New Horizons is a spacecraft launched by NASA in 2006, as part of their New Frontiers program. Its primary mission was to fly past the dwarf planet Pluto, and then an object in the Kuiper Belt. On its way to Pluto, the spacecraft approached Jupiter, and collected data about Jupiter's atmosphere and moons to test the instruments.
In 2015, New Horizons flew 12,500 km above the surface of Pluto. It was the first spacecraft to explore the dwarf planet. New Horizons then studied a Kuiper Belt object called PT1, which was discovered by the Hubble Space Telescope as a good target for the mission. The object is about 30 km long and very elongated in shape.
New Horizons passed Jupiter in 2007. The spacecraft went into hibernation from 2007 until 2014, on its approach to Pluto. This preserved the on-board systems and allowed the spacecraft to operate for many years. It awoke when it neared Pluto and could begin to take measurements of the dwarf planet.
On board the spacecraft is a variety of scientific instruments. There is a dust sensor, three optical instruments, a radio receiver, a temperature probe, and a barometer to measure the atmospheric pressure.