NASA's New Horizons mission has not yet discovered any more around the Ultima Thule, but team members are still looking.
Credit: NASA / Johns Hopkins University Applied Physics Laboratory / Southwest Research Institute
The farthest ever heavenly object ever explored may have a moon, and astronomers hardly try to find them.
On January 1, NASA's New Horizons spacecraft crossed the small, lasting Thule Thule, which is more than 4 billion miles from Earth. The probe sent only a small portion of its flight data so far, but the mission team members are already starting to obtain the goods on the distant stone.
For example, scientists now know that the 21-mile (33 km) Last Thule consists of two spherical lobes that seem to have started their lives as independent and flying objects. The duo quickly spiraled closer and closer together, gathering in the early days of the solar system to form a red-haired "snowman." [New Horizons at Ultima Thule: Full Coverage]
Modeling works suggest that the two constituent bodies, called "Ultima" and "Thule," probably have completed a rotation every 3 or 4 hours around the time they joined, said mission team members. But New Horizons notes that the current Last Thule lasts about 15 hours to make a complete spin.
"Well, the best way to understand is if there is another month, or two or three, that orbits this system," said Mark Showalter, co-investigator of New Search for Extraterrestrial Intelligence (SETI) Mountain View, California, said on Thursday (January 3rd) a press conference.
"Essentially, what those satellites would do is put the brakes on the two bodies in the middle – to slow them down", removing the angular impulse of the duo, he added.
So the Ultima Thule satellite hunt – which really started a while ago when the mission team investigates the potential dangers that could complicate the New Year's epic flight – is hardly a lark.
The mission team ruled out the existence of any considerable world at least 500 miles (800 kilometers) away from Ultima Thule or 160 kilometers from the object, said Showalter. But this middle area is a big question mark and will remain so until the end of January when New Horizons launches home observations covering the region.
And, crucially, this area between areas is most likely a place to have satellites in the system, "said Showalter.
He and his colleagues really hope they'll be back for at least a month because such a breakthrough will help tease the key details about Ultima Thule that it will be hard to determine in any other way.
"Any month, on any orbit, will tell us mass and density to a fairly decent accuracy," Showalter said. "And we are very, very enthusiastic about this perspective."
Even if the search is finally empty, this does not mean that Ultima Thule – officially known as MU69 2014 – did not host Monday, he added. As "braking" satellites meet an angular momentum in the central bodies of their systems, these months move further and further into space. So it is possible that Ultima Thule has ever had such satellites, but these satellites have moved so far that they have eventually been lost.
The New Horizons mission, worth 700 million dollars, was launched in January 2006, tasked with bringing back Pluto's first ascending images. The mission accomplishes this goal when it traveled to the dwarf planet in July 2015, revealing that Pluto is a world of stunning beauty and geological diversity.
Last Thule flyby is the central part of the extended mission of New Horizons, which runs until 2021. The spacecraft has enough fuel and power and has a good enough health to pass through a third object if NASA grants a new extension of the mission members said.
Mike Wall's book on the search for alien life "There"(Grand Central Publishing, 2018, illustrated by Karl Tate) is out now. Follow it on Twitter @michaeldwall. Follow us @Spacedotcom or Facebook. Originally published on Space.com.