Satellite laboratories, designed to ignite interest in technical and computer science topics, employ cross-age peer tutoring and physical computing platforms. Catering to students from 5th grade onwards, these laboratories are led by tutors from 9th grade onwards. Employing a design-based research approach, the project aims to comprehensively understand teaching and learning dynamics and address well-founded problems. This study investigates the impact of satellite laboratories on (situational) interest and subsequent course choices, recognizing the decline in STEM interest as students age, particularly in computer science. To combat this trend, early stimulation of STEM interest is deemed crucial. Thirteen students were interviewed, revealing that many already held STEM interests before participating. The data, analyzed through structured content analysis, demonstrates alignment with the four-phase model of interest genesis, highlighting situational epistemic and emotional interest. Students view satellite laboratories as valuable introductions influencing future course selections. This research underscores the significance of initiatives fostering early STEM interest to sustain engagement and combat declining interest in computer science.