One of the ultimate goals of Mars exploration is to bring samples from the surface to Earth, especially those that could be examined for evidence of life on the Red Planet.
Such an undertaking would be expensive and the samples risk contamination during their journey to Earth. So, one option is to analyze the samples in their natural habitat on Mars before bringing them to the Earth for further study. The Mars Science Lab and other Mars rovers are already studying samples on Mars in-situ with an array of instruments that image and assess the chemical make-up of various Mars samples. However, there are only a few techniques that can unambiguously determine if life is present.
On Earth, one instrument that scientists use to examine living and other biological materials is an atmospheric or environmental scanning electron microscope (ASEM or ESEM). ESEMs are capable of imaging with a resolution of better than 10 nanometers, or roughly a one-thousandth the width of a human hair, and are also capable of determining the composition of the same sample. Commercial ESEMs are typically very large and power-hungry. However, one team has undertaken the challenge of miniaturizing an ESEM to make it suitable for in-situ operation on Mars