One last job… New Horizons will swing by a Kuiper belt object in 2019 NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Steve Gribben

Onwards and outwards. Following its spectacular fly-by of Pluto last July, the New Horizons spacecraft is now officially headed for one final job before its fuel runs out. NASA this week formally approved an extension of the mission to visit 2014 MU69, a small, ancient object just 30 to 40 kilometres across, minuscule compared with the 2370-kilometre diameter of Pluto.

“We’re excited to continue onward into the dark depths of the outer solar system to a science target that wasn’t even discovered when the spacecraft launched in 2006,” said Jim Green, NASA’s director of planetary science.

To reach MU69, New Horizons will head out towards the Kuiper belt, which is home to millions of icy bodies that are reckoned to be remnants from the birth of our solar system 4.6 billion years ago. If all goes according to plan, it will reach MU69 on 1 January 2019.


“It’s extremely good news that NASA’s approved the mission extension,” says Wesley Fraser of Queens University Belfast in the UK, who investigates the origins of the solar system. Fraser says that MU69 was among debris that was blown to the fringes of the solar system following the formation of the gas giants — Jupiter, Saturn, Uranus and Neptune. “We think they formed a lot closer to one another then pushed each other around into their current orbits, but the small stuff ended up in the Kuiper belt.”

Building blocks

Because objects such as MU69 are thought to have been in place since the early days of the solar system, almost like a time capsule, they might hold clues to the building blocks of planetary systems. “It’s known to be red, because it’s been baked by the sun,” says Fraser. The red coloration is probably organic material, long-chain hydrocarbons that appear red because they absorb visible and ultraviolet radiation. But Fraser is hopeful that the probe may discover rocks on the surface too.

“I’ve spent quite a few years looking for rocks in the outer solar system, and MU69 is the last hope to identify rock, what kind, and how much might be there,” says Fraser, as objects in the Kuiper belt are mostly made of ice. “It will tell us about the geology of things crashing together.”

NASA also approved a mission extension for the Dawn spacecraft, but unfortunately it won’t be jetting off to visit a third asteroid after Vesta and Ceres, as had been rumoured. Instead, the probe will stay in a long-term, stable orbit around Ceres to learn more about this mysterious and tiny world.