Have to admit I was a bit confused by this strip until I realized that the guy in the helmet is not Spirou… This episode is by Nykko & Bannister, who respectively write and illustrate Les Enfants d’Ailleurs (published in English as The Elsewhere Chronicles). Bannister was previously featured here with an X75 strip.
Bannister is usually represented in the Journal de Spirou with the comic Les enfants d’ailleurs (something like “The Further Children”).
Poster for a comics festival in Rochefort. This year’s guest of honor is Spirou (whatever that means); other guests include Tarrin, Feroumont and Bertrand Pissavy-Yvernault (La véritable histoire de Spirou).
The Turbotraction car keys are a nice detail! (I assume the telescope is some sort of local reference. The monument in the background is the Porte de l’Arsenal.)