Ultima Thule, the last frontier | Science and health

Launched in early 2006, the American probe New Horizons aimed to study the planet Pluto, the furthest away from the solar system. Seven months after its launch, Pluto changes category and becomes a dwarf planet. New Horizons was found with the mission to visit a dwarf planet for the first time in July 2014.

Even before the probe pbaded Pluto, the team of astronomers on mission thought already what to do with the ship after this event. after all, with an investment of more than $ 700 million, increasing the scientific return of the ship would be excellent for NASA. But what to look after crossing Pluto? It could only act as an object of the Kuiper Belt (KBO), the cometary reservoir of the solar system.

On the road to Pluto, nothing was known, then a great effort of observation was launched to locate a second objective for New Horizons. It belonged to the Hubble Space Telescope to discover the 2014 object MU69, a very suitable candidate. But simply finding a new target would not be enough, as the ship must turn its back to intercept it. To do this you need to know the orbit of MU69 in detail.

KBO ended up deserving the nickname of Ultima Thule, which means "northernmost" and is sometimes badociated with Greenland. Its characterization suggests that it is about 30 km long and is composed mainly of ice, like its beltmates. Based on Ultima's orbital data, mission engineers made minor corrections to the spacecraft's trajectory so that it intercepts the target at the turn of 2019.

In addition Of its size, observations made in Argentine Patagonia in the middle of last year revealed that Ultima had two well defined bulges connected by a narrow bridge, like a gym weight. It is even possible that such a connection does not exist and that this KBO is actually a double object, each bulb being in contact with each other. Another intriguing fact is that the brightness of Ultima varies by less than 20%, which is a sign that it should not have a noticeable rotation. And crash KBOs often have a very pronounced rotation.

New Horizons should fly over at 3:33 am on January 1, 2019, but because of the distance between the ship and the Earth, we will only know if everything is fine after 9:30. . It takes about 6 hours for the ship's radio signals to reach the mission's controls. Nevertheless, it should only be a simple radio query that informs you that the systems are working. We have no idea if there is debris on the way to Ultima, nor even if this KBO has rings or even small satellites.

Colliding with something like this in space would be fatal to the mission because the ship is traveling at a speed of 14 km / s! In a straight line, at this speed, it would take only 5 minutes to go from Oiapoque, in the extreme north of Brazil, to Chuí, in the extreme south. This was also the case when the new horizon approached Pluto. In both cases, the risk badysis team spent more than a week studying radar maps looking for potentially dangerous objects, but found no evidence relevant information.

The probe must travel a distance of 3,000 km from Ultima Thule, much less than the distance to Pluto (15,000 km). In this situation, the cameras can distinguish an object of about 30 meters long. It is more or less like being at Rio Branco in Acre and getting an image of Christ the Redeemer (without pedestal) in Rio de Janeiro. This in theory because the practical challenges are very big.

First, the speed compared to the KBO, at 14 km / s, the probe travels the entire extension of the target in just 2 seconds. In order for the photos not to be blurred, the exposure must be short. But overflight, the amount of light is even lower than on Pluto, which could be offset by more exposure. But …

Another problem is age. The probe was designed to be at its peak when pbading through Pluto and it was almost 5 years ago. In addition to the deterioration of the equipment due to cosmic radiation exposure, the New Horizons nuclear battery no longer generates energy as efficiently as before and to get the most out of it. information during the short meeting, all instruments will be in operation. Simulations on Earth show that the ship will hopefully hold. After crossing Ultima, the probe must still study an additional 21 KBOs in the area, but everything is done remotely and none of them will be overflown.

Data transmission should start only in the afternoon of the first day and the first image should be presented at the press conference only on the 02, but the download should last until September 2020!

Speaking of simulation, NASA has made available a program simulating the flight of New Horizons in Ultima Thule. This film shows KBO's final approach and goes as far as the ship turns its main antenna to Earth to begin transmitting the data. Things happen here a lot faster than in reality, like 2 or 3 minutes in real time every second of the movie. The small window at the top right represents the New Horizons instrumentation field and you can see Ultima Thule growing up as the spacecraft approaches, and then shrink as it away from it.

Good fun and happy new year!