### Characterization of Optical Fiber Cables for Space Flight

New Proposal Continuing NEPP Work

##### Total \$ Funding for FY02: 

**Technology Type:** Newly Available (COTS) Emerging/Advanced

**Project Area:** Parts Packaging Radiation

**Proposing Centers:** NASA GSFC & GRC

**([Estimated]{.underline} Center 64** % GSFC **36** % GRC % LaRC % JPL

**Participation, %\$):** % MSFC % JSC Other

**Collaborators:** W.L Gore, Lucent SFT, USCONEC

**Point of Contact:** Melanie N. Ott, NASA Goddard Space Flight Center

301-286-0127

melanie.ott@gsfc.nasa.gov

Dr. Margaret Tuma, NASA Glenn Research Center

216 433-8665

margaret.l.tuma@lerc.nasa.gov

Harry C. Shaw, NASA Goddard Space Flight Center

301-286-6616

harry.c.shaw@gsfc.nasa.gov

**Investigator(s):** Melanie Ott, Sigma Research and Engineering/ NASA
GSFC

Dr. Margaret Tuma, NASA GRC

Harry C. Shaw, NASA GSFC

**Objective(s):**

-   The continuation of characterization studies on COTS cable
    assemblies and high reliability cable assemblies for space flight
    use.

-   To provide infusion of new technologies as they become available to
    space flight missions by identifying available designs and
    evaluating candidates for usage in a wide variety of space flight
    environments.

-   To provide lessons learned on the proper usage of optical fiber
    cables in space flight environments.

-   To provide through characterization testing a family of candidates
    for a variety of space flight environments.

**Task Description:**

This task proposes the continuation of characterization studies on COTS
cable assemblies and high reliability cable assemblies for space flight
use. New technologies are being developed each year, so to make sure
that projects have the widest variety of products to chose from, we need
to be able to characterize the cables which are emerging on the market.
This task will identify newly available designs and will evaluate the
best candidates for avionics and flight use. This requires testing of
several different cables each year in a variety of environments
including thermal, mechanical, vibration, and radiation. The results of
these tests, and comparisons to cables currently in use by NASA will be
provided. Feedback will also be given to the manufacturers regarding
improvements that can be implemented to enhance the reliability of their
products.

**Task Approach to Meeting NEPP Objectives:**

This program provides information to projects on usage of optical fiber
cables in space flight environments as well as which candidates are most
suitable for a variety of environments. NASA enterprises benefit from
our ability to validate new fiber optic cables. The information gained
by prior work in this area have enabled NASA centers to benefit from the
lessons learned through this program both from our engineers and from
the vendors themselves. Over the past several years programs including:
GLAS, EO-1, and MAP and ISS have directly benefited from this work by
having the test data and report already available on commercially
available cables such that these projects did not have to conduct the
research themselves. They have made use of our publications from our
website to guide them in the selection of space flight optical fiber
cable assemblies and their usage.

Our work helps the vendors understand the issues faced by NASA fiber
users and how they can modify their products to meet NASA mission
requirements. We have had great successes working with Spectran and W.L.
Gore and must continue to do so with the increasing number of suppliers
of this type of component. The data provided to NASA and the
manufacturers through this task have usefulness in the avionics,
commercial, military and flight hardware sectors that include Codes S,
Y, M and R.

**Technical Background:**

Through this program we have collected information regarding how to test
for known failure and degradation modes of optical fiber cable
assemblies for usage in space flight environments. Based on this
information we are able to characterize a cable, for a given environment
to bring out these known failure mechanisms. We are building on our
previous work by using our test methods for evaluation of upcoming
technologies in the prototype stage as well as commercially available
cables that have not yet been used or tested for space flight
environments. The tests we use to characterize a cable include: thermal
cycling, low temperature testing (when necessary), post fabrication
strength testing of the optical fiber, radiation testing at cold
temperature for germanium doped fiber, radiation testing during thermal
changes for commercially available fiber, and vibration of cables when
terminated. The information this program provides has become an integral
part of current space flight project specifications and designs. We
continue to make this information available through NEPP reports as well
as technical publications. We will continue to provide useful
information in formats that are readily available.

Work that has been done on evaluating fiber optic cables for the NEPP
program and other GSFC projects by GSFC can be found on the Technology
Validation Assurance website under \"Photonics\"
(http://misspiggy.gsfc.nasa.gov/tva/photonics.htm). See references.

**Technical Approach:**

-   Obtain samples of commercially available cable being considered for
    use from projects or from manufacturers with strong product bases.

