We are Aetherspace, a student-led aerospace team from KU Leuven (Belgium), developing Aether: T-ReX: a 3U re-entry CubeSat demonstrator that will fly aboard a REXUS sounding rocket in March 2027. Our mission is to make space research more accessible by developing a low-cost platform capable of returning scientific payloads back to Earth. Throughout the project, AISLER has been our trusted PCB manufacturing partner, helping us iterate quickly on the electronics that make our mission possible.
Introduction
Hi everyone!
We are Aetherspace, a student team from the Technovation postgraduate programme at KU Leuven, Campus Groep T in Leuven, Belgium.
Our team currently consists of 8 full-time students, more than 10 part-time members, 2 PhD researchers, 2 coaches, and dozens of alumni who continue to support the project. Besides building spacecraft, we’re also running an organization ourselves—managing budgets, partners, outreach activities, and engineering projects.
Our current mission, Aether: T-ReX, has been selected for REXUS Cycle 17, where it will be launched aboard a REXUS sounding rocket from Esrange Space Center in Sweden.
The long-term vision behind Aether: T-ReX is simple: make returning experiments from space significantly cheaper and more accessible. Today, returning samples often requires expensive ISS missions. We believe CubeSats can become an affordable alternative.
Our project
Aether: T-ReX consists of two major elements:
- a Rocket Mounted Unit (RMU) that remains inside the rocket;
- a Free Falling Unit (FFU), our actual re-entry CubeSat.
After reaching approximately 80–90 km altitude, the FFU is ejected from the rocket and begins its autonomous descent back to Earth.
One of the key technologies we’re demonstrating is an inflatable heat shield. Shortly after deployment, our Inflation System fires cool gas generators that inflate a torus surrounding the spacecraft, deploying the heat shield that protects the CubeSat during re-entry.
Throughout the flight we collect data including:
- heat shield temperatures;
- stagnation pressure;
- atmospheric pressure and temperature;
- acceleration;
- GNSS position;
- torus pressure;
- onboard video.
Our goal is to compare the measured flight data with our simulations and validate the feasibility of CubeSat-scale re-entry systems.
Our electronics
Electronics form the backbone of the entire mission.
The Free Falling Unit follows the CubeSat PC104 architecture, where every subsystem has its own dedicated PCB communicating over a shared CAN bus.
Our major subsystems are:
- Electrical Power System (EPS)
- On-Board Computer (OBC)
- SATCOM & GNSS
- Inflation System
- Camera System
- UHFCOM
- Turnstile antenna
- Rocket Mounted Unit interface board
Each subsystem is built around an STM32L476 microcontroller, while the camera system uses a Raspberry Pi Compute Module 4 driving two OV4657 cameras.
The OBC collects telemetry from every subsystem, stores mission-critical data directly to SD card sectors for maximum reliability, communicates through an Iridium modem, and distributes commands over CAN. Meanwhile, our UHFCOM subsystem continuously transmits telemetry over the 868 MHz ISM band toward our ground station.
The project combines many different PCB design challenges:
- controlled impedance RF routing for our GNSS, Iridium and UHF communication boards;
- dense routing inside a compact 3U CubeSat;
- fine-pitch packages;
- high-current switching for the Inflation System;
- redundant power architectures;
- thermal management in near-vacuum conditions;
- mechanical robustness against launch loads up to 20 g.
Our schematics and layouts are designed in Altium, allowing our team to collaboratively develop every subsystem.
One thing we’ve learned during development is that designing electronics for space is about much more than making a circuit work. Every design decision needs to consider manufacturability, repairability, thermal performance, vibration resistance, and the reality that you only get one chance during flight.
What is our favorite AISLER feature?
One of our favorite AISLER features is the fast turnaround time.
As a student team, development moves quickly and PCB revisions happen frequently. Being able to order new boards and receive them within just a few days allows us to iterate much faster than our development schedule would otherwise permit.
We also really appreciate the excellent manufacturing quality. Several of our boards contain dense routing and fine-pitch components, all of which have assembled reliably and exactly as expected.
Our proudest achievement
Our proudest achievement so far is seeing years of development come together into a complete integrated spacecraft.
What started as a concept has evolved into a fully functional CubeSat with custom electronics, onboard communications, cameras, an inflatable heat shield, and a complete ground station.
Knowing that a student team designed nearly every subsystem from scratch—and will soon see it launched aboard a sounding rocket—is incredibly rewarding.
What’s something that went wrong?
Like every engineering project, we’ve had plenty of redesigns.
One lesson we learned early was to avoid using QFN packages wherever possible. Although they save space, replacing damaged components shortly before integration became unnecessarily difficult. We redesigned several boards to use packages that are easier to inspect and rework.
Another redesign involved our power OR-ing circuitry. Our original implementation introduced a larger voltage drop than expected and reacted too slowly to changing load conditions, so we redesigned the circuit to improve both efficiency and transient performance.
We also switched battery architectures during development, which required selecting a completely new Battery Management System and updating several PCBs accordingly.
Looking back, every redesign made the overall system more robust.
Tips & tricks
Our biggest advice for anyone building complex embedded hardware is:
Design for testing from day one.
Test points, debug connectors, current measurement locations and modular subsystem interfaces have saved us countless hours during integration.
Also, don’t underestimate mechanical constraints. In aerospace, PCB layout is only one part of the challenge—the electronics, mechanics, thermal behaviour and manufacturability all influence each other.
Finally, build hardware early. Simulations are invaluable, but nothing replaces having a real PCB on your desk.
Looking ahead
Over the coming months, Aether: T-ReX will undergo vibration, thermal, thermal-vacuum, EMI/EMC and drop testing before its launch from Esrange Space Center in March 2027.
We’re excited to continue sharing our progress with the AISLER community and look forward to posting updates as we move closer to launch.
If you’re interested in CubeSats, embedded systems, PCB design or aerospace engineering, we’d love to connect and answer any questions. 
The REXUS/BEXUS programme is realised under a bilateral Agency Agreement between the German Space Agency at DLR and the Swedish National Space Agency (SNSA). The Swedish share of the payload has been made available to students from other European countries through a collaboration with the European Space Agency (ESA).