Spectroscopic Planet Observatory for Recognition of Interaction of Atmosphere "HISAKI" (SPRINT-A) is the world's first space telescope for remote observation of the planets such as Venus, Mars, and Jupiter from the orbit around the earth.

Venus and Earth may be called twins planet, and it recently becomes clear that three terrestrial planets in the solar system including Mars have very similar environment in the beginning era of the solar system. However, in three planets, which could be called the brothers, during the finite period within one billion years after the birth of the solar system each environment evolution of growth and change results into the different and specific current state. At Venus, it became the very dry atmosphere consisting mainly of carbon dioxide as a result that water ran away to outer space, and it is now the scorching world where the temperature of its surface reaches 400 degrees Celsius by the strong greenhouse effect. On the other hand, in Mars, most of atmospheric carbon component producing the greenhouse effect run away to outer space, and it is now in the chilly world.