Low-velocity collisions between centimeter-sized snowballs: Porosity dependence of coefficient of restitution for ice aggregates analogues in the Solar System

► Snowballs with 44-80% porosity were made to collide at 0.44-4.14 m s−1. ► The coefficient of restitution of snow decreased from 0.3 to 0 with porosity. ► No-bounce/sticking occurred at porosity larger than 60%. ► The dynamic yield strength of snow increased from 0.01 MPa to 2 MPa with porosity.