A View from the Cheap Seats: MER and its Implications for Future Mars Exploration

The spectacular success of the Mars Exploration Rover mission is reflected by the exciting scientific discoveries that Spirit and Opportunity have made concerning habitability potential and geologic history of two sites on Mars. The apparent discovery of strong evidence for the presence of liquid water at the Opportunity site is of historic importance (although at the time of this writing we must note that there is not yet any peer-reviewed publication of this result). But perhaps even more importantly, the success of MER provides key validation of a strategy and approach to Mars exploration. Here, we highlight some of the strategic successes, as well as lessons learned for refining our approach to Mars exploration, and for future exploration endeavors across the solar system and beyond. Almost more than imaginable, MER has validated both the "follow the water" strategy and the "seek-in situ-sample" approach of the Mars Exploration Program developed by a broad, inclusive group of Mars explorers. Seeking interesting, water-relevant sites with remote observations from orbit resulted in one clear success at Meridiani, and in perhaps what is most optimistically termed "delayed success" at Gusev. Three lessons from this are clear. First, it's always better to fly two spacecraft! Second, significant mobility enables greatly enhanced science return. Third, mineralogical evidence appears more reliable than geomorphic evidence if the goal is to seek preserved evidence of aqueous processes (Pathfinder results also support this observation), although the combination of mineralogical information with high-resolution imagery is almost certainly the best way to optimize for success. The 2005 Mars Reconnaissance Orbiter's spectral mapping and imaging capability will thus be critical to future landing site selection. And yet, it is important to note that in spite of mineralogical evidence pointing to Meridiani as a site of "aqueous interest", and the detailed regional geological observations leading to multiple hypotheses for the formation environment of this site, virtually all hypotheses were incorrect or of insufficient detail to predