Numerical Simulations on the Tether Deployment including an Attitude Motion of the Mother Satellite

Paper number

IAC-06-C1.P.3.01

Author

Mr. Shoichi Yoshimura, Japan Aerospace Exploration Agency (IAT/JAXA), Japan

Year

2006

Abstract

An in-house study is being carried out on the on-orbit verification test of the electrodynamic tether(EDT) system for the debris mitigation. As a probable mother satellite of 50 kg sub-satellite, the second stage(3400 kg) of H2A launching vehicle is assumed after inserting an H2 Transfer Vehicle(HTV) into the mission orbit. 
In this study, the deployments of the 5 km/10 km-long conductive tethers before the passage of an electric current have been numerically simulated in the Earth’s gravitational field including J2 term, provided that an attitude motion of the mother satellite is disturbed by the reaction of the sub-satellite release in the event of a malfunction of the attitude control system. In the simulation, an oscillation-damping tension control law and the following station keeping tension control law have been applied.
The mother satellite is modeled as a rigid body, sub-satellite as a point mass, and tether as a massless hinge. The EDT system attached location is specified with respect to the body-fixed frame [Xb, Yb, Zb] of the mother satellite: Yb is a pitch axis(nominally normal to the orbital plane), and Zb is a minimum principal moment of inertia axis(nominally local vertical direction).
The main parameters are: the ejection force Fe (square pulse of 0.5 sec. duration) and the reeling-out friction Trf : (1) Fe =150 N(target ejection velocity Ve =1.5 m/s), Trf =0.08 N, and for conceivable larger Trf, (2) Fe =200 N(Ve =2.0 m/s), Trf =0.10 N, for both 5 km and 10 km deployments. The EDT system attached location coordinates in meters are: (a) [0, 0, 5], (b) [1, 0, 5], and (c) [2, 0, 5]. 
An angle that the tether line makes with Zb axis, relative angle, the angular distance between the in-orbital-plane libration angle of the tether line and the pitch angle, is introduced to evaluate the possible contact of tether line with the surrounding equipment or fuselage of the mother satellite. 
For the 5 km deployment, the relative angle in the case of (a) varies in the moderate range throughout the deployment and station keeping, and in rather wide range in the case of (b), but in the very wide range of up to near 90 deg. in the case of (c).  For 10 km deployment, similar tendencies in the relative angle histories have been observed. 
The results would be useful to decide on the location for EDT system attaching, although not arbitrarily, considering the worst event of a malfunction of the attitude control system. 

Abstract document

IAC-06-C1.P.3.01.pdf

Manuscript document

IAC-06-C1.P.3.01.pdf (🔒 authorized access only).

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