How much of the Earth's moon's mass would have to be lost for the satellite to overcome it being tidally locked and begin rotating?

The objects that are tidally locked are medium-sized. If the Moon had a much larger mass, it could have resisted tidal locking the way the Earth has, or if it had a very small mass, its size would be too small to feel much in the way of tidal forces, and again it would not be locked. But to get to that situation, you would need to take away most of the Moon's mass.

Have you been listening to Stephen Hawking? I think the media put a very bad twist on his last interview and focused on his daughter.

I could be wrong on phaishazamkan's original question, but I had the same thought.

This tidal locking would be dependent on rate of rotation, the mass of and the composition of wouldn't it.?

A molten core might react differently than a solid. ?
The distance from and gravity affect.?

Yes, but one can imagine controlling all those other variables.

If I read this question correctly, it's worth pointing out that simply removing (or adding) mass will not make the moon "begin rotating". It will retain its currently synchronized rate of rotation, unless acted on by some outside force. Relatively small forces would be all that were required to maintain sychronization as the moon migrated tidally. So a moon that would not have dropped into tidal locking if it were originally rotating briskly, might drop easily into tidal locking if it happened to be rotating near the synchronous rate.

Grant Hutchison

...what is tidal locked?

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Tidal locked means the Moon rotates once per orbit. If you think about it, this means we always see the same side of the Moon (the side that is sometimes described as "the man in the moon", the other side mislabeled as "the dark side"). The reason for this is that, once the tidal bulges form on the Moon, they can stay aligned with Earth without any rocks having to be lifted or squeezed like they would if the Moon had a different rotation.

A broader definition of "tidally locked" would also include resonance, such as Mercury, where the rotation and revolution are in a ratio of 3:2.

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T. Anderson

Yeah, that applies to highly elliptical orbits. Eventually Mercury's orbit will be circularized, I would imagine, and then it will be in a normal tidally locked situation.

I think we might use the term tidal aligning..or some such...since the effect, though long lived ...is not permanent. Eventually, the resonance detunes, and the rotation drifts to another one. Students reading tidal-locking will think it can never change, which is not quite the case for a teaching forum. Pete.

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Nah, nothing's ever permanent. Everybody knows that.

I don't see "locking" as being permanent. I lock my door when I leave home.

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T. Anderson

So if the Moon is receding from us, and its orbit becoming longer, I wonder how that will affect its rotational period.

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It'll stay locked to its orbital period, so it will continue to turn one face towards Earth all the time.

Grant Hutchison

I wonder how much force would have to be applied to the Moon to unlock it. If we could apply enough force to increase its equatorial rotaion speed by 1 cm / s, would it be able to resist? Or would we see it slowly, over the course of several years, turn its far side towards us? Just how delicate is its tidal lock?

Here is a neat list of tidally locked objects we know of...

Click

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Yes it would begin to rotate. It would not require a huge force to begin such a rotation. Once rotation began it would require an equal force to stop it. A fleet of unused shuttles could do it maybe. All you need to do is get them and, their fuel there. . . This is not a good idea.
Gravity is not a strong force but it is relentless and very persistent.

In essence, one could literally knock anything with an orbit loose with enough force?

So the Sun (no "orbit") would be out of the question, right?

No. Not at all. The sun is in a orbit around the galactic core. It would only require a object of conciderable mass to nudge it loos. A near star or passing black hole could do it easy.

No wonder those science challenged people freak out about stuff like this! Me, being one of them.

While it is theoretically possible, space is big, and unless it was a really close interaction with something very massive, you'd barely be able to tell except by instruments.

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