Use of ED-Tethers for Orbit Maintenance and Deorbit - NASA GLAST Mission

Abstract

The use of electrodynamic tethers (EDTs) to support such mission needs as deorbit, drag make-up, and inclination change are evaluated for a large, 4000-5000 kg class, spacecraft in low Earth orbit for astronomical applications. We specifically evaluate the use of an EDT for NASA's planned GLAST mission. GLAST is a next generation high energy gamma-ray observatory designed for making observations of celestial gainma-ray sources in the energy band extending from 20 MeV to more than 300 GeV and is part of NASA's Office of Space and Science Strategic Plan, with launch anticipated in ,2006. The 4500-kg GLAST observatory is planned to be launched into a 28.5' inclination orbit from Kennedy Space Center by a Delta 2920-10H for a 5year mission with a goal of 10 years. End of mission deorbit of the GLAST spacecraft using an EDT is assessed against a hydrazine based approach and is found to require approximately a third of the mass. The use of a drag make-up EDT is also evaluated as a means to place the spacecraft at a lower altitude (400 vs. 550 km) to be below more of the negative effects of the South Atlantic Anomoaly (SAA) while assuring the required orbit lifetime. Chemical and electric propulsion alternatives for drag make-up are also evaluated. It is found that the EDT is the lowest mass approach. *Associate Professor, Electrical Engineering and Space Systems, AIAA Senior member

Optimizing Electrodynamic Tether System Performance

“…*** The tether widths of 30 and 35 mm were different than that of the original simulations performed by Gilchrist et al. 49 This is due to the fact that current collection differences between the varying widths are now understood better, and can be accounted for.…”

“…Unique simulations are presented to investigate the issues that were not covered in the initial simulation work by Gilchrist et al. 49 For this case study, the orbit inclination was analyzed at 5 , instead of 28.5 to reduce the time spent in the South Atlantic Anomaly (SAA) § § . A more complete simulation using different width porous tethers was also conducted using previous experimental results.…”

Benefits and risks of using electrodynamic tethers to de-orbit spacecraft

“…Various conducting tether configurations have been studied and their de-orbiting performances have been extensively assessed by several authors [2][3][4][5][6][7][8][9][10][11][12].…”

Analysis of tape tether survival in LEO against orbital debris

“…An EDT works on the basis of the interaction between the electric current flowing along the tether and the geomagnetic field, which produces a Lorentz drag force, the current being itself induced by the tether motion relative to the Earth's magnetized ionosphere; this reflects on the thermodynamic character of that interaction, always leading like air-drag, to a decrease in the relative motion of tether and ambient plasma. For more than a decade till now different studies have been carried out on various tether configurations and deorbiting performance (Forward et al, 1998;Vannaroni et al, 1999;Van der Heide and Kruijff, 2001;Ahedo and Sanmartin, 2002;Gilchrist et al, 2002;Nishimine, 2002;Pearson et al, 2003), providing a propellantless, cost-effective solution to deorbiting dead satellites as well as future satellites after their desired work-life. The bare tether concept, which has the tether bare of insulation, collecting electrons itself, has eliminated the need for a plasma contactor at the anodic end (Sanmartin et al, 1992;Sanmartin et al, 1993).…”