2016.A.4.2. Orbit Determination for a deep-space CubeSat

Author(s)

Boris Segret (1)
Jordan Vannitsen (2)
Gary Quinsac (3)
Daniel Hestroffer (4)
Jiun-Jih Miau (2)

Paris Observatory, LESIA-ESEP, France
National Cheng Kung University, Taiwan
Paris Sciences Lettres Research University, France
Paris Observatory, IMCCE, France

Session

A.4

Keywords

Autonomous navigation

Abstract

State of progress of current studies are presented for an autonomous navigation technology at CubeSat scale, called BIRDY. The technology has been proposed in the context of an autonomous cruise from Earth to Mars, as they are many opportunities for CubeSat to Mars in the coming years. It is well adapted to a CubeSat mission that has to reach a distant target or to follow a precise path in deep-space on its own without relying on a frequent link with the Deep Space Network. The navigation consists in three steps: determining the current location on the basis of optical measurements of planets in front of distant stars, determining the need for a trajectory correction, applying the maneuver with an on-board 0.5U electric propulsion that provides both the attitude and orbit corrections. The talk focuses on the feasibility of the first step, i.e. the on-board orbit determination. Before flight a reference trajectory is computed on ground as well as the ephemeris of a selection of bodies from this reference. These data are stored on-board the CubeSat before the launch. The current algorithm is based on 4 optical measurements with two major assumptions: the shift of the actual trajectory compared to the reference one is small and the velocity of the CubeSat remains constant during the sequence of 4 measurements. The measurements are then reduced and organized in a linear over-constrained system. A problem inversion is performed according to the method of the steepest descent in order to anticipate and master the on-board computing resources. The sensitivity of this approach is analyzed for various sources of uncertainties that yields some requirements on the accuracy of the optical system and on the ground preparation of the cruise phase before flight. Eventually a discussion and a roadmap are introduced about the next steps of the studies, including alternative algorithms to relax some assumptions and alternative deep-space contexts, in the general frame of the roadmap for the BIRDY deep-space navigation technology as a whole. The BIRDY technology aims at providing a CubeSat with its navigation function with the lowest possible use of on-board resources in terms of volume, power, complexity and computation.