Both planets are going to be visited soon.
Uranus and Neptune have so far not been a major objective for NASA. Many spacecrafts have passed these planets, but none have either studied or landed on one. But a new announcement change in the future.
The following missions would involve orbiting of the two planets and an eventual landing which brings new probes to study their surface. NASA scientists are planning four missions that would begin in 2034.
Three of the four missions would involve spacecrafts to orbit around both planets, and the fourth would be just passing.
It is required to find out the composition and internal structure of the planets, as main objective, but their energy fields will also be studied. Although we can observe the surface climate conditions, orbiting around Neptune could have a plus: A study of the biggest moon in the Solar System, Triton.
The journey takes about 14 years and a nuclear power would be needed to power the spaceship systems because the solar energy is irrelevant at that huge distance. Plutonium-238 batteries would be needed, but they are very rare because there are agreements against radioactive material deposits.
The first mission will be launched to Uranus in 2034, but if NASA misses it, a new attempt could take two years. For Neptune, if the mission has to fail, the next chance would take place in 2041.