AC8 ODAR with signatures

0653-EX-PL-2014 Text Documents

Aerospace Corporation, THE

2014-11-05ELS_155435

AeroCube-8 ODAR                                                      The Aerospace Corporation


                                    AeroCube-8
             Orbital Debris Assessment Report (ODAR)
                          Report Version: 1.0, 19 May 2014


    Prepared for NASA in compliance with NPR 8715.6A by The Aerospace Corporation.

  This document contains proprietary information of The Aerospace Corporation and is not
                                suitable for public release.

                    Software used in this analysis: NASA DAS v2.0.2



Revision       Date              Pages             Description                 Author
  1.0       19 May 2014     14 + appendices        First version,             K. Gates,
                                                requires signatures      Astrodynamics Dept.
   2.0       1 Nov 2014     15 + appendices      Edited for public            D. Hinkley
                                                      release              PICOSAT Program




                                      Page 1 of 15


AeroCube—8 ODAR                                                       The Aerospace Corporation


                     VERSION APPROVAL and FINAL APPROVAL*:




                The Aerospace Corporation




               ofi
                <
               Timothy Graves
               AeroCube—8
               Principal Investigator
               The Aerospace Corporation




                  PB
               AndreaHsu ~*~
               AeroCube—8
               Program Manager
               The Aerospace Corporation




              J.239—
               James Nokes:
               Principal Director
               Space Materials Laboratory
               The Aerospace Corporation


* Approval signatures indicate acceptance of the ODAR—defined risk.

** Signatures required only for Final ODAR




                                            Page 2 of 15


AeroCube-8 ODAR                                                                                    The Aerospace Corporation




Self-Assessment of Requirements per NASA-STD 8719.14A
                                                                                               Compliance
Requirement                                                                                                 Comments
                                                                                               Assessment
         All debris released during the deployment, operation, and disposal phases shall                    AeroCube-8 will
4.3-1a   be limited to a maximum orbital lifetime of 25 years from date of release.            Compliant    release no debris.
         The total object-time product shall be no larger than 100 object-years per                         AeroCube-8 will
4.3-1b   mission.                                                                              Compliant    release no debris.
         For missions leaving debris in orbits with the potential of traversing GEO,                        AeroCube-8 will not
         released debris with diameters of 5 cm or greater shall be left in orbits which
4.3-2    will ensure that within 25 years after release the apogee will no longer exceed       Compliant    operate in or near
         GEO-200 km.                                                                                        GEO.
         For each spacecraft employed for a mission, the program or project shall
4.4-1    demonstrate…that the integrated probability of explosion for all credible             Compliant
         failure modes of each spacecraft is less than 0.001.
         Design of all spacecraft shall include the ability and a plan to deplete all
         onboard sources of stored energy and disconnect all energy generation sources
4.4-2    when they are no longer required for mission operations or post-mission               Compliant
         disposal or control to a level which cannot cause an explosion or deflagration
         large enough to release orbital debris or break up the spacecraft.
         Planned explosions or intentional collisions shall: a) be conducted at an                          AeroCube-8 has no
         altitude such that for orbital debris fragments larger than 10 cm the object-time
4.4-3    product does not exceed 100 object-years, and b) not generate debris larger           Compliant    planned explosions or
         than 1 mm that remains in Earth orbit longer than one year.                                        intentional collisions.
         Immediately before a planned explosion or intentional collision, the probability                   AeroCube-8 has no
4.4-4    of debris, orbital or ballistic, larger than 1 mm colliding with any operating        Compliant    planned explosions or
         spacecraft within 24 hours of the breakup shall be verified to not exceed 10-6.                    intentional collisions.
         For each spacecraft in or passing through LEO, the program shall demonstrate
4.5-1    that, during the orbital lifetime of each spacecraft, the probability of accidental   Compliant
         collision with space objects larger than 10 cm in diameter is less an 0.001.
         For each spacecraft, the program shall demonstrate that, during the mission of
         the spacecraft, the probability of accidental collision with orbital debris and                    AeroCube-8 will use
4.5-2    meteoroids sufficient to prevent compliance with the applicable post-mission          Compliant    natural orbit decay.
         disposal requirements is less than 0.01.
         A spacecraft with a perigee altitude below 2000 km shall be disposed of by one
         of the following three methods: a) leave the space structure in an orbit in
         which natural forces will lead to atmospheric reentry within 25 years, b)                          AeroCube-8 will use
4.6-1    maneuver the space structure into a controlled de-orbit trajectory, c) maneuver       Compliant    natural orbit decay.
         the space structure into an orbit with perigee altitude above 2000 km and
         apogee less than GEO-500 km.
                                                                                                            AeroCube-8 will not
         A spacecraft or orbital stage in an orbit near GEO shall be maneuvered at EOM
4.6-2    to a disposal orbit above GEO.                                                        Compliant    operate in or near
                                                                                                            GEO.
         For space structures between LEO and GEO, a spacecraft shall be left in an                         AeroCube-8 will not
         orbit with a perigee greater than 2000 km above the Earth’s surface and apogee
4.6-3    less than 500 km below GEO, and a spacecraft shall not use nearly circular            Compliant    operate in or near
         disposal orbits near regions of high-value operational space structures.                           MEO.
         NASA space programs shall ensure that all post-mission disposal operations to
4.6-4    meet the above requirements are designed for a probability of success of no           Compliant
         less than 0.90 at EOM.
         For uncontrolled reentry, the risk of human casualty from surviving debris
4.7-1    shall not exceed 0.0001.                                                              Compliant
         Intact and remnants of severed tether systems in Earth orbit shall meet the
                                                                                                            AeroCube-8 has no
4.8-1    requirements limiting the generation of orbital debris from on-orbit collisions       Compliant    tether system.
         and the requirements governing post-mission disposal.




