NASA’s new horizons spacecraft reached Pluto on July 14, 2015. In doing so, it became the first spacecraft to investigate the dwarf planet closely. On January 1, 2019, it passed a large 36-kilometer long Kuiper belt object known as Arrokoth. That object is a rocky, icy body in a river of similar comet-like objects that circles the solar system not previously studied.
It’s impressive that New Horizons could accomplish two firsts, and now it has the opportunity for another historic milestone. New Horizons was set to pass an invisible line in space at exactly 8:42 AM EDT today that would place it 7.5 billion kilometers from Earth. That works out to 50 astronomical units away. An astronomical unit is the distance between the earth and the sun.
Reaching that distance away from its homeworld makes New Horizons one of only a tiny cadre of spacecraft to travel that far away from home. The distance is so vast that commands sent from Earth traveling at the speed of light require seven hours to reach the spacecraft.
We’ll likely hear more from New Horizon in the future. The spacecraft is powered by a radio-thermal generator, a nuclear power source that could keep the spacecraft operating until the late 2030s. At the speed it’s traveling, by the late 2030s, it will be more than double its current distance from Earth and will eventually exit the solar system.
As New Horizons continues to travel, it will be on the lookout for other Kuiper Belt objects in its path that it will be able to explore. Sadly for New Horizons, it can never be the spacecraft that is the furthest from the Earth, the best it will ever be able to do this fifth-place.