The moment of truth: 
the New Horizons probe arrives to the very distant asteroid informally

named Ultima Thule

(31/12/2018)

Ultima Thule, the far away asteroid destination of the New Horizons mission, is one of the less eccentric objects in the Kuiper Belt (zone of the Solar System that is very distant from the Sun where there are a great number of objects and dwarf planets).

Known as a "classical" KBO (Kuiper Belt Object), Ultima Thule it's also part of the "cold" population, which means it has never received any energy from collisions or gravitational interactions. It's just been sitting there, doing relatively little, since the solar system formed. Much of what we know about it comes from Hubble observations, or from occultations where the object passes in front of a background star. The dip in the star's brightness tells us about what's blocking it, and three occultations by Ultima Thule in 2017 were studied by a special group of astronomers formed by the New Horizons team. This study of occultations is the same process that is often used to observe exoplanets around distant stars, but even with this data Ultima Thule remains a mystery.
We will probably find out if there is and what type of organic matter is present, and perhaps, if there are viable microorganisms o spores, confirming the panspermia hypothesis.
 "We don't know if it's two objects, or if it's binary, but we know its shape is not round," said Bannister. "Binary systems are very common in the population to which this little world belongs, and this ties directly into how they formed. A solar system starts off being made of dust and gas, and this starts forming little objects, and they have to get over about a meter in diameter and suddenly they're full-on asteroids that can start accreting material much, much faster. This whole process is something people are very actively working to understand, but binary objects might be implying that, when you initially make little worlds, you make them binary, so it tells us a lot about what physics to put into simulations of how planets are formed." 

Whatever Ultima Thule is like, New Horizons is well equipped to tell us all about it, as the startling images of red-and-white plains and mountains on Pluto showed. "We have a very powerful set of seven scientific instruments," Stern said. "They will map its surface composition, search for an atmosphere, search for satellites, search for rings and make other kinds of studies. And I hope that we put together a very complete picture of what this typical Kuiper Belt object is like, because not only is this the first time that an object like this has been explored, but nobody's planning another mission out to the Kuiper Belt, so I think that this dataset is something that's going to be valuable scientifically for decades to come."

How long New Horizons can carry on sending back this kind of remarkable data is limited by the power and fuel supplies on the spacecraft, as well as the availability of suitable targets in its path. When you're travelling over 36,040 mph (58,000 kilometres), changing direction isn't easy. 

Stern isn't worried about the future, however. "We have a very healthy spacecraft," he said. "We have the fuel and the power in our nuclear battery to run it for at least 15 years, maybe 20 years. If NASA continues to fund it, if NASA judges that it's scientifically worthwhile, this spacecraft will be operated into the mid-2030 or later. It's very much like the Voyagers which finished their exploration of the planets in the 1980s, but are still returning useful scientific data 40 years after launch." 

Author: Ian Evenden

Reference:

https://www.space.com/42860-new-horizons-beyond-pluto-ultima-thule.html