Gravitational Influence on an Oscillating Chemical Reaction

Abstract

Pattern formation, oscillations and wave propagation as processes in excitable media can be controlled by small external forces including gravity. The Belousov–Zhabothinsky (BZ) reaction is possibly the best studied system and exhibits temporal as well as spatial patterns. Wave propagation in BZ systems already has been shown to depend on gravity, due to interactions with diffusion and convection. In a stirred bulk BZ system stable oscillations exist in the absence of diffusion, sedimentation, buoyancy and convection with a period in the minute range. In parabolic flight missions such a system can be investigated under gravity conditions changing between 1 g, 1.8 g and μ-g just on this timescale. Here we have found that the temporal pattern formation of an oscillating BZ reaction locks to the period of the gravity changes but is also destabilized due to the partially stochastic nature of the gravity changes. This points out to a gravity dependence of chemical rate constants as given in a formal description of the BZ-system. The BZ-reaction is the perfect system for such studies and serves as a model for self-organization and pattern formation, also in biological systems. The possibility to study the lack of gravity or changes in gravity destabilizing self-organization and pattern formation is of major interest to identify the underlying mechanisms.