Thermosphere gas and the ionospheric plasma. The International Space Station orbits the Earth within the middle of the thermosphere, between . It is convenient to separate the atmospheric regions according to the two temperature minima at about 12 km altitude (the tropopause) and at about 85 km (the mesopause) (Figure 1). The thermosphere (or the upper atmosphere) is the height region above 85 km, while the region between the tropopause and the mesopause is the middle atmosphere (stratosphere and mesosphere) where absorption of solar UV radiation generates the temperature maximum near 45 km altitude and causes the ozone layer. The density
S-1 (satellite) 4". "S-1" was the first geocentric orbit launch attempt for the rocket; its second attempt on August 14, 1959, carrying the "Beacon 2" inflatable sphere experiment to low Earth orbit, also failed. Eventually, both the Juno II and a re-launch of the "S-1" mission, designated "Explorer 7" or "S-1A", found success on October 13, 1959. The satellite, which ended its mission in August 1961, is still orbiting the Earth today. S-1 (satellite) S-1, also known as Explorer S-1 and Explorer 7X, was a geoscience satellite equipped with a suite of scientific instruments to study the environment around the Earth. The