Flame trenches of the Ariane 6 launch complex: inspections and a digital twin at 1.5 mm per pixel

Background

At an Ariane 6 lift-off, the engine exhaust is sent into two concrete flame trenches, east and west of the pad. Their walls, inclined floors and ceilings take the heat and blast at every launch, and their condition must be known before the next one. They are deep, enclosed volumes, hard to reach, where interference on the drone link was a concern.

What we did

The first inspection, in November 2023 for CNES, also served to find the limits of the equipment in these volumes: pilot guided on site, photos of the concrete walls of all four faces, the sprinkler nozzles, the jet guide and the deflector. The same survey was repeated after the first Ariane 6 launch, in July 2024. On 7 May 2025, for Groupe ADF, the walls of the east and west trenches were photographed again position by position and compared with their November 2023 state: the report of 15 May locates the deterioration that appeared between the two dates, with mosaics viewable in the browser. Ordered in June 2025, a full photogrammetric survey produced a digital twin of the inside of both trenches, from which eight orthophotos at about 1.5 mm per pixel were extracted: vertical walls, inclined floors and ceilings, and the end of the trenches near the deflector. A web interface is used to measure them, overlay successive surveys and draw plans. Like all imagery on the base, the images go through the CNES security department and are not published.

4 related missions in the log

1. June 2025

   LiDAR and photogrammetryFrench Guiana

   Digital twin of the inside of the ELA4 flame trenches

   Guiana Space Centre · Groupe ADF

   Full photogrammetric survey of both flame trenches: digital twin, eight orthophotos at about 1.5 mm per pixel of the walls, floors and ceilings, and a web interface to measure and overlay surveys.

   • 8 orthophotos
   • 1,5 mm per pixel
2. May 2025

   InspectionFrench Guiana

   ELA4 flame trench concrete walls compared with their November 2023 state

   Guiana Space Centre · Groupe ADF

   Photos of 7 May 2025 retaken position by position and compared with those of November 2023; the report of 15 May locates the deterioration that appeared on the walls of the east and west trenches.

3. July 2024

   InspectionFrench Guiana

   Flame trenches, jet guide and deflector inspected after the first Ariane 6 launch

   Guiana Space Centre · CNES

   After the July 2024 maiden flight: concrete walls of the flame trenches, sprinkler nozzles, jet guide in 360° views over its full height and deflector, with mosaics viewable in a web interface.

4. November 2023

   InspectionFrench Guiana

   First survey of the inside of the ELA4 flame trenches

   Guiana Space Centre · CNES

   Photos of the concrete walls on all four faces of both flame trenches, the sprinkler nozzles, the jet guide, outside and inside, and the deflector; this first inspection also set the limits of the equipment in these enclosed volumes.

All missions