The main problem in transporting samples, equipments and other material in other planet is that the transporting vehicle will consume big power, it takes longer time that will be reason for more consumption of resources like more oxygen for the astronauts and so on.
This payload design is a very small rover that can travel in temporary rail road provided by bigger rover where the rail road can be extended to give simple and low power consumption travel access for the small payload rover in specific area and compress the temporary rail road in to the bigger rover when change of travel location is needed.
Meaning, when astronauts what to transport materials which is heavy to transport in one travel from location A to B this mechanism will lay out a temporary rail road using the bigger rover. At the back of the bigger rover there is a fixed roller. Inside the roller there is a flexible rail that extend and compress based on the action of the roller. On the flexible rail, there is a very small pay load that can move in one axis when the rail road is extended. Then the astronaut starts activating the roller at location B and move the bigger rover to location A simultaneously. When the bigger rover reaches location A, smaller rover is activated to move in to the location A from location B using the temporary rail. The smaller rail can travel many times forward and back ward using small power and shorter time and we can transport number of materials. Then when the astronauts are done, they can reverse the process and go to another site repeating same process.
This mechanism save time and power big time because when transporting supplies and samples, the bigger rover only need to travel once t lay the temporary rail road and the smaller rover will do the transportation from location A to B with very low power consumption and difficulty.