CubeSat Design Guidelines Professor A. Chen Professor J. Juang Teacher Assistant J. Vannitsen 16 Oct. 2012 SPACE SCIENCE AND SATELLITE SYSTEM ENGINEERING

CubeSat Design Guidelines

Professor A. ChenProfessor J. JuangTeacher Assistant J. Vannitsen16 Oct. 2012

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: http://www.cubesat.org/images/developers/cds_rev12.pdf

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.


-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: www.agi.com/products/free-software/


- Launch later half 2015, circular orbit, 100km, altitude inclination>20°.Orbit period: determined to be 7065 seconds (117.75minutes) or 12.229 orbits per Earth day.

Subsystems

PAYLOAD

AOCSPOWER

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.


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: www.cubesatshop.com- GOM Space Shop: http://gomspace.com/index.php?p=products- Clyde Space Shop: www.clyde-space.com/products- Pumpkin Shop: www.cubesatkit.com

NCKU Tracking Station position

Longtitude: 120°16'32.13" EastLatitude: 22°56'19.76" North

Altitude: 12 meters

Subsystems - COMMUNICATIONS

6U Lunar Design CubeSat Example

1. Data Rate: The data rate of 863.42bps 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: www.cubesatshop.com- GOM Space Shop: http://gomspace.com/index.php?p=products- Clyde Space Shop: www.clyde-space.com/products- Pumpkin Shop: www.cubesatkit.com

OBDH = On Board Data Handling

Subsystems - OBDH


1. Data Rate: Requirements: Image of 10MB and 10 images per day and constant telemetry rate of 39.1207bps. 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 430.2 minutes per day total data downlink per day requires a data rate for downlink of 863.42bps.

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


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.


For the purposes of determining the spacecraft power requirements six distinctspacecraft 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.


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: www.cubesatshop.com- GOM Space Shop: http://gomspace.com/index.php?p=products- Clyde Space Shop: www.clyde-space.com/products- Pumpkin Shop: www.cubesatkit.com


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

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: www.cubesatshop.com- GOM Space Shop: http://gomspace.com/index.php?p=products- Clyde Space Shop: www.clyde-space.com/products- Pumpkin Shop: www.cubesatkit.com


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: www.cubesatshop.com- GOM Space Shop: http://gomspace.com/index.php?p=products- Clyde Space Shop: www.clyde-space.com/products- Pumpkin Shop: www.cubesatkit.com


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: http://sourceforge.net/apps/mediawiki/free-cad/index.php?title=DownloadNote: 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!


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


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

Component Mass Margin Mass 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


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


Your CubeSat report

Introduction

1. The CubeSat Mission1.1 Mission Requirements1.2 Mission Objectives1.3 Mission Analysis

2. Subsystems2.1 Payload2.2 Communications2.3 OBDH2.4 Power2.5 AOCS

3. Structure and Configuration

4. Technology Readiness Level

5. Mass Budget

5. Cost Estimate

Conclusion

Conclusion

VOLUME AND MASS OF

COMPONENTS GO UP

VERY FAST!

WORK AS A TEAM!

ALL YOUR SUBSYSTEMS ARE LINKED!

REMEMBER!

你們有問題 !

[email protected]

Questions?

謝謝您的觀賞

SPACE SCIENCE AND SATELLITE SYSTEM ENGINEERING COURSE

Documents

CubeSat Design Guidelines Professor A. Chen Professor J. Juang Teacher Assistant J. Vannitsen 16 Oct. 2012 SPACE SCIENCE AND SATELLITE SYSTEM ENGINEERING