Form 9.B Project Summary



Proposal Number:


Project Title:

The Terminator Tether: A Low-Mass

System for End-of-Life Deorbit of LEO


Technical Abstract (Limit 200 words)

The Terminator Tether will utilize propellantless

electrodynamic tether drag to provide a low-mass

means of removing LEO spacecraft from orbit at

the end of their operational lifetimes to prevent the

build-up of orbital debris. The Terminator Tether

will be a small autonomous package that is attached

to a spacecraft before launch. When the satellite

fails, or is no longer needed in orbit, the system will

deploy a conducting tether weighing a small

percentage of the spacecraft mass. This tether will

interact with the Earth's magnetic field, generating

a voltage along the tether. The induced voltage will

drive a current along the tether. The interaction of

the current with the geomagnetic field will generate

a force opposed to the spacecraft's orbital motion.

This drag force is sufficient to deorbit the

spacecraft within several weeks or months,

compared to decades or millennia for atmospheric

drag alone. The SBIR effort will develop innovative

concepts for lightweight subsystems for deploying

survivable conducting tethers, controlling the

dynamics of the tether, and emitting electrons from

the negative end of the tether. These innovations

will enable the Terminator Tether to provide a rapid

deorbit method that requires significantly less mass

than a conventional rocket system.

Potential Commercial Applications (Limit 200 words)

The Terminator Tether will find commercial

applications on every satellite and upper stage

placed into orbits between 500 and 1500 km

altitude. Within the next decade, the number of

satellites in LEO will grow rapidly. Unless these

spacecraft are removed from LEO at the end of

their lifetimes, LEO will soon become filled with

derelict spacecraft and orbital debris. The standard

method of deorbiting a satellite is to use rockets.

This method, however, requires that a large fraction

of the satellite launch mass be allocated for deorbit

propellant. Moreover, it requires that the rocket

and guidance systems be functional. The

Terminator Tether can provide rapid deorbit while

requiring only a small percentage of the launch

mass, maximizing the amount of payload mass that

can be used for transponders and stationkeeping

propellant. In addition, it can deorbit satellites even

after the satellite's power and attitude control

systems have failed. Commercial potential is

demonstrated by the fact that Teledesic has

expressed a strong interest in using the Terminator

Tether on their satellites and dispensers, a launch

system company has offered free test flights worth

$4,500,000, and an investment group has expressed

interest in providing $2,000,000-$5,000,000 in

Phase III funding.

Name and Address of Principal Investigator (Name,

Organization Name, Mail Address, City/State/Zip)

Dr. Robert P. Hoyt

Tethers Unlimited, Inc.

1917 NE 143rd St.

Seattle , WA 98125-3236

Name and Address of Offeror (Firm Name, Mail Address,


Dr. Robert L. Forward

Tethers Unlimited, Inc.

8114 Pebble Ct.

Clinton , WA 98236