CubeSat Design Guidelines Professor A. Chen Professor J. Juang Teacher Assistant J. Vannitsen 16 Oct SPACE SCIENCE AND SATELLITE SYSTEM ENGINEERING COURSE

- Introduction - Mission Requirements - Mission Objectives - Mission Analysis - Subsystems - Environment Considerations - Structure and Configuration - Technology Readiness Level - Mass Budget - Cost Estimate - Your CubeSat report - Conclusion Table of Contents

Introduction CubeSat 是什麼？ CubeSat concept: In 1999, Bob Twiggs/Stanford University & Jordi Puig- Suari/California Polytechnic State University. 2U: 10cmx10cmx20cm 2Kg (2.6Kg)1U: 10cmx10cmx10cm 1Kg (1.3Kg) 3U: 10cmx10cmx30cm 3Kg (4Kg) CubeSat 是什麼？

Introduction Basic CubeSat Design Specifications driven by its deployer. For your report use the CubeSat Design Specifications developed by CalPoly. Freely available here: P-POD = Poly Picosatellite Orbital Deployer

Mission Requirements YOUR CUBESAT DESIGN 1. 皮米衛星的大小不得大於 10x10x30cm ，重量不得大於 4kg. 2. 軌道限制為 Low Earth Orbit (LEO) ，也就是地表以上 160km~2000km 範圍。軌道 傾角 (i) 與離心率 (e) 不設限. 3. 通訊系統為 UHF/VHF Band, 通訊速率為 9600bps. 6U Lunar CubeSat Design Example 1. 皮米衛星的大小不得大於 10x20x30cm. 2. Inserted directly to Low Lunar Orbit (LLO) ，也就是地表以上 100km 範圍。軌道傾 角 (i)>20°. 3. Payload Narrow Angle Camera (NAC) dimensions 30cmx10cmx10cm, weight 1930g.

Mission Objectives YOUR CUBESAT DESIGN - You should define your CubeSat Mission Objective. - Mostly, the CubeSat Missions include: Technology Demonstrator; And/Or Earth Remote Sensing. Advice: Look at the Website List sent by Professor Chen and make some researches by yourself on the Internet for Past, Present and Future CubeSat Missions developed worldwide. 6U Lunar CubeSat Design Example -To take pictures of the Moon with a Narrow Angle Camera for at least 6 months.

Mission Analysis YOUR CUBESAT DESIGN - Choose a launcher, launch location and date. Note: In reality those information are not always known when a CubeSat project is started. It is done here so you can use specific values to define in STK. -Determine the orbital parameters (altitude, inclination, orbit period). Note: Data driven by the launcher. Mostly the CubeSats are not main passengers of the launchers, then they depend on the main satellite mission for orbital parameters. - Compute those information in STK  Free: 6U Lunar CubeSat Design Example - Launch later half 2015, circular orbit, 100km, altitude inclination>20°. Orbit period: determined to be 7065 seconds (117.75minutes) or orbits per Earth day.

Subsystems PAYLOAD AOCS POWER OBDH COMM EVERYTHING IS LINKED! Modifications on a Subsystem will affect the other Subsystems! POWER COMM PAYLOAD POWER COMM OBDH PAYLOAD POWER COMM

Subsystems - PAYLOAD YOUR CUBESAT DESIGN -In your Payload Definition pay attention to the following parameters: - Mass; - Power Consumption; - Dimensions; - Data output; - Cost. 6U Lunar CubeSat Design Example

Subsystems - COMMUNICATIONS YOUR CUBESAT DESIGN 1. Data Rate: The data rate calculation is achieved using the total accrued data per day and the total communication window per day to the ground station. Note: Use the NCKU Tracking Station position for the Ground Station Location and define the total communication window per day to the ground station with STK. 2. Select your Hardware: To select your Communication system you can choose to use COTS (Components On The Shelf). List of products available on the websites below: - ISIS Shop: - GOM Space Shop: - Clyde Space Shop: - Pumpkin Shop: NCKU Tracking Station position Longtitude: 120°16'32.13" East Latitude: 22°56'19.76" North Altitude: 12 meters

Subsystems - COMMUNICATIONS 6U Lunar Design CubeSat Example 1. Data Rate: The data rate of bps is based on the average communication window and is assumed that the excess data storage capability can store the data from the shorter communications day to be transmitted on the longer communications days. 2. Selected Hardware:

Subsystems - OBDH YOUR CUBESAT DESIGN 1. Data Rate: - Depends on DATA needed to realize your mission AND downlink time of the ground station. 2. Data Storage: - All the data accrued during non-downlink time. Take into account download time of the ground station. 3. Select your Hardware: To select your OBDH system you can choose to use COTS (Components On The Shelf). List of products available on the websites below: - ISIS Shop: - GOM Space Shop: - Clyde Space Shop: - Pumpkin Shop: OBDH = On Board Data Handling

Subsystems - OBDH 6U Lunar CubeSat Design Example 1. Data Rate: Requirements: Image of 10MB and 10 images per day and constant telemetry rate of bps. The images compressed to 1.6Mb.  Total data per day: 19.4Mb, including a 15% margin for overheads (encoding etc.), this increases to 22.3Mb/day. As average downlink time of minutes per day  total data downlink per day requires a data rate for downlink of bps. 2. Data Storage: - The minimum data storage requirement: To store data accrued during non-downlink time plus one additional NAC image (15.6Mb + 1.6Mb) is 17.2Mb, using an additional 20% margin this increases to 20.1Mb. Note: Data storage capability should be much higher than this absolute minimum requirement (i.e. per day) to account for ground station down time and shorter communications windows. 3. Selected Hardware:

