Design and Develop an Embedded System to Manage and Control a Biological Experiment in Space
CubeSat Embedded System Design for a Biological Experiment in Space
Master of Engineering thesis, University of Canterbury, 2023. Jonathan Edwards.
Getting a biological experiment to work in orbit is mostly an electronics problem. The payload has to run 40 protein crystallisation experiments, keep them alive for more than six months, and do it on a power budget with no headroom. Nobody can service the board once it launches.
This thesis designs that embedded system using commercial off-the-shelf parts rather than space-qualified electronics, and works through what the Low Earth Orbit environment actually does to them.
What the Research Covers
COTS Electronics in Orbit
Space-qualified parts are expensive and slow to source. The research tested whether commercial off-the-shelf electronics can do the job in Low Earth Orbit instead, using a 'Careful COTS' risk approach rather than assuming one part class fits every mission.
Radiation Effects and Mitigation
Two things damage electronics in orbit: dose that builds up over time, and single particles that strike and upset a device instantly. The research found accumulated dose to be a minor concern for these parts, while single event effects are the real threat to mission life.
Fault-Tolerant Architecture
How long the system survives depends on the hardware and software protections built into the architecture. The design work covers detecting an upset, recovering from it without human intervention, and keeping the payload running through faults that cannot be prevented.
Power Budget and Autonomy
A large-scale prototype running a Linux-based operating system autonomously monitors, manages, and controls every subsystem, while staying inside both the operational power limit and a 24-hour energy consumption constraint.
Abstract
As published in the University of Canterbury Research Repository.
This thesis pertains to the design and development of an embedded system with low-cost and low-power Commercial-Off-The-Shelf (COTS) electronics for a CubeSat-based protein crystallisation experimental payload, which will operate in the microgravity Low Earth Orbit (LEO) environment. The experimental payload will consist of up to 40 experiments and must be able to survive longer than 6 months to obtain relevant data from the experiments. The primary objective of the embedded system is to autonomously monitor, manage, and efficiently control all subsystems. This research will focus on comprehending the uncertainties of the space environment and how it impacts electronics in space.
The embedded system I designed uses a scientific 'Careful COTS' risk approach and a 'no one-fits-all strategy' (i) to understand the effects of the LEO environment on electronics and mitigation techniques and found COTS electronics to be a suitable replacement instead of qualified space-graded electronics in LEO; (ii) to construct a power-efficient, reliable, and robust embedded system architecture capable of lasting 6 months in LEO.
The LEO space environment primarily comprises radiation accumulation (i.e., Total Ionising Dose (TID)) and radiation instantaneous particle striking events (i.e., Single Event Effects (SEEs)). I found TID to be a minor concern for COTS electronics of the embedded system, while SEEs, on the other hand, are a major concern. The lifespan of the embedded system depends on the intensity and probability of particle striking events and the implementation of robust hardware and software protections into the architecture design.
I successfully designed a large-scale prototype embedded system using COTS electronics which is controlled by a Linux-based Operating System (OS). This allows the experimental payload to autonomously monitor, manage, and efficiently control all subsystems while meeting both the operational power and 24-hour energy consumption constraints. Furthermore, the current and future SEE hardware and software mitigation strategies designed will allow the embedded system to last longer than 6 months in the LEO environment.
How This Applies to Field Hardware
The same failure modes, on a shorter cable run.
A satellite payload and a charge controller on a mooring have more in common than they look. Both run unattended. Both have to survive conditions that corrupt memory, brown out supplies, and lock up processors. Both need to come back on their own when something goes wrong, because nobody is going out there to press reset.
That is why this research shows up in MicroCore's commercial work. Watchdog strategy, brown-out behaviour, memory error handling, and safe recovery paths get designed in at architecture stage rather than added after a field failure. The same thinking runs through the IP67 marine solar charge controller and the wireless CAN bus adapter, and it shapes the engineering consultancy work on power budgeting and system architecture.
Citation
Permanent identifier for referencing this work.
Edwards, J. (2023). Design and develop an embedded system to manage and control a biological experiment in space (Master of Engineering thesis). University of Canterbury. doi:10.26021/16205
The full text is held in the University of Canterbury Research Repository. All rights reserved by the author and the University of Canterbury.