Beyond Pluto: How will New Horizons spend its remaining fuel?

NASA’s overachieving space probe, New Horizons, has a new mission after its spectacular flyby of Pluto


Zooming past Pluto at 52,000km/h might be considered enough for one car-sized spacecraft’s lifetime, especially when it’s sent back such amazing pictures of a never-before-seen world.

Not for New Horizons, though. Its journey out of the solar system is taking it deeper into the Kuiper Belt, a mysterious region of small bodies beyond the orbit of Neptune.

Its target, 2014 MU69, is a classical Kuiper Belt Object (KBO), or “cubewano” (the name comes from the first object discovered after Pluto – named 1992 QB1), estimated to be up to 45km in diameter, orbiting around a billion miles from Pluto and 44AU from the sun. An AU, or astronomical unit, is the distance from the Earth to the sun – 93 million miles – and 44AU expressed in miles is the sort of number that will make your calculator run out of zeroes.

“2014 MU69 is a great choice because it is just the kind of ancient KBO, formed where it orbits now, that the Decadal Survey [a National Research Council project that flags up potential NASA missions] desired us to fly by,” says New Horizons principal investigator Alan Stern, of the Southwest Research Institute in Boulder, Colorado. “Moreover, this KBO costs less fuel to reach [than other candidate targets], leaving more fuel for the flyby, for ancillary science, and greater fuel reserves to protect against the unforeseen.”

The probe won’t reach its target until the very end of 2018 at the earliest, so what else is out there in the Kuiper Belt?

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