                                                              Page 3 of 15


AeroCube-8 ODAR                                                      The Aerospace Corporation


NOTE: When manifested for flight, AeroCube-8 will fly as a secondary payload. Compliance
with requirements levied by NASA-STD 8719.14A on the launch vehicle will be the
responsibility of the primary payload and/or launch provider.

Section 1: Program Management and Mission Overview
Mission Directorate: The Aerospace Corporation, Picosatellite Group

Program Executive: James Nokes

Principal Investigator: Timothy Graves, The Aerospace Corporation

Program Manager: Andrea Hsu, The Aerospace Corporation

Foreign government or space agency participation: none

Nominal Schedule of Mission Design and Development:



                        Event                               Date
                        Project initiation                  13 Jun 2013
                        System Requirements Review (SRR)    8 Aug 2013
                        Preliminary Design Review (PDR)     7 Nov 2013
                        Critical Design Review (CDR)        19 Mar 2014
                        Flight Readiness Review (FRR)       21 Nov 2014
                        Delivery                            1 Dec 2014
                        Target launch date                  1 May 2015


Brief Description of the Mission:

The AeroCube-8 (AC8) mission shall demonstrate R&D products in space. AeroCube-8’s
mission is a multifaceted technology demonstration for a Scalable ion Electrospray Propulsion
(SiEPro) system and novel Carbon Nanotube Technology (CNT). Two identical 1.5U CubeSats
will be utilized towards this goal. AeroCube-8 will carry several payloads. The primary payload
for the satellite is SiEPro. The secondary payloads are CNT harnesses, a CNT-filled PolyEther
Ether Ketone (PEEK) material, a CNT radiation shielding material, and advanced solar cells.

AeroCube-8 is the first known (scalable) electric propulsion demonstration for CubeSat
technology. It is also the first known demonstration of multi-cube satellite propulsion
maneuvering, providing innovative insight into iEPS satellite operations and control and the
development of satellite control and guidance during microthrust maneuvers.




                                          Page 4 of 15


AeroCube-8 ODAR                                                                     The Aerospace Corporation


The CNT material carried onboard will be used to test this technology’s efficacy at radiation
shielding of electronics in the space environment. Harnesses shielded by CNT-filled PEEK will
be exposed to space and their performance degradation compared to control harnesses housed
within the satellite bus. Other dosimeters onboard will compare radiation measurements with
and without CNT-based shielding.




       Figure 1. The AeroCube-8 spacecraft with radiation shield, assorted sensors, solar cells, and antenna.



