[thegrim33]

Some quick prompting seems to say a G force of somewhere between 16-160 billion Gs, for a CPU-equivalent object getting hit by a solid object moving at 3I's escape velocity. Compared to a "typical" artillery shell of 10-15 thousand Gs. Not sure you're manufacturing anything that could survive 6-7 orders of magnitude more Gs than an artillery shell.

Of course the G-load would lessen based on how much you sped up to match its speed beforehand, but still, I think you'd need to be pretty much sped up to near the same speed as it before you could remotely possibly survive the impact.

[actionfromafar]

Wow, I clearly didn't think this through. That's brutal.

That leads to another idea - if something more substantial was placed in its path - the resulting debris and gas cloud from the impact could reveal something about the contents of the object.

Or, if it's an alien probe, it would force their hand. :-D We could see some exotic manuevering.

[TheOtherHobbes]

Or an interstellar war.

But they're probably used to it. At 61,000 m/s, 0.5mv^2 must turn every collision with a small rock into quite a big bang.

[mcswell]

A "solid object". But it's not clear how solid a comet is (or more to the point, this or any interstellar comet). If it were a fuzzball of snow, maybe 20 km across, you could in theory decelerate through it more slowly, maybe using a very large parachute initially, then discarding that for successively smaller parachutes as you approach denser and denser parts of the comet. The EPOXI mission to the Hartley 2 comet was reportedly hit nine times by "snowflakes" coming off the comet, but not damaged (https://www.astronomy.com/space-exploration/spacecraft-sees-...).

Of course your point is probably still valid.