DA 04-1724

Report No. SPB-208

June 16, 2004

**International Bureau Satellite Division Information**

Orbital Debris Mitigation:

Clarification of 47 C.F.R. Sections 25.143(b), 25.145(c)(3),
25.146(i)(4) and 25.217(d)

Regarding Casualty Risk Assessment for Satellite Atmospheric Re-entry

Sections 25.143(b), 25.145(c)(3), 25.146(i)(4) and 25.217(d) of the
Commission's Rules require applicants requesting certain satellite
authorizations to submit a narrative statement describing the design and
operational strategies, if any, that they will use to mitigate orbital
debris. These rules specifically require applicants to submit a casualty
risk assessment if planned post-mission disposal involves atmospheric
re-entry of the spacecraft.[^1]

To date, the assessments submitted for those cases in which disposal of
a spacecraft by atmospheric re-entry is contemplated have generally been
inadequate to permit completion of Commission consideration.
Consequently, in this Public Notice, we clarify the minimum information
that must be submitted to the Commission to satisfy this requirement.
All casualty risk assessments must include the following information:

1.  A statement as to whether the atmospheric re-entry of the satellite
    will be controlled or uncontrolled.

2.  For controlled re-entry, the projected geographic region of the
    debris field of the surviving components/fragments, if any, and any
    measures taken to forewarn people who are likely to be in the
    geographic region during the time period of the re-entry.

3.  For uncontrolled re-entry:

    a.  An estimate of the number of components/fragments, and their
        estimated dimensions and mass, likely to survive to the Earth's
        surface.

    b.  An estimate of the probability of human casualty resulting from
        surviving components/fragments of the satellite.[^2]

    c.  A full description of the assumptions and parameters used in
        developing the estimates.

In the event the information on the satellite design characteristics,
satellite components and satellite ground track during re-entry are not
yet known, the applicant must provide the above required information
based on assumptions and parameters of a "worst-case" scenario.

In preparing such exhibits, applicants may find guidance in the U.S.
Government Orbital Debris Mitigation Standard Practices[^3] and in a
related Safety Standard developed by the National Aeronautics and Space
Administration.[^4] Further, the software tools at the NASA website may
prove useful in completing the debris mitigation statements, including
the casualty risk assessment. [^5]

Applicants with space station applications pending before the Commission
must provide this information on or before **July 19, 2004**, if the
applicant plans or is contemplating post-mission disposal by atmospheric
re-entry. Failure to do so shall result in the dismissal of the
application as incomplete.

Applicants filing new space station applications must also provide this
information as part of their application, if the applicant plans or is
contemplating post-mission disposal by atmospheric re-entry. Failure to
do so shall result in the dismissal of the application as incomplete.

For further information contact Sankar Persaud of the Satellite
Engineering Branch, Satellite Division, International Bureau, at (202)
418-2441 or email: <Sankar.Persaud@fcc.gov>.

[^1]: The Commission has proposed to consolidate these
    "service-by-service" requirements into a single rule applicable to
    all space stations. *See* Mitigation of Orbital Debris, *Notice of
    Proposed Rulemaking*, 17 FCC Rcd 5586, 5607 (2002). This Public
    Notice is intended to provide guidance for applicants under any
    Commission rule requiring submission of a casualty risk assessment.

[^2]: One method for making this estimate is to derive the total
    casualty area for the reentry, and from that figure derive the
    probability of casualty. The total casualty area can be defined as
    the sum of the casualty areas for each component/fragment, where the
    casualty area of each component/fragment is the squared sum of the
    square root of the cross-sectional area of a person and the square
    root of the cross-sectional area of the surviving component/fragment
    of the satellite, i.e., \[(Cross-sectional Area of a Person)^1/2^ +
    (Cross-sectional Area of Fragment surviving re-entry)^1/2^\]^2^,
    summed for all surviving components/fragments. The probability of
    casualty may then be calculated, as follows: Probability of Casualty
    = 1-(1-P~0~)^N^ where P~0~ = \[Average Casualty Area x Average
    Population Density, (people per m^2^) that may potentially be struck
    by the surviving components/fragments of the satellite\]; N is the
    number of surviving components/fragments. The average casualty area
    is defined as the total casualty area divided by N, the number of
    surviving components/fragments. One source for information regarding
    population density for different geographic regions of the Earth is
    available at:
    <http://sedac.ciesin.columbia.edu/plue/gpw/index.html?main.html&2>.

[^3]: <http://www.orbitaldebris.jsc.nasa.gov/library/USG_OD_Standard_Practices.pdf>.

[^4]: National Aeronautics and Space Administration Safety Standard
    1740.14.
    <http://orbitaldebris.jsc.nasa.gov/library/NSS1740_14/nss1740_14-1995.pdf>.

[^5]: <http://www.orbitaldebris.jsc.nasa.gov/reentry/reentry.html>