The SMiLE payload is designed to study liquid behavior in microgravity aboard the ISS. The original design had challenges, so the author redesigned it with a Raspberry Pi computer, cameras, sensors, and software implemented in Python. Testing was limited due to COVID-19 closures. The redesign satisfies project requirements but integration and unit testing are recommended along with prototyping, a PCB board, and adapting the hardware structure.

1. SMiLE
PAYLOAD
Design and Development of
an ISS Payload for Liquid
Behavior Study in
Microgravity
Author: Mohamed Elhariry
Supervisor: Yadvender Singh Dhillon
External Advisor (ESA): Dr. Barnaby Osborne
Individual Project Report (IPR) ISU – Master of Space Studies 2020 (MSS20) 1
(Brandt, 2014)

2. CURRENT DESIGN ANALYSIS
CHALLENGES
REDESIGN & IMPLEMENTATION
Current payload design, disassembly
Current hardware and software challenges
Rationale and implementation
TABLE OF
CONTENTS
02
03
04
Collection and analysis of results, future work
05 RESULTS & RECOMMENDATIONS
THE SMiLE PAYLOAD01
Introduction and IP objectives
2

3. SMiLE PAYLOAD
01
3

4. ● The Spun Microgravity Liquid Experiment (SMiLE) is a project developed to
study the behavior of liquid droplets in a microgravity environment
● Payload has been designed to fly aboard the International Space Station in the
Nanoracks platform
● Equipped with sensors and actuators to autonomously perform experiments
without requiring crew attention
INTRODUCTION
4
(NASA, 2015)
(ESA, 2019b)
(Nanoracks, 2013)

5. INTRODUCTION
5
(Franki, 2014)

6. ● Study and Analysis of the SMiLE Payload
● System Requirements Identification
● Market Research of COTS Components
● Software Architecture Design
● Software Requirements Implementation
● Integration Testing
● PCB Design
IP - AIMS & OBJECTIVES
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7. CURRENT DESIGN
ANALYSIS
02
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8. PAYLOAD DESIGN
Bearing
Mount
Viewing
Chamber
Water
Reservoir
Nanoracks
Interface
Centrifuge
Cameras
Onboard
Computer
Structure
8(Brandt, 2014)

9. DISASSEMBLY
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10. CHALLENGES
03
11

11. SOFTWARE
● Scarce documentation
● Lacks ADC for battery level reading
● Over engineered electronics
HARDWARE
● Non-modular design
● Does not interact with sensors and actuators
● Lack of safety mechanisms
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12. REDESIGN &
IMPLEMENTATION
04
13

13. HARDWARE INITIATION
Set hardware components to a
known state
INJECTION AND RECORDING
Inject water into viewing
chamber, start video recording
SPIN AND RECORDING
Start centrifuge, keep video
recording
DRAIN AND RETURN
Return all water into reservoir,
terminate video recording
OPERATIONAL MODES
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14. ● Quad Core Cortex-A53 64-bit CPU
● Interfaces USB, I2C, 1xCSI, GPIO
● CPU Clock 1.4 GHz
● Micro SD Card Slot
● RAM 512 MB
ONBOARD COMPUTER
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(Raspberry, 2013)

15. ● Hybrid architecture for cameras
● Introduction of ADC for battery voltage detection
● Addition of temperature sensor with 1-Wire protocol
HARDWARE ARCHITECTURE
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16. ● UC80MPA Camera makes use of the USB Bus
● Raspberry Pi Camera makes use of the CSI Bus
● Framerate of 25 FPS for USB BUS, and 90 FPS for CSI
VIDEO RECORDING
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(Seeedstudio.com, 2019)
(Spinel, 2017)

17. ● Built-in Threading support for simultaneous operations
● Modular design for flexibility and maintainability
● Make use of Classes and Inheritance features
SOFTWARE DESIGN
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Code
Local Variables
Thread
Code
Local Variables
Thread
Code
Local Variables
Thread
Global Variables
Process

18. ● Software had been implemented in Python 3.7
● Resilient to sudden power failures and reboots
● Five main functions:
○ Hardware Initiation
○ Safety Checks
○ Injection and Recording
○ Spinning and Recording
○ Drain and Return
SOFTWARE IMPLEMENTATION
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19. HARDWARE INITIATION
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20. SAFETY CHECKS
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21. INJECTION AND RECORDING
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22. SPINNING AND RECORDING
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23. DRAIN AND RETURN
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24. RESULTS &
RECOMMENDATIONS
05
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25. ● Project requirements successfully satisfied:
○ Successfully redesigned SMiLE with COTS components
○ Video recording is stored on the onboard micro SD card
○ Frame rate for USB camera is 25 FPS
○ Frame rate for CSI camera is 90 FPS
○ Code successfully implemented with threading capabilities
○ Software architecture and implementation permits for fully
autonomous operations
○ Safety checks implemented, including temperature and battery level
monitoring
● Objectives not satisfied:
○ No testing aside for RPi3 A+ and cameras due to lab closure (COVID-19)
RESULTS
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26. 1. Perform integration testing with the full set of hardware components attached
to the onboard computer
2. Perform unit testing on the AnalogSensor, Battery, Bubble, Motor,
Temperature, and Lighting classes
3. Create and implement automated testing procedures within the code
4. Design and test breadboard prototypes of the payload
5. Design PCB board to connect components together
6. Adapt hardware structure of the payload to host the onboard computer and
cameras
RECOMMENDATIONS
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27. Question?
mohamed.elhariry@community.isunet.ed
u
isunet.edu
THANKS!
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