Atmospheric Research with the Small Expendable Deployer System: Preliminary Analysis

Data on the structure of the lower thermosphere are extremely limited because of the inaccessibility of this region to research vehicles. Downward-deployed tethered satellites can provide access to this region of the atmosphere. A preliminary analysis of the potential use of the end mass of the Small Expendable Deployer System as a scientific platform for atmospheric and aerothermodynamic research is presented. To this end, the deployment and attitude dynamics of the end mass during the first mission have been numerically simulated. It is shown that measurements of the atmospheric mean density with the end-mass onboard accelerometers can be performed only in a short time interval around the orbit perigee; in addition, the analysis of the payload attitude dynamics shows the need for attitude control. A preliminary analysis of end-mass attitude control techniques is then performed. Results show that the stringent attitude control requirements can be satisfied by active control devices