The next layer of the atmosphere is the mesosphere. This part of the earth's atmosphere is measured from 50 kilometers up to 85 kilometers above the earth. Scientists do not actually know much about it. The problem is that few instruments can be used for studying the mesosphere, given its height. Weather balloons and planes cannot fly that high. Satellites circle the earth above the top of the mesosphere. The only instruments useful at the height of the mesosphere are special rockets. Such rockets are not sent up to circle the earth but return after doing tests or collecting data.