The first touchdown of the Hayabusa2 spacecraft on the asteroid Ryugu is scheduled for this week. If successful, the craft will take a bullet in the rock to get the samples to return to Earth.
The Japan Aerospace Exploration Agency (JAXA) is in the middle of preparing for the touchdown of the probe, and recreating the asteroid and bullets here on Earth to practice, according to a statement. This followed a delay in the planned blocking, after scientists understand that the composition of the asteroid is different from their expectations.
Japanese scientists expect to find "powdery regolith" in the asteroid, according to release. But when Hayabusa2 dropped the MASCOT and MINERVA-II1 rovers over, they found that it was actually covered in centimeters-sized gravel grain. The team delayed the touchdown of the probe to make sure their collection mechanism still works on larger grit.
Trials of researchers involved shooting a similar 5-gram ammunition from a tantalum element to a pile of gravel in a vacuum room at 300 meters per second. Fortunately, these tests have revealed that ammunition will open and release sufficient material of the right size for Hayabusa2 to gather samples.
The JAXA release declares that the team has conducted tests under the gravity of the Earth, and more rocks are released under microgravity conditions of the asteroid.
Hayabusa2 launched in 2014 to identify and collect samples the asteroid Ryugu form. It succeeded in chaos, but ultimately successful Hayabusa mission, and joined NASA's OSIRIS-REx as one of the two missions that are currently investigating asteroids up-close.
If successful, Hayabusa2 will receive three samples from the surface of Ryugu and return them to a Earth capsule in December 2020.