The Aurora Plasma Brake (APB) is a deorbiting system that harnesses the Coulomb drag effect by using a 4-wire tether to electrostatically extract momentum from the ionospheric plasma. The tether itself is constructed from 50µm thick aluminium wire, and its length can vary significantly, from 150 meters up to 5 kilometers, depending on the specific satellite targeted for de-orbiting.
The initial Plasma Brake core technology and its deployment mechanism were developed for de-orbiting SmallSats weighing up to 500kg. This system comprises a Base Unit, which interfaces with the satellite, and a Remote Unit, which houses the tethers and associated electronics. The deployment process begins with the Remote Unit being released from the Base Unit using ejection springs, propelling it at least 100 meters away from the satellite. Subsequent deployment and unreeling of the Main Tether are driven by gravity gradient force. Once the Main Tether is fully deployed, a Tape Tether is then deployed to function as an electron collecting surface, crucial for the operation of the Main Tether. To deorbit, both the tethers are deployed, after which the system charges the Main Tether with a -1 kV high voltage, enabling the Coulomb drag effect and the satellite's deorbiting. Critical deployment functions, such as the release of the Remote Unit, control of Main Tether unreeling, and Tape Tether deployment, were identified and tested using a breadboard model.
Following the successful development of the core Plasma Brake technology and its critical functionalities, a 'downscaled' version, known as the ‘TunaCan’ Plasma Brake, was developed for CubeSats to fit within their smaller form-factor. A significant difference for the TunaCan version is its tether deployment method: due to its shorter tether length (150-200 meters), spin deployment is utilized instead of gravity gradient. Additionally, it does not require a separate remote unit. Electron gathering for the TunaCan Plasma Brake occurs through the satellite frame itself, eliminating the need for a separate tape tether. After design verification and qualification testing of the Engineering Model, a Flight Model was manufactured and delivered to a pilot customer for integration and testing. An In-Orbit-Validation plan has been defined, encompassing commissioning, spin-up/deployment/high voltage activation, and de-orbiting at the mission's disposal phase.
A design for an Autonomous Plasma Brake was completed. It aims for a fully self-sufficient deorbiting system. This autonomous system includes its own power and control subsystems, in addition to the TunaCan Plasma Brake and an ARM-C spin-up thruster. It is designed to autonomously initiate disposal, even if communication with the platform is lost, via a long-term "Watchdog Timer".
To build the capacity of manufacturing Plasma Brake modules the automation of Hoytether manufacturing with integrated quality control is a key challenge addressed by this project. The tether, essential for the Aurora Plasma Brake, is manufactured from four thin aluminium wires, two main lines and two crossing lines bonded by twisting. This process occurs in the source spool platform, which features two rotators holding wire rolls and a lifter to switch crossing wire spools between rotors, forming an x-pattern and intertwining the wires. After twisting, the tether moves through a bonding platform where clamps strengthen the twist, and then to an end reel platform that ensures correct tether width and even spreading onto the spool. This automated manufacturing machine evolved from a manual version producing 1 meter per hour to a first automated revision achieving 7 meters per hour. Based on durability testing and identified improvements the next Third Generation Tether Machine was developed. This next-generation machine is expected to perform at 10-20 meters per hour, features heavy-duty metal components for increased precision and service-life, and allows for adjustable tether widths between 20 and 50 mm. Its design also emphasizes ease of maintenance, with parts changeable even during production.
