Mission scientists at the Japan Aerospace Exploration Agency (JAXA) are celebrating today after data from the Hayabusa 2 probe confirmed a successful touchdown on its target, a kilometer-wide near-Earth asteroid called Ryugu. This in itself is a triumph for the team, but the indications are that the spacecraft's effort to snaffle dust from the surface were also successful, meaning an invaluable sample holding potential secrets of the early solar system will soon be making its way back to Earth.
Launched in 2014, the Hayabusa 2 mission is a successor to JAXA's historic Hayabusa mission, which remains the only spacecraft to return an asteroid sample to Earth. Hayabusa 2 finally entered orbit around Ryugu in June last year, and then deployed a pair of hopping rovers to the surface in September, followed by a larger lander a few weeks later to investigate the asteroid's surface.
But the real moment of truth for the mission was a plan to launch metal projectiles into the surface of Ryugu in order to kick up dust for collection by a sampling arm. This maneuver had to be postponed when the spacecraft's observations revealed a far rockier surface than anticipated, calling for some further testing before mission control pulled the trigger.
But on Wednesday, JAXA saw fit to kick off the touchdown sequence, sending the spacecraft from its orbit at an altitude of 20 km (12 mi) down toward the surface. Its encounter with the gravely grounds of Ryugu appears to have gone off without a hitch, with the early data indicating the maneuver went exactly to plan.
Hayabusa 2 will remain at Ryugu for around another 18 months, before making a break for Earth in late 2020. If it makes it back safely with the surface samples in tow, it could provide scientists here on Earth with a window into the formative stages of the solar system.
Primitive asteroids such as Ryugu are thought to have gone largely unchanged since the solar system formed around 4.6 billion years ago. That means analyzing dust collected from the surface at an atomic level may reveal organic compounds like sugars or amino acids that can serve as the building blocks for life.
Source: JAXA (Twitter)