You can only carry a certain amount of instruments at a time, so you want to start off broad, then send incrementally more specific detectors as you identify th

You can only carry a certain amount of instruments at a time, so you want to start off broad, then send incrementally more specific detectors as you identify things that are interesting. An 'is this definitely life?' experiment will probably not be sent until we have some very good likely candidates and the mission will probably be to get samples back off planet and into to a earth or LEO lab (depending on paranoia) where in depth experiments can be put together in person without the brutal restrictions on equipment that come with extra terrestrial rovers.