text: We have only just started on such a program with the Mars Science Laboratory (the "Curiosity" rover), the first rover since Viking to directly search for life, due to land on Mars on August 5, 2012. It's just a beginning as, for instance, its "hand lens", though high resolution of 14.5 micrometers per pixel, can't observe endospores or other dormant states directly, it's of course limited to a single location of Mars, can't dig far beneath the surface, and has no modern equivalent of the Viking nutrient experiments (instead, it searches for the signatures of life by techniques such as firing a laser at the sample, X-ray spectroscopy and the like).