NASA’s methodical approach to the exploration of Mars has not yet answered the questions of whether biological life forms ever emerged on Mars and whether, presuming such life forms having left fossil traces to begin with, those traces can still exist in some moist recesses of the cold and arid planet.
and whether, presuming such life forms having left fossil traces to begin with, those traces can
and whether, if it is presumed that such life forms left some fossil traces to begin with, can those traces
and whether, presuming such life forms left fossil traces to begin with, those traces
and, presuming such life forms did leave some fossil traces to begin with, if they can
and, presuming such life forms to have left fossil traces to begin with, if they
Behind this methodical approach is the enduring question of whether life ever emerged on Mars and left some fossil traces, and whether it still exists in some moist recesses of this cold, arid world.
It doesn't need past perfect sense, nor does it need can. "Can" specifiies the ability to do something. Fossil traces have no life. whether they can be preserved relys on the natural environment not themselves.