Results from a space experiment on bubble thermocapillary migration conducted on board the Chinese 22nd recoverable satellite were presented. Considering the temperature field in the cell was disturbed by the accumulated bubbles, the temperature gradient was corrected firstly with the help of the temperature measurement data at six points and numerical simulation. Marangoni number (Ma) of single bubble migrating in the space experiment ranged from 98.04 to 9288, exceeding that in the previous

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... periment data. The experiment data including the track and the velocity of two bubble thermocapillary migration showed that a smaller bubble would move slower as it was passed by a larger one, and the smaller one would even rest in a short time when the size ratio was large enough. bubble, thermocapillary migration, microgravity, interaction A bubble or drop will move to the hotter side when placed in another immiscible fluid under a temperature gradient. This motion happens as a consequence of the variation of the interfacial tension with the temperature. Young et al. first investigated the thermocapillary migration of bubbles and drops with their linear YGB model when Reynolds number (Re) and Marangoni number (Ma) are small, which means that both convective momentum and energy transport are negligible [1] . During the recent several decades, many researchers studied the thermocapillary migration of bubbles and drops. Their work was reported by Wozniak [2] and Subramanian [3] [4] [5] . The experiments on thermocapillary migration of bubbles and drops on the ground are limited by the effect of gravity. In order to decrease the effect of buoyancy and buoyancy flow on the ground, researchers had to use small drops and bubbles and could only obtain small Re and Ma. Some experimental results showed that the YGB model was reasonable at small Re and Ma number, and others showed that there were obvious differences between the predictions by the YGB model and the experimental results. Then a lot of theoretical and numerical methods were used to correct the YGB model at large Re and Ma number [4, 5] . However the microgravity is necessary for ex-