The job as a pioneer means that you live on a planet that is under investigation to determine if it is suitable or not for a larger settlement.
The pioneer lives there, usually alone but in some cases with his/her family, for an extended period of time to identify hazards and fenomens in the environment that must be taken into account when colonizing the planet, and otherwise gather as much knowledge about the environment as possible to facilitate the colonization.
Usually the pioneers are lone wolfs, and as the planet is colonized they move on to an uninhabited area. The job is full of hazards since not everything is usually known about the planet before the pioneer settles there. Therefore, after the investigation period the pioneer if still alive is entitled to retirement benefits and gets the title "honor citizen" in the new colony.
The pioneer settlement is designed to be as self-sustained as possible, but some goods and tools needs to be replenished every now and then, which is done with specially designed cargo ships, that are also used when setting up the settlements and to transport pioneers to and from their settlements.