Persistent Multispectral, Day–Night Imaging of the Arctic from a Highly Elliptical Orbit

Persistent satellite observations are essential for monitoring and understanding Earth's environmentally sensitive and rapidly changing Arctic region. This paper describes compact wide field of view imagers onboard satellites in a highly elliptical orbit (HEO) that would stare at the Arctic and collect multispectral, high dynamic range visible and near-infrared imagery with sensitivity similar to the VIIRS Day Night Band (DNB). These HEO Day-Night Imagers (HDNIs) would provide high contrast imagery through the long polar night with dynamic range that extends from the brightest clouds, ice, and snow to reflected moonlight from open water, thereby enabling cloud/ice/sea surface discrimination even under very low light and low thermal contrast conditions. Rapidly refreshed HDNI data would result in frequent updates to key environmental products such as cloud imagery, cloud microphysical properties, ice and open water distribution including real-time maps of where leads are opening and new ice is forming, vector ice motion and vector polar winds from cloud motion. HDNI approaches described in this paper offer a number of advantages over scanning sensors currently used in geosynchronous orbit, including significantly smaller size, lighter weight, better sensitivity and more rapidly updated imagery. These imaging systems could also incorporate anamorphic image stretching to provide near uniform spatial resolution across their full field of view and zoom lenses to maintain nearly constant ground resolution from different positions along their orbit. HDNIs would provide unique information on the dynamic Arctic environment, improving weather forecasting (vector wind, cloud microphysics), and routine monitoring of natural disasters (e.g., volcanoes) and ice conditions with higher-contrast and higher-resolution imagery than available from existing and planned infrared sensors. The compact sensor design makes it ideal for deployment as a hosted payload.