Identification of the anticipated launch vehicle and launch site: AeroCube-8 has been
manifested on ULTRASat, which will fly as a secondary payload on AFSPC-5, an Atlas V
launch scheduled for May 2015. The launch vehicle will deploy AeroCube-8 to a roughly 350 x
700 km altitude orbit inclined at 57 degrees.

Identification of the proposed launch date and mission duration: The AeroCube-8 mission
anticipates a launch as a secondary payload in May 2015. The main mission phase is
approximately 3 months. The stretch mission will extend the operational lifetime to > 1 year.

Description of the launch and deployment profile: As a secondary payload, the AeroCube-8
spacecraft will be deployed from the launch vehicle to minimize risk to the primary payload and
upper-stage space structures. Depending on the launch provider, deployment may occur before or
after deployment of the primary payload. Typically, after deploying the primary payload, the

                                                  Page 5 of 15


AeroCube-8 ODAR                                                         The Aerospace Corporation


upper stage performs a small burn to alter the orbit (eliminating the risk of collision with the
primary) before releasing any secondary payloads.

Reason for selection of operational orbit: As a secondary payload, AeroCube-8 has minimal
control over the selection of operational orbit. AeroCube-8 can perform its mission in any LEO
orbit, although the altitude must be low enough to ensure natural decay and reentry within the
timeframe specified by NPR8751.6A. The altitude to which the ULTRASat CubeSats will be
delivered (including AeroCube-8) satisfies that requirement.

Identification of any interaction or potential physical interference with other operational
spacecraft: As one of several CubeSats deployed by ULTRASat, there is a small risk of
recontact whether between the two AeroCube-8 vehicles or between AeroCube-8 and another
CubeSat. The timing of satellite deployments from ULTRASat is intended to mitigate as much
of this as possible. Debris mitigation for the deployment process is the responsibility of
ULTRASat. In the event of recontact shortly after deployment, the relative velocities between
CubeSats is on the order of centimeters per second, which would not provide enough force to
cause catastrophic breakup of the satellites or generate significant amounts of debris (the glass
coverings of solar cells may crack). The launch vehicle trajectory and mission plan is designed
to ensure there is no risk to the primary payload. There is no anticipated risk to any other
operational spacecraft.


Section 2: Spacecraft Description

Physical Description: The AeroCube-8 mission consists of a pair of one-and-a-half unit (1.5U)
CubeSats with dimensions 10.25 x 10.25 x 17 cm. Each satellite contains multiple Sun sensors
and Earth sensors, RF communications antennae, GPS receiver, a medium-field camera, and
narrow-field camera. No components of the spacecraft extend beyond the dimensions of the 1.5U
bus.




                                            Page 6 of 15


AeroCube-8 ODAR                                                                The Aerospace Corporation




                            Figure 2. Exploded isometric view of AeroCube-8.



Total spacecraft mass at launch: <2.2 kg

Dry mass of spacecraft at launch: <2.2 kg

Description of all propulsion systems: AeroCube-8 carries an electric propulsion system,
SiEPRO. The working principle behind ion electrosprays is based on the electrostatic extraction
and acceleration of positive and negative ions from an ionic liquid—a zero-vapor pressure
conductive salt that remains in the liquid phase at room temperature. In order to extract these
ions, electric fields on the order of 1 V/nm are required. Such intense fields are routinely
achieved at the tip of electrically stressed liquid menisci or Taylor Cones, which have sizes from
a fraction to several micrometers and are produced at the end of sharp emitter structures, such as
sharpened capillaries or needles biased with respect to a downstream extractor aperture.

The thruster system comprises four thruster pairs, or 8 thruster heads, each of which comprises a
small PEEK (Polyether ether ketone) reservoir, which is filled completely in a vacuum with an
ionic liquid. The reservoir contains a porous substrate with pores that are ~1 micron in size with
a field of micromachined emitter tips. In operation, an electric field is created between this
substrate and an extractor grid above to accelerate ions away from the spacecraft, producing
thrust.

                                            Page 7 of 15


AeroCube-8 ODAR                                                               The Aerospace Corporation




                      Figure 3. Scalable ion Electrospray Propulsion (SiEPRO) system.



