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Description
The OWL (Orbital Whereabout Locator) is a flight-proven VHF beacon and tracking unit developed to provide continuous transmission of satellite identification, key telemetry and GNSS-based position information. The original OWL design was tailored to CubeSat missions and has gained flight heritage on board multiple satellites. Building on this heritage, the current development aims to extend the OWL concept toward a more versatile subsystem that can be integrated into both CubeSats and larger satellite platforms. The new configuration also incorporates additional onboard sensors to improve the accuracy and robustness of the information provided by the unit, and can be equipped with a body-mounted solar array to further enhance operational autonomy. In this way, the development preserves the original core functionality of OWL while broadening its applicability and operational relevance.
The new version of the system includes multiple onboard sensors, such as an IMU, magnetometer, and, optionally, a TID sensor. These sensors continuously collect data, which are packaged into periodic beacon messages transmitted via an omnidirectional VHF radio link. The sensor sampling rate and beacon transmission interval are configurable. The OWL supports optional two-way communication with the host satellite via UART, allowing the host to send telemetry and health data and to request information (e.g., GNSS-based position data). It can also operate independently via a dedicated ground station network providing tracking and telemetry data through a real-time web service interface. The infrastructure can be complemented by mobile ground station units for special mission scenarios.
Most importantly, the new OWL delivers continuous position and velocity telemetry from a dual-antenna, multi-constellation GNSS subsystem, enhanced through a high-performance onboard EKF estimator. Based on this technology, the functionality of the OWL is also being extended with precise attitude determination. This independent navigation source supports the following space debris mitigation use cases:
Space Traffic Management (STM) and Regulatory Compliance: Provides autonomous orbit determination for real-time traceability and collision avoidance. Outputs are compatible with standardized Conjunction Data Messages (CDM), supporting operator response to emerging STM frameworks. Compliance with FCC and ITU orbit filing obligations can be facilitated where applicable.
End-of-Life and Disposal Assurance: PVT data provides verifiable confirmation of de-orbit manoeuvres or controlled re-entry, supporting compliance with ESA Clean Space policy, ECSS debris mitigation standards, and international guidelines. Telemetry continuity ensures operators can demonstrate due diligence in disposal planning, anomaly cases, and liability assessments.
Deorbit Assurance: Provides critical information even following a critical AOCS failure resulting in complete loss of attitude control authority. This facilitates end-of-life burns for safe disposal, contributing to compliance with post-mission deorbit policies and Clean Space objectives.
The new OWL version combines enhanced onboard sensors for position and attitude determination, multiple available beacon communication options, and a panel-format structure, emphasizing modularity and configurability across six configurations for different mission requirements. An additional goal of this activity is to secure a place for the enhanced OWL module on ESA’s DRACO mission (Destructive Reentry Assessment Container Objects), which offers a unique opportunity to demonstrate OWL’s capabilities and thereby enhance its market appeal and technological credibility.