The new year is only a few days old, and already we have exciting news from the astronomy and astrophysics community with the announcement that the New Horizons probe has just completed the most distant flyby in history.

Many of you will remember the New Horizons probe for its flyby of the planet Pluto and its moons a while back in 2015, with the stunning photos of the icy planet still being studied and analyzed to this day. The data sent back by New Horizons from Pluto and Charon have revealed many interesting and unexpected features of this distant world, and that achievement alone would make the New Horizons mission a success.

However now it has completed another mission for scientists with the flyby over the holiday season of the distant object, Ultima Thule. 

Ultima Thule is the nickname that NASA has given to the minor planet, known formally as  (486958) 2014 MU69, which orbits the sun as part of the Kuiper Belt beyond the edge of the known Solar System. As it is formed of two small spheres, each only 15km to 20km in diameter, it was only discovered by astronomers in June 2014 when they were using the Hubble Space Telescope to search the Kuiper Belt for previously unknown objects. It is believed that the Ultima Thule pair orbit the Sun once every 298 years, and may have been formed as one of the earliest objects in our Solar System.

After the New Horizons probe completed its primary missions of studying Pluto and its moons, it was still operational and therefore the team behind the mission made the decision to send it into the Kuiper Belt to study minor objects at the edge of the Solar System. Although numerous candidates were considered, in the end Ultima Thule was considered the most interesting object within reach of the probe. 

After the Pluto flyby was completed, the mission controllers redirected New Horizons to begin the three year journey to Ultima Thule. In August 2018 the probe was able to take the first photographs of the object, for use in navigating towards it. Due to its small size and relative dimness, bright images of the object were not possible until only a few days or even just a few hours before the closest flyby. However on January 1, 2019 the New Horizon probe passed within 3500km of Ultima Thule, and began taking as many photographs and other data readings as it could during its short rendezvous before setting off again. 

This flyby has also set a number of interesting new records. It is the first Kuiper Belt object to be studied in detail by a space probe. It is the first flyby of an object whose existence was not known about when the space probe was launched. And at approximately six and a half billion kilometers from Earth it also set a record for being the most distant flyby ever completed by a man-made probe, with only the Pioneer and Voyager probes going further into space (but not completing specific missions at that distance).

Now that this flyby has been completed, the New Horizons probe will start transmitting back all of the images and data that it was able to collect and store in its onboard memory. This process will last approximately twenty months, and should be completed by September 2020.

At this point in time the probe and its onboard cameras and sensors are still functional and still have a decent amount of power left to operate for a while longer. As such astronomers are now searching through the outer rim of the Kuiper belt for an even more distant object that will be in range of the New Horizons probe in another five to ten years, at which point if everything goes well the team will attempt another flyby and set an even greater distance record. After that happens, the probe will likely be at the end of its useful life.

There is some discussion of ending the mission with a self-portrait of the Earth, in an updated form of the "Pale Blue Dot" image made famous forty years ago by Carl Sagan, but this will depend on the probe still having sufficient energy to turn itself around, and it all likelihood the bright light from our Sun will destroy the camera shortly after the photo is taken. Either way the New Horizons probe will lose power shortly after that point and will drift into interstellar space for the rest of time.

For now though, scientists are celebrating another successful mission into space and are eager to start studying the images and other data from the most distant object ever to be studied by a man made probe. Ultima Thule may just look like a distant snowman, but it could hold interesting new information on the formation of our Solar System.

So congratulations to the New Horizons team on another great success!