Form 9.B Project Summary
Chron:
970528
Proposal Number:
08.02-0400
Project Title:
The Terminator Tether: A Low-Mass
System for End-of-Life Deorbit of LEO
Spacecraft
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,
City/State/Zip)
Dr. Robert L. Forward
Tethers Unlimited, Inc.
8114 Pebble Ct.
Clinton , WA 98236