Japanese officials say they are pleased with the quality of the asteroid (小行星) material collected by a spacecraft and returned to Earth.

Last week, officials from Japan described the samples (样品), which were collected from the Ryugu asteroid in July 2019. Ryugu sits more than 300 million kilometers from Earth. Japan’s unpiloted Hayabusa2 spacecraft removed the material after making a hole into the asteroid.

The space agency said the July 2019 mission (任务) aimed to collect samples from below the surface of Ryugu. During an earlier operation in February 2019, Hayabusa2 collected material from a different part of the asteroid. The second collection effort resulted in sample pieces as big as 1 centimeter. The black material looked similar to charcoal and was very hard. It did not break apart when picked up or poured into another container.

Earlier this month, space officials described the samples Hayabusa2 removed on its first mission as smaller, sandy pieces. They were collected from the surface of Ryugu. Hayabusa2 was launched in December 2014 and arived near Ryugu in June 2018. The Japanese space mission aims to use the samples to learn more about how our solar system formed.

To get the second set of samples in July, Hayabusa2 used an impactor to knock the asteroid’s surface. The aim was to collect material unaffected by space radiation or other environmental conditions. The size differences suggest different hardness of the bedrock of the asteroid. One possibility is that the place of the second touchdown was a hard bedrock and larger particles broke and entered the container.

Hayabusa2 is now on another mission to a smaller asteroid, called 1998KY26. The Japanese government expects the aircraft to take 11 years to reach that asteroid. Hayabusa2’s new mission aims to study possible ways to prevent large meteorites (陨石) from hitting Earth.