Scientists have discovered all five nucleobases (adenine, guanine, cytosine, thymine and uracil), the molecular building blocks of DNA and RNA, in samples from asteroid Ryugu. The samples were collected by Japan's Hayabusa2 spacecraft, which landed on the asteroid in 2019 and returned around 5.4-gram of material to Earth in 2020. It's the second asteroid confirmed to carry all nucleobases.