FENRIR - A REXUS Project

About our project

FENRIR (Free fall Experiment uNit for Reduced gravity Investigations and Research) is a student experiment based at Luleå University of Technology, which will fly on board one of the cycle 15 REXUS rocket in February of 2025. The main focus is the development of an easy-to-use platform for future free-falling experiments that need to be ejected from sounding rockets. The major goal of this platform is to eject a payload housing Free Falling Unit (FFU) from a Rocket Mounted Unit (RMU) and safely recover it with the help of a parachute. To prove the feasibility of the platform, two payloads will be housed within the FFU: an Attitude Stabilisation System (ATSS) and an experiment in the field of Phase Change Material (PCM) Science. The ATSS, which is in part a legacy of the RX30 project Attitude Stabilized Free Falling Experiment (ASTER), will stabilize the FFU and therefore enhance the reduced gravity conditions for other experiments housed within the platform. The second payload observes the behavior of PCMs in a reduced gravity environment. This class of materials is of particular interest since they can offer an order of magnitude increase in heat capacity with very small or negligible temperature change, compared to other commonly used materials in space applications. The platform will be developed modular, offering future students the opportunity to include their own scientific experiments as seen fit, thus lowering the threshold for reduced gravity research.


Our electronics department has designed five unique PCBs that will be used to control and support our free falling unit on its descent from an altitude of around 100km above the sea. These PCBs consist of,

  • our rocket-mounted PCB which will provide our system with operational information and power during ascent,
  • our electrical power PCB which will provide our system with power during descent and recovery,
  • our main PCB which will control our other PCB, as well as handle communication to our ground station using the Iridium network,
  • and our two payload PCBs which are meant to be modularly replaced.

Currently, our two payload PCBs are our attitude stabilisation PCB and our phase change material PCB. The attitude PCB is going to control three motors with reaction wheels, and the phase change PCB is going to induce and monitor a phase change of a certain material.


For our mission to be successful we need to have these five PCBs manufactured and assembled. This is where PCBWay comes in as their support would allow us to keep to our strict budget and the tight schedule that a REXUS project entails. It's through competent PCB manufacturers like them that student projects like ours can continue to give invaluable experience to future engineers all over the globe.


Below is an image of our free-falling unit with four of our five PCBs.


Above is a picture of our team as of May 2024 in Kiruna, Sweden.


Other useful links

Our parent-organisation website: https://gironspace.org/projects/fenrir/

Our GitLab home page: https://gitlab.com/project-fenrir

Our LinkedIn: https://se.linkedin.com/company/project-fenrir

Our Instagram: https://www.instagram.com/fenrir_ltu/

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Jun 05,2024
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