13 year mission
Early on New Year’s Day, when New Horizons passes by the Ultima Thule ice world at a distance of only 3,500 km, the satellite has travelled 6.5 billion km through the Solar System since its launch in 2006.
New Horizons has hibernated for 1.5 years
In the first half of 2015, New Horizons passed by the dwarf planet of Pluto at a distance of 12,500 km, and in August 2015, Ultima Thule was chosen as its next destination. The course was set in 2016, and subsequently, the probe was made to hibernate, as it flew 1.5 billion km. In January 2018, it was revived and began to measure dust and charged particles in the Kuiper Belt. In February, New Horizons photographed two ice worlds 6.12 billion km from Earth, beating Voyager 1’s 30-year-old record for the remotest photographed object.
Aprecision manoeuvre – that is the best description of the exercise carried out when, on New Year’s Day, NASA’s New Horizons probe passes close by the only 30-km-long ice world of Ultima Thule on the outskirts of the Solar System: the Kuiper Belt. From a distance of only 3,500 km, the probe will take close-ups of the surface and collect dust samples.
New Horizons was launched from Cape Canaveral on 19 January 2006 as part of the American space agency’s New Frontiers programme. The probe’s primary aim was to explore the dwarf planet of Pluto and its five moons over a 6 month fly-by in 2015. New Horizons solved the problem beyond all expectations, and the mission was extended. In August 2015, the small ice world of 2014 MU69 was identified as the next destination, and the course was set. Now, New Horizons has travelled 1.5 billion km beyond Pluto and has almost reached its destination, Kuiper Belt object 2014 MU69, which is now named Ultima Thule – meaning the borders of the known world.
Ultima Thule will be the remotest object that any craft has ever visited, and at the same time, it is one of the most primitive. With the assistance of seven of the probe’s instruments, the visit will not only reveal what the millions of small worlds that orbit on the outskirts of the Solar System look like, rather also show how the four exterior planets – Jupiter, Saturn, Uranus, and Neptune – originated.
First stop Pluto
The Kuiper Belt consists of 1+ million worlds orbiting the Sun in a belt stretching billions of km beyond Neptune. Apart from small ice worlds such as Ultima Thule, the belt includes at least 5 dwarf planets like Pluto.
The mission to Pluto, which is located five billion km from Earth, took 9.5 years, and New Horizons hibernated during almost the entire flight to save energy and fuel. Before the mission, our knowledge about the dwarf planet was limited. Astronomers almost only knew that Pluto had five moons, a thin atmosphere, and a reddish surface with ice of frozen methane, nitrogen, and carbon monoxide. Now, they know a lot more.
New Horizons made observations for six months, revealing that Pluto’s diameter was 2,376 km and so 47 km larger than expected. The probe also spotted up to 4.5-km-high mountains, whose peaks were covered in methane ice, gorges stretching hundreds of km, and huge glaciers consisting of frozen nitrogen. The largest one, Sputnik Planitia, is larger than France, and we have never observed anything like it in the Solar System. The glacier does not include any impact craters, meaning that the ice is renewed.
Much to the surprise of scientists, Pluto is also still geologically active, and so, the rocky core beneath the ice must include an internal heat source that drives the process. New