> Anything that can return a sample. Notice that Curiosity collects samples, but omits the sample return rocket.

NASA (and also the Soviet Union and ESA) have repeatedly designed Mars sample return missions, but have not done them for budgetary reasons; it would be tremendously difficult and expensive.

Here's the current one: https://en.wikipedia.org/wiki/NASA-ESA_Mars_Sample_Return - however, given that it was hitting funding problems even _before_ ol' minihands gutted NASA funding, it seems destined to become yet another NASA/ESA canceled program (there's a bit of a history of ambitious NASA/ESA collaborations which die when one side or the other pulls the budgetary plug; JWST was likely lucky to escape this fate, say).

This puts it in a particularly weird place, as the earth return section is already built and due to launch on an Ariane 6 in two years (it will then proceed, slowly, to Mars using an ion drive, and await the lander and Mars launcher, which will presumably never arrive because budgets).