After a 42-month journey through space, the Japanese probe Hayabusa 2 has finally reached its destination – a rocky little cube called Ryugu, originally known as Asteroid 162173, about 200 million miles from Earth. Japan Aerospace Exploration Agency (JAXA) confirmed the arrival of the spacecraft in an announcement earlier this week.
During their 18-month mission, the spacecraft will analyze the tiny rock with a series of tests and three miniature rovers will deploy the surface. Before it even goes, it even blows up a new crater in the surface, collects some material that has been removed, and then returns to Earth with the samples on board.
– haya2kun (@ haya2kun) June 28, 2018
The asteroid was named after a dragon's palace a Japanese folk tale. In the story, a Japanese fisherman emerges from the hiding place with a box full of treasures.
Technically, a near-Earth object (NEO) is classified as it orbits on an elliptical path from Mars to Earth and back again. But there is no chance that it will hit Earth, at least not in the next few hundred years.
The spacecraft used its engines to maneuver into a stable orbit within 12 miles of Ryugu, where it began to analyze the asteroid rest of its mission. Ryugu, dotted with boulders, is roughly diamond-shaped and has an equatorial ridge. As Earth Sky suggests, it resembles the asteroid Bennu, the target of the NASA Osiris REx mission in 2020.
The mission, launched in December 2014, carries four small lander. Three come from Japan (called MINERVA-II) and one from Germany (MASCOT-1, for Mobile Asteroid Surface Scout). These are not the conventional rovers you are familiar with, like those who take selfies on Mars. Because the half a mile wide Ryugu has a very low gravity, the small lander has only the weight of a drop of water here on earth.
So the lander has no wheels – instead, the small foot-width boxes have internal offset weights that allow them to "flop" across the surface with short jumps.
Hayabusa 2 will also be pumping up some stuff while it's there. With a "space cannon", the probe explodes a copper bullet at the surface to form a landing crater and expose material beneath the surface. During a short touch-and-go landing on the surface, the probe shovels up some of the debris and stores it for the return journey.
By 2020, the probe will drop the samples into a bowl-shaped reentry capsule, landing over a parachute in Australia.
"Together with you all, we became the first eyewitnesses to see the asteroid Ryugu," said project leader Yuichi Tsuda. "I feel that this is an amazing honor as we continue with missionary operations."