The development of gas pores and volumetric contraction have been observed during equiaxed solidification of thin samples of Al-20wt.%Cu grain-refined alloy, using a micro-focus X-ray source and high resolution solid state detector/CCD camera. Furnace design is a key element in achieving a field-of-view which is geometrically isothermal throughout solidification, ensuring an even and random distribution of nucleation sites. Experimental improvements to reduce gas porosity are explained, and the effects of sample orientation and gravity on equiaxed solidification, pre-coherency grain motion, and shrinkage contraction are presented. Total elimination of gravity effects were achieved on the Maser-13 sounding rocket flight, launched from the Swedish Space Corporation’s Esrange Space Center, northern Sweden, on 1 December 2016, resulting in the only grain movement being due to the volumetric contraction at high fraction solid and during final intergranular eutectic growth. The project was funded by the European Space Agency.