2018-06-27. Japan’s new asteroid probe reaches its target after 3.2-billion-kilometer journey.

posted Jul 2, 2018, 2:55 PM by Alan Gould
By Dennis Normile, Science Magazine. For GSS A Changing Cosmos chapter 7. Excerpt: SAGAMIHARA, JAPAN—After 3.5 years traveling 3.2 billion kilometers through space, Japan’s Hayabusa2 spacecraft officially arrived at the asteroid it will land on later this year to pick up surface and subsurface soil and rock samples and—hopefully—return them to Earth for analysis. The findings are expected to shed light on the materials that existed in the early solar system and the formation and evolution of planets and their arrangement. They might provide evidence for the theory that asteroids and comets are one source of Earth’s water and its amino acids—the building blocks of life. ...Next spring, Hayabusa2 will blast a crater into Ryugu using a 2-kilogram projectile with a hardened copper nose traveling at 2000 meters per second. ...Images of the impact are expected to shed light on how craters are formed on heavenly bodies. Hayabusa2 will then return to the site of the blast to collect rock samples that have not been subjected to eons of space weathering, hopefully yielding insights into the material as it was during the formation of the solar system. The craft is expected to return its samples to Earth at the end of 2020. Preliminary observations “are really thrilling,” says Seiichiro Watanabe, a project scientist at Nagoya University in Japan. The diamond-shape asteroid is about 900 meters across and rotates around its own axis every 7.5 hours or so, more slowly than other similarly sized asteroids for reasons that are not yet clear, Watanabe says. The surface is strewn with boulders larger than would be expected to have accumulated on an asteroid of its size, something that has triggered a debate among planetary scientists.... http://www.sciencemag.org/news/2018/06/japan-s-new-asteroid-probe-reaches-its-target-after-32-billion-kilometer-journey