We report on experiments in which millimeter-sized Si O2 dust aggregates consisting of (sub)-micrometer-sized grains impact into centimeter-sized targets that consist of the same kind of dust particles. The porosity of the granular targets is between 74% and 88%. Impact speeds are between 16.5 and 37.5 m/s with most impacts around 25 m/s . Compaction of the… (More)