1 AC14 ODAR

0520-EX-CN-2019 Text Documents

Aerospace Corporation, The

2019-06-26ELS_232991

AC14 ODAR The Aerospace Corporation AeroCube 14 (AC14) Orbital Debris Assessment Report (ODAR) Report Version: 1.0, 17 April 2019 Prepared for NASA in compliance with NPR 8715.6A by The Aerospace Corporation. Software used in this analysis: NASA DAS v2.0.2 Revision Date Pages Description Author 1.0 17 Apr 2019 13 Initial Release B. Hardy Page 1 of 11 Approved for public release. OTR 2019-00707.

AC14 ODAR The Aerospace Corporation VERSION APPROVAL and FINAL APPROVAL*: The Aerospace Corporation Brian Hardy Principal Investigator AeroCube 14 The Aerospace Corporation David Wu Project Manager AeroCube 14 The Aerospace Corporation * Approval signatures indicate acceptance of the ODAR-defined risk. ** Signatures required only for Final ODAR Page 2 of 11 Approved for public release. OTR 2019-00707.

AC14 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 AC14 will release 4.3-1a be limited to a maximum orbital lifetime of 25 years from date of release. Compliant no debris. The total object-time product shall be no larger than 100 object-years per AC14 will release 4.3-1b mission. Compliant no debris. For missions leaving debris in orbits with the potential of traversing GEO, AC14 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 AC14 has no altitude such that for orbital debris fragments larger than 10 cm the object-time planned explosions 4.4-3 product does not exceed 100 object-years, and b) not generate debris larger Compliant or intentional than 1 mm that remains in Earth orbit longer than one year. collisions. AC14 has no Immediately before a planned explosion or intentional collision, the probability planned explosions 4.4-4 of debris, orbital or ballistic, larger than 1 mm colliding with any operating Compliant or intentional spacecraft within 24 hours of the breakup shall be verified to not exceed 10e-6. 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 4.5-2 meteoroids sufficient to prevent compliance with the applicable post-mission Compliant 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) maneuver AC14 will use 4.6-1 the space structure into a controlled de-orbit trajectory, c) maneuver the space Compliant natural orbit decay. structure into an orbit with perigee altitude above 2000 km and apogee less than GEO-500 km. AC14 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 AC14 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 AC14 has no tether 4.8-1 requirements limiting the generation of orbital debris from on-orbit collisions Compliant system. and the requirements governing post-mission disposal. NOTE: AC14 is currently manifested to 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. Page 3 of 11 Approved for public release. OTR 2019-00707.

AC14 ODAR The Aerospace Corporation Section 1: Program Management and Mission Overview Mission Directorate: The Aerospace Corporation, Small Satellite Department Program Executive: Darren Rowen Mission Director: Brian Hardy, The Aerospace Corporation Program Manager: David Wu, The Aerospace Corporation Foreign government or space agency participation: none Nominal Schedule of Mission Design and Development: Event Date Project initiation April 2018 System Requirements Review (SRR) June 2018 Design Review (DR) October 2018 Mission Readiness Review (MRR) September 2019 Delivery September 2019 Target launch date October 2019 Brief Description of the Mission: The AeroCube 14 (AC14) program consists of two identical spacecraft, AeroCube 14 A&B (AC14-A and AC14-B), that will demonstrate new star-tracker baffle technology, a variety of nanotechnology payloads, and test the performance of advanced solar cells. Identification of the anticipated launch vehicle and launch site: AC14 is manifested as part of an upcoming Commercial Resupply Service mission to the International Space Station (ISS). AC14 will be deployed directly from the resupply spacecraft at the end of its mission. The resupply mission will launch from the Mid-Atlantic Regional Spaceport on Antares 230/Cygnus. The mission orbit will be circular between 470 km and 500 km and will be inclined 51.6°. Identification of the proposed launch date and mission duration: The AC14 mission anticipates a launch in October 2019. The main mission phase is approximately 12 months. Description of the launch and deployment profile: The AC14 spacecraft will be deployed from the launch vehicle from a CubeSat dispenser. Typically, the launch vehicle will optimize separation timing to reduce the likelihood of collision between CubeSats. Each AC14 will fill a 3U slot in a flight qualified spacecraft dispenser. Reason for selection of operational orbit: As a secondary payload, AC14 has no control over the selection of operational orbit. AC14 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 deployment vehicle and its payloads will be delivered (including AC14) satisfies that requirement. Page 4 of 11 Approved for public release. OTR 2019-00707.

AC14 ODAR The Aerospace Corporation Identification of any interaction or potential physical interference with other operational spacecraft: As one of many CubeSats deployed on the mission, there is a small risk of contact between AC14 and another CubeSat. The timing of satellite deployments from the dispenser is intended to mitigate this risk as much as possible. Debris mitigation for the deployment process is the responsibility of the launch vehicle. In the event of contact 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 AC14 spacecraft are 3U CubeSats with outer dimensions of 34 cm x 11 cm x 11 cm. Deployable solar panels extend off the long axis of the spacecraft with dimensions 34 cm x 10 cm. The exterior bus is made from 6061-T6 aluminum and houses all payload and electronics components. Total spacecraft mass at launch: The AC14 spacecraft will weigh 3.5 kg at launch. Dry mass of spacecraft at launch: The AC14 spacecraft have no propulsion system. The dry mass is 3.5 kg. Description of all propulsion systems: The AC14 spacecraft have no propulsion system. Identification of all fluids planned to be on board: The AC14 spacecraft carry no fluids. 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: AC14 has 3-axis attitude control via nine 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 0.15-0.2 A-m2 when the satellite passes current through the wire. The rods generate negligible magnetic field when powered off. The torque rods are made from 35.5 cm-diameter mu-metal rods that are 5.5 cm long. The pico reaction wheels have flight heritage on three AeroCube-4, three AeroCube-5, and one AeroCube-7 spacecraft. Attitude sensors include Earth nadir sensors, two-axis Sun sensors on various spacecraft surfaces, a 3-axis magnetometer, and two-star trackers of the same type and model that are flying on AeroCube-7. A high-accuracy 3-axis rate gyro will be used to provide an inertial attitude reference when 0.7° 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: AC14 has no pyrotechnic devices. Page 5 of 11 Approved for public release. OTR 2019-00707.

AC14 ODAR The Aerospace Corporation Description of the electrical generation and storage system: Power for the AC14 spacecraft is generated by solar cells mounted onto panels that will be deployed from both sides of the bus, as well as cells affixed to the spacecraft bus. These cells are capable of producing up to 23 W of power. 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 are shock and thermally isolated by a thermoplastic mount. Each battery is composed of two cells. Two batteries are rated at 10 W-hr while the other two are rated at 9 W-hr, for a total of 38 W-hr on the spacecraft. Specific details of the batteries’ manufacture appear in Section 4. Identification of any other sources of stored energy: There are no other sources of stored energy on AC14. Identification of any radioactive materials on board: AC14 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: AC14 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 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 that may lead to an accidental explosion: Page 6 of 11 Approved for public release. OTR 2019-00707.

AC14 ODAR The Aerospace Corporation Battery risk: A possible malfunction of the lithium ion or lithium polymer 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, AC14 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.” Underwriters Laboratories (UL) certifies the batteries used on AC14. In general, these batteries are similar in size and power to cell phone batteries. Model Number Number Manufacturer Energy Stored (UL Listing) of Cells <=10 W-hr per cell ICR18650M Molicel 2 (2 batteries total) <=9 W-hr per cell INR18650A Molicel 2 (2 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 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 AC14 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 AC14 to experience similar conditions during their orbital life span. While the sources of failure would not be external heat on orbit, analysis of the Page 7 of 11 Approved for public release. OTR 2019-00707.

AC14 ODAR The Aerospace Corporation 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° F (100° C) safe operation limit. Continual charging with 2 to 6 W average power from the solar panels over an orbital life span greater than 15 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 AC14 batteries against explosion, ten potential failure modes for lithium batteries and their applicability or mitigation in AC14 are addressed in the following table: Failure Mode Applicability or Mitigation The AC14 body and internal design prevents deformation or crushing 1 Internal short circuit 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 AC14 have charge interrupt devices that activate Overcharging and excessive 3 during cell internal pressure buildup (due to cell internal chemical that charge rate 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. Low level current leakage or short circuit through battery pack case 7 Satellites are stored in a controlled environment. or 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 AC14 are UL-certified as non- explosive in over-heating scenarios. Polarity reversal due to over- A 2.7 V discharge cutoff threshold circuit in AC14 has been verified 9 discharge in acceptance tests for the electric power system. Excess battery temperatures due to post-mission orbital The circuit that charges the batteries cannot exceed 4.1 V and 10 environment and constant therefore will never overcharge the batteries. 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. Detailed plan for any designed breakup, including explosions and intentional collisions: AC14 has no plans for intentional breakups, explosions, or collisions. Page 8 of 11 Approved for public release. OTR 2019-00707.

AC14 ODAR The Aerospace Corporation List of components, which are passivated at EOM: No systems on AC14 will require being 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 AC14 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 Section 5: Assessment of Spacecraft Potential for On-Orbit Collisions Collision probabilities have been calculated using DAS v2.0.2 with the assumption of the maximum anticipated release altitude at a 500 km x 500 km altitude orbit, 51.6° inclination; 3.5 kg mass, and 0.035722 m2/kg area-to-mass ratio (the average area-to-mass configuration of the spacecraft post-mission). 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 Post-Mission Disposal Plans and Procedures Description of spacecraft disposal option selected: The AC14 mission has selected atmospheric reentry for disposal. The vehicle is a 34 x 11 x 11 cm bus. The AC14 mass is 3.5 kg. The minimum cross-sectional area for AC14 will be ~100 cm2, though the spacecraft will spend most of its time in a tumble state, with an average cross-sectional area of about 500 cm2. DAS Page 9 of 11 Approved for public release. OTR 2019-00707.

AC14 ODAR The Aerospace Corporation v2.0.2 analysis predicts a lifetime of 2-3 years, using the orbit assumptions listed at the beginning of Section 5. This lifetime is compliant with ODAR requirements. 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 AC14. Natural orbit decay is sufficient to deorbit the spacecraft. 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 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 AC14 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 patch antennas, and three small reaction wheels and the reaction wheel motor cases. Requirement 4.7-1 requires that all surviving debris from an uncontrolled spacecraft reentry have a risk of human casualty of less than 1:10,000. Human casualty is defined as an impact from an object with an energy of at least 15 J. DAS v2.0.2 analysis predicts that no objects from the AC14 spacecraft will survive reentry, posing zero risk of human casualty. Therefore, the AeroCube 14 mission is fully compliant with Requirement 4.7-1. Summary of objects expected to survive an uncontrolled reentry: DAS v2.0.2 analysis predicts that no spacecraft objects will 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 Page 10 of 11 Approved for public release. OTR 2019-00707.

AC14 ODAR The Aerospace Corporation Section 8: Assessment for Tether Missions The AC14 mission has no tether. All requirements are COMPLIANT. Sections 9–14: Assessment of Launch Vehicle Debris AC14 will fly as a secondary payload. Assessment of launch-vehicle debris is the responsibility of the primary payload. These sections are N/A for AC14. Page 11 of 11 Approved for public release. OTR 2019-00707.


Document Created: 2019-06-19 13:55:33
Document Modified: 2019-06-19 13:55:33
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