4 Capella Space Corp Appendix B Mitigation of Orbital Deb

0066-EX-CN-2018 Text Documents

Capella Space Corporation

2018-01-26ELS_203933

APPENDIX B

MITIGATION OF ORBITAL DEBRIS ASSESSMENT

Each of the Capella Space Corp. (“Capella”) Synthetic Aperture Radar (“SAR”) satellites
(the “Capella Satellites”) proposed in this application will release two small debris during the
deployment of their solar panels. These consist of two structural vectran tie lines that will be cut
in order for the solar panels to deploy. The generated debris meets NASA-STD 8719.14
Requirement 4.3-1.

Capella intends to utilize the Capella Satellites for their intended purposes from the point
at which the satellites are placed into their operational orbits until final re-entry into the
atmosphere is imminent. Reentry will be imminent at an altitude of approximately 200 km. At
all altitudes down to the reentry altitude, Capella will maintain the Capella Satellites’ power flux
density at levels within the applicable International Telecommunication Union limits by reducing
satellite transmitter power on a graduated basis as the Capella Satellites near the Earth.1

Capella has assessed and limited the possibility that the Capella Satellites could become a
source of debris as a result of collision with large debris or other operational spacecraft. Capella
does not intend to place the Capella Satellites in an orbit that is identical to or very similar to an
orbit used by other space stations. Capella will also work closely with its launch providers to
ensure that the Capella Satellites are deployed in such a way as to minimize the potential for
collision with any other spacecraft, specifically including manned spacecraft.

To the best of Capella’s understanding, the International Space Station and China’s
Tiangong-2 Space Station module are the only presently or imminently inhabited orbiting
objects.2 The operational altitude of the International Space Station is approximately 400 km,3
and the altitude of the Tiangong-2 space module is approximately 393 km.4 While both facilities
are significantly below the Capella Satellites’ operational orbit altitudes of 550 km or higher,
Capella will be proactive in ensuring that any risks to inhabitable orbiting objects posed by the
Capella Satellite are mitigated. This will include coordinating with the National Aeronautics and
Space Administration (“NASA”) to ensure protection of the International Space Station on an

1
Capella satellite transmitters are able to adjustment the RF output power from 0.01 to
10W.
2
The Tiangong-2 spacecraft is an experimental space module that is destined to be part of
a larger space complex over the next decade. It will be intermittently inhabited.
3
See AstroViewer, NASA, Current Position of the ISS, available at
http://iss.astroviewer.net/.
4
See Chinadaily.com.cn, Tiangong-2 space lab enters preset orbit for docking with
manned spacecraft, at http://www.chinadaily.com.cn/china/2016-
09/26/content_26891749.htm.

ongoing basis, and coordinating with the China National Space Agency with respect to
Tiangong-2 and successor vehicles. Capella will provide both agencies with any information
they need to assess risks and ensure safe flight profiles, and with contact information for Capella
personnel on a 24 hours per-day/7 days per-week basis. Through these measures, Capella will be
able to avoid collisions even if, at some point in the future, there is less separation in orbits than
is anticipated today.5

Capella has also assessed the possibility of the Capella Satellites becoming a source of
debris by collision with small debris or meteoroids of less than 1 cm in diameter that could cause
loss of control and prevent post-mission disposal. At an altitude of 600 km, the probability of
mission failure from a small object is 0.001435%, as predicted by the NASA DAS v2.0.2.

Capella has assessed the possibility of accidental explosions during and after completion
of mission operations through a failure mode verification analysis. As part of the satellite
manufacturing process, Capella has taken steps to ensure that debris generation will not result
from the conversion of energy sources onboard the Capella Satellites into energy that fragments
the satellites. All sources of energy onboard the Capella Satellites will have been depleted or
safely contained when they are no longer required for mission operations or to accomplish
post-mission disposal.

Subsection 25.114(d)(14)(iii) of the Federal Communications Commission’s rules calls
upon applicants to specify the accuracy with which the orbital parameters of their non-
geostationary satellite orbit space stations will be maintained.6 The Capella Satellites will
include a propulsion system and, as a result of regular corrective propulsive maneuvers by
Capella, are anticipated to remain in their planned orbit within the accuracy ranges given in
Table 1 below. At end of life, the Capella Satellites will be in orbits that gradually decay over
time until the satellites reenter the atmosphere. At the maximum initial altitude of 600 km, the
Capella Satellites in their nominal end of life configuration will reenter the atmosphere in
approximately 6 to 12 months, as calculated by NASA Software DAS v2.0.2.

5
Capella will take similar proactive measures with respect to any other inhabitable orbiting
objects that may be introduced during the time the Capella Satellites are in orbit. In
particular, Capella notes that testing of inhabitable space objects by Bigelow Aerospace
LLC may occur during the license term.
6
47 C.F.R. § 25.114(d)(14)(iii).
2

Capella Orbital
Parameters Accuracy

Inclination Angle (deg) +/- 0.1
Apogee (km) +/- 20
Perigee (km) +/- 20
Semi-major Axis (km)7 +/- 1.0
Right Ascension of the +/- 0.25
8
Ascending Node (deg)

Table 1. Anticipated orbit maintenance accuracy for the Capella Satellites

Capella’s disclosure of the above information can assist third parties in identifying
potential problems that may result from proposed operations. This information also lends itself
to coordination between Capella and other operators located in similar orbits.

Finally, the orbits of the Capella Satellites will decay because of atmospheric drag. The
Capella Satellites will eventually naturally de-orbit by atmospheric reentry. At the end of the
mission operations, the attitude control system can orient the Capella Satellites into a maximum
drag configuration with the solar panels and SAR antenna in the direction of the velocity, thus
accelerating the orbital decay. This configuration is the stable equilibrium under gravity gradient
and drag, which means that even in the case of Attitude, Determination, and Control System
(“ADCS”) failure, the satellite will eventually assume this position naturally.

The analyses below were done assuming natural orbit decay.

With regard to the post-mission disposal of the Capella Satellites in or passing through
low Earth orbit, the altitude of the Capella Satellites is computed from their initial circular orbit
at the altitude of 600 km, in their end of mission configuration. The atmospheric reentry occurs
less than 12 months after launch, assuming the highest possible apogee (600 km) and nominal
end-of-life configuration of the Capella satellites. Even in the worst-case scenario where the
minimum drag configuration is maintained throughout the entire lifetime, the Capella Satellites
will reenter within 7 years, which is well within the acceptable 25-year reentry time.

7
Semi-major axis will be maintained with a tight tolerance. Eccentricity will be kept
small, but is expected to vary, causing fluctuations in apogee and perigee altitudes.
8
RAAN tolerance given is relative to a rotating sun-sync orbital plane, which regresses to
match the Sun's apparent motion to the Earth.

3

Document Created: 0520-04-27 00:00:00
Document Modified: 0520-04-27 00:00:00

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