ASTRA personnel are involved in the interpretation of GRACE accelerometer data to investigate thermospheric density variations. These density variations are not well understood, and can vary by 100% along a single satellite orbit. Although the GRACE mission is designed to improve our specification and understanding of Earth’s gravity field, the highly sensitive accelerometers on each satellite provide data that can be analyzed to obtain thermospheric density and winds. The largest densities occur at high latitudes during geomagnetic activity.
The Global UltraViolet Imager (GUVI) onboard NASA’s TIMED satellite performs extended scans across the earth’s disk and onto the limb, proving a wealth of valuable data on the atmosphere. ASTRA personnel have been involved with the GUVI project since its inception. We are focused on interpreting the column integrated O/N2 data from the dayside disk, together with the composition and temperature profiles on the limb.
ASTRA is working to understand thermospheric neutral density variations for Earth and Mars via modeling and data analysis. On both planets, thermospheric density is important because of its effects on satellites. Changes in the density of the neutral atmosphere create variable satellite drag, adversely affecting missions like maneuver planning, re-entry prediction, collision avoidance, risk analysis, and identification and tracking of objects in space using narrow field-of-view sensors.
ASTRA regularly conducts scientific investigations of the state of the ionospheric (and plasmaspheric) plasma and are working to understand how the ionosphere responds to changes in the inputs and coupling mechanisms which therefore will improve the understanding of the underlying physics. The electron density is one of the most copiously observed ionospheric state variables and is one of the primary responses to the physical drivers and interactions that govern the solar, magnetosphere, ionosphere coupling and dynamics.
ASTRA is using a combined analysis of modeling (TIME-GCM) and data assimiliation (AMIE, IDA4D) to improve predictions of high latitude conductances, ExB drifts, and field-aligned currents (FAC). Field-aligned currents are the connections that close theelectrodynamic circuitry between the potential (current) drivers in themagnetosphere and the resistance (conductance) in the ionosphere. Therefore, an improved specification and understanding of field-alignedcurrents will allow an improved understanding of the electrodynamicprocesses in the magnetosphere and ionosphere and the role FAC plays inMagnetosphere-Ionosphere coupling.