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Bulletin Bulletin
NASA's Space Environments and Effects Program
Fall 1997 Issue
Developing Tomorrow's Space Technologies Today
Bulletin
Bulletin
SEE
NASA Participation in Space Technology Research Vehicle
ith the current trend of the
smaller, better, cheaper,
faster philosophy,
spacecraft systems are
increasingly using
commercial off-the-shelf (COTS)
technologies for satellite applications. The
feature size of these modern
microelectronics continually decreases
while the component density increases.
These practices increase the radiation
sensitivity, causing concerns for attaining
reliable performance of the electronics.
In the last 25 years, numerous spacecraft
anomalies have been attributed to effects
from radiation. Only flight experiments
can provide the necessary data to improve
the predicted performance capabilities for
future missions. The Space Technology
Research Vehicle-1d (STRV) mission
contains specific flight experiments to
better understand the space radiation
environment and its effects on the
electronics. The objectives are to provide
low-cost access to space for flight
validation of microelectronic devices and
to develop validation protocol/test
matrices to minimize the uncertainties
between ground radiation test results and
space results.
The United Kingdoms Defense
Evaluation and Research Agency
(DERA) will launch the STRV-1d on an
Ariane-5 launch vehicle early in 1999,
corresponding to solar maximum which
occurs every 11 years. It will have a fully
operational life of 1 year. The satellite
will be delivered to an elliptical orbit,
with perigee at 620 km and apogee at
36,000 km, an inclination of 7 degrees,
and an orbital period of about 10.5 hours.
This is an especially harsh orbit in terms
of radiation. During each orbit, it will
pass through the Van Allen Belts, which
consists of a trapped proton region and an
inner and outer electron belt. The charged
particles in these belts cause serious
problems for satellite operations.
NASA is preparing 5 flight
experiments to fly aboard the STRV-1d
mission to evaluate the effects of the space
radiation environment on electronics.
These 5 experiments comprise the NASA
Space Radiation and Electronics Testbed
(NASRET). NASAs Space
Environments and Effects (SEE) program,
managed by the Marshall Space Flight
Center, is leading this effort with major
participation from:
National Aeronautics and Space
Administration Headquarters (NASA HQ) Goddard Space Flight Center (GSFC) Jet Propulsion Laboratory (JPL) Langley Research Center (LaRC) Aerospace Corporation
The NASA experiments, among
others, will be located on the Electronics
Test Bed (ETB), which is being developed
and integrated by the Ballistic Missile
Defense Organization (BMDO). The goals
of the ETB are to reduce size, weight,
power, cost, and production time for future
spacecraft as well as to increase their
reliability. This will be achieved by
collecting flight data and ground test data
for advanced and COTS microelectronic
components and collecting on-orbit
ionizing radiation environment data.
Flight and ground data will be used to
improve single event effects rate
continued on page 4
Contents
NASA Participation in Space
Technology Research Vehicle ... 1
1997 Spacecraft Contamination &
Coatings Workshop .................... 2
Design Guidelines for Shielding
Effectiveness, Current Carrying
Capability, and the Enhancement
of Conductivity of Composite
Materials (NASA CR 4784) ......... 2
Meteoroid and Debris Database 3
Definition Phase for International
Space Station Environmental
Monitoring Package .................... 5
Recent Website Additions ......... 6
Coming in Next Issue ................. 6
Bulletin Subscribers
If you have moved, changed E-
mail addresses, etc., please
inform the SEE Program
Coordination Office so we may
update our database. You may
do this by E-mailing Billy
Kauffman:
billy.kauffman@msfc.nasa.gov NASA's Space Environments and Effects Program
Fall1997 Issue

2
1997 Spacecraft
Contamination & Coatings
Workshop
Philip Chen, Goddard Space Flight Center
The 1997 Spacecraft Contamination &
Coatings Workshop was held on July 9 and
10, 1997, at the Historic Inns of Annapolis
in Annapolis, MD. The workshop was
sponsored by the Space Environments and
Effects (SEE) Program and organized by
the Thermal Engineering Branch (Code
724) at Goddard Space Flight Center
(GSFC). The SEE program is a major
activity under the Advanced Technology
and Missions Studies Division of the
NASA Office of Space Science. The
objective of the workshop was to provide a
forum for exchanging new developments
in spacecraft contamination and coatings.
The contamination presentations
covered the first one and a half days and
included overall policy, control
engineering, mission experience,
modeling, hardware, requirements, flight
data, and testing. The coatings
presentations were a half day on the
second day and included new technologies,
facilities, and testing. Approximately 130
people attended the Workshop and
participated in the technical sessions and
round table discussion. Presenters and
attendees at the workshop represented
government agencies, industry, and
universities concerned with spacecraft
contamination and coatings engineering,
including NASA, JPL, DoD, Boeing,
McDonnell Douglas, Lockheed, and
Phillips Laboratory, to name just a few.
The keynote speech was delivered by Dr.
Peter Ulrich, Director of the Advanced
Technology and Missions Studies Division
at NASA Headquarters. The Workshop
has received considerable positive
feedback and, as a result, will probably
continue to be held on a regular basis. The
presentation materials are being compiled
and published as proceedings for
distribution to attendees and interested
parties.
The workshop was organized by Drs.
Philip Chen and Steve Benner of the
Thermal Engineering Branch at the GSFC.
Four technical sessions were chaired by
continued on page 3
Design Guidelines for Shielding Effectiveness,
Current Carrying Capability, and the Enhancement of
Conductivity of Composite Materials (NASA CR 4784)
The NASA Space Environments & Effect (SEE) Program funded a task to develop
electromagnetic compatibility (EMC) guidelines for spacecraft using composite
materials. The task consisted of fault current and lightning tests to determine effects on
composite materials and joints and a literature review primarily for shielding
information.
Shielding effectiveness depends largely upon the conductivity of the material.
Graphite epoxy can provide useful shielding against RF signals even though it is about
1000 times more resistive than the most conductive metals. The shielding effectiveness
of vehicle skin or equipment cases with metal walls of any reasonable thickness is
limited by the apertures, joints, and other discontinuities, rather than the metal itself.
Shielding effectiveness of graphite epoxy material may approach that of the apertures in
the enclosure depending on the conductivity of the material. When shielding is required
of composite material enclosures, calculation of the shielding effectiveness of the
composite material as well as the apertures should be made. Calculation methods and
estimates of shielding effectiveness based on the conductivity of the material are
described in NASA CR 4784.
The current carrying capability of graphite epoxy is adequate to dissipate static
charges, but higher current through graphite epoxy may ignite the material. Tests were
performed to determine the current carrying capability of graphite epoxy in case a
power line shorted to the material. The tests showed that graphite epoxy could carry up
to 5 amps of fault current. Above this value, smoke, sparks, and flame developed at the
shorting point, the current exit point, and at joints where the area of electrical contact
was restricted. Graphite epoxy should not be used for intentional circuit return. Any
composite should undergo current carrying tests before use in a spacecraft where a
power short to the material may occur or where a short circuit return current must pass
through the material. One sample of high temperature graphite-phenolic material did
not burn when subjected to 30 amps of current. However, any of the composite
materials may have enough resistance, especially where several joints are involved, to
limit fault current t