Hayabusa-2: Japan's rovers ready for touchdown on asteroid
Two robotic explorers are descending to the surface of an asteroid.
Japan's Hayabusa-2 spacecraft despatched a pair of "rovers" to the 1km-wide space rock known as Ryugu.
If all goes well, Hayabusa-2 will be the first spacecraft to successfully place robot rovers on the surface of an asteroid.
Rover 1A and Rover 1B will move around by hopping in Ryugu's low gravity; they will capture images of the surface and measure temperatures.
Hayabusa-2 reached the asteroid Ryugu in June this year after a three-and-a-half-year journey.
The 1km-wide space rock known formally as 162173 Ryugu belongs to a particularly primitive type of asteroid, and is therefore a relic left over from the early days of our Solar System. Studying it could shed light on the origin and evolution of our own planet.
The rovers are stored in drum-shaped container at the base of the Hayabusa-2 "mothership". Collectively, they form a 3.3kg science package known as Minerva II-1.
Early on Thursday morning (BST), Hayabusa-2 began descending towards the surface of Ryugu in preparation for the deployment.
At around 0500 BST on Friday (1pm JST) - at a distance from the asteroid of about 60m - Hayabusa-2 initiated the release of the two robots.
Japanese space agency officials said that when the front of the drum is jettisoned into space, the two rovers are then ejected from the container and fall independently to the surface of the asteroid.