GTD, a technology company based in Barcelona, has played an important role in the SALTO project through the development of an autonomous flight safety system (AFSS). This system integrates software, hardware, and extensive testing to support new-generation launchers, with focus on reusable concepts. As the space sector evolves toward reusability and reduced operational costs, GTD’s innovations aim to redefine how flight safety is managed in Europe.

 

What Is a Flight Safety System?

A flight safety system is responsible for monitoring a launch mission in real time to ensure the safety of people and property. Traditionally, this system is ground-based and human-supervised.

During a launch:

  • Vehicle dynamics and status is monitored by 2 means: navigation data from the vehicle are transmitted to ground stations via telemetry antennas and vehicle position is tracked with radars.
  • The flight safety system processes these data and presents them to trained operators.
  • Operators evaluate whether the mission remains within safe parameters—nominal trajectory, impact area, and flight corridors.
  • If necessary, they issue a command to terminate the mission.

This ground-based setup is critical for safe launch operations, but it presents limitations—particularly as Europe moves toward reusable launch systems.

 

GTD’s Existing Flight Safety Systems in Europe

GTD currently develops and maintains the only three operational flight safety systems in Europe:

1. Guiana Space Centre (French Guiana)

The system in French Guiana, in service for more than three decades, uses data from launchers and sensors to generate safety criteria and support human operator decisions. It operates according to the classical ground-supervised model.

2. Esrange Space Center (Sweden)

3. Andøya Space Center (Norway)

For these spaceports, GTD has implemented more advanced systems including autonomous decision-making functions. These include algorithms capable of replicating human operator safety decisions in real time, with only supervisory oversight needed.

A notable milestone occurred on 25 March 2023, when the maiden flight of the ISAR Spectrum launcher was neutralized by GTD’s autonomous system—demonstrating the operational readiness of this approach.

 

The Challenge for SALTO: Flight Safety for Reusable Launchers

While existing ground-based systems support expendable launchers, reusability introduces new complexities.

Multiple Vehicles, Multiple Risks

Reusable launch systems may involve:

  • Boosters returning independently
  • Upper stages performing controlled reentry
  • Several objects flying simultaneously

Ground-based systems are not designed to monitor and neutralize multiple independent vehicles reliably and cost-effectively.

The Need for Onboard Autonomy

To enable reusability, safety decision-making must transition from the ground to the vehicle itself.
In the SALTO project, GTD works to embed the safety criteria and decision logic directly onboard the launcher, enabling it to:

  • Evaluate its own trajectory
  • Diagnose the status of critical equipment
  • Make autonomous safety decisions in real time

This eliminates the need for extensive ground infrastructures and reduces operational costs.

Reusability adds a crucial dimension: equipment diagnostics.
A safe reentry is impossible if key components fail—such as engine actuators or aerodynamic surfaces. Therefore, SALTO’s AFSS must:

  • Track flight dynamics
  • Monitor equipment health
  • Diagnose anomalies before reentry decisions are made

This represents a major evolution from traditional flight safety systems.

 

Designing for an Uncertain Regulatory Landscape

Europe’s regulations for autonomous flight safety are still evolving. Spaceports and launcher operators do not yet know which standards will ultimately apply. Therefore, GTD designed SALTO’s system to be:

Modular and Library-Based

Software components are built as reusable libraries, enabling adaptation across missions and future requirements.

Reconfigurable Without Recompilation

A “missionisation tool” allows the system to read mission configurations even after compilation—ensuring flexibility and avoiding costly requalification cycles.

Compatible with Varying Navigation Systems

Since launchers may use different navigation units, GTD developed hybrid navigation solutions for multiple sensor qualities and configurations.

Scalable and Lightweight

Every design choice—redundancy, power consumption, computation load—supports scalability for future launcher generations and evolutions.

 

Testing and Qualification Roadmap

GTD has established a clear roadmap for maturing the autonomous flight safety system developed under SALTO:

Suborbital Test Flights

  • Objective: Fly the SALTO AFSS on COTS hardware at a European spaceport
  • Goal: Increase system maturity and validate onboard autonomy

Reusability Support Tests

GTD has submitted proposals to test the AFSS for reusable launchers.
Targets include:

  • Upgrading software classification from Class C to Class B
  • Integrating AI-enabled real-time diagnostics via edge computing hardware
  • Partnering with Barcelona-based companies for onboard AI frameworks

2027: Full Qualification Ambitions

Work to be done beyond SALTO project. For the mid-term:

  • Qualify the most critical software components to Class A
  • Conduct full power qualification
  • Interface onboard diagnostics with ground-based AI prognostics used for refurbishment of reusable vehicles

GTD’s contribution to SALTO marks a pivotal shift toward autonomous, on-board flight safety—an essential capability for Europe’s future reusable launchers. By developing scalable architectures, onboard diagnostics, and AI-ready frameworks, GTD is helping prepare Europe for a more competitive, cost-efficient, and autonomous space transportation ecosystem.