The last time Hayabusa2 was seen with the naked eye, Barack Obama was president of the United States and Brexit was a distant Europhobe fantasy.
Six years and three days after its groundbreaking mission began, the Japanese spacecraft will drop a capsule on to the Australian outback carrying pristine asteroid fragments that scientists believe could shed light on the formation of the solar system and the origins of life.
By the time it reaches the skies high over Woomera, South Australia, in the early hours of Sunday, the probe will have completed a round-trip of around 6bn km (3.7bn miles) that included two brief stops on the surface of a moving asteroid.
The unmanned craft will release the capsule from a height of about 220,000km (136,700 miles), the Japan Aerospace Exploration Agency (Jaxa) said.
Sunday’s operation will mark the climax of a ¥30bn (£215m) mission that began when Hayabusa2, whose name means falcon in Japanese, left the Tanegashima space centre in south-west Japan in December 2014.
The probe reached its stationary position above the asteroid – named Ryugu after an undersea dragon palace in a Japanese fairy tale – in June 2018 after travelling 3.2bn km on an elliptical orbit around the sun for more than three years.
One of several critical stages of the mission came in February last year, when it briefly landed on Ryugu and fired a tiny tantalum pellet at the asteroid’s surface to kick up dust for collection, before blasting back to its holding position.
Five months later, it achieved a world-first when it landed a second time to collect dislodged rock fragments and soil from beneath the surface of the 4.6bn year-old asteroid.
Jaxa believes those sub-surface samples contain carbon and organic matter that, having been shielded from space radiation and other environmental factors, are in the same state as they were when the solar system was formed.
Makoto Yoshikawa, a Hayabusa2 project mission manager at Jaxa, said scientists were especially interested in analysing organic materials in the Ryugu samples.
“Organic materials are the origins of life on Earth, but we still don’t know where they came from,” Yoshikawa said at a briefing. “We are hoping to find clues to the origin of life on Earth by analysing details of the organic materials brought back by Hayabusa2.”
The capsule, protected by a heat shield, will turn into a fireball during re-entry into Earth’s atmosphere at 200km above ground. At about 10km above ground, a parachute will open and, if all goes to plan, the capsule will send out signals indicating its location on the ground.
Jaxa experts, who arrived at Woomera last month, have set up satellite dishes at several places to pick up the signals, while the Australian space agency and the Department of Defence will be on standby to help in the search and retrieval mission.
Without local assistance, the search for the capsule, which is just 40cm in diameter, “would be extremely difficult”, Yoshikawa said.
Hayabusa2’s work will not yet be done at that point, however. After releasing the capsule, it will head for another distant asteroid, named 1998KY26, in a mission that is expected to last a decade.
