100% has been explored as far as topography, imaged. Only a few areas have been photographed close up from orbit - those can be seen with resolutions of about 1 meter - but you need to decide which area of Mars to observe with that high level of resolution. But - the basic topography is better known than the Earth because so much of Earth is masked by forests and oceans. With the problem of course, that we don't have much ground truth to interpret the results so we are still in the dark about a lot of details of the geology - but with the geology experiments on Opportunity, Spirit, Curiosity, Sojourner etc we've made a good start on the geological study of Mars.
However I'd say that 0% of it has been studied biologically. It's true that Viking did biological experiments back in the 1970s. But we didn't know as much about Mars as we do now, of course - and turned out that none of the experiments could tell us that much about the situation on Mars - they just weren't sensitive enough to detect it at the thin levels expected. One experiment did have that senstiivity - but it didn't take account of the unusual and unexpected chemistry on Mars so it also gave results that are suggestive but most scientists would say do not prove that there is life on Mars (though Gilbert Levin thinks it did).
Curiosity is able to detect organics, but not life, not in the small concentrations expected if there is any present day life in the equatorial regions it is now studying - which some think is a possibility. Life is much more likely in the higher latitudes but are one or two possibilities in the equatorial regions.
Again we know just about nothing there. ExoMars in 2018 will be the first biological mission to Mars since the 1970s. And it still is just a first mission and will need many follow up missions to find out more - and need to send missions to many parts of Mars - because the terrain is so varied.
It will be a long time before we have even 1% coverage of Mars for biological exploration at the rate we are doing it at present.
However I'd say that 0% of it has been studied biologically. It's true that Viking did biological experiments back in the 1970s. But we didn't know as much about Mars as we do now, of course - and turned out that none of the experiments could tell us that much about the situation on Mars - they just weren't sensitive enough to detect it at the thin levels expected. One experiment did have that senstiivity - but it didn't take account of the unusual and unexpected chemistry on Mars so it also gave results that are suggestive but most scientists would say do not prove that there is life on Mars (though Gilbert Levin thinks it did).
Curiosity is able to detect organics, but not life, not in the small concentrations expected if there is any present day life in the equatorial regions it is now studying - which some think is a possibility. Life is much more likely in the higher latitudes but are one or two possibilities in the equatorial regions.
Again we know just about nothing there. ExoMars in 2018 will be the first biological mission to Mars since the 1970s. And it still is just a first mission and will need many follow up missions to find out more - and need to send missions to many parts of Mars - because the terrain is so varied.
It will be a long time before we have even 1% coverage of Mars for biological exploration at the rate we are doing it at present.
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
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