Man in the Loop—Benefits of the ISS Platform for Characterizing Low-Light Visible Observations from the Suomi NPP Day/Night Band

On 28 October 2011, the Suomi National Polar-orbiting Partnership (NPP), first in a series of next-generation U.S. operational environmental satellites constituting the Joint Polar-orbiting Satellite System (JPSS), launched successfully into a 1330 sun-synchronous orbit. The five earth-observing sensors (VIIRS, CrIS, ATMS, OMPS, and CERES) carried on board Suomi-NPP offer dramatically improved analyses for NOAA's operational weather forecasts and continuity to NASA's research in climate change, the earth's energy budget, and the global cycling of water and carbon. Perhaps the most novel and promising among the new sensor technologies is the Visible/Infrared Imager/Radiometer Suite (VIIRS) Day/Night Band (DNB) sensor, which provides the unique ability to sense extremely low-levels of visible light emission and reflected moonlight at night. The 742 m resolution DNB data, with on-board calibration, 14-bit radiometric resolution, and sensitivity to signals more than 100 times fainter than reflected moonlight, offers a paradigm shift in capability to the heritage low-light sensors that have flown for over 40 years on the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS).

Over the years, low-light visible observations have revealed several unexpected and fascinating new capabilities. The first satellite-based (DMSP/OLS) characterization of a bioluminescent Milky Sea, reported by a merchant vessel offshore of Somalia in 1995, not only justified centuries of mariners' accounts, but also expands possibilities for a new frontier of research. More recently, the discovery that the VIIRS/DNB has sufficient sensitivity to detect sources of airglow and reflected starlight broadens the scope of utility for low-light visible measurements and suggests a 24-hour visible-based weather monitoring capability is within reach. Due to the extremely low levels of light involved, however, much remains unknown about many of the features observed. Such analyses would no-doubt benefit greatly from having a top-down human-assisted perspective. Here, the potential of International Space Station (ISS) coordination to provide better insight via both qualitative confirmation and supporting observations is very high.

Here we present a high level review of selected low-light visible sensing capabilities from the new Suomi NPP/VIIRS DNB, including examples of the new airglow/starlight imaging capability. The latter findings prompted communications with NASA Johnson Space Center, and ultimately an introduction to NASA astronaut Donald Pettit and interactions while he was deployed on the ISS. Ground track intercepts between Suomi NPP and the ISS were provided with the design of conducting of opportunistic co-located measurements. We consider mechanisms for possible on-orbit coordination, including ISS-implemented space photography techniques such as the barn-door tracker technique and specialized nighttime cameras which may provide an ability to observe airglow wave patterns atop thunderstorms, or limb photography to confirm synoptic-scale airglow structures. A goal is to stimulate discussion and additional ideas from the community on how ISS can help confirm the occurrence and spatial extent of various features detectable by next-generation low-light environmental sensors.