Six years ago to the month, the Japanese Space Agency (JAXA) launched one of the most ambitious exploration missions ever conceived. The Hayabusa2 set out for the far reaches of space to rendezvous with, observe, contact, and return samples of the asteroid Ryugu to Earth.
The spacecraft stirred up and captured dust and small pebbles from Ryugu’s surface into its sealed container in 2019. That container landed in the Australian desert earlier this week and has been shipped to Japan for study.
Ryugu makes sense for earth-bound scientists to want to study. Asteroids, along with comets, are thought to be rubble left over from the formation of planets in the early solar system. Discovered in 1999, Ryugu is a near-Earth object, or NEO, that crosses our orbit. Hayabusa2 first approached the space rock in 2018, four years after its launch, and found a diamond-shaped body lurking in the dark.
Asteroid 162173 Ryugu is a diamond-shaped space rock visited by the Japanese spacecraft Hayabusa2, which took a sample from the asteroid’s surface to return to Earth. This material will help scientists better understand the origins of the solar system and, possibly, life on our planet.
Ryugu was discovered in 1999 by the Lincoln Near-Earth Asteroid Research (LINEAR) project, a collaborative, U.S.-based project to catalogue and track space rocks. The Japanese space agency, JAXA, estimates the asteroid to be about 2,952 feet (900 meters) in diameter (other scientists have calculated the asteroid to be slightly smaller). Ryugu is orbiting the sun between Earth and Mars and occasionally crosses Earth’s orbit, which means the space rock is classified as “potentially hazardous,” though the body poses no imminent danger to our world. As it soars through space, the asteroid spins around like a top, rotating every 7.6 hours, according to JAXA.
It made contact with Ryugu and collected the sample in February 2019 in a perfect landing.
As the probe gently touched down, a bullet fired into the surface, kicking up sand, pebbles and fragments of rock into a collection chamber, called a sampler horn. Had this failed, the horn has teeth that can lift surface material to the probe as a back-up method.
Yuichi Tsuda, the mission’s project manager, later confirmed at a press conference that the sequence for the projectile firing to collect samples had happened as planned, but they await confirmation that there is material in the sampler horn.
Both the name given to the asteroid and the spacecraft that visited it are taken from Japanese mythology. Ryugu means “dragon palace” and according to Japanese folklore, a fisherman visits the dangerous lair and escapes with a mysterious box. The spacecraft’s name, “hayabusa,” means “peregrine falcon.” The spacecraft had to dive in, much like its namesake, to capture about a tenth of a gram off the asteroid’s surface and whisk it away.
That such a complex mission has now succeeded demonstrates just how far we’ve come in the span of a little over a century — from the first flight at Kittyhawk to landing humans on the moon to sampling an asteroid more than 200 million miles from home and bringing a little bit of it back.
Scientists in Japan have opened the sample, which left them “speechless.” The spacecraft managed to pick up both physical and gaseous samples, and more of the former than expected.
Scientists at the Japanese space agency JAXA on Tuesday removed the screws to the capsule’s inner container, having already found a small amount of asteroid dust in the outer shell.
“When we actually opened it, I was speechless. It was more than we expected and there was so much that I was truly impressed,” said JAXA scientist Hirotaka Sawada.
“It wasn’t fine particles like powder, but there were plenty of samples that measured several millimetres across.”
This sample is the second taken from an asteroid and returned to Earth. Previously, the first Hayabusa mission returned a sample of the asteroid Itokawa in 2005. The tiny samples returned from that mission revealed the early solar system was a very violent place. Itokawa itself had undergone collision, destruction, and re-formation.
One 4.5 billion year old pattern shows crystallization from intense heat. At this time period, Itokawa was part of a larger asteroid. The second pattern indicates a collision with a meteor about 1.3 billion years ago. Another pattern was formed by exposure to the solar wind between 1 million and 1,000 years ago. A fourth pattern detected by scientists shows that the particles have been rubbing against each other.
The team has concluded that Itokawa didn’t always exist in its current shape and form. When it was formed over 4 billion years ago, it was about 40 times bigger than it is now. That parent body was destroyed, and the researchers think that Itokawa re-formed from fragments of the parent body.
The sample Hayabusa2 collected is much larger and includes gaseous material. What it will teach us awaits testing in labs belonging to JAXA, NASA, and other organizations.
Coincidentally, the sample of Ryugu returns the same month China has become the third nation to return samples of the Moon to Earth. Its Chang’e 5 mission successfully landed on the lunar surface, scooped some moon rocks and dust, and returned them to Earth this week. The samples have yet to be tested.
As demonstrations of technology go, it’s clearly an advantage to the allies. China landing a robotic mission on the Moon is one thing; landing on and sampling an asteroid millions of miles away is quite another. Earthlings have had moon rocks in labs for decades. There’s even a moon rock you can touch at the National Air & Space Museum in Washington.
The allied advantage won’t last forever. China is planning manned missions to the Moon and the eventual construction of a lunar base. So is the United States, unless Joe Biden changes NASA’s focus away from exploration, as President Barack Obama did, and toward environmental and political missions.