Effects of random motions on critical point measurements: Liquid-gas systems in microgravity

The effects of random accelerations on the measurements of quantities in the vicinity of the liquid-gas critical point are considered when the system is in a microgravity environment. These accelerations couple to the order parameter through the transverse component of the velocity field, whose dynamics are also governed by critical point properties of the liquid-gas system. The action of the accelerations is amplified by the singular static and dynamic response of the gas-liquid system. A general formulation, based on ''model H'' critical dynamics allows for the calculation of a variety of quantities. It is found that the random accelerations expected in a microgravity environment will not compromise the accuracy of any experiment that is currently envisioned.