Subsystems - POWER YOUR CUBESAT DESIGN 1. Solar Array Sizing

Subsystems - POWER 6U Lunar CubeSat Design Example 1. Solar Array Sizing

Subsystems - POWER YOUR CUBESAT DESIGN 2. Spacecraft Modes (Definition) Spacecraft modes will depend on your mission. Note: You can use the below 6U Lunar CubeSat Spacecraft Modes example as a reference. 6U Lunar CubeSat Design Example For the purposes of determining the spacecraft power requirements six distinct spacecraft modes were defined: 1. Imaging, used only when the NAC is taking images; 2. Data Dump, used when the spacecraft is down-linking data to the ground station; 3. Momentum dump, used when the spacecraft is dumping the momentum from its reaction wheels using the gas propulsion; 4. Nominal, which is used for the majority of the time when the spacecraft is only sun pointing; 5. Slew; 6. Safe, used in failure modes and for use during the maximum eclipse periods.

Subsystems - POWER YOUR CUBESAT DESIGN 2. Spacecraft Modes (power consumption) You should define the power consumption of each subsystem depending on the mode. Note: You can use the below 6U Lunar CubeSat Example Table as a reference. 6U Lunar CubeSat Design Example

Subsystems - POWER YOUR CUBESAT DESIGN 3. Select your Hardware: To select your POWER system you can choose to use COTS (Components On The Shelf). List of products available on the websites below: - ISIS Shop: - GOM Space Shop: - Clyde Space Shop: - Pumpkin Shop: 6U Lunar CubeSat Design Example

Subsystems - AOCS YOUR CUBESAT DESIGN 1. Pointing Requirements: The attitude and orbit control subsystem accuracy is driven by your payload pointing requirements. 2. Torque Analysis: Solar Radiation Torque Calculation Gravity Torque Calculation AOCS = Attitude and Orbit Control System

Subsystems - AOCS 6U Lunar CubeSat Example Solar Radiation Torque Calculation

Subsystems - AOCS YOUR CUBESAT 3. Select your Hardware: To select your AOCS you can choose to use COTS (Components On The Shelf). List of products available on the websites below: - ISIS Shop: - GOM Space Shop: - Clyde Space Shop: - Pumpkin Shop: 6U Lunar CubeSat Example

Environment considerations 1. Radiations 2. Thermal Thermal analysis are performed taking into account the temperature which is influenced by the Space environment AND by the satellite systems. Note: For your study it is not necessary to take into account the radiations and the thermal environment as this require many analysis. Take it into account at least basically (in your geometric configuration, do not expose your electronic boards directly outside of the CubeSat, do not put all the subsystems which emit heat very close to each other, etc…). Calculate the radiations received by each subsystem If yes, add shielding or change susbsytem location Verify if radiation dose is too high

Structure and Configuration YOUR CUBESAT Select your structure: To select your Structure you can choose to use COTS (Components On The Shelf). List of products available on the websites below: - ISIS Shop: - GOM Space Shop: - Clyde Space Shop: - Pumpkin Shop: 6U Lunar CubeSat Example

Structure and Configuration YOUR CUBESAT Configuration: To propose a preliminary design of your CubeSat you can use CATIA or FreeCAD. FreeCAD available here for free: cad/index.php?title=Download Note: Use it to predict the centre of mass and inertia tensors (for use in torque calculations – AOCS section). After proposing a configuration you have to produce a table for the Mass budget! 6U Lunar CubeSat Example

Technology Readiness Level Definition: Assess the maturity of evolving technologies (materials, components, devices, etc.) prior to incorporating that technology into a system or subsystem. Define the TRL Level of your subsystems.  Get a rough assessment of the feasibility and risk of your mission.  Help to define the mass margins. TRL 是什麼？ YOUR CUBESAT

Technology Readiness Level 6U Lunar CubeSat Example Low because developed by students Low because only laboratory tests done. Note: In your study only give a number for your TRL no letter needed.

Mass Budget YOUR CUBESAT ComponentMassMarginMass inc. margin Component A Component B... Total Additional System Margin (Conservative = 20%) Total Margins are applied according to the TRL of the components and the confidence in the COTS mass when considering modification Take into account general margin + margin for electrical and data harness

Mass Budget 6U Lunar CubeSat Example

Cost estimate YOUR CUBESAT COST ESTIMATE Satellite Components Ground Support, Equipment, AIT… Launch Note: In your study only give a cost estimate for the Satellite components Satellite Components Ground Support, Equipment, AIT…

Cost estimate 6U Lunar CubeSat Example

Your CubeSat report Introduction 1. The CubeSat Mission 1.1 Mission Requirements 1.2 Mission Objectives 1.3 Mission Analysis 2. Subsystems 2.1 Payload 2.2 Communications 2.3 OBDH 2.4 Power 2.5 AOCS 3. Structure and Configuration 4. Technology Readiness Level 5. Mass Budget 5. Cost Estimate Conclusion

REMEMBER! ALL YOUR SUBSYSTEMS ARE LINKED! WORK AS A TEAM! VOLUME AND MASS OF COMPONENTS GO UP VERY FAST!

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