\n<\/p>\n
The asteroid Dinkinesh and its binary contact satellite<\/p>\n
NASA\/Goddard\/SwRI\/Johns Hopkins APL<\/p>\n<\/div>\n<\/figcaption><\/figure>\n<\/p>\n
The asteroid Dinkinesh\u2019s newfound moon is actually a contact binary \u2013 two objects lightly touching at their ends. This is the first time such a binary has been found orbiting another asteroid.<\/p>\n
Dinkinesh was the first rock visited by NASA\u2019s Lucy spacecraft, which flew past on 1 November. When the spacecraft went by, it found a smaller rock orbiting Dinkinesh, which the Lucy team has provisionally named Selam.<\/p>\n
But as Lucy has sent more data back to Earth, it has become clear that Selam isn\u2019t just a single object. Instead, it appears to be two similar-sized rocks connected at the end, resulting in a sort of peanut shape. The team missed it at first because in the images from Lucy, one lobe of the asteroid must have been hidden behind the other.<\/p>\n
\u201cAll of these rocks are going to be their own individuals, but I must admit I would have never expected to have a bilobed satellite like this,\u201d says Hal Levison at the Southwest Research Institute in Colorado, head of the Lucy mission. \u201cThere are several things about it that I just don\u2019t understand.\u201d<\/p>\n
For one, the processes that shape these small satellites aren\u2019t expected to form multiples of the same size, says Levison. Also, for the two to be connected as they are, instead of fully merged, they would have had to collide at extremely low speeds.<\/p>\n \u201cThese small bodies are sort of a laboratory of all the physics that we need in order to try to understand how solid bodies grew to become planets,\u201d says Levison. The strange properties of Selam might indicate something not quite right about our current ideas of how planets formed, he says.<\/p>\n Over the course of the rest of its mission, Lucy is slated to visit eight more asteroids \u2013 one more in the main asteroid belt, and then seven asteroids that share Jupiter\u2019s orbit, called Trojans. Levison says that there are almost certainly more extra satellites and other surprises in store. \u201cEach one of these systems is unique, it\u2019s gone through a unique evolution, so I would be surprised if we don\u2019t find a lot of stuff we\u2019re not expecting,\u201d he says.<\/p>\n