Nasa has received “puzzling” data from a spacecraft that was studying a distant asteroid.
The space agency’s Lucy Spacecraft left Earth in 2021, with the aim of studying “Jupiter trojans”, a set of asteroids that fly around the Sun along Jupiter’s orbit and remain largely mysterious. Recently, scientists decided to send it to visit another small object on its way, largely as a test of the systems on the spacecraft that let it track asteroids for its mission.
When Lucy arrived at that object – a main belt asteroid named Dinkinesh – it found a surprise, however. Images taken of the asteroid showed that it had a satellite, which flies around the asteroid like a tiny moon of its own.
Now, further examination of those images show that the satellite is not one but two objects. Those objects make up a “contact binary”, or two smaller objects that are touching each other as they fly through space.
The unexpected discovery explains some of the strange data that scientists had received as they approached Lucy. But it opens up more confusion about the whole system, which one called “bizarre”.
“Contact binaries seem to be fairly common in the solar system,” said John Spencer, Lucy deputy project scientist, in a statement. “We haven’t seen many up-close, and we’ve never seen one orbiting another asteroid.
“We’d been puzzling over odd variations in Dinkinesh’s brightness that we saw on approach, which gave us a hint that Dinkinesh might have a moon of some sort, but we never suspected anything so bizarre!”
The flyby of Dinkinesh was only intended as a test of the spacecraft’s systems but has now posed new possible research for scientists.
“It’s truly marvelous when nature surprises us with a new puzzle,” said Tom Statler, Lucy program scientist from NASA Headquarters in Washington. “Great science pushes us to ask questions that we never knew we needed to ask.”
“It is puzzling, to say the least,” said Hal Levison, principal investigator for Lucy, also from Southwest Research Institute. “I would have never expected a system that looks like this. In particular, I don’t understand why the two components of the satellite have similar sizes. This is going to be fun for the scientific community to figure out.”
The scientists were only able to confirm the nature of the system with the multiple images that were sent back by Lucy in the wake of its encounter with Dinkinesh. Nasa is working now to get the rest of the data from the spacecraft, which might include yet more surprises.
Lucy itself will continue flying through space on a journey that is due to take 12 years. Lucy is actually heading back to Earth, which it will use for a gravity assist to propel it onto the next part of its journey, back through the main asteroid belt and onto the Trojan asteroids.