Atmosphere of Earth and balloons, and too low to permit orbital spacecraft. The mesosphere is mainly accessed by sounding rockets and rocket-powered aircraft. The stratosphere is the second-lowest layer of Earth's atmosphere. It lies above the troposphere and is separated from it by the tropopause. This layer extends from the top of the troposphere at roughly above Earth's surface to the stratopause at an altitude of about . The atmospheric pressure at the top of the stratosphere is roughly 1/1000 the pressure at sea level. It contains the ozone layer, which is the part of Earth's atmosphere that contains relatively high concentrations of
Opus: The Day We Found Earth their planet of origin to live among the stars. By then, Earth has become a mythical planet and the belief in its existence has become a religion called "Earthology". On the other hand, the human gene pool has deteriorated after millennia of genetic engineering, and the only way to revert this damage is to trace back to the oldest sample of genes left on their long forgotten home planet. Project Earth was then founded and a spaceship named OPUS was launched in order to search for Earth and save the failing human race. The story follows a childlike robot Emeth,