WELCOME

We are exploring the scientific principles of the variability and evolution of planetary atmospheres as well as exploring the unknown for human beings on planets including the Earth. Research is the pursuit of the unseen and making possible of what was impossible. We are looking forward to your participation with a strong will to challenge the unknown, with flexible ideas and creativity.　(Professor Naoki Terada)

The atmospheres of the Earth and planets are constantly being blown out into space under the influence of solar ultraviolet radiation and the solar wind (supersonic plasma flows constantly blown out of the Sun). The amount and composition of planetary atmospheres have evolved over billions of years due to the atmospheric escape into space. We are investigating this atmospheric escape using a combination of satellite and ground-based observations and numerical simulations. Ever since the Soviet Phobos-2 spacecraft, launched in 1988, observed such a large escape rate that all the oxygen in the Martian atmosphere will be lost in 100 million years, the escape of the Martian atmosphere has been an important scientific target. Japan’s first Mars exploration mission Nozomi was launched in 1998 to investigate the atmospheric escape phenomenon and the interaction processes of the solar wind with the upper atmosphere of Mars. Unfortunately, the Nozomi spacecraft was not successfully injected into Mars orbit due to a problem during its cruise. But in 2000s, geomorphological analysis and observations of hydrated minerals by European and US Mars exploration missions revealed that Mars was once covered with a large amount of liquid water in its early history.However, it is still not well understood why Mars has changed from such a warm and humid environment to the cold and dry environment today. The escape of the atmosphere into space is one of the most likely causes of this drastic environmental change. The US NASA’s Mars explorer MAVEN was launched from Cape Canaveral in 2013, with the aim of understanding the Martian atmosphere’s escape into space. Our group, in collaboration with the University of Tokyo, ISAS/JAXA, and Max Planck Institute for Solar System Research (MPS) in Germany, is participating as part of the scientific team of the MAVEN mission. We have been trying to understand the evolution of planetary atmospheres by using our original numerical codes and state-of-the-art observation methods.