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-   Perform a process inspection for manufacturers which whom NASA has
    little experience. Note materials and processes that have critical
    impact on the reliability of the cable.

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-   Survey the latest project needs for re-evaluation of test plans if
    necessary.

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-   Design tests that address the critical design aspects and rugged
    environmental conditions based on the current upcoming missions or
    generic typical environment

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-   Feedback results to the manufacturers and projects and establish a
    partnership with manufacturers who are willing to modify their
    processes to satisfy NASA needs and whose product has good potential
    for wide-ranging usage.

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-   Assess modified products

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-   Issue report of findings and test results.

**NASA Customers:**

Projects that benefit from this work include: MAP, GLAS, NGST and any
other programs who request information on optical fiber cable assemblies
that will function in space flight environments.

**Clearly Stated Deliverables:**

-   With each round of testing that yields significant results, a report
    is published for the projects to download from the NEPP web site and
    a report is published at an international conference. This report is
    provided at the end of the year and includes: the reasons for the
    testing, the environmental parameters, the failures modes based on
    the research to date, justification for testing to the parameters
    described, objectives of the testing, equipment set up, description
    of the candidates cables tested with significant specifications,
    data, results of testing and relevant conclusions. A summary of all
    results is presented to evaluate candidates under testing for the
    specific environments. This report will be published at the end of
    each fiscal year.

**Top Level Schedule:**

Q1/02: Select cable candidates for testing based on construction and
lessons learned. Survey most up-to-date mission requirements and write
test plan for testing based on known failure mechanisms associated with
candidates for test.

Q2/02: Assemble equipment for testing and begin testing.

Q3/02: Complete testing and perform analysis on available data.

Q4/02: Write final report and presentations for NEPP deliverables.

**References:**

[Fiber Optic Cable Assemblies for Space Flight Applications III:
Characterization of Commercial Cables for Thermal Effects]{.underline},
Melanie Ott, March 31, 2000, Report to the NEPP.

[Characterization of Commercial Optical Fiber Cables for Space Flight
Environments at NASA Goddard Space Flight Center]{.underline}, Melanie
Ott, Presentation to the IMAPS/NEPP Advanced Technology Workshop,
Washington D.C., May 24, 2000.

[Assurance of COTS Fiber Optic Cable Assemblies for Space Flight,
Presentation to the Commercialization of Military and
Space,]{.underline} Melanie Ott, Electronics Conference, Los Angeles,
CA, February 10, 1999

[Twelve Channel Optical Fiber Connector Assembly: From Commercial off
the Shelf to Space Flight Use]{.underline}, Melanie Ott, Joy Bretthauer
SPIE Proceedings Vol. 3440 Photonics for Space Environments VI, 1998

[Fiber Optic Cable Assemblies for Space Flight II: Thermal and Radiation
Effects]{.underline}, Melanie Ott, SPIE Proceedings Vol. 3440 Photonics
for Space Environments VI, 1998, Aerospace Electrical Interconnection
System Conference, Williamsburg VA, October 29,1997, JPL Packaging
Workshop January 14, 1998.

[Fiber Optic Cable Assemblies for Space Flight Applications: Issues and
Remedies]{.underline}, Melanie Ott and Jeannette Plante, American
Institute of Aeronautics and Astronautics/Society of Automotive
Engineers World Aviation Congress Anaheim, CA, Oct 1997

[Fiber Optic System Qualification at Goddard Space Flight
Center]{.underline}, Melanie Ott, JPL Packaging Workshop, 1997

[Assurance of COTS Fiber Optic Cable Assemblies for Space
Flight]{.underline}, Melanie Ott

#### List of Procurements FY02 FY03 

GSFC:

Cable/fixtures

Materials for testing set-ups:

GSFC Contractor Labor

GRC Labor

**Manpower Loading:** Average Heads (FTEs)

  --------------- ------------- -------------- -------------- --------------
                  **Q1**        **Q2**         **Q3**         **Q4**

  NASA/GSFC                                                   

  GSFC Contractor **0.36**      **0.36**       **0.36**       **0.36**

  GRC             **0.23**      **0.23**       **0.23**       **0.23**
  --------------- ------------- -------------- -------------- --------------

**Leveraging:** Work performed for NEPP in past years as well as work
performed for space flight projects such as MAP, ISS, GLAS and EO-1 is
all incorporated in our lessons learned and continued testing. This
work, prior and continuing, has enabled characterization studies to be
fostered by knowledge based assessments.