Complex sentence: It was discovered along with Hydra (Pluto's outermost known satellite) in June 2005, and is to be imaged along with Pluto and Charon (Pluto's largest moon) by "New Horizons" in July 2015.
Split into simpler sentences: It was discovered along with Hydra (Pluto's outermost known satellite) in June 2005. It is to be imaged along with Pluto and Charon (Pluto's largest moon) by "New Horizons" in July 2015.