The thruster operates using a dense array of emitters, firing in parallel. This is achieved by
merging the working principles behind ion electrospray thrusters with recent developments in
Micro Electro Mechanical Systems (MEMS) materials and processes. Emitters are fabricated on
porous materials, so that propellant can flow via capillarity through the bulk of the material and
driven by the ion evaporation process. Therefore, no pressurization is required for pumping
(or storing) the propellant. These characteristics allow ion electrospray thrusters to achieve
high specific impulse (Isp > 2000 s) at high efficiency in a compact package only a few mm
thick. Performance for the thruster is estimated at greater than 50 m/s, assuming an Isp > 2000s,
propulsion system mass of 90g, and using 0.2g propellant. Another characteristic of ion
electrospray thrusters is that both positive and negative species can be emitted. In consequence,
there is no need for an electron-neutralizing cathode. In its current configuration, the thruster
consists of two separate head modules or two groups of modules emitting oppositely charged
ions of comparable mass and producing similar thrust.

This system meets CubeSat specifications for on-board propulsion systems, namely it is non-
toxic, non-flammable, and operates with no pressurization.

Identification of all fluids planned to be on board: The AeroCube-8 electric SiEPRO
propulsion system uses ionic liquid, a zero-vapor pressure conductive salt that remains in the
liquid phase at room temperature. The liquid is stored on board with no pressurization (not
sealed). The total mass of propellant carried by AeroCube-8 is 12 grams.

Description of all active and/or passive attitude control systems with an indication of the
normal attitude of the spacecraft with respect to the velocity vector: Each AeroCube-8
spacecraft has 3-axis attitude control via three torque rods and three “pico” reaction wheels. The
torque rods are a mutually orthogonal triad of coiled wire, wrapped around a high magnetic
permeability alloy that can generate a magnetic dipole of 0.15 to 0.2 Amp-m2 when the satellite
passes current through the wire but generate negligible magnetic field when powered off. The

                                              Page 8 of 15


AeroCube-8 ODAR                                                        The Aerospace Corporation


torque rods are made from 14 inch-diameter mu-metal rods that are 2.16 inches long. The pico
reaction wheels have flight heritage on three AeroCube-4 and two AeroCube-5 spacecraft.
Attitude sensors include eight infrared thermometer arrays on various spacecraft surfaces, two-
axis sun sensors on various spacecraft surfaces, and a 3-axis magnetometer in the main body. A
high-accuracy 3-axis rate gyro will be used to provide an inertial attitude reference when 0.7 deg
or better pointing accuracy is required and the sun and Earth are not simultaneously visible by an
appropriate sensor, and a medium-resolution 3-axis rate gyro and 3-axis magnetometer will serve
as a backup.

Description of any range safety or other pyrotechnic devices: AeroCube-8 has no pyrotechnic
devices.

Description of the electrical generation and storage system: Power for AeroCube-8 is
generated by solar cells mounted on the spacecraft bus. These cells are capable of producing up
to 10 W of power (predicted 4 W max and 2 W of orbit-averaged power due to vehicle attitude
and shading). Power is stored on-board with lithium-ion batteries. The satellite has 4 batteries
mounted in an aluminum 6061-T6 structure as a unit and they are shock and thermally isolated
by a low-outgassing rubber grommet. Each battery is composed of a single cell storing 9.25 W-
hr, for a total of 37 W-hr on the spacecraft. Specific details of the batteries’ manufacture appear
in Section 4. AeroCube-8 has a single transmitter at 915 MHz, which is half-duplex with the up
and down frequency being the same. This reduces the average power at the cost of downlink
speed. The radio output power at the radio is less than 2 W.

Identification of any other sources of stored energy: There are no other sources of stored
energy on AeroCube-8.

Identification of any radioactive materials on board: AeroCube-8 carries no radioactive
materials.

Section 3: Assessment of Spacecraft Debris Released during Normal
Operations
Identification of any object (>1 mm) expected to be released from the spacecraft any time
after launch: AeroCube-8 will release no objects into space during normal operations.

