Tether Missions

With the fundamental concepts of tethers in mind it is illustrative to examine the actual uses of tethers in space to date. The following table provides a brief overview of each mission, the goal, and degree of accomplishment.

Mission Year Scientific Goal Results

Gemini 11,12 1966 Investigate use of tethers for manned spacewalks. Tethers up to 100 ft provided safety and life support.

Oedipus 1989, 1995 Observation of various space plasma phenomena including weak magnetic fields. 958 m deployment length for Oedipus-A while 1170 m length on Oedipus-C.

TSS-1 1992 Demonstration of gravity-stabilized deployment of tethers from the space shuttle for scientific research. Deployed 268 m before the reel jammed. However, favorable demonstration of stability during twenty hours of operation.

SEDS-I 1993 Demonstration of long tether deployment. Successfully deorbited a 25 kg payload with a 20 km tether.

PMG 1993 Experiment to determine the ability to generate power or thrust through interaction with the surrounding plasma field. Employed a 500 m tether. Successful reversal of current flow between power generation and thrust generation modes.

SEDS-II 1994 Studied the controllability and survivability of a long tether in space. Successful stabilization of the tether within 10° of the vertical. Also highlighted the micrometeoroid risk as the tether failed after an impact five days into the mission.

TSS-1R 1996 Exploration of the interaction between a conducting tether and the Earth's magnetic field, and surrounding plasma. Deployed 19.7 km before the tether failed due to an electrical arc. Confirmed the large EMF potentials possible at orbital speeds.

TiPS 1996 Examined the dynamics and long duration survivability of a tether in space. Longest duration of a space tether-still in orbit as of 2000.

AteX 1998 Investigate tether control. Deployment failed ending the mission.

Many of the missions provide encouragement by confirming the basic theories regarding space tethers, especially with regards to power generation and passive propulsion. Despite this fact, tether missions have also demonstrated the difficulty in deploying extremely long tethers, as half of the missions encountered tether failures. Additionally, ongoing safety concerns have severely limited the use of tethers. Should the tether fail a few kilometers away from the shuttle or other manned spacecraft, the resulting recoil and entanglement poses a significant risk. Hopefully new developments, like the mesh tether, will allow for additional research missions in the future.
MEMS Research Mission

Mission	Year	Scientific Goal	Results
Gemini 11,12	1966	Investigate use of tethers for manned spacewalks.	Tethers up to 100 ft provided safety and life support.
Oedipus	1989, 1995	Observation of various space plasma phenomena including weak magnetic fields.	958 m deployment length for Oedipus-A while 1170 m length on Oedipus-C.
TSS-1	1992	Demonstration of gravity-stabilized deployment of tethers from the space shuttle for scientific research.	Deployed 268 m before the reel jammed. However, favorable demonstration of stability during twenty hours of operation.
SEDS-I	1993	Demonstration of long tether deployment.	Successfully deorbited a 25 kg payload with a 20 km tether.
PMG	1993	Experiment to determine the ability to generate power or thrust through interaction with the surrounding plasma field.	Employed a 500 m tether. Successful reversal of current flow between power generation and thrust generation modes.
SEDS-II	1994	Studied the controllability and survivability of a long tether in space.	Successful stabilization of the tether within 10° of the vertical. Also highlighted the micrometeoroid risk as the tether failed after an impact five days into the mission.
TSS-1R	1996	Exploration of the interaction between a conducting tether and the Earth's magnetic field, and surrounding plasma.	Deployed 19.7 km before the tether failed due to an electrical arc. Confirmed the large EMF potentials possible at orbital speeds.
TiPS	1996	Examined the dynamics and long duration survivability of a tether in space.	Longest duration of a space tether-still in orbit as of 2000.
AteX	1998	Investigate tether control.	Deployment failed ending the mission.