For the first time, scientists are about to get their hands (carefully gloved) on asteroid earth so ancient that it may contain clues as to how our solar system formed and how water came to Earth.
A capsule containing two little dirt from the asteroid Ryugu arrived in Japan on December 7, where researchers will finally have a chance to measure how much has been collected. The goal of the Japanese Hayabusa2 mission was to collect at least 100 milligrams of both surface and underground material and send it back to Earth.
“Hayabusa2 is at home,” project chief Yuichi Tsuda of the Japanese Aerospace Exploration Agency or JAXA said at a news conference on Dec. 6, hours after the sample’s return capsule successfully landed in Woomera, Australia. "We picked up the treasure chest."
Ryugu is an ancient carbon-rich asteroid with the texture of freeze-dried coffee (SN: 16/03/20). Planetary scientists think it contains some of the oldest solids that have formed in the solar system, making it a time capsule in the history of the solar system.
Hayabusa2 explored Ryugu from June 2018 to November 2019 and took two samples of the asteroid (SN: 22/02/19). One came from inside an artificial crater that Hayabusa2 launched against the asteroid's surface, giving the spacecraft access to the asteroid's interior (SN: 5/5/19). On December 4, the spacecraft launched the sample's return capsule about 220,000 kilometers above the Earth's surface. The capsule created a bright ball of fire as it passed through the Earth's atmosphere.
At a "quick-look installation" at Woomera, the gases that the asteroid material may have emitted were initially analyzed. But the capsule will not open until it reaches the JAXA center in Sagamihara, Japan.
Hayabusa2 is the second mission to successfully return an asteroid sample to Earth. The first Hayabusa mission visited the stony asteroid Itokawa and returned to Earth in 2010. Engineering and logistics problems meant that its return was years later than planned and it only took 1,534 grains of asteroid material (SN: 14/06/10 ).
However, for Hayabusa2 it seems that everything went as planned. The spacecraft itself still has enough fuel to visit another asteroid, the 1998 KY26, which is smaller and spins faster than Ryugu. It will study how these asteroids formed, how they hold together, and what can happen if one collided with Earth. The spacecraft will reach that asteroid in July 2031, though it will not take any more samples.