Pivalic acid dendrites grown and observed as part of the USMP-4 isothermal dendritic growth experiment aboard the space shuttle Columbia show an initial transient followed by an accelerating tip growth that may approach a constant growth rate. The mechanism responsible for this behavior is not as yet clear and may be due to experimental factors such as the long-range thermal interactions between the dendrite and its neighbors or container, or it may arise from a fundamental characteristic of isothermal, diffusion-limited, dendritic growth.

• Received 28 May 1999

DOI:https://doi.org/10.1103/PhysRevLett.83.2997