Complex sentence: On 14 July 2015, the "New Horizons" probe will fly by Pluto, the first spacecraft to do so, when it is intended to take detailed measurements and images of Pluto and its moons.
Split into simpler sentences: On 14 July 2015, the "New Horizons" probe will fly by Pluto, the first spacecraft to do so. NASA plans for "New Horizons" to take detailed measurements and images of Pluto and its moons.