On New Year’s Day, the New Horizons interplanetary probe will pass just 2,200 miles from the object that is one billion miles further from Earth than Pluto, the distant dwarf planet in the Kuiper belt that itself is four billion miles from us. It will two years to send back all its data on the object officially known as 2014 MU69, but nicknamed Ultima Thule, a Latin phrase meaning “’beyond the borders of the known world”.
Alan Stern, the mission’s principal investigator said that on December 15, the team had decided there were no rings or moons in the path of New Horizons.
“I informed Nasa that we are “go” to fly by Ultima on the trajectory that yields the best science,” he wrote on the Nasa website.
“As a result, New Horizons will approach to within 3,500 kilometres (about 2,200 miles) of Ultima early on New Year’s Day. There is no longer any chance we will divert to a farther flyby distance with consequently lower-resolution images.”
He added: “What will Ultima reveal? No one knows. To me, that is what’s most exciting—this is pure exploration and fundamental science.”
Nasa launched New Horizons in 2006. The size of a baby grand piano, it flew past Pluto in 2015, providing the first close-up views of the dwarf planet.
The Associated Press said that with the successful flyby behind them, mission planners won an extension from Nasa set their sights on a destination deep inside the Kuiper Belt. As distant as it is, Pluto is barely in the Kuiper Belt, the so-called “twilight zone” stretching beyond Neptune.
Other than how far away it is, little is known about Ultima Thule. Indeed, it was only in 2014, that Marc Buie, New Horizons co-investigator from the Southwest Research Institute in Boulder, Colorado, and others discovered Ultima using the Hubble Space Telescope in 2014.
In 2016, researchers determined it had a red colour. In 2017, a Nasa campaign using ground-based telescopes traced out its size – just about 20 miles across – and irregular shape when it passed in front of a star, an event called a “stellar occultation”, the AP added.
Mr Stern said the flyby – due to take place at at 12:33am EST on January 1 – will provide huge amount of information. “New Horizons will map Ultima, map its surface composition, determine how many moons it has and find out if it has rings or even an atmosphere,” he wrote.
“It will make other studies, too, such as measuring Ultima’s temperature and perhaps even its mass. In the space of one 72-hour period, Ultima will be transformed from a pinpoint of light — a dot in the distance — to a fully explored world. It should be breathtaking.”
He said that close approach images other kinds of data will already start to flow from New Horizons on flyby day.
“We expect to have an image with almost 10,000 pixels on Ultima by that night, ready for release on January 2,” he said.
“By that first week of January we expect to have even better images and a good idea of whether Ultima has satellites, rings or an atmosphere.”
Deputy project scientist Cathy Olkin, also of the Southwest Research Institute, said: “From Ultima’s orbit, we know that it is the most primordial object ever explored. I’m excited to see the surface features of this small world.”
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