I remember as a kid seeing the first photos of Uranus and Neptune from the Voyager probes. What's sad to me is they remain to this day the only time we've ever visited these ice giants. There have been a number of proposals over the years but none have been selected and it seems like 2045-2050 is the soonest we could get to Uranus (more for Neptune) but that pretty much requires a launch by 2034 and we've pretty much run out of time for a mission to be selected to that window given that it would be a complex and expensive flagship mission. I guess it depends on whether it's a flyby (like New Horizons) or an intercept mission, which would take substantially longer.

Obital mechanics are a funny thing however. You see this with the complicated BepiColombo trajectory to Mercury [1] that requires multiple passes on Venus. Mercury orbits at ~48km/s (compared to Earth's 30km/s). Fun fact: the escape velocity of the Sun is 42km/s so it's easier to leave the Solar System than intercept Mercury.

One difficulty is there aren't large gas giants to slingshot or brake around.

Uranus's orbital velocity is ~6.8km/s so it's both really far and requires a ton of delta-V to slow down to intercept.

Anyway, I digress.

So Voyager 1's speed seems to be ~17km/s, I guess relative to the Sun. People talk about the time required for interplanetary (let alone interstellar) travel but we can do much better than this with relatively near-future technology.

We need a whole bunch more Earth-orbit space infrastructure and industry to do anything, really. Lower launch costs in particular. I think this future is orbital rings [2]. This would revolutionize getting stuff into orbit but also launching vehicles to other planets. Basically you accelerate on the inside of the ring at ~2G with magnetic levitation to counter the linear momentum. You can reasonably get ~15km/s with this, adding to the EArth's 30km/s ideally so even without fuel you can get to ~45km/s.

[1]: https://www.youtube.com/watch?v=BK3F4fmqtbA

[2]: https://www.youtube.com/watch?v=LMbI6sk-62E

I see China is proposing a fair few missions to the outer system with Jutiper in a few years with Uranus and Neptune to follow. But they are just proposals still, but it is good to see they are at least considering it.