Rationale/necessity for release of each object: N/A

Time of release of each object, relative to launch time: N/A

Release velocity of each object with respect to spacecraft: N/A

Expected orbital parameters (apogee, perigee, inclination) of each object after release: N/A

Calculated orbital lifetime of each object, including time spent in LEO: N/A

                                           Page 9 of 15


AeroCube-8 ODAR                                                         The Aerospace Corporation


Assessment of spacecraft compliance with Requirements 4.3-1 and 4.3-2:

Requirement 4.3-1a: COMPLIANT

Requirement 4.3-1b: COMPLIANT

Requirement 4.3-2: COMPLIANT


Section 4: Assessment of Spacecraft Intentional Breakups and
Potential for Explosion
Identification of all potential causes of spacecraft breakup during deployment and mission
operations: There is no credible scenario that would result in spacecraft breakup during normal
deployment and operations.

Summary of failure modes and effects analyses of all credible failure modes which may
lead to an accidental explosion:

Battery risk: A possible malfunction of the lithium ion batteries or of the control circuit has been
identified as a potential, but low probability, cause of accidental breakup or explosion. Natural
degradation of the solar cells and batteries will occur over the post-mission period and poses an
increased chance of undesired battery-energy release. The battery capacity for storage will
degrade over time, possibly leading to changes in the acceptable charge rate for the cells.
Individual cells may also change properties at different rates due to time degradation and
temperature changes. The control circuit may also malfunction as a result of exposure over long
periods of time. The cell pressure relief vents could be blocked by small contaminants. Any of
these individual or combined effects may theoretically cause an electro-chemical reaction that
results in rapid energy release in the form of combustion.

Notwithstanding these potential sources of energy release, AeroCube-8 still meets Requirement
4.4-2 as the on-board batteries cannot “cause an explosion or deflagration large enough to release
orbital debris or break up the spacecraft.” The batteries used on AeroCube-8 are certified by
Underwriters Laboratories (UL). In general, these batteries are similar in size and power to cell-
phone batteries.

      CubeSat    Model Number                                  Number
                               Manufacturer                                   Energy Stored
       Name       (UL Listing)                                 of Cells
                   ICR18650H                                                9.25 W-hr per cell
    AeroCube-8                   Molicel                          1
               (BBCV2.MH27672)                                               (4 batteries total)


The batteries are consumer-oriented devices. The batteries have been recognized as UL tested
and approved. UL recognition has been determined through the UL Online Certifications

                                           Page 10 of 15


AeroCube-8 ODAR                                                                   The Aerospace Corporation


Directory, which clearly shows that these cell batteries have undergone and passed UL
Standards. Furthermore, safety devices incorporated in these batteries include pressure release
valves, over-current charge protection, and over-current discharge protection.

The fact that the AeroCube-8 batteries are UL recognized indicates that they have passed the UL
standard testing procedures that characterize their explosive potential. Of particular concern to
NASA is UL Standard 1642, which specifically deals with the testing of lithium batteries.
Section 20 Projectile Test of UL 1642 subjects the test battery to heat by flame while within an
aluminum- and steel-wire-mesh octagonal box, “[where the test battery] shall remain on the
screen until it explodes or the cell or battery has ignited and burned out” (UL 1642 20.5). To pass
the test, “no part of an exploding cell or battery shall penetrate the wire screen such that some or
all of the cell or battery protrudes through the screen” (UL 1642 20.1).

It is reasonable to expect the batteries on AeroCube-8 to experience similar conditions during
their orbital life span. While the sources of failure would not be external heat on orbit, analysis
of the expected mission thermal environment shows that given the low power dissipation for
CubeSats, the batteries will be exposed to a maximum temperature well below their 212 deg F
safe operation limit. Continual charging with 2 to 6 W average power from the solar panels over
an orbital life span greater than 12 years may expose the batteries to overcharging, which could
cause similar heat to be generated internally. Through the UL recognition and testing, it has been
shown that these batteries do not cause an explosion that would cause a fragmentation of the
spacecraft.

