NASA’s Marshall Space Flight Center in
Huntsville, Ala., is
implementing NASA’s plans for an International
Station propulsion system intended to help
maintain the
research facility’s orbit during its 15-year
mission in space.

Known collectively as the U.S. Propulsion
System, the new
system will consist of two principal elements:
a “node,” or
connective module, and at least one propulsion

Node 4, a prototype of the Node 1 connector
now in orbit,
has been tapped to serve as the connective
module. The
versatile nodes are designed to serve numerous
aboard the Space Station, providing space for
crew cabins and other facilities. Node 4 will
serve a dual role:
as the berthing location for the U.S.
propulsion module, and
also as the primary docking port for the Space

Once connected to the Space Station, at the
forward end of
Node 1, Node 4 will be outfitted with one or
two detachable
propulsion modules. These reusable components

containing fuel tanks and thrusters for
boosting the Station
into its proper orbit, maintaining attitude
control and providing
collision avoidance — are designed to be
carried back and
forth from Earth to orbit by the Space Shuttle
for refueling and

The U.S. Propulsion System will provide backup
supplementary propulsion for the Russian
service module
Zvezda, the station’s primary propulsion

The Boeing Co. — NASA’s primary contractor
for Space
Station development and construction — will
lead the U.S.
Propulsion System integration and perform
processing of
Node 4, according to Linder Metts, U.S.
Propulsion System
manager at Marshall.

Boeing is preparing for an industry
competition for
development of the propulsion module, Metts
Procurement actions are anticipated to begin
in spring of

The U.S. Propulsion System is expected to
reach orbit
aboard the Space Shuttle in June 2004.