How much miles does the mesosphere extends above the earth's surface?

The Aeronomy of Ice in the Mesosphere (AIM) satellite mission is exploring Polar Mesospheric Clouds (PMCs), also called noctilucent clouds, to find out why they form and why they are changing.

The AIM mission has been extended by NASA through the end of FY12. During this time the instruments will monitor noctilucent clouds to better understand their variability and possible connection to climate change. Individual instrument data collection status, as well as spacecraft and instrument health, will be monitored throughout the life of the mission and reported periodically on this earth

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