TETHER SATELLITE SYSTEM COLLISION STUDY
V.A. CHOBOTOV and D.L. MAINS
Center for Orbital and Reentry Debris Studies, The Aerospace Corporation,
2350 E. El Segundo Blvd., El Segundo, CA 90245-4691, USA (Tel.: (310)336-4280;
Fax: (310)336-5827; E-mail: firstname.lastname@example.org)
(Received 16 February 1999; Accepted 5 December 1999)
Abstract. A study was performed to determine the probability of collision with resident space objects and
untrackable debris for the tether component of the Tethered Satellite System (TSS) after it broke away from
the Space Shuttle orbiter (mission STS-75) in February 1996. Both an analytical and a numerical approach
were used in this study, and the results obtained with these two methods were found to be in good agreement.
These results show that the deployed tether is expected to have been impacted by several particles 0.1 mm or
larger in size. The probability of collision with objects 10 cm in size or larger was on the order of 10
month. Since the severed tether reentered within one month after deployment, the collision hazard to other
objects while in orbit was small. The analytical methods used in this study are useful for tether collision
evaluations in general.
Keywords: micrometeoroids, probability of collision with space debris, tethers, Weibull distribution
The ﬁrst Tethered Satellite System (TSS-1) mission, ﬂown in August 1992 on STS-46, gave
a limited demonstration of the ability to deploy and retrieve a satellite connected to the
orbiter with a tether and allow the current to ﬂow along the tether. A length of 268 m rather
than the planned 20 km was reached due to the difﬁculties of deploying the tether (NASA,
On 25 February 1996 the TSS-1R (STS-75) mission was ﬂown (NASA, 1996). This was
a reﬂight of the TSS-1 mission. The orbiter achieved a 296 km altitude at 28.45
and deployed the Italian-built TSS satellite radially upward from the shuttle using the same
20 km conducting tether as in the TSS-1 experiment. At 19.7 km the tether broke at the
orbiter. The satellite and the 19.7km tether moved to a 321 by 407 km altitude orbit and
achieved a gravity-gradient (along the local vertical) attitude.
Post ﬂight inspection of the tether end showed it to be charred, with an apparent ﬁnal ten-
sion failure of a few strands of Kevlar. It was established that the failure was a result of arcing
and burning of the tether. At the time of the failure, the nominal load on the tether was 65 N.
Although the damaged area of the insulation was destroyed due to burning, the evidence
from tests and analysis suggested that foreign object penetration of the insulation layer in
manufacturing or handling was the probable cause of the breach of the insulation layer.
The TSS characteristics were (NASA, 1996):
Satellite diameter 1.6 m
Satellite mass 518 kg
Space Debris 1, 99–112, 2000.
© 2000 Kluwer Academic Publishers. Printed in the Netherlands.