the process of being built.

Aside from Ribbons ESF invading and forcing a few Middle Eastern countries/populations into colonies in Season 2, there wasn't any push to get people into colonies that we saw.

[MythSearcher]

A little bit different than the topic question but in 00 world they seemed to be a lot of asteroids near Earth. I seem to remember hearing in discussions that they (humanity/governments/corporations/etc) moved them there for easy access to mining but not sure whether that's stated in an in-universe profile somewhere or just speculation.

And if they did move them there, would it economically make sense theoretically? There are a few colonies functioning on 00 and more being constructed but they also can bring material up fairly cheaply with the Orbital Elevator presumably (assuming Earth mines haven't run dry or anything like that)? Compared to just grabbing them and transporting them from wheverever it is they got it from.

Makes very little sense to do so. You get very high chance of Kessler syndrome(https://en.wikipedia.org/wiki/Kessler_syndrome)
Orbital velocity is still very high around 50,000km or even 100,000km.