A Memory Foam Mattress is distinguished from a regular 'inner-coil' mattress in the way that it is made. Memory foam mattresses are made only with memory foam, which is made from polyurethane with additional chemicals that add to its viscosity level. Memory foam was initially developed by NASA to protect astronauts from G forces and impact on landing. Different types of memory foam mattresses have different thicknesses and densities of memory foam in the layers of memory foam that provide the support.