The best gift of this holiday season came in a small package, parachuted from far within our solar system in the Australian desert on December 5, 2020.
Inside, astronomers were delighted to unpack the first significant samples from a rocky asteroid that is currently 9 million kilometers (5.6 million miles) away, returning to Earth in “perfect” shape.
Photos of the pristine pebbles have finally been released, and while the tiny, black-colored grains inside may look like nothing more than dirty coal, this galactic gift is hardly a rebuke. It’s the culmination of a five-year journey that requires careful planning and execution.
The samples were originally collected by the Hayabusa2 mission in Japan, which was sent to circle and sample the diamond-shaped asteroid Ryugu, following the success of its first mission.
The samples from asteroid Ryugu in the re-entry capsule weigh approximately 5.4 g! This is much higher than the target yield of 0.1 g (the amount needed for the initial scientific analysis) established during the design of Hayabusa2.
(Article in Japanese: https://t.co/IZFGinhuFc)– HAYABUSA2 @ JAXA (@ haya2e_jaxa) December 18, 2020
The first Hayabusa spacecraft returned from the asteroid Itokawa in 2010 with the first direct sample of an object near Earth. All told, the surface material weighed less than a milligram, and yet that was still enough to provide crucial information about the asteroid’s age and geological history.
The new samples from Ryugu – collected last year – date even further and contain more material than astronomers could have hoped for, at about 5.4 grams.
The name Ryugu refers to a magical underwater ‘dragon palace’ in Japanese folklore, in which a fisherman is offered a mysterious box to take home – much like Hayabusa’s sealed capsules.
The hoard in this case is believed to be over 4.5 billion years old – a relic of our early solar system, which contains potentially ancient material that once formed our sun and its orbiting planets.
By opening the carefully sealed chambers, astronomers have found many particles larger than a millimeter. The ones in Room C were slightly larger than the rest and were collected from the second landing of the mission.
Sample collection chamber A, collected by an optical microscope. (JAXA)
Because this landing occurred slightly north of a crater deliberately made earlier in the mission, researchers expected the sample to contain chunks of underground material. That would be quite an achievement, since all the other asteroid samples collected in space are only coming from the surface.
Before these direct samples, most of our knowledge on the subject of asteroids came from meteorites, which are asteroids or comets that land on Earth’s surface.
Unfortunately, without the protection of a man-made capsule, much of that material is destroyed or polluted by our planet’s atmosphere upon entry, not to mention all the weathering that occurs once these rocks come to rest on the ground.
Ryugu is a C-type asteroid, which means that the rock is very porous and contains a lot of carbon and water. Astronomers suspect that this particular pile of dark debris formed billions of years ago, when it broke off another large chunk of rock somewhere in the asteroid belt between Mars and Jupiter.
Because the surface of Ryugu looks unusually dry and shows a red color, some experts believe it once flew closer to the sun.
Yet not all of the material collected in these containers is so primordial. One of the capsules contains a clear anachronism (pictured below).
Sample collection chamber C, collected by an optical microscope. (YESA)
“Artificial material appears to be present in room C,” said a press release from the Hayabusa2 project.
“The origin is being investigated, but a likely source is aluminum scraped off the spacecraft’s monster horn when the projectile was fired to agitate material during landing.”
Later, one Updating Twitter said the object was still unconfirmed, but it may have been separated from the sampler horn used during the collection.
Curation work for the Ryugu monster is progressing steadily. On December 21, sample collection chambers B & C were opened and then the contents of chamber A & C were moved to the collection containers in the photo. The largest particles in chamber C are about 1 cm! pic.twitter.com/yWO15cKhG9
– HAYABUSA2 @ JAXA (@ haya2e_jaxa) December 24, 2020
Scientists have already begun to analyze these new samples, including some gas trapped in the capsules that is believed to have also collected on Ryugu’s surface.
If researchers are correct, it is the world’s first gas sample to be returned from deep space.
Very present.