Although New Horizons is now closer to Pluto than the Earth is to the Sun, the Pluto system resembles little more than bright dots in the distance. But NASA scientists and engineers operating the spacecraft are using these views to refine their knowledge of Pluto’s location, and skillfully navigate New Horizons toward a precise target point 7,750 miles (12,500 kilometers) from Pluto’s surface.
Pluto, the largest known body in the Kuiper Belt, has a nitrogen atmosphere, complex seasons, distinct surface markings, an ice-rock interior that may harbor an ocean, and at least five moons. Among these moons, the largest – Charon – may itself sport an atmosphere or an interior ocean, and possibly even evidence of recent surface activity.
When the New Horizons mission was developed in 2001, it was a mission to just Pluto and Charon, before the four smaller moons were discovered by the Hubble Space Telescope (Nix and Hydra in 2005, Kerberos in 2011, and Styx in 2012).
The spacecraft’s suite of seven science instruments – which includes cameras, spectrometers, and plasma and dust detectors – will map the geology of Pluto and Charon and map their surface compositions and temperatures; examine Pluto’s atmosphere, and search for an atmosphere around Charon; study Pluto’s smaller satellites; and look for rings and additional satellites around Pluto.
But the spacecraft’s work doesn’t end with the July flyby. Because it only gets one shot at its target, New Horizons is designed to gather as much data as it can, as quickly as it can, taking about 100 times as much data on close approach as it can send home before flying away. And although the spacecraft will send select, high-priority datasets home in the days just before and after close approach, the mission will continue returning the data stored in onboard memory for a full 16 months.