SAINT-PAUL (974) 24.06.2017

During an astrophotography session at Piton Maïdo on Réunion on 24 June 2017, a witness noticed an unusual luminous phenomenon while taking photographs. He described a shooting-star-like streak that turned into a cone of intense white light, then a spherical cloud whose trace took several minutes to fade. He sent GEIPAN his photographs. Only 1 account was collected. GEIPAN identified the phenomenon as the passage and subsequent passivation of the final stage of the Falcon 9 launched on 23 June 2017; the source refers to a video of the launch. The launch took place in Florida at 19:10 UTC, or 23:10 Réunion local time. GEIPAN explains that the launcher travelled east along the equator and, an hour later, at the time of the observation on Réunion, was already at an altitude of 8,000 or 10,000 km. Sunlit, it was visible over a wide area on the ground, including due east of Réunion. Reconstructing the photographs' positions in the sky from the stars they show revealed a straight trajectory due east, descending towards the horizon as the launcher was about to pass behind Earth as seen from Réunion. The source refers to the reconstruction map. GEIPAN explains that the cone in the photograph corresponds to gas vented during passivation, when the launcher's tanks were emptied. The expanding volume of gas appears as a cone because of the 40-second exposure. The disappearance of the launcher's reflected light probably resulted from rotation, either natural or commanded at the time of passivation, changing the mirror-like reflection of sunlight. GEIPAN notes that this known phenomenon has prompted several reports, including one from Réunion with similar viewing geometry involving an Ariane launch from Kourou: ENTRE-DEUX (974), 21 August 2015, on its website. It also refers to the Ciel des Hommes article “Luminous halo in the Indian Ocean sky”, dated 29 September 2013. The evidence and precedents enabled GEIPAN to identify a rocket without committing further investigative resources, particularly to a precise reconstruction of Falcon 9's position in the witness's sky. GEIPAN classified the case A: rocket.