Pluto may no longer be a planet, but next year it will be getting some love and attention from NASA. On December 6th, the New Horizons probe will awake from hibernation in order to prepare for its big encounter with the dwarf planet and its moons.
Sleeping for much of its nine year journey allows New Horizons to preserve its electronics, but this is not a case of a spacecraft romantically woken from a multi-year sleep by a long distance kiss blown by Earth engineers. Instead New Horizons has had 18 shut-downs over its journey, with the longest lasting 202 days. The current one will be just 99 days when the craft restarts operations.
“New Horizons is healthy and cruising quietly through deep space – nearly three billion miles from home – but its rest is nearly over,” said Alice Bowman, mission operations manager at the Johns Hopkins University Applied Physics Laboratory. “It’s time for New Horizons to wake up, get to work, and start making history.”
As with humans, “sleep” for New Horizons does not mean a complete shut-down in activity. A flight computer keeps check on system health and sends a status update to Earth once a week. During its brief wake up cycles, instruments are calibrated, activities practiced, and even some research conducted despite its enormous distance from astronomical objects.
New Horizons will get to work on January 15th studying the Pluto/Charon system from a distance of 260 million kilometers. It reaches its closest approach on July 14th.
The faint reflections off the surface of objects so far from the sun make measurements slow, but New Horizon will investigate the geology and topography of Pluto and Charon. The interaction between these two objects is one of the things that makes Pluto a worthy target. Not only are they similar enough in mass that the point around which both rotate is outside Pluto's radius, but each is tidally locked so that they keep the same face to each other. There is even speculation that the warmth from their tidal relationship may maintain a subsurface ocean on Pluto, something that might be revealed if the surface shows signs of tectonic activity.
Pluto's thin atmosphere and four smaller moons will also get some attention, and it is possible that tinier objects, or even rings, will be detected.
Given its immense velocity relative to Pluto, getting New Horizons into orbit is not possible, so the craft will sail on past, conducting more research as the frozen objects fall behind.
Even after Pluto, New Horizons has miles to go before it (permanently) sleeps, with plans to adjust its trajectory—funding permitting—so it can make a close approach to another Kuiper Belt object. This may help answer the question of whether Pluto is really just a typical representative of the Kuiper Belt we happened to discover long before the others, or represents something unusual or even unique.