HOW DO SIMULATE THE SOIL THAT SPIRIT IS STUCK IN?
As soil simulant they have settled on is 1 part of Perma-Guard food grade diatomaceous earth and 2 parts of Lincoln 60 Fire Clay (by weight). The reason they chose DE is because it is a fine powder, it does not ignite and is readily available. The feel from the pool grade DE is different from the food grade. The first is more abrasive, the second one is more chalky. There is absolutely no evidence that the material on Mars is DE of course. They really can’t try to replicate the exact soil characteristics that have been measured with spectrometers and MIs but try to replicate how the vehicle behaves during the embedding event and hope it will be representative enough for testing the extrication maneuvers. They have used some of the information recevied on particle size, but ultimately the vehicle is the best instrument they have to select the soil simulant.
