6-DOF AEROBRAKING TRAJECTORY RECONSTRUCTION BY USE OF INERTIAL MEASUREMENT UNIT (IMU) DATA FOR THE IMPROVEMENT OF AEROBRAKING NAVIGATION

摘要

For any interplanetary mission, there are certain types of data that are used as a means of determining both the position and velocity of a spacecraft. NASA's Deep Space Network (DSN) is employed for the purpose of transmitting and receiving data to and from the spacecraft, respectively. For this exchange of information to take place, both the DSN and spacecraft antennae must be pointed towards each other. This mutual geometry is not maintained throughout aerobraking, specifically while the spacecraft is within the atmosphere. Some spacecraft are equipped with an Inertial Measurement Unit (IMU), which typically is comprised of gyroscopes and accelerometers. The IMU provides information about the spacecraft's non-conservative acceleration and angular motion. Since the spacecraft loses telemetry during the drag pass, this research focuses upon the possibility of using IMU data as a means of augmenting the current state knowledge of the spacecraft. This knowledge could also assist in obtaining best estimates for subsequent periapse times and altitudes (integral aspect of aerobraking operations). This research focuses upon the use of the IMU data (collected during the radiometric data gap) as a means of augmenting aerobraking navigation capabilities.