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Core formation in small planetary bodies likely involves percolation of immiscible liquids (e.g. S- and C- rich iron alloys) through pore spaces in a silicate medium. The manner in which this phenomenon occurs is not fully understood. Furthermore, it is unknown whether the metallic melts can physically segregate during percolation. To improve our understanding of core formation in small planetesimals, we performed analog experiments. We used an emulsion of oil and water to simulate an emulsion of S-rich and C-rich iron alloys, respectively. The experiments were performed in a Hele-Shaw cell, a thin “channel” made of two acrylic plates (51 cm x 15 cmx 1.3 cm) kept apart with a thin aluminum plate (0.27 mm). A U-shaped cut out of the aluminum plate formed the channel. We used a syringe pump to inject the emulsion into the channel through a hole in the top plate. We investigated the effect of injection rate and droplet size on the percolation behavior of the emulsion. We observed that droplet velocity was size dependent. The smallest droplet size detected was 0.0133 mm2 with a velocity of 0.67 mm/s. Medium size droplets ranged from 0.03mm2 – ~10 mm2 with average velocity of ~0.43 mm/s. Larger droplets moved faster: the largest droplet, with an area of 91.4 mm2, had a velocity of 7.95 mm/s. We suggest that (1) suspended droplets slow down when they begin to touch the Hele-Shaw plates (medium size droplets), and (2) droplets flow faster when they become large enough to deform with the flow. We also tested percolation through a channel filled with polydisperse acrylic particles of diameter < 50 µm. When injected into the granular matrix, the oil formed a wetting front while the water advanced in “pulses”. These pulses may represent the faster flow of larger water droplets. In conclusion, the size of the droplets affects their velocity and possibly their ability to migrate through pore networks. The results suggest that immiscible liquids could potentially segregate due to different percolation efficiencies of the non-wetting/wetting phases. Consequently, this would affect the distribution of the metallic components within differentiated planetesimals. 

Abstract Blasting experiments were performed that investigate multiple explosions that occur in quick succession in unconsolidated ground and their effects on host material and atmosphere. Such processes are known to occur during phreatomagmatic eruptions at various depths, lateral locations, and energies. The experiments follow a multi‐instrument approach in order to observe phenomena in the atmosphere and in the ground, and measure the respective energy partitioning. The experiments show significant coupling of atmospheric (acoustic)‐ and ground (seismic) signal over a large range of (scaled) distances (30–330 m, 1–10 m J^−1/3). The distribution of ejected material strongly depends on the sequence of how the explosions occur. The overall crater sizes are in the expected range of a maximum size for many explosions and a minimum for one explosion at a given lateral location. As previous research showed before, peak atmospheric over‐pressure decays exponentially with scaled depth. An exponential decay rate ofwas measured. At a scaled explosion depth of 4 × 10⁻³ m J^−1/3ca. 1% of the blast energy is responsible for the formation of the atmospheric pressure pulse; at a more shallow scaled depth of 2.75 × 10⁻³ m J^−1/3this ratio lies at ca. 5.5%–7.5%. A first order consideration of seismic energy estimates the sum of radiated airborne and seismic energy to be up to 20% of blast energy. Finally, the transient cavity formation during a blast leads to an effectively reduced explosion depth that was determined. Depth reductions of up to 65% were measured.