The Apollo 10 lunar module, called Snoopyis apparently in heliocentric (solar) orbit.
Theoretically, would the only thing standing in the way of acutally intercepting and capturing the lem be knowing where it is? Does anyone like NASA actually do know where it is at any one time? Thanks!

I think the main barrier to recapturing it would be actually having a reason to do so. The module isn't causing any harm out there and it will cost millions of dollars to get it back. They normally just let the modules burn up in the Earth's atmosphere. I don't think they want to recapture it.

They probably have some idea of where it is, if not a perfect idea.

You are right, knowing where Snoopy actually is would be a major obstacle to retrieving it -- assuming we had both the motive and the money to do so. It's a VERY small object in a VERY large solar system.

Back in 2003, an object was discovered in a highly elliptical earth orbit by a telescope looking for near-earth asteroids. Had it been there previously it should have been been earlier, but wasn't. Spectroscopic analysis was consistent with titanium dioxide - white paint pigment. The consensus is that this was the spent upper stage of the Saturn V from the Apollo 12 mission, temporarily recaptured into earth orbit.

Snoopy is not necessarily in the same kind of solar orbit that would cause it to be temporarily recaptured by the earth from time to time. This makes for a much smaller needle in a much bigger haystack than Apollo 12's S-IVB stage, and I think that keeps its recovery firmly in the realm of the imagination for the time being.