The effects of spaceflight are induced by three concomitant factors: poor social interactions in a reduced living space, microgravity, and the radiation bath. To understand how these parameters can influence behaviors, animal studies are being carried out, modelling each of these parameters independently or not of the others. These studies allow to challenge different strategies of countermeasures to prevent spaceflight multisystemic deconditioning. In the NEBULA project, we developed an original suspension system that allows interaction between 2 conspecifics, to tackle the effects of microgravity independently from social restrictions. This device closely reproduces the musculoskeletal, cardiovascular and immune system adaptations due to spaceflight. It involves two mice in Hindlimb Unloading (HU), in the same cage, allowing them to move and interact freely. The behavioral effects of social isolation are generally well described, however, the effects of simulated microgravity on social interactions have not been evaluated until now, since the protocols were conducted on isolated animals during the HU period. Here, mice have been tested longitudinally before unloading, after 21 days of HU and after 28 days of recovery. Locomotor abilities were evaluated in rotarod tasks, social interactions were analyzed during the first 10 min of interaction, and innate memory for object recognition were assessed with two different delays between learning and memory retrieval. Our results suggest a modification of behaviors inherent to simulated microgravity, which should be associated with astronaut data obtained during questionnaires and exchanges in order to improve behavioral countermeasures.