During the Mars Sample Return mission the Athena Rover will acquire remote sensing andin-situ measurements of surface materials, drill into rocks and collect cores, acquire soil samples, and place the rock and soil samples in an ascent vehicle on the lander. After the ascent vehicle and its sample cache are launched, the rover will conduct an extended mission focused on exploration and discovery. The Field Integrated Design and Operations (FIDO) Rover simulates these sampling and exploration activities with a science payload similar to the Athena Rovers. In its initial field trials, FIDO was deployed and controlled remotely for 2 weeks in the Silver Lake area of the Mojave Desert in California. FIDO successfully completed traverses of over 500 m in diverse terrains while acquiring imaging and spectral reflectance data. FIDO also successfully identified, maneuvered to, and cored into rocks. The trials validate the mission operations approach andprovide many lessons that will maximize the science return associated with rover-based observations and sampling activities.