In addition to the aforementioned certification of the AeroCube-8 batteries against explosion, ten
potential failure modes for lithium batteries and their applicability or mitigation in AeroCube-8
are addressed in the following table:

     Failure Mode                        Applicability or Mitigation
                                         The AeroCube-8 body and internal design prevents deformation or
1    Internal short circuit
                                         crushing of the batteries that could lead to internal short circuit.
     Internal thermal rise due to high
2                                        See Failure Mode #4.
     load discharge rate
                                         The battery cells on AeroCube-8 have charge interrupt devices that
     Overcharging and excessive charge
3                                        activate during cell internal pressure buildup (due to cell internal
     rate
                                         chemical that forms a gas) that occurs during overcharging conditions.
     Excessive discharge rate or short   The bus batteries have an internal positive temperature coefficient
4    circuit due to external device      (PTC) device that acts as a resettable fuse during external short circuit
     failure                             that limits the cell output current during such an event.
                                         Vents have access through the structure that holds them and into the
5    Inoperable vents                    larger satellite volume. Venting will not be inhibited by physical
                                         obstructions.
6    Crushing                            Satellite body and internal design prevent loads on battery cases.




                                               Page 11 of 15


AeroCube-8 ODAR                                                                      The Aerospace Corporation

     Low level current leakage or short
     circuit through battery pack case or
7                                           Satellites are stored in a controlled environment.
     due to moisture-based degradation
     of insulators
                                            Thermal sensors on the batteries provide telemetry on battery
     Excess temperatures due to orbital     temperature. There is no cutoff for overheating batteries except
8    environment and high discharge         whatever is inherent in the cell itself. However, as noted earlier in this
     combined                               section of the ODAR, the batteries on AeroCube-8 are UL-certified as
                                            non-explosive in over-heating scenarios.
     Polarity reversal due to over-         A 2.7 V discharge cutoff threshold circuit in AeroCube-8 has been
9
     discharge                              verified in acceptance tests for the electric power system.
     Excess battery temperatures due to
                                            The circuit that charges the batteries cannot exceed 4.1 V and therefore
10   post-mission orbital environment
                                            will never overcharge the batteries.
     and constant overcharging



Through a combination of UL certification, compliance with AFSPCMAN 91-710 V3
requirements, and an understanding of the general behavior of the failure modes associated with
these types of batteries, it is possible to conclude that the batteries meet Requirement 4.4-2.

Propulsion-system risk: The propulsion system is free-venting, including the propellant reservoir,
which is assumed to be completely filled with propellant and capped with a porous substrate.
Therefore, it will not become a pressure vessel upon launch as it contains no gas and the vapor
pressure of the ionic liquid propellant is immeasurably small. The electric ion propulsion system
aboard AeroCube-8 contains no pressurized liquids, and therefore poses no explosion risk.

Detailed plan for any designed breakup, including explosions and intentional collisions:
AeroCube-8 has no plans for intentional breakups, explosions, or collisions.

List of components, which are passivated at EOM: Before EOM, AeroCube-8 will deplete
any remaining propellants from its electric ion propulsion system. However, as described above,
failure to deplete propellant does not risk explosion or debris-producing events. No other systems
on AeroCube-8 will be passivated at EOM.

Rationale for all items which are required to be passivated, but cannot due to their design:
As described above, the batteries do not present a debris-generation hazard per Requirement 4.4-
2, and in the interest of not increasing the complexity of the AeroCube-8 power system, it was
decided not to passivate the batteries at EOM.

Assessment of spacecraft compliance with Requirements 4.4-1 through 4.4-4:

Requirement 4.4-1: COMPLIANT

Requirement 4.4-2: COMPLIANT

Requirement 4.4-3: COMPLIANT

Requirement 4.4-4: COMPLIANT

                                                  Page 12 of 15


AeroCube-8 ODAR                                                        The Aerospace Corporation



Section 5: Assessment of Spacecraft Potential for On-Orbit
Collisions
Collision probabilities have been calculated using DAS v2.0.2 with the assumptions: 389 km x
700 km orbit, 57 deg inclination, 2 kg mass (initial and final), and 0.01233 m2/kg area-to-mass
ratio (the maximum-area configuration).

In addition to the DAS analysis, The Aerospace Corporation has performed additional analysis
looking at the collision probability of AeroCube-8 with 0th-, 1st-, and 2nd-generation debris
objects with 95th-, 50th-, and 5th-percentile solar cycle assumptions. The probability of collision
for all cases considered is below the 0.001 requirement. A summary of the Aerospace analysis is
appended to this ODAR.

