A Japanese space probe dropped a capsule containing two samples from the 4.6-billion-year-old Ryugu asteroid above Earth on Saturday, as scientists await the arrival of materials that could help explain the origin of life.
The capsule, released from the Japan Aerospace Exploration Agency's Hayabusa2 space probe, is due to reenter Earth's atmosphere early Sunday before landing in a desert of southern Australia, according to JAXA.
The specimens, which are estimated to weigh one gram in total, include the world's first sub-surface asteroid sample. Scientists hope the primordial materials will help further research into the origin of life on Earth and the evolution of the solar system.
After landing, a JAXA recovery team will search a region within the Woomera Prohibited Area, of several hundred square kilometers, to collect the capsule.
Once located, the capsule will be taken to a "quick look facility" at an Australian Defense Force facility in Woomera to analyze gasses that may have been emitted by the asteroid material, according to Masaki Fujimoto, deputy director general of JAXA's Institute of Space and Astronautical Science.
"We sealed the capsule very tightly, but still gas samples can be lost easily," Fujimoto said at a press briefing on Friday.
"We don't want to miss anything, so as soon as the capsule is back to the headquarter building we can extract the gas sample so the best science can be obtained from the precious sample we are returning from asteroid Ryugu," he said.
If gasses are detected, Fujimoto said it is a positive, though unofficial, sign that asteroid samples were successfully collected.
The capsule itself will not be opened in Australia, but flown to Japan for further analysis.
The Ryugu asteroid is a C-type or carbonaceous asteroid, which is believed to have undergone minimal change since the formation of the early solar system and is therefore an example of the kinds of meteorites that may have struck early Earth.
Scientists believe that at the beginning of Earth's formation, the planet was too close to the sun for water to condense. Once the planet cooled, water and organics were delivered to Earth by meteorites similar to Ryugu, thus making the planet habitable.
"It really shows the miracle of how life exists on this planet and so it's a rich question, and this is a small first step to answer that rich question, but somebody has to make it, and we're really proud to be the one," Fujimoto said.
The Hayabusa2 space probe was launched from Japan's Tanegashima Space Center in December 2014 and reached Ryugu in June 2018.
Hayabusa2 made two landings on Ryugu despite the asteroid's unexpectedly rocky surface.
During the first landing in February 2019, the probe collected a surface sample of Ryugu. The second touchdown in July the same year saw the probe collect the first-ever subsurface samples from an asteroid after creating an artificial crater by shooting a copper projectile at the asteroid.
The two samples will provide scientists with an above-and-below-surface comparison as materials below the asteroid's surface will not have experienced the same weathering and potential contamination from other meteorite impacts.
Hayabusa2 will not return to Earth but instead continue on an extended mission to explore another distant asteroid named 1998KY26.