Now the New Horizons team has announced a candidate for the probe's second stop, pending official approval from NASA to extend their mission.
The object, called 2014 MU69, sits nearly 1 billion miles further out into the Kuiper Belt than Pluto does. It's a small Kuiper Belt Object, and one of an entirely different sort than Pluto -- which means scientists would get a look at a totally unknown Kuiper world. At 30 miles across, PT1 (short for potential target 1) is more than 10 times larger and 1,000 times more massive than a typical comet, but only about 0.5 to 1 percent of the size (and about 1/10,000th the mass) of Pluto. Because of that size, scientists believe it may be similar to the building blocks that came together to form Pluto and other relatively large Kuiper Belt Objects (KBOs).
Why study KBOs? The Kuiper Belt is far enough from the sun that it basically acts as a cosmic refrigerator, keeping its objects cool and pristine, largely unchanged from their state at birth (at least compared with the incredibly dynamic planets cooking in our own neighborhood). And the objects are old -- about as old as the solar system itself. So opening up that Kuiper ice box can give scientists a glimpse of the building materials present at the dawn of our solar system. Understanding what was there then can help us figure out how more complex planets -- ones that can harbor life -- evolve.
The New Horizons team is still hard at work receiving and interpreting data from July's flyby. But to extend their mission beyond that data retrieval phase, they'll have to submit an official proposal -- due in 2016 -- for independent review. The extension of the mission will cost much less than the $700 million of New Horizons initial funding, since the spacecraft is already designed, built, and launched. But NASA officials will have to weigh the funding needed for other proposed planetary missions before sealing the deal.
If the spacecraft is maneuvered properly during the next year, it will reach the target on Jan. 1, 2019. That's going to be one heck of a New Year's Eve party.