Our favorite outer solar system spacecraft is back on the job! New Horizons woke up from a five-month hibernation on its way to the distant world 2014 MU69. It’s still more than a year before the spacecraft gets to its next target, but it has a lot of work to do in the meantime. The current plan is to have it look at objects in the Kuiper Belt, measure the radiation environment it’s passing through, and check out the distribution and density of dust and gas. These are all “first-time” measurements of a regime of the solar system planetary scientists are eager to study.

New Horizons isn’t the first to transit the Kuiper Belt. The Voyagers and Pioneers passed through the same region and returned some data as their instruments would allow. Today, the Voyagers continue to measure the outermost region of the solar system and have crossed the heliospheric boundary to interstellar space. The Pioneers haven’t communicated back to Earth since 1995 and 2003, respectively. New Horizons is on a similar headlong trajectory out of the solar system and will return data for at least a couple of decades if all the instruments continue to work.

Mission Operations for New Horizons

Now that New Horizons is up and ready for a few months of work, the mission team will be outfitting it with new software packages and getting ready for a trajectory course correction. That will help refine its path toward its next target. This kind of “maintenance” is important. We want a healthy working spacecraft. By all accounts, New Horizons is functioning right on the nominal. Each week it has been sending back a little “I’m here” signal to let controllers know it’s doing okay. That beacon, speeding across more than 3.6 billion kilometers of space, is a signal from our planetary probe scout. It’s checking out the territory ahead and sending back critical updates along the way.

Next Up

In December, New Horizons slips into sleep again (still sending out its little signal). That happens December 9th. This time the spacecraft will snooze until June 4th. At that point, controllers will begin prepping it for the close flyby of 2014 MU69, which will take place on January 1, 2019. It’ll be another high-speed flyby, this time of a much smaller, dimmer world than Pluto. Nothing is known first-hand about any other Kuiper Belt world than Pluto and its moons. Pictures and data will really open a window into the kinds of worlds that populate this distant region of space. There are

There are many more M69-type worlds out there, and the next flyby is sure to provide some surprises about what they look like. There’s so much to learn about the Kuiper Belt — from the compositions of distant KBOs — to their origins and evolution. Sure, planetary scientists have a good general idea of how these places formed and changed over time, but actual images and data will help cement that understanding.

Exploring Distant Reaches

We’ve come a long way in our perception of the solar system since the first time Galileo trained a telescope on Jupiter in 1610. Today, the Kuiper Belt is the third regime of the solar system and it’s huge. Its inner boundary is at 30 astronomical units and stretched out to beyond 50 astronomical units. In linear measure, that’s a range of 20 astronomical units, covering a straight-line distance of 2,980,000,000 kilometers. Another way to think of it is about the distance between the Sun and planet Uranus. The Kuiper Belt surrounds the Sun at that far distance. It’s the vast wilderness of the solar system, compared to the better-explored areas of the terrestrial and gas giant planets. Who knows how many worlds are out there? For now, we have New Horizons to explore it, along with a cadre of Earth-based (and orbiting) telescopes. Stay tuned!

Is MU69 A Double-lobed World?

In just under a year and a half, the New Horizons spacecraft will pass by a distant Kuiper Belt Object called 2014 MU69.

Earth-based observations gave the New Horizons scientists a tantalizing look by watching what’s called a “stellar occultation”. They watched as MU69 passed in front of a star on July 17, 2017,  watching a little eclipse-type event more accurately called an “occultation”. This was after a first occultation observation mission on June 3, 2017, was set up for observers in South Africa and Argentina, and a crew aboard the airborne Strategic Observatory for Infrared Astronomy (SOFIA) watched the event on July 10. The observations, plus high-resolution scans using Hubble Space Telescope (which looked for debris in the area right around MU69) gave clues to this little world’s shape.

Unlike eclipses, which can last for minutes, the MU69 occultations lasted only a few seconds. That was precious little time to gather information about the size and shape of the object. Scattering observers along pre-selected sites from where the event could be seen (and imaged) gave the New Horizons team much more data. That gave a better feel for what MU69’s shape must be.

What Does 2014 MU69 Look Like?

It turns out 2014 MU69 is pretty weird-looking, at least from our great distance from it. The measurements reveal what looks like a double-lobed object or maybe a tiny world with a big bite taken out of it. It’s not a perfectly round place. It’s also possible that 2014 MU69 could be two objects orbiting very close to (or even touching) one another — too close to be distinguished from each other. Right now, MU69 is more than 6.5 billion kilometers from Earth and its tiny size (about 30 km) makes it difficult to get a final answer about that oddball shape. Still, it’s a pretty amazing feat to use occultations and high-resolution measurements to get this far 17 months ahead of the flyby. It will be interesting to see how it all pans out as the spacecraft gets closer and returns better images. That won’t happen until later in 2018.

Threading the Needle at MU69

Not only is this information pretty cool to know for its own sake, but the observations made this summer also help the New Horizons mission planners do a more accurate job of targeting the flyby. That’s set for January 1, 2019. The closer they can get for a safe flyby, the better the science will be. However, it’s like threading an incredibly tiny needle. Obviously, it’s good to know if there’s a debris field orbiting along with 2014 MU69. We don’t want to see New Horizons whack into something that could be avoided.

Mission Science

The science to be gained at MU69 itself is incredibly important. However, the upcoming flyby will also tell us a lot about its environment. The Kuiper Belt, the third “regime” of the solar system, contains many objects that range in size from fairly small to some larger than Pluto. This one is among the smaller worldlets out there. The short-period comets also come from this region, and Pluto is among its more famous planetary bodies. MU69 lies on the way “out” of the solar system along the New Horizons trajectory from Pluto (which it explored on a quick flyby in July 2015). The mission is essentially sampling KBOs as it goes. From its data, we may see more than just this oddball world; if there’s debris, then that will also give clues to the population of objects in the neighborhood.

Questions about 2014 MU69

I can imagine all kinds of questions to be answered by the next flyby, all aimed at figuring out just how MU69 (and any companions) formed. Is nearby debris the result of an ancient collision? Or, could it be left over from MU69’s formation (which itself could be the result of a collision)? What’s it all made of? Are they mostly rocks? Mostly ice? A mix? If so, which ices are predominant out there? What do the surfaces look like? These are all questions to be answered with images and data from the flyby. New Horizons is our “forward scout”, exploring the territory ahead and giving ever-more-detailed answers about the outer frontiers of the solar system.

Addendum:  Check out the comments below, where artist Adolph Schaller shares his interpretation of the occultation data for MU69. He does a remarkable job of extrapolating the possible shape of this object.