Electromagnetic Formation Flight for Multisatellite Arrays

Abstract

The use of propellant to maintain the relative orientation of multiple spacecraft in a sparse aperture telescope such as NASA's Terrestrial Planet Finder (TPF) poses several issues. These include fuel depletion, optical contamination, plume impingement, thermal emission, and vibration excitation. An alternative is to eliminate the need for propellant, except for orbit transfer, and replace it with electromagnetic control. Relative separation, relative attitude, and inertial rotation of the array can all be controlled by creating electromagnetic dipoles on each spacecraft, in concert with reaction wheels, and varying their strengths and orientations. Whereas this does not require the existence of any naturally occurring magnetic fields, such as the Earth's, such fields can be exploited. Optimized designs are discussed for a generic system and a feasible design is shown to exist for a five-spacecraft, 75-m baseline TPF interferometer. NomenclatureA c = conductor cross-sectional area a = coil radius c = conductor current density c 0 = constant defined in Eq. (8) i = current J = mission efficiency metric l c = conductor length m coil = electromagnetic coil mass m em = electromagnetic mass m sa = solar array mass m sys = total system mass m tot = total spacecraft mass m 0 = core bus and payload mass n = number of coil turns P = power P w = solar array specific power p c = conductor resistivity R = resistance r = conductor radius s = array baselinë x = spacecraft acceleration γ = mass fraction of total electromagnetic mass η = amp turns µ 0 = permeability of free space ρ = coil density = relative mission efficiency ω = rotation rate

An LMI-based decoupling control for electromagnetic formation flight

“…Most pioneering research works on EMFF were conducted by the MIT Space Systems Lab and the University of Tokyo [1][2][3][4][5][6] . These studies focused on the benefits, challenges, dynamics, magnetic dipole determination and hardware technology associated with experimental results.…”

Satellite formation flight and realignment maneuver demonstration aboard the International Space Station

“…Assuming identical satellites is certainly reasonable as collectors in a formation serve the same purpose. The rotating maneuver of the formation follows the standard trajectory for Michelson interferometers ( [3]), while symmetric distribution around a center corresponds to optimal configurations such as Golay or Cornwell arrays ( [4]). Since these configurations have some sort of axial symmetry, most results pertaining to circular configurations are trivially generalizable by treating the Golary or Cornwell array as a set of smaller arrays arranged on concentric circles.…”

Adaptive Terminal Sliding Mode Control of Electromagnetic Spacecraft Formation Flying in Near-Earth Orbits

“…Elias et al [12] designed a linear optimal controller based on the linearized dynamics. Kong et al [13] addressed the use of electromagnetic dipoles for relative position and orientation maintenance as needed for the terrestrial planet finder (TPF). Reference [14] derived the dynamics of an N-spacecraft EMFF (in 2D) for deep space missions and discussed a nonlinear control law using potential functions.…”