There has also been no evidence yet of any moons or satellites orbiting Ultima Thule, which is a bit more frustrating. The discovery of any moon on any orbit in the vicinity of the bi-lobed object would allow scientists to determine its mass and density, said Mark Showalter, a New Horizons co-investigator from the SETI Institute in Mountain View, Calif. That information would in turn offer clues to the composition of its interior, he said.

Source: Los Angeles Times January 03, 2019 22:18 UTC