The New Horizons spacecraft completed its primary mission by making a flyby of the dwarf planet Pluto and taking extensive photographs and measurements about the little system and its collection of moons. It collected so much data, they will be downlinking the data into the Fall of 2016 – But like every NASA mission, the space agency likes to squeeze as much science as possible out of every gram of robot and drop of propellent.
The extended mission has not yet been funded, but to be fuel-efficient the team needs to pick a target and adjust New Horizons’ trajectory now. 2014 MU69, nicknamed PT1 for Potential Target 1, is a tiny, dim world (magnitude 26.8) of an estimated 30 to 45 kilometers (19 to 28 miles) diameter, which is roughly the size of Pluto’s mid-sized moons Hydra and Nix and ten times larger than most comets.
By mass it’s 1,000 times larger than Rosetta’s Comet 67P/Churyumov–Gerasimenko and 1/10,000th the mass of Pluto. MU69 is easier to get to than the other lead contender, 2014 PN70, which means the team will have more flexibility to tweak the trajectory when closer to the object. But most importantly, it’s a totally different type of Kuiper Belt Object than Pluto is, giving us our first up-close look at a different type of object. New Horizons Principal Investigator Alan Stern gushes over the selection.
“2014 MU69 is a great choice because it is just the kind of ancient KBO, formed where it orbits now, that the Decadal Survey desired us to fly by. 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”, says Stern.
New Horizons was originally designed to fly beyond the Pluto system and explore additional Kuiper Belt objects. The spacecraft carries extra hydrazine fuel for a KBO flyby; its communications system is designed to work from far beyond Pluto; its power system is designed to operate for many more years; and its scientific instruments were designed to operate in light levels much lower than it will experience during the 2014 MU69 flyby.
“Because we think that Kuiper Belt Objects haven’t been heated or changed much in the 4.6 billion year history of our Solar System, we’re optimistic that this little world will be a timecapsule into what the outer edges looked light while planets were busy colliding and accreting in the inner solar system.” New Horizons science team member John Spencer explains:
“There’s so much that we can learn from close-up spacecraft observations that we’ll never learn from Earth, as the Pluto flyby demonstrated so spectacularly. The detailed images and other data that New Horizons could obtain from a KBO flyby will revolutionize our understanding of the Kuiper Belt and KBOs.”
The New Horizons spacecraft will be making a series of burns in late October and early November to set it on a trajectory to encounter MU69. The closest approach is anticipated for January 1, 2019, although that may shift with later corrections.The closest approach of the flyby will when the object is nearly 6.5 billion kilometers (43.4 AU) from the Sun; we’re expecting that New Horizons will skim by the world even closer than it did to Pluto this summer.
We only discovered the world on June 26, 2014 as part of an intensive search for candidates for a New Horizons flyby. It’s so new to us that we aren’t even sure how long a year is for MU69! (We think it takes 293 Earth-years for it to make a single trip, but with a healthy margin of ±24 Earth-years error.) It also marks the shortest time between the discovery of a world and its exploration. Planetary astronomer Jason Cook teases that it’s downright rare for a discoverer to get to see their new worlds. More pragmatically, it’ll be interesting to see if the International Astronomical Union hustles to name it faster than its usual plodding process.
Along the way, New Horizons will be making opportunistic observations of any other Kuiper Belt Objects we can. Stern anticipates we might be able to see up to fifty other Kuiper Belt Objects. The observations will be simple – basic population characteristics, searching for binary objects, estimated sizes, and if we’re very lucky a few occultations of stars.
The extended mission to actually keep New Horizons operating with a human support team and time to send back data on the Deep Space Network isn’t actually approved yet. The science team will be writing and submitting a research proposal in 2016 for external review. John Grunsfeld, astronaut and chief of the NASA Science Mission Directorate, cautions:
Even as the New Horizon’s spacecraft speeds away from Pluto out into the Kuiper Belt, and the data from the exciting encounter with this new world is being streamed back to Earth, we are looking outward to the next destination for this intrepid explorer. While discussions whether to approve this extended mission will take place in the larger context of the planetary science portfolio, we expect it to be much less expensive than the prime mission while still providing new and exciting science.
Many space exploration missions do get extended missions – the Mars Opportunity rover’s primary mission ended after 90 days, and Cassini’s primary mission finished after four years back in 2008. However, if you want to help NASA get the political power of clear and loud public support, here’s how you can write to your Congressional representatives about approving the New Horizons extended mission.
After the flyby, the team hopes to keep New Horizons operating as it continues beyond the Kuiper Belt, following in the spirit of Voyager 1 and Voyager 2 as it discovers what lays beyond the edges of our Solar System.