Structures and Thermal - cubesat-project/CubeSat GitHub Wiki

Contents

  1. Current Status
  2. Requirements
  3. Mechanical Constraints from Nanoracks
  4. Things to Consider
  5. Structural Design
  6. Manufacturing
  7. Assembly
  8. Gold Engraving
  9. Finite Element Analysis
  10. CAD Drawings
  11. Thermal

Current Status

  • Remove unnecessary ADCS components from structural model (photodiodes and GPS)
  • Add tuna can at end opposite to antenna
  • Add solar panel model to structural model
  • Update axes in Solidworks model to match NRCSD requirements

Structural Requirements

Requirement # Requirement Parent Req ID Verification Strategy
STR-01 The structure shall conform to launcher interface specifications SY-SS16, SY-SS06 By verification of STR-23 to STR-54
STR-02 The structure shall be 2U form factor SY-SS01 By design, by inspection, by review
STR-03 The CubeSat shall survive the launch and deployment environment SY-SS02, SY-SS16 Ensure CubeSat withstands Mil-STD 1540C vibration test
STR-04 The CubeSat shall have remove before flight switches SY-SS03 By design, by inspection, by review
STR-05 The structure shall house all CubeSat subsystems SY-SS01 By design, by inspection, by review
STR-06 The structure shall not outgass SY-SS07 Choosing metallic materials for the structure (outgassing is insignificant)
STR-07 The CubeSat shall have deployment switches SY-SS04 By design, by inspection, by review
STR-08 The structure shall meet Nanoracks dimension requirements SY-SS02 By measuring the dimensions of the CubeSat and comparing it with the Nanoracks dimension requirements
STR-09 The CubeSat shall adhere to integration and testing guidelines SY-SS14, SY-SS15 By ensuring to follow integration and testing guidelines
STR-10 The spacecraft structure must support the mechanical static and dynamic loads encountered during its entire lifetime, including: manufacturing, handling, transportation, testing, and launch SY-SS50 By complying with STR-03 and STR-36
STR-11 The spacecraft structure must be within the constraints of a 2U CubeSat architecture in a stowed configuration (10 x 10 x 20 cm) SY-SS01 By measuring the dimensions of the CubeSat in a stowed configuration and comparing it with the dimension requirements described
STR-12 The spacecraft structure must comply with constraints of using a NanoRacks CubeSat Deployer SY-SS02 By following NanoRacks constraints while designing the CubeSat and by inspection at the end
STR-13 The spacecraft structure must be modular in order for ease of access for inspection and testing SY-SS55 Use railing system to ensure easy assembly and disassembly of structure
STR-14 The mode of the spacecraft must be a natural frequency above 305 Hz (TBC) MR-PR05 Conduct modal analysis on Solidworks and verify
STR-15 All of the CubeSat structure and flight items must be free of sharp corners, edges, or burrs SY-SS02 By designing the CubeSat such that there are no sharp corners, edges, or burrs. Inspect the CubeSat at the end to confirm
STR-16 All of the CubeSat materials mustl have a Total Mass Loss (TML) of less than 1% (TBC) SY-SS07 By testing (see notes for suggestion)
STR-17 The CubeSat platform must be designed to accommodate ascent venting per ventable volume/area less than 50.8 meters (TBC) SY-SS84 By calculation and confirming that it is less than 50.8 meters
STR-18 The CubeSat spacecraft center of gravity must be located within 2 cm from its geometric center in the X and Y direction and within 4 cm from its geometric center in the Z direction SY-SS80 By checking mass properties on Solidworks to ensure the CG  is not located outside of the region
STR-19 The CubeSat Structural subsystem mass must not exceed 1500 g (TBC) SY-SS02, MR-PR07, SY-SS79 By determining mass through Solidworks and weighing the actual mass when built
STR-20 The XYZ axis rails and standoffs that contact the CubeSat Deployer must be hard anodized aluminum SY-SS02 By ensuring manufacturer is certified for hard anodizing process
STR-21 Every element must be designed to have a positive Safety Margin. The Safety Margin is defined as: MR-PR05, MR-OP04 *Requirement is not given
STR-22 Mechanisms must be designed to have a Safety Margin greater than 2 without considering the kinetic energy of moving parts MR-PR07, MR-OP04 By conducting FEA on components and ensuring Safety Margin is greater than specified number
STR-23 The CubeSat must meet the quasi-static and angular acceleration requirements, according to Table 3.3.1.1, based on finite element analysis using Solidworks MR-PR05 Conducting FEA and confirming that it meets quasi-static and angular acceleration requirements
STR-24 The CubeSat subsystems and payload must be shown to fit within the allocated volume of the CubeSat structure using CAD software SY-SS01, SY-SS02, MR-PR05 By design
STR-25 The CubeSat must slide into the CubeSat Deployer envelope without touching, except the outer rails and the NRCSD SY-SS02 By design, by inspection
STR-26 The CubeSat subsystems and payload must be shown to fit within the allowed volume of the CubeSat structure using physical models SY-SS01, SY-SS02 By design, by inspection
STR-27 The CubeSat must be shown to fit within the NanoRacks CubeSat Deployer envelope using physical model with only the outer rails in contact with the deployer SY-SS02 By design, by inspection
STR-28 Acceleration (quasi-static) tests on the CubeSat must be verified by hand calculations and finite element analysis using a safety factor of 2 MR-PR05, MR-OP04 By conducting FEA on components and ensuring Factor of safety is less than 2
STR-29 The CubeSat must pass the random vibration tests for both Soft Stow and/or Hard Mount Test Profiles as per Figure 10, Table 5 and Table 6 MR-PR05 By conducting tests and ensuring CubeSat structure passes
STR-30 Resonance surveys must be performed before and after every random vibration test to ensure peak resonance is at a constant frequency throughout the tests MR-PR05 Surveys should be completed after every random vibration test
STR-31 Resonance surveys must be performed in the range of 20 Hz to 2000 Hz and at an amplitude of 0.5 g MR-PR05 Analyzing displacement plot from testing
STR-32 TheCubeSat must be capable of withstanding a force of 1200 N across all rail ends in the z axis SY-SS02, MR-OP04 A loading test should be completed to verify that it can widthstand the force
STR-33 Deployable components and mechanisms on the CubeSat must adhere to the constraints and design requirements SY-SS83 ,SY-SS88 By design
STR-34 Deployable components function and performance must be verified by analyses and tests SY-SS88 By design. Completed tests and analysis
STR-35 The CubeSat must withstand a static load of 4g along the X and Y axis, and 7g in the Z axis (as per Table 4), induced by the launch environment, plus a 20% margin (TBC) MR-PR05, SY-SS16 By conducting FEA on components and ensuring there is at least a 20% margin
STR-36 Venting to allow for depressurization must be included in the design of the spacecraft SY-SS84 Calculate MEVR of cubesat and verify that it meets CSA requirements
STR-37 The Cubesat shall have four (4) rails along the Z axis, one per corner of the payload envelope, which allow the payload to slide along the rail interface of the NRCSD as outlined in Figure 4.1-1 SY-SS02 By design, by inspection, by review
STR-38 The CubeSat rails and envelope must adhere to the dimensional specification outlined in Figure 4.1-1 SY-SS02 By design, by inspection, by review
STR-39 Each CubeSat rail must have a minimum width (X and Y faces) of 6mm SY-SS02 By measuring the width of the rails
STR-40 The edges of the CubeSat rails must have a radius of 0.5mm+/- 0.1mm SY-SS02 By measuring the radius
STR-41 The CubeSat +Z rail ends must be completely bare and have a minimum surface area of 6mm x 6mm SY-SS02 By ensuring dimensions of +Z rail ends are equal to or greater than 6mm in each direction
STR-42 The CubeSat rail ends (+/-Z) must be coplanar with the other rail ends within +/- 0.1mm. SY-SS02 By verifying through Solidworks measurements and inspecting again once it is built
STR-43 The CubeSat rail length (Z axis) must be the following (+/-0.1mm): b. 2U rail length: 227.00mm SY-SS02 By measuring the rail length such that it complies with the dimension required
STR-44 The CubeSat rails must be continuous. No gaps, holes, fasteners, or any other features may be present along the length of the rails (Z-axis) in regions that contact the NRCSD rails. SY-SS02 By design, by inspection, by review
STR-45 The minimum extension of the +/-Z CubeSat rails from the +/-Z CubeSat faces must be 2mm. SY-SS02 By measurement
STR-46 The CubeSat rails must be the only mechanical interface to the NRCSD in all axes (X, Y and Z axes). SY-SS02 By ensuring exterior regions that will contact the NRCSD are part of the structure
STR-47 The CubeSat rail surfaces that contact the NRCSD guide rails must have a hardness equal to or greater than hard-anodized aluminum (Rockwell C 65-70) SY-SS02 By design, by inspection, by review (unless hardness is not supplied by manufacturer, then by testing)
STR-48 The CubeSat rails and all load points must  have a surface roughness of less than or equal to 1.6 μm SY-SS02 By design, by inspection, by review (unless manufacturer cannot comply with specification)
STR-49 The CubeSat must have a remove before flight (RBF) feature or an apply before flight (ABF) feature. The RBF / ABF shall be physically accessible via the NRCSD access panels on the +Y face of the dispenser SY-SS03 By design, by inspection, by review
STR-50 Deployment switches of the pusher/plunger variety must be located on the rail end faces of the CubeSat’s -Z face. SY-SS04 By design, by inspection, by review
STR-51 Deployment switches of the roller/lever variety must be embedded in the CubeSat rails (+/- X or Y faces). SY-SS04 By design, by inspection, by review
STR-52 Roller/slider switches must maintain contact with 75% of the NRCSD rail width along the entire length of the rail. SY-SS02 By design, by inspection, by review
STR-53 The CubeSat deployment switches must be captive. SY-SS02 By design, by specification, by inspection
STR-54 The force exerted by the deployment switches must not exceed 3N. SY-SS02 By specification of deployment switches
STR-55 The total force of all CubeSat deployment switches must not exceed 9N. SY-SS02 By design, by inspection, by review
STR-56 The CubeSat must be capable of withstanding a deployment velocity of 0.5 to 2.0 m/s at ejection from the NRCSD. SY-SS02 Ensure CubeSat withstands Mil-STD 1540C shock events
STR-57 The CubeSat must be capable of withstanding up to five (5) deg/sec/axis tip-off rate. SY-SS02 By design, by analysis
STR-58 Payload safety critical structures must (and other payload structures should) provide positive margins of safety when exposed to the accelerations documented in Table 4.3.1-1 at the CG of the item, with all six degrees of freedom acting simultaneously SY-SS02 By conducting FEA analysis on parts and ensuring safety margin is met
STR-59 Since the NRCSD launches in the soft-stow configuration (wrapped in bubble wrap and secured in a foam- lined CTB, as outlined in Section 3.4.2.7), the satellites contained within the NRCSD are exposed to a soft- stow random vibration launch environment. This allows the payload developer to test in a flight equivalent configuration if desired. The acceptable random vibration test options for CubeSat payload developers are outlined below. 1) Random vibration test the flight article in the soft-stow flight configuration to the Maximum Expected Flight Level (MEFL) +3dB (‘Soft-Stow Test Profile’ in Figure 4.3.2.1-1 / Table 4.3.2.1-), for a duration of 60 seconds in each axis. Note: Test configuration is the CubeSat integrated with the NRCSD or mechanically equivalent test fixture wrapped in flight approved bubble wrap and foam. NanoRacks must provide flight approved packing material for test. 2) Random vibration test the flight article in the hard-mount configuration to a combined test profile that envelopes the MEFL+3dB and a minimum workmanship level (MWL) vibe (‘Hard-Mount Test Profile’ in Figure 4.3.2.1-1 / Table 4.3.2.1-), for a duration of 60 seconds in each axis. Note: Test configuration is the CubeSat integrated with the NRCSD or mechanically equivalent test fixture bolted directly to a vibration table. This test profile also includes additional margin to the MEFL profile beyond that of the +3dB to account for potential amplification of the acceleration loads caused by the foam during flight. SY-SS02 Ensure CubeSat can withstand NanoRacks vibration test
STR-60 The CubeSat must be capable of withstanding the random vibration environment for flight with appropriate safety margin as outlined in Section 4.3.2.1. SY-SS02 Ensure CubeSat can withstand NanoRacks vibration test
STR-61 The CubeSat must be capable of withstanding the loads inside of the NRCSD when exposed to the acceleration environment defined in Table 4.3.4-1 SY-SS02 Ensure CubeSat can withstand NanoRacks vibration test

Mechanical Constraints from Nanoracks

The document outlining the constraints can be found here.

  • Maximum length: 227 mm
  • Maximum mass: 3.60 kg
  • There must be deployment switches that are either plunger type on the negative z face of the rails, or roller/lever type embedded in the rails
  • The CubeSat shall withstand a 1200N force across all rail ends in the Z-axis
  • The remove before flight (RBF) pin must be accessible from the positive y face of the deployer.
  • The CubeSat will be launched from a NRCSD, and must have an XYZ coordinate system that matches that of the NRCSD shown below. The positive Z-face of the CubeSat will enter the NRCSD first.

NRCSD Coordinate System

  • The CubeSat shall withstand a deployment velocity of 0.5 to 2 m/s upon ejection from the NRCSD, and a tipoff rate of up to 5 deg./sec/axis.
  • The CubeSat will have a center of mass that is within the following range relative to its geometric center: ±2mm in the X- and Y-direction, ±4mm in the Z-direction.
  • The CubeSat will have continuous rails in each of its four corners running along the Z-axis. These will be the only interface with the NRCSD.

The rails must meet the following specifications:

  • The rails will have a width of 6mm
  • Rounded edges with a radius of 0.5mm ± 0.1mm
  • 2U length of 227mm.
  • The rails will extend in the Z direction a minimum of 2mm beyond the ± Z faces of the CubeSat
  • The rail ends will be coplanar with a tolerance of ±0.1mm.
  • The rails will have a hardness equal to or greater than Hard Anodized Aluminum (Rockwell C 65-70).
  • The rails will have a roughness equal to or less than 0.6 micron

Design Considerations

  • It is important to design for assembly and manufacturing, and take into account the mechanical/electrical interface.
  • There must be adequate room for wires, and the bend radii of the wires must be accommodated for.
  • As there are no moving parts after the antenna is deployed, there are not strict zones that mechanical or electrical cannot interfere with.
  • Bolt/nut access for assembly.

Structural Design

Manufacturing

Component Manufacturing Method Reason
Mounting Plates Laser cut, then sheet metal bending It is easier and quicker to laser cut the thin material as opposed to milling it. Laser cutting is cheaper and more accurate than water jet cutting.
Rails Milling The mounting holes for the plates must be in specific locations and the outer bend radius is specified by nanoracks. It will be expensive, but I don’t know how else to achieve the bend radius of 0.5 mm. Stock material has a larger bend radius
Cover Plates Milling They cannot be laser cut due to the different depths. They should not be hard to mill, just some what time consuming. This will also probably be somewhat expensive. - Maybe 3D printing: look into cost and if it is allowed in space. Be sure to consider that the entire load from the deployer will be on the rail ends.
Solar Panel Plated Laser cut *Note: Design is not complete so this may change

Assembly

List of Acronyms

EPS Electrical Power System
CB2 Custom Board 2
CB1 Custom Board 1
OBC On-Board Computer
UHF Ultra-High Frequency Transceiver

Steps

  1. Bottom Cover Plate
    • Start the assembly process with the Bottom Cover Plate and placing it face down on a flat surface
  2. Threaded Rods
    • Screw in the 4 threaded rods all the way into each corner of the Bottom Cover Plate
  3. M3 Nuts: Support for Bottom Camera Mounting Plate
    • Screw M3 nuts on all 4 threaded rods at a height of 17.1 mm from the face of the Bottom Cover Plate
  4. Bottom Camera + Bottom Camera Mounting Plate
    • Attach the Bottom Camera to the Bottom Camera Mounting Plate via screws
    • Place the Bottom Camera + Bottom Camera Mounting plate assemble through the threaded rods such that it rests on the aforementioned spacers and the Bottom Camera is facing the negative-Z direction.
  5. EPS (Electrical Power System)
    • Place the EPS through the threaded rods such that it rests on the Bottom Camera Mounting Plate
    • Connect PC104(1) pins into female pin holes on EPS
  6. M3 Nuts: Support for EPS
    • Screw M3 nuts on all 4 threaded rods such that it touches and holds down the EPS
  7. M3 Nuts: Support for CB1 Mounting Plate
    • Screw M3 nuts on all 4 threaded rods at a height of 62.83 mm from the bottom of the M3 nut to face of the Bottom Cover Plate
  8. CB1 Mounting Plate
    • Place the CB1 Mounting Plate through the threaded rods such that it rests of the aforementioned M3 nuts
  9. CB1
    • Screw the Permanent Magnet onto the positive-Z face of CB1
    • Place CB1 + Permanent Magnet assembly through the threaded rods such that it rests on the CB1 Mounting Plate and the Permanent Magnet is sticking upwards in the positive-Z direction
    • Connect the pins on the bottom of CB1 into the PC104(1)
    • Connect another PC104(2) into the female pin holes on CB1
  10. M3 Nuts: Support for CB1
    • Screw M3 nuts on 3 of the 4 threaded rods such that it touches and holds down CB1
    • Do not place a nut in the bottom-right corner, as this would interfere with the switch that would be eventually placed there
  11. M3 Nuts: Support for CB2 Mounting Plate
    • Screw M3 nuts on all 4 threaded rods at a height of 84.84 mm from the bottom of the M3 nut to face of the Bottom Cover Plate
  12. CB2 Mounting Plate
    • Place the CB2 Mounting Plate through the threaded rods (and through the Permanent Magnet) such that it rests of the aforementioned M3 nuts
  13. CB2
    • Place CB2 through the threaded rods such that it rests on the CB2 Mounting Plate
    • Connect the pins on the bottom of CB2 into PC104(2)
    • Connect a PC104(3) into the female pin holes on CB2
    • Connect another PC104(4) into the previous PC104(3)
    • Connect another PC104(5) into the previous PC104(4)
  14. M3 Nuts: Support for CB2
    • Screw M3 nuts on all 4 threaded rods such that it touches and holds down CB2
  15. M3 Nuts: Support for Engraving Mounting Plate
    • Screw M3 nuts on all 4 threaded rods at a height of 122.02 mm from the bottom of the M3 nut to face of the Bottom Cover Plate
  16. Engraving + Engraving Mounting Plate
    • Screw the Engraving onto the positive-Z face of the Engraving Mounting Plate
    • Place the Engraving + Engraving Mounting Plate assembly through the threaded rods such that it rests on the aforementioned M3 nuts
  17. M3 Nuts: Support for Engraving Mounting Plate
    • Screw M3 nuts on all 4 threaded rods such that it touches and holds down the Engraving Mounting Plate
  18. M3 Nuts: Support for OBC Mounting Plate
    • Screw M3 nuts on all 4 threaded rods at a height of 131.34 mm from the bottom of the M3 nut to face of the Bottom Cover Plate
  19. OBC Mounting Plate
    • Place the OBC Mounting Plate through the threaded rods such that it rests of the aforementioned M3 nuts
  20. OBC
    • Place the OBC through the threaded rods such that it rests on the OBC Mounting Plate
    • Connect the pins on the bottom of the OBC into the PC104(5)
  21. M3 Nuts: Support for OBC
    • Screw M3 nuts on all 4 threaded rods such that it touches and holds down the OBC Mounting Plate
  22. M3 Nuts: Support for UHF Mounting Plate
    • Screw M3 nuts on all 4 threaded rods at a height of 154.18 mm from the bottom of the M3 nut to face of the Bottom Cover Plate
  23. UHF Mounting Plate
    • Place the UHF Mounting Plate through the threaded rods such that it rests of the aforementioned M3 nuts
  24. UHF
    • Place the UHF through the threaded rods such that it rests on the UHF Mounting Plate
  25. M3 Nuts: Support for UHF
    • Screw M3 nuts on all 4 threaded rods such that it touches and holds down the UHF Mounting Plate
  26. Spacers
  27. Top Camera + Top Camera Mounting Plate
    • Attach the Top Camera to the Top Camera Mounting Plate via screws
  28. M3 Nuts: Support for Top Camera Mounting Plate
    • Screw M3 nuts on all 4 threaded rods at a height of ______ mm from the face of the Bottom Cover Plate
    • Screw M3 nuts on all 4 threaded rods such that it touches and holds down the Top Camera Mounting plate
  29. Antenna Assembly + Antenna Mounting Plate
    • Attach the Antenna Assembly to the Antenna Mounting Plate via screws
  30. Attaching the Antenna Assembly + Antenna Mounting Plate
    • Plate the Antenna Assembly + Antenna Mounting Plate over the threaded rods on the top, and slightly unscrew the threaded rods from the Bottom Cover Plate such that they screw into Antenna Mounting Plate
  31. Rails
    • Attach switches to rails
  32. Solar Panels

Gold Engraving

  • Space allocated for the engraving is 55 mm x 55 mm x 5 mm
  • The interface with the engraving plate is going to be M3 button head bolts – the length of which will be determined after the height of the engraving is confirmed. Ideally 4 of them, one in each corner.

Finite Element Analysis

  • In Progress.

CAD Drawing

Redesign CubeSat_TunaCan_correctOrientation

Thermal

Requirements

Requirement # Requirement Parent Req ID Verification Strategy
TH-01 The CubeSat's components shall be shielded from extreme temperatures SY-SS17
  • Extreme temperatures defined as temperatures which induce component failure
  • Success is indicated when components do not reach extreme temperatures in NX thermal simulation results and in thermal chamber testing
    		•
    TH-02 The Cubesat shall have temperature sensors SY-SS17
  • Inspect physical location of temperature sensors
  • Success is indicated by connection of temperature sensors to OBC
    • TH-03 Subsystem components shall remain within operating temperatures when operating SY-SS17
  • Operating temperatures defined by component specs
  • Success is indicated when components remain within operating temperatures while operating in NX thermal simulation results and in thermal chamber testing
    • TH-04 Subsystem components shall remain within survival temperatures when not operating SY-SS17
  • Survival temperatures defined by component specs
  • Success is indicated when components remain within survival temperatures while not operating in NX thermal simulation results and in thermal chamber testing
    • TH-05 CubeSat temperature levels shall be regulated passively SY-SS17
  • No active thermal regulation techniques will be considered
  • Success is indicated by completion of thermal management system integrated into CubeSat with only passive components
    • TH-06 The spacecraft thermal control system must use battery heaters to control internal temperatures according to battery specifications SY-SS17, MR-PR05
  • Success is indicated upon incorporation of battery heaters to manage internal temperatures.
  • Success is indicated when battery heaters successfullly manage temperatures in NX thermal simulations and thermal chamber testing
    		•
    TH-07 Heaters used for the purpose of meeting performance specifications must be oversized by a minimum of 25% SY-SS17, MR-PR05
  • Performance spec determined through NX simulation and component operating/survival temperatures
  • Success indicated by integrating of 25% oversized heaters into CubeSat stack
    • TH-08 Sufficient telemetry and housekeeping information must be provided for monitoring of thermal status SY-SS09
  • Connect thermistors, boot up OBC, check for thermal data
  • Success is indicated when OBC receives thermal data
    • TH-09 The CubeSat must be capable of withstanding the temperature extremes outlined in Table 4.5.1.1 (TBC) defined in [AD6] SY-SS17
  • Extreme temperatures defined as temperatures which induce component failure
  • Success is indicated when components do not reach extreme temperatures in NX thermal simulation results and in thermal chamber testing
    • TH-10 Thermal simulations must be performed using Siemens NX MR-PR05
  • Success is indicated when NX thermal test results are used to implement thermal management
    		•
    TH-11 Removable covers must normally be removed for thermal vacuum testing SY-SS65, SY-SS66
  • Removable covers will be inspected to be removable
  • Success is indicated when they are removed
    		•
    TH-12 TThe Ukpik-1 satellite must pass the Thermal Cycling Tests as per Table 4.5.2.1 (TBC) defined in [AD6] SY-SS65, SY-SS66
  • NX simulations will be used to simulate the orbital environment as closely as possible to the thermal cycling tests defined in Table 4.5.2.1. NX results will then source our thermal design. Success is indicated when NX simulations show passing these test is very likely, and ultimately determined once the CubeSat passes the thermal cycling tests.
    		•
    TH-13 The CubeSat must be capable of withstanding the expected thermal environments for all mission phases, which are enveloped by the on-orbit, EVR phase prior to deployment. The expected thermal environments for all phases of the mission leading up to deployment are below in Table 4-3.6-1. SY-SS17
  • NX Thermal simulations and thermal chambers to test thermal susbsystem design and sizing
  • Success is indicated when CubeSat withstands expected thermal environements in NX thermal simulation results and in thermal chamber testing

    • Background

    The CubeSat uses both passive and active thermal control to keep component temperatures within operational and survival ranges. It also features a set of temperature sensors for telemetry. Passive thermal control involves the use of AZ-93 paint to coat the endplates of the CubeSat, allowing it to both efficiently radiate heat from those faces and reflect solar radiation. The Electrical Power System (EPS) batteries use a set of built-in heaters operated by thermostats to keep them from freezing at low temperatures. Additional temperature sensors are incorporated to the solar panels, which will be exposed to direct sunlight.

    Passive Thermal Control

    The thermo-optical properties of the AZ-93 paint, applied to the endplates of the CubeSat, are provided in the table below.

    Property Value
    Thermal Emissivity 0.91 +/- 0.02
    Solar Absorptivity 0.15 +/- 0.02

    Active Thermal Control

    The Endurosat EPS battery is equipped with three heaters, drawing 100, 150, and 200 mA. The heater controller turns on heaters as needed to regulate battery temperature using a temperature hysteresis algorithm.

    Temperature Sensors

    Temperature sensors are located on all thermally critical components of the CubeSat to provide telemetry.

    Component Quantity Location
    Solar panels 4 On panel backing, one TMP122-EP sensor each.
    OBC 1 On CPU.
    UHF 1 Inside unit.
    NISA cameras 6 Inside cameras, three each.
    EPS 4 On battery cells, one each.
    Total 16  

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