Calculation of spacecraft probability of collision with space objects larger than 10 cm in
diameter during the orbital lifetime of the spacecraft: Probability = 0.00000, per DAS v2.0.2

Calculation of spacecraft probability of collision with space objects, including orbital
debris and meteoroids, of sufficient size to prevent post-mission disposal: Because the
mission has selected natural de-orbit (see Section 6) for disposal and no systems will be
passivated at EOM (see Section 4), small debris do not pose a threat to prevent post-mission
disposal.

Assessment of spacecraft compliance with Requirements 4.5-1 and 4.5-2:

Requirement 4.5-1: COMPLIANT

Requirement 4.5-2: COMPLIANT

Section 6: Assessment of Spacecraft Postmission Disposal Plans and
Procedures
Description of spacecraft disposal option selected: The AeroCube-8 mission has selected
atmospheric reentry for disposal. The vehicle is a 10.25 x 10.25 x 17 cm bus. Each vehicle’s
mass is approximately 2 kg. The longest possible orbital lifetime occurs if the vehicle were
permanently aligned with the smallest face pointing in the direction of motion, with a cross-
sectional area of 105 cm2. Although in practice after EOM the vehicle will tumble with a higher
“average” cross-sectional area, the analysis in DAS assumed the worst-case low-drag
configuration for lifetime. DAS evaluates a lifetime of 8.16 yr, using the orbit assumptions listed
at the beginning of Section 5 (except for using a lower area-to-mass ratio of .00525 m2/kg). This
lifetime is compliant with ODAR requirements.



                                          Page 13 of 15


AeroCube-8 ODAR                                                       The Aerospace Corporation


In addition to the DAS analysis, The Aerospace Corporation has performed additional analysis
looking at the orbital lifetime of AeroCube-8 assuming the ULTRASat (March 2015) launch and
an alternate GRACE (December 2015) launch. For both cases (with 95th- and 50th-percentile
solar cycle assumptions), the lifetime is below the 25-year requirement. A summary of the
Aerospace analysis is appended to this ODAR.

Identification of all systems or components required to accomplish any post-mission
disposal operation, including passivation and maneuvering: As discussed in Section 4, no
disposal or passivation is planned for AeroCube-8. Natural orbit decay is sufficient to terminate
the mission.

Plan for any spacecraft maneuvers required to accomplish post-mission disposal: None

Calculation of area-to-mass ratio after post-mission disposal, if the controlled reentry
option is not selected: N/A

Preliminary plan for spacecraft controlled reentry: N/A

Assessment of compliance with Requirements 4.6-1 through 4.6-4:

Requirement 4.6-1: COMPLIANT

Requirement 4.6-2: COMPLIANT

Requirement 4.6-3: COMPLIANT

Requirement 4.6-4: COMPLIANT




                                          Page 14 of 15


AeroCube-8 ODAR                                                              The Aerospace Corporation


Section 7: Assessment of Spacecraft Reentry Hazards
Detailed description of spacecraft components by size, mass, material, shape, and original
location on the space vehicle, if the atmospheric reentry option is selected: The AeroCube-8
vehicles are primarily constructed of aluminum and PCB electronic board material. The only
components with a higher density or resistance to melting are stainless steel screws, ceramic path
antennas, three nickel-iron alloy torque rods, and three small stainless steel reaction wheels. The
spacecraft components used in the DAS 2.0.2 analysis are shown in Table 1. The DAS analysis
shows these materials pose no risk per the ODAR requirement.
                        Table 1. Spacecraft Components used for DAS 2.0.2 Analysis




Summary of objects expected to survive an uncontrolled reentry: No objects are expected to
survive uncontrolled reentry.

Calculation of probability of human casualty for the expected year of uncontrolled reentry
and the spacecraft orbital inclination: Zero

Assessment of spacecraft compliance with Requirement 4.7-1:

Requirement 4.7-1: COMPLIANT

Section 8: Assessment for Tether Missions
The AeroCube-8 mission has no tether. All requirements are COMPLIANT.

Sections 9–14: Assessment of Launch Vehicle Debris
AeroCube-8 will fly as a secondary payload. Assessment of launch-vehicle debris is the
responsibility of the primary payload. These sections are N/A for AeroCube-8.




                                            Page 15 of 15



Document Created: 2014-11-05 19:24:21
Document Modified: 2014-11-05 19:24:21

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