page_title: Aeronomy of Ice in the Mesosphere
section_title: Noctilucent clouds
hierarchical_section_title: Aeronomy of Ice in the Mesosphere / Noctilucent clouds
caption_attribution_description: AIM Spacecraft in Clean Room
context_page_description: The Aeronomy of Ice in the Mesosphere is a satellite originally launched to conduct a 26-month study of noctilucent clouds. Its mission was extended, and as of 2019 is still operational. It is the ninetieth Explorer program mission and is part of the NASA-funded Small Explorer program. On April 25, 2007 AIM was boosted into a 600 km high polar orbit by a Pegasus-XL rocket, which was air-launched from the Lockheed L-1011 Stargazer aircraft operated by Orbital Sciences.
context_section_description: The noctilucent clouds AIM is to study, also known as Polar mesospheric clouds, occur in the Earth's atmosphere at high altitudes of roughly 80 kilometers (50 mi) above the surface, far higher than other clouds. The AIM mission will help determine what factors — temperature, water vapor, and dust particles — lead to the formation of these clouds. The clouds seem to be a relatively recent phenomenon: they were first seen in 1885, and lately seem to be occurring more frequently. The clouds always occur during the summer season near the poles and the Northern season always starts around the same time.  Scientists have found that the start of the Southern season can vary up to a month however.
caption: AIM in clean room
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