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Electrodynamic Tethers for Reboost of the International Space Station and Spacecraft Propulsion

Authors:
ELECTRODYNAMIC TETHERS
FOR
REBOOST
OF THE
INTERNATIONAL SPACE
STATION
AND
SPACECRAFT PROPULSION
Les
Johnson, NASA Marshall Space
Flight
Center
Huntsville,
Alabama
Joe
Carroll,
Tether Applications Company
Chula
Vista, California
Robert
D.
Estes
&
Enrico Lorenzini, Smithsonian Astrophysical Observatory
Cambridge, Massachusetts
Brian
Gilchrist,
The
University
of
Michigan
Ann
Arbor, Michigan
Manuel
Martinez-Sanchez,
Massachusetts Institute
of
Technology
Cambridge, Massachusetts
Juan
Sanmartin,
Polytechnic University
of
Madrid
Madrid, Spain
Irwin
Vas, Boeing Space
and
Defense Company
Huntsville, Alabama
Abstract
The
International
Space
Station (ISS) will require
periodic reboost
due to
atmospheric aerodynamic drag.
This
is
nominally achieved through
the use of
thruster
firings
by the
attached
Progress
M
spacecraft. Many
Progress flights
to the ISS are
required annually.
Electrodynamic
tethers provide
an
attractive alternative
in
that they
can
provide periodic reboost
or
continuous
drag cancellation using
no
consumables,
propellant,
nor
conventional propulsion elements.
The
system could
also serve
as an
emergency backup
reboost
system used
only
in the
event resupply
and
reboost
are
delayed
for
some
reason.
The
system
also
has
direct application
to
spacecraft
and
upper stage propulsion.
Electrodynamic tethers have been demonstrated
in
space previously with
the
Plasma Motor Generator
(PMG) experiment
and the
Tethered
Satellite
System
(TSS-1R).
The
advanced
electrodynamic
tether proposed
for
this application
has
significant advantages over
previous systems
in
that higher thrust
is
achievable
with
significantly shorter tethers
and
without
the
need
for
an
active current collection device, hence making
the
system simpler
and
much
less
expensive.
Propellantless
Reboost
for the
ISS:
An
Electrodvnamic
Tether
Thruster
The
need
for an
alternative
to
chemical thruster
reboost
of the ISS has
become increasingly apparent
as
the
station
nears
completion.
We
propose
a
system
to
utilize
ISS
electrical power
to
generate thrust
by
means
of
a new
type
of
electrodynamic tether attached
to the
station (Fig.
1). A
flexible
system could
be
developed
to
generate
an
average thrust
of 0.5 to 0.8 N for 5 to
10
kW
of
electrical power.
By
comparison, aerodynamic
drag
on
755
is
expected
to
average
from
0.3 to 1.1 N
(depending upon
the
year).
The
proposed system uses
a
tether
with
a
kilometers-long uninsulated (bare) segment capable