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Science & Technology
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Feature: Noctilucent Clouds, Comets, and Meteor Showers
During summer months, observers at high northern latitudes may be treated to a rare atmospheric phenomenon. Just after the sun has dropped below the horizon and the sky begins to darken, look west and you may be able to see Noctilucent or "Night Shining" Clouds. Also called PMCs (Polar Mesospheric Clouds), these apparitions are a bit of a puzzle for scientists because it is not entirely clear how they form.
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Guidance, Navigation, and Control Technology Assessment for Future Planetary Science Missions Part III, Surface Guidance, Navigation, and Control
This document-Part III, Surface Guidance, Navigation, and Control-is the third, and last, in a series of technology assessments evaluating the capabilities and technologies needed for future missions pursuing SMD PSD's scientific goals.
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