Millimeter-Wave Band Monitoring Observationsof the Planetary Middle Atmospheres of the Solar System with 10m Single-dish Ground Based Telescope.

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Solar activities such as solar winds, solar flares, solar proton events have affected the environments and evolutions of planetary atmospheres. To further understand the habitable zone and atmospheric physical and chemical balance of solar and extra-solar planets, it is important to study the influence of activities of our Sun, which is a typical G-type star, on the atmospheres of Venus and Mars as well as of Earth. In order to study the relationship between solar activities in the atmospheric environments and climates of solar planets we started a long-term and regular monitoring observation project, SPART (solar planetary atmosphere research telescope), in 2011 by launching a single dish ground-based 10m-telescope. This is the utilization of the heritage of the Nobeyama Millimeter Array. The planetary middle atmosphere, which plays an important role in controlling the atmospheric environment of a planet, is sensitive to such activities because of its moderately low density. CO2is the main component in Mars and Venus's atmosphere. CO is formed from CO2basically by a photo-dissociation process owing to solar UV - X-ray radiation and incident high energy particles produced by solar flare events like coronal mass ejections. By the 115 GHz band monitoring heterodyne spectroscopies with SPART, we found that in Venus the CO mixing ratio at the altitude of around 80 km has decreased possibly for the past thirty years