Software Adaptation and System Testing of the Radiation-Tolerant Langmuir Probe Instrument for MEO Operations

The increasing use of small satellites for scientific missions beyond Low Earth Orbit (LEO)
introduces new challenges relating to radiation exposure, onboard autonomy, and the
reliable operation of embedded systems. The ROMEO mission, developed by the Institute of
Space Systems (IRS) at the University of Stuttgart, aims to demonstrate a radiation-tolerant
small satellite platform that can operate in both LEO and Medium Earth Orbit (MEO). As part
of the mission, a double Langmuir probe instrument, developed at KTH Royal Institute of
Technology, will be used to investigate plasma properties and spacecraft-plasma interactions
in different orbital regions. This thesis focuses on adapting, integrating and validating the
radiation-tolerant implementation of the Langmuir Probe subsystem. This involves migrating
the existing flight software from a commercial off-the-shelf architecture to a radiation-tolerant
LEON3 platform running the RTEMS real-time operating system. A software-in-the-loop test
environment is established to support subsystem verification. This environment is based on
the TSIM3 LEON3 simulator and the JULIET testing framework, and is used for end-to-end
telemetry and telecommand validation. Additionally, hardware-level integration and
communication testing is performed on the target platform. In addition to software adaptation
and verification, the thesis investigates operational concepts for Langmuir probe
measurements during different mission phases, including survey and enhanced science
operations, under realistic telemetry and power constraints. This work contributes to the
operational preparation of the ROMEO Langmuir Probe subsystem and supports the wider
adoption of radiation-tolerant embedded platforms in scientific small satellite missions.