Japan Has Successfully Landed The First Ever Rovers On An Asteroid

Two rovers sent to the surface of an asteroid by a Japanese spacecraft have landed successfully, a thrilling moment in the history of space exploration.

Called Rover 1A and 1B, together known as Minerva II-1, the two rovers were released by the Japan Aerospace Exploration Agency's (JAXA) Hayabusa-2 spacecraft on Friday 21 September. Following a descent lasting several hours they successfully touched down, with confirmation arriving today.

"Both rovers are confirmed to have landed on the surface of Ryugu," the Hayabusa-2 team posted on Twitter. "They are in good condition and have transmitted photos & data. We also confirmed they are moving on the surface."

Each tiny rover weighs about 1 kilogram (2 pounds), and they're designed to hop across the surface of the asteroid. They were carried to Ryugu, located about 280 million kilometers (175 million miles) from Earth, by Hayabusa-2 after launching in December 2014.

Earlier on Friday the team had shared a rather stunning image showing the shadow of the spacecraft on Ryugu. Following the separation, Hayabusa-2 raised its altitude to several kilometers above the asteroid.

Early on Friday, reaching a distance as low as 55 meters (180 feet) from the asteroid, the spacecraft released these first two landers. The successful landing means they are the first movable rovers ever to be deployed on an asteroid. /

The rovers will "hop" across the surface by spinning a mass inside of them. This transfers momentum, which causes them to tumble or jump across the surface. Each movement must be carefully controlled so the landers don’t accidentally jump too high and escape the asteroid’s gravity.

This is because the gravitational pull of the asteroid is incredibly weak. While on Earth they weigh a kilogram, on Ryugu each lander has a relative mass of less than a quarter of a gram.

Each hop can reach a distance of several meters, moving at up to 9 centimeters (3.5 inches) per second.

On board each rover are cameras that will send back images from the asteroid. They also contain sensors that will measure the surface temperature at different locations. The images and data will be sent back to Hayabusa-2, which will relay the information to Earth.