Hayabusa2 capsule and cargo are back

A little bit of outer space is temporarily in South Australia. A team from the Japanese Aerospace Exploration Agency (JAXA) retrieved the landing capsule from its Hayabusa2 mission near the small outback town of Woomera on Sunday morning, local time.

Inside was only the second asteroid sample ever returned to Earth, and the first from beneath an asteroid’s surface.

Hours earlier the capsule had successfully detached from its mothership, re-entered Earth’s atmosphere and treated scientists and residents alike to a light show as it arced across the sky in a searing blaze.

Mission specialists then jumped into action to locate and recover the 40-centimetre-diameter capsule from the desert expanse.

The successful return is the culmination of a six-year, 5.2-billion-kilometre journey and an “historic milestone for the global space, science and research community,” says Anthony Murfett, Deputy Head of the Australian Space Agency.

You can read more about the build-up and background in Lauren Fuge’s preview story for Cosmos.

Launched in 2014, Hayabusa2 rendezvoused with the water- and carbon-rich asteroid Ryugu in 2018. It spent a year studying and sampling the 4.5-billion-year-old space rock – an ancient relic of the early Solar System – before setting course for Earth again in late 2019. 

The race is now on to return the capsule to Japan. It won’t be opened until then to avoid contamination, and if it doesn’t reach a specialised storage facility within 100 hours there is risk of the sample degrading.

Scientists estimate they have a one-gram sample of Ryugu. “One gram may sound small for some of you, but for experts, one gram is huge – it’s enough to address the science questions,” says Masaki Fujimoto from JAXA.

The fact that this sample is well-protected and sealed – and therefore uncontaminated by Earth’s organic material – is a boon for scientists. While chunks of outer space often rain down on Earth in the form of meteorites, these are unavoidably blasted and battered by the atmosphere, and are contaminated as soon as they hit the ground.

A pristine piece of asteroid – even just a single gram – may give us unprecedented insights into the Solar System.

Spectroscopic readings of Ryugu have revealed rocks containing traces of water-bearing minerals, which means the sample could hold clues about organic matter, water, minerals and how they led to planet formation.

As part of an agreement with JAXA, NASA scientists will be given 10% of the sample for study; in return, JAXA will obtain the same percentage of NASA’s OSIRIS-REx sample, which touched down on the asteroid Bennu in October and is expected to return to Earth in 2023.

This is not the end of the Hayabusa2 story, however. The spacecraft itself has enough xenon fuel left in its electric propulsion system to visit two further asteroids of interest – in 2026 and 2031.

The Royal Institution of Australia has an Education resource based on this article. You can access it here.