The spacecraft with a precious asteroid cargo is almost home after 5 billion kilometers of travel



In the dusty desert town of Woomera in the South Australian desert, scientists are preparing. On December 6, 2020, after six years in space, the Japanese Aerospace Exploration Agency’s Hayabusa2 probe will finally return to Earth.

It carries with it an incredibly rare, precious and hard-won cargo: at least 100 milligrams of material collected from the surface of the asteroid Ryugu. It will leave the capsule containing the sample on Earth, while the spacecraft itself will continue to visit other asteroids.

The return of Hayabusa2 will mark a milestone in an extraordinary feat of space science, a total journey of approximately 5.24 billion kilometers (nearly 3.3 billion miles). The asteroid Ryugu – formerly known as 1999 JU3 – is in an elliptical orbit that carries it just within the orbital path of the Earth around the Sun and almost to the orbit of Mars.

Hayabusa2’s travel planning involved calculating where the asteroid would be in the future and plotting a path that would take the spacecraft to where it needed to go, using Earth’s gravity for bursts of acceleration.

Thus, the spacecraft had to be able to land on the asteroid twice, collect material both times, and bounce back to the asteroid, before returning to where Earth would be at the end of the return journey.

The spaceship is on that stretch of road now and the capsule collection team has arrived in Australia. Capsule recovery trials and testing of the technology that will be used to monitor the incoming capsule are underway.

Preliminary team members who have already canceled the two-week COVID-19 quarantine arrived at the Royal Australian Air Force Base in Woomera last week and began preparations for landing and recovery.

That small load is a big deal. Only one other mission successfully returned an asteroid sample. JAXA’s original Hayabusa mission to the Itokawa asteroid returned a sample to Earth in 2010, but the sampling device had failed and only a few micrograms of material was transported home.

One hundred milligrams is an sheer wealth of material in comparison, and scientists hope to be able to conduct detailed tests. Since Ryugu is a primitive carbonaceous asteroid, it is thought to have preserved some of the most pristine material in the Solar System, relatively unchanged (except for some radiation) since it formed about 4.5 billion years ago.

That small sample, scientists hope, will be able to provide some insight into the early days of the Solar System and the formation and evolution of the inner rocky planets.

The capsule is expected to descend between 3.30 and 4.30 ACDT (Australian Central Daylight Time) on 6 December 2020, creating a brilliant fireball produced by the heat of the atmospheric inlet. A special heat shield will protect the capsule from temperatures around 3,000 degrees Celsius (5,400 degrees Fahrenheit).

After deploying his parachute, he is expected to land within a 100 square kilometer (40 square mile) region within the Woomera protected area, sending a radio signal to the recovery team. Once the lighthouse lands, this signal will not be detectable by ground stations, so a helicopter will be flown over to track down the capsule.

Once located, the capsule will be flown by helicopter to a Quick Look facility. There, all the gases inside the container will be sampled, before the container is placed in a sealed transport box and flown to Japan. At that moment the next phase of the research process will really begin, as the scientists will begin the painstaking work of studying and analyzing the rock.

While most of the world won’t be able to watch the re-entry live, JAXA has released observation and photography tips for those who can and, for all, an AR app for iOS to track the capsule’s trajectory. JAXA is also considering a live stream of the capsule release and atmospheric entry.

Meanwhile, Hayabusa2’s flight will continue. Its next stop will be asteroid (98943) 2001 CC21 in July 2026, after which it will continue on asteroid 1998 KY26 for a rendezvous in July 2031.

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