The "giant-impact hypothesis," a traditional model of the birth of the moon, explains the formation of the moon by the collision of a Martian-sized asteroid with the protoplanet.According to this model, it has been thought that there are no volatile substances such as water and carbon in the moon because the moon at the time of collision becomes a fireball in a high temperature state.

　However, this time, when this research group investigated the degassing material of the moon photoionized by sunlight from the observation data of the plasma mass spectrometer mounted on "Kaguya", carbon was constantly generated from the entire surface of the moon. I discovered that ions were flowing out.It is said that the regional difference (the flow from the sea in the new age is larger than the flow from the highlands) was also clarified from the estimation of the outflow amount, and even if the carbon carried from the solar wind and cosmic dust is taken into consideration, it is still originally carbon in the moon. It is said that the result cannot be explained if it does not contain.

　The discovery of carbon in this study strongly suggested that the Moon contained carbon from the time of its birth.Regarding the birth of the moon, it is considered to be a great opportunity to shift from the conventional theory (dry theory) that evaporates all volatile substances to a new way of thinking (wet theory) that allows volatile substances to remain.

　In addition, JAXA's BepiColombo / MIO (Mio) and Martian Moons eXploration (MMX), the Martian moons eXploration, are scheduled to make observations using a mass analyzer similar to Kaguya.If we can observe the ions flowing out of the moon Phobos on Mercury and Mars, it is expected to make a great contribution to the science of the solar system, such as research on the origin and evolution of each celestial body.

Paper information:[Science Advances] KAGUYA observation of global emissions of indigenous carbon ions from the Moon