also offer great flexibility; in any scientific investigation it is advantageous to be able to alter the analytical strategy as new information emerges. This is particularly critical in astrobiological investigations, where the characteristics of extraterrestrial organisms or prebiotic chemistry cannot be confidently predicted. Some analytical flexibility has been demonstrated in Mars Exploration Rover (MER) missions, in which adaptations of instrument protocols have been employed to analyze unexpected rock compositions, but changes in sample-handling capabilities and instrumentation are clearly impossible for investigations involving remote analysis by spacecraft.
Pros and Cons of Sample Return and In Situ Analysis
Mars sample return and in situ analyses both have advantages and disadvantages, as summarized below. The two are actually quite complementary.
Mars Sample Return
Pros. The factors favoring sample return include the following:
Cons. The factors arguing against sample return include the following:
Finally, sample return is particularly important for astrobiology investigations on Mars, since it is certain that any significant finding with potentially far-reaching implications will require corroboration by multiple replications of the same analyses (ideally in different laboratories and by different investigators) and by different types of analyses. Moreover, investigations with an astrobiological focus are likely to be a significant component of any future human exploration of Mars. In addition to being of the highest scientific priority in its own right, sample return by a robotic spacecraft has been identified in several NRC reports as being an important if not essential