By contrast, SOLIS100 does not simulate microgravity. Instead, it investigates the human consequences of long-term isolation and confinement, including limited social interaction. The study examines impacts on mental health, team dynamics, stress regulation, sleep, cognitive performance, as well as changes in the crew and habitat microbiome.

Both approaches are essential, as no single ground‑based analogue can replicate all aspects of spaceflight. Physiological deconditioning caused by microgravity, psychological strain resulting from isolation and operational challenges linked to increased autonomy and decision‑making represent different yet interacting risk domains.

By running bed rest, dry immersion and isolation studies in parallel, ESA can address the full spectrum of risks relevant to future exploration missions. This integrated research strategy ensures that both the physiological and human behavioural challenges of long‑duration missions are addressed.