New pictures of "Ultima Thule": The strange thing in the depths of space

The probe "New Horizons" has sent new images of the most distant object of the solar system that humans have ever seen. "Ultima Thule," as the celestial body is called by Nasa, has a startling shape.

The NASA space probe "New Horizons" has a prominent fan. Queen guitar legend Brian May recently released a song called "New Horizons (Ultima Thule Mix)". Good: The musician is incidentally studied and doctorate astrophysicist. This explains May's personal enthusiasm for the US probe, which has gone as far into the cosmos as a few Earth devices. But now also laymen are interested in the probe: With "Ultima Thule", "New Horizons" has recently photographed the body of the solar system that has been farthest away from us.

That was at the turn of the year. Therefore, the message outside the Astroszene may have gone down a bit. Now new pictures show: The Brocken - officially it is called 2014 MU69 - has a quite surprising form. That it consists of two different sized parts, which are bound together by the effect of gravity, was already clear since the flyby. At first, the photos looked as if the celestial body, with its total diameter of about 30 kilometers, had the shape of a flying snowman. But now it turns out that it does not consist of balls - but at least one of the structures is flat as a pancake. And the other one is deformed too.

NASA / Johns Hopkins University Applied Physics Laboratory / Southwest Research Institute

Graphics on the suspected form of "Ultima Thule"

Ralf Jaumann from the Institute of Planetary Research of the German Aerospace Center (DLR) in Berlin calls the new pictures "rather unusual". "So far, our impression of Ultima Thule has been based only on the limited number of photos that 'New Horizons' sent from flyby to Earth," comments Alan Stern of the Southwest Research Institute at Boulder, the mission's chief scientist. "But now we have more data, and they change our view".

"We have," says Stern, "never seen anything like this object orbiting the Sun." His colleague Jaumann believes that 2014 MU69 is the result of a collision of the two parts - and that they had their characteristic shape before this collision. Explain the peculiar geometry by the forces acting: "The gravity was not large enough that forms a ball - and the centrifugal forces were again not large enough that the whole thing is flying apart."

Long distance, cold and dark

2014 MU69 was not even discovered when "New Horizons" was launched in January 2006. The primary goal of the mission was namely the Pluto, who in turn was still considered as a planet when taking off the probe. However, apart from a few fundamentals, not much was known about the distant, cold and gloomy celestial body, "New Horizons" was supposed to change that.

Brian May - New Horizons (Ultima Thule Mix)

And indeed: the flyby in the summer of 2015 has virtually revolutionized our image of this distant world - even though Pluto is now officially only around the sun as a dwarf planet. The pictures show extremely varied ice landscapes: A total of 30 different terrain types, including mountains, gorges, crater-rugged landscapes and smooth ice levels, announce an active geology.

Behind the pluto, the probe was allowed to fly on, fuel was still sufficiently available. With the "Hubble" telescope you had already spied out looking for targets in the Kuiper belt, that of Abertausenden frosty chunks populated zone beyond Pluto, are distracted from the comets into the interior of the solar system every now and again. And the 2014 MU69, discovered in the summer of 2014, was cheap.

Time capsule from the childhood days of the solar system

With 50,000 kilometers per hour, "New Horizons" finally rushed past the celestial body in the first hours of this year - and came much closer to it than Pluto: The distance was 3000 kilometers, the dwarf planet had been about 12,500 kilometers. By comparison, the International Space Station is about 400 kilometers from Earth, while communications and weather satellites in geostationary orbit are nearly 36,000 kilometers.

2014 MU69 is like a time capsule from the childhood days of our solar system about 4.5 billion years ago. Since then, the material has probably never been melted at temperatures just above absolute zero. Its red color, as seen in some of the "New Horizons" images, owe the celestial body probably frozen gases such as ammonia and methane compounds, says researcher Jaumann.

What fascinates him especially: The distant celestial body is possibly the precursor of a comet such as Churjumow-Gerasimenko, called "Tschuri". This had been examined by the European space probe "Rosetta" with its German landing robot "Philae" - and was probably also catapulted from the region beyond Neptune into the interior of the solar system. It too consisted of two parts, held together solely by the action of gravity. "There are probably a lot of bodies that are so gravitationally related," says Jaumann.

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Because "New Horizons" is now about 6.6 billion kilometers from Earth, data transmission is extremely slow. In total, it will take about two years for all the data collected during the flyby to be sent to NASA's Deep Space Network antennas.

The currently evaluated images are among the last that "New Horizons" has done in the flyby - "Ultima Thule" was already behind her at this time. Meanwhile, the probe continues on its way into the Kuiper Belt. Not only Alan Stern, the chief scientist of the probe, is hoping for an extension of the mission. Even Brian May could be sure, maybe even a new song would be in there.