Relative Navigation Schemes for Formation Flying of Satellites
Session
Session 7: Big Picture
Abstract
This paper will present a survey of relative navigation methods that can be adapted to the Virtual Telescope for X-ray Observations (VTXO) project. VTXO is a collaboration between educational institutions (NMSU, UNM) and NASA GSFC and supports NASA’s Science Technology Mission Directorate (STMD) and Science Mission Directorate (SMD). The VTXO mission is a sub-arcsecond resolution X-ray telescope that will utilize two CubeSats flying in formation. The two CubeSats will carry a lens and camera mounted on a leader and a follower, respectively. The main objective of the mission is to investigate technologies that will enable a full Virtual Telescope space mission. This mission will require very precise alignment and determination (sub-arcsecond to milli-arcsecond) to enable imaging at a higher quality than currently available. This will be made possible through relative navigation methods that enable formation flying of the CubeSats. Formation flying consists of satellites, in a constellation, that maneuver around or maintain a position relative to one another. Formation flight utilizes principles of relative navigation to resolve position and velocity telemetry relative to both an inertial frame and two or more satellites in the constellation. High precision alignment requirements call for precise knowledge of both spacecraft’s position relative to one another. In the case of a pair of satellites, a leader and follower scheme is used. The absolute position and velocity with respect to an inertial frame is determined for each vehicle using GPS, radar or other techniques that will be discussed. The relative position with respect to each spacecraft can then be resolved and corrections can be made to the follower’s attitude to align itself with respect to the leader. The technology enabled by formation flight enables smaller spacecraft to perform complex science missions such as interferometry, stereographic imaging, telescope-occulter imaging, and others. A technology driver in the development of the science for relative navigation and formation flying is the need for autonomy. As deep space exploration interest grows, the need for autonomous relative navigation systems also expands. Systems such as GPS and NASA’s DSN work well for near earth missions but do not satisfy the precision requirements needed for autonomous formation flying in deep space. The insight gained by this survey will provide valuable information for the VTXO mission where bilateral communication between the CubeSats is required for alignment. The survey of relative navigation systems will examine both developed and state-of-the-art techniques: GPS tracking, Deep Space Network (DSN), Ground station to satellite Doppler, X-ray pulsars, and others. These systems will be categorized based on the mission altitude, their nominal performance at relative distance, and their applicability to Small Satellites. These technologies will be analyzed with the context of how they can be leveraged for use on the VTXO mission.
Presentation
Relative Navigation Schemes for Formation Flying of Satellites
This paper will present a survey of relative navigation methods that can be adapted to the Virtual Telescope for X-ray Observations (VTXO) project. VTXO is a collaboration between educational institutions (NMSU, UNM) and NASA GSFC and supports NASA’s Science Technology Mission Directorate (STMD) and Science Mission Directorate (SMD). The VTXO mission is a sub-arcsecond resolution X-ray telescope that will utilize two CubeSats flying in formation. The two CubeSats will carry a lens and camera mounted on a leader and a follower, respectively. The main objective of the mission is to investigate technologies that will enable a full Virtual Telescope space mission. This mission will require very precise alignment and determination (sub-arcsecond to milli-arcsecond) to enable imaging at a higher quality than currently available. This will be made possible through relative navigation methods that enable formation flying of the CubeSats. Formation flying consists of satellites, in a constellation, that maneuver around or maintain a position relative to one another. Formation flight utilizes principles of relative navigation to resolve position and velocity telemetry relative to both an inertial frame and two or more satellites in the constellation. High precision alignment requirements call for precise knowledge of both spacecraft’s position relative to one another. In the case of a pair of satellites, a leader and follower scheme is used. The absolute position and velocity with respect to an inertial frame is determined for each vehicle using GPS, radar or other techniques that will be discussed. The relative position with respect to each spacecraft can then be resolved and corrections can be made to the follower’s attitude to align itself with respect to the leader. The technology enabled by formation flight enables smaller spacecraft to perform complex science missions such as interferometry, stereographic imaging, telescope-occulter imaging, and others. A technology driver in the development of the science for relative navigation and formation flying is the need for autonomy. As deep space exploration interest grows, the need for autonomous relative navigation systems also expands. Systems such as GPS and NASA’s DSN work well for near earth missions but do not satisfy the precision requirements needed for autonomous formation flying in deep space. The insight gained by this survey will provide valuable information for the VTXO mission where bilateral communication between the CubeSats is required for alignment. The survey of relative navigation systems will examine both developed and state-of-the-art techniques: GPS tracking, Deep Space Network (DSN), Ground station to satellite Doppler, X-ray pulsars, and others. These systems will be categorized based on the mission altitude, their nominal performance at relative distance, and their applicability to Small Satellites. These technologies will be analyzed with the context of how they can be leveraged for use on the VTXO mission.
