The Optical Profiling of the Atmospheric Limb (OPAL) CubeSat Experiment

The Optical Profiling of the Atmospheric Limb (OPAL) is a recently selected mission in the NSF CubeSat-based Science Missions for Geospace and Atmospheric Research program. The objective of the proposed mission is to understand the thermospheric temperature signatures of the dynamic solar, geomagnetic and internal atmospheric forcing. A student team, supported by professional scientists and engineers will design, build and execute the OPAL Instrument and mission. OPAL will measure lower thermospheric temperatures from 90-140 km altitude by observing the daytime O2 A-band (near 762nm) emission with a high-sensitivity, hyper-spectral limb imager. The instrument will be incorporated into a 3U Colony 2 CubeSat bus provided by the National Reconnaissance Office for launch in late 2015 with mission duration > 8 months. Two critical science questions will be answered: 1. How much do geomagnetic storms alter the temperature structure of the lower thermosphere at low- and mid-latitudes? 2. What are the temperature signatures of internal atmospheric waves in the lower thermosphere? The high-latitude region of the thermosphere responds promptly to energy inputs, relatively little is known about the global/regional response to these energy inputs. Global temperatures are predicted to respond within 3-6 hours, but the details of the thermal response of the atmosphere as energy transports away from their high-latitude source region is not well understood. This is the motivation of the OPAL mission to observe the temperature structure of the lower thermosphere at low- and mid-latitudes. Wave coupling from lower to higher altitudes in the neutral atmosphere represents key additional pathways for the flow of energy and momentum into the thermosphere. A diverse spectrum of neutral atmospheric waves exists in the Mesosphere and Lower Thermosphere (MLT) region, excited mainly by solar inputs at lower altitudes, and manifest as solar tides, planetary waves and gravity waves. Together, these waves span a broad range of spatial and temporal scales and are believed to be the major drivers of the thermospheric variability under quiet solar and geomagnetic conditions. However, direct evidence for the penetration and effects of these waves on the thermal structure of the lower thermosphere and its variability is only just emerging. Within this paper we overview the mission and science objectives of OPAL.