Also wasteful of a perfectly good lolcow. instead stuff him into an L4 or L5 Lagrange point where we can keep an eye on him.
That's a waste of a perfectly good Lagrange point. Plus we might want to use it for something someday (though the collection of micro debris there makes it difficult), and having Chris there would curse it.
We should put him at Sun-Earth L3. If we forget about him then eventually the station keeping will fail and he'll be ejected so there is no surprise Chris for future travelers, and while he's there we won't have to look at him since the sun is in the way.
Technically the least energy solution is the ITN, but it takes a hell of a lot of time. A solar sail would be next lowest and next slowest.
I was talking in the context of presently-available technology.
I did mention the ITN, just not by name. There's a limit in the gravity assists you can do because you have to ensure your spacecraft remains functional the whole time. Once you reach solar escape velocity, then it's no problem if the spacecraft breaks as Chris will not return.
A solar sail is definitely an option, but we haven't engineered one yet that can practically reach solar escape velocity. To do it you need to either make it with a surface to weight ratio that lets it accelerate to the correct speed starting from Earth orbit, or do a retrograde burn to take it close to the sun, then open it at perihelion (and you can also use the Oberth effect there to target it toward Jupiter for an extra gravity assist), with your sail surviving proximity to the sun. While test sails have been built, nobody has built anything to this standard yet.
You could also build a laser-driven light sail, but that uses manmade energy (which we're trying to avoid), and we're not even close to building something like that.
Or we could duct tape Chris to a manhole cover and light off a nuke under it. It probably won't work, but that's a risk I'm willing to take.
The manhole was certainly vaporized. While this is not a negative in terms of Chris, it's also not the goal set out in this exercise.
Also that's using a lot of man-made energy.
I don't know about that. Microbial slime inhabit those pools, so Chris and Barb might stand a chance.
I think you're confusing them with Bella.
I think we want to try to avoid known stars and galaxies as much as possible to minimize the possibility of Chris contaminating life on other worlds.
Or worse, an advanced civilization finds Chris, repairs him, and he returns to Earth as a V'ger-like superbeing.