We describe the design and rationale for a project in which a room-sized mixed reality simulation was created to develop middle school students' knowledge and intuitions about how objects move in space. The simulation environment, called MEteor, uses laser-based motion tracking and both floor- and wall-projected imagery to encourage students to use their bodies to enact the trajectory of an asteroid as it travels in the vicinity of planets and their gravitational forces. By embedding students within an immersive simulation and offering novel perspectives on scientific phenomena, the intent is to engage learners in physics education at both an embodied and affective level. We describe a study showing improved attitudes towards science and feelings of engagement and learning for participants who used the whole-body MEteor simulation compared to a desktop computer version of the same simulation. We also discuss general implications for the design of technology-enhanced physics education environments.