As far as I know the missions are:
- Flying a cool helicopter
- Drilling holes and leaving samples behind
- Driving to some old river delta and checking for signs of life in the sediment
The samples will be picked up by another rover made by ESA in the future which will be part of another NASA mission. Then that ESA rover will launch itself into orbit again and to be be picked up by an ESA orbiter that will then fly back to earth.
If that works I am gonna lose my shit. Sound fucking amazing.