[wongarsu]

Take decades to catch up to the location of either voyager probe. The probes have be traveling for a long time. They have also taken advantage of a rare planetary alignment that allowed them to visit a lot of planets and get gravity assists from them (converting a tiny portion of the planet's angular momentum into orbital speed for the spacecraft)

[anovikov]

Won't ion engines power by something like Kilopower reactor let us do better?

[bragr]

Bunch of napkin math: you'd need something like 10 kilowatts and 140 km/s detla-v to catch up to Voyager in a decade, assuming a New Horizons equivalent Earth escape velocity. The amount of xenon is technically possible, however even assuming impressive 8000 Isp thrusters, your fuel mass fraction ends up being 90+% fuel which doesn't leave a lot of mass for that reactor and radiators.

A 20 year intercept would be pretty reasonable though. It needs about 15 km/s delta v after that NH style escape, about a kilowatt of power, and maybe a 25% fuel mass fraction at 6000 Isp. That's all very reasonable by current standards.

[anovikov]

I understand that celestial mechanics are involved, because "stuff in space do not fly on straight lines", but why is the delta V budget 10x smaller for 2x more time? That feels counterintuitive :/

[jandrese]

Is that including a Jupiter/Saturn assist?

[bragr]

No, that's more than napkin math but I feel the numbers stand for themselves that we can't really do better than decades. A few km/s won't change that.