These images were taken at Operational Readiness Tests in the test bed at the Jet Propulsion Laboratory in Pasadena. A model of the actual IMP is used in practice sessions to prepare scientists for the landed mission, and it is this model which made the images you see.
This mosaic was made during Operational Readiness Test 3, March 6-7, 1997. It is a mosaic made from eight images. In the left corner you can see tracks left by the rover model, and on the right you see the deflated airbags and part of a Pathfinder petal.
This mosaic of fifteen IMP images was made during ORT 4, April 10-11, 1997.
Image of rover made during ORT 5, April 21-25. 1997