Just today, (April 4) the NASA probe New Horizons reached its halfway point between the Pluto system and its next target in the Kuiper belt, the small object 2014 MU69.
2014 MU69 is a trans-Plutonian, rather small Kuiper Belt object; with an average diameter of only about 30 miles it is only about 1% the size of Pluto and only around 0.01% as massive. The object was discovered via composite imaging of the celestial space view from Pluto, with high exposure times allowing for the detection of its movement. However, at nearly five billion miles from Earth (it takes 2014 MU69 293 years to orbit the Sun), a flyby mission will make it far more noteworthy for the most distant body visited by spacecraft. A 2014 MU69 flyby is expected to occur around January 1, 2019 – for more on that rendezvous read on here, and plans have been made for successive visits to be made to at least 20 other Kuiper Belt objects, and for a continuous analysis of the unique charged-particle-and-dust environment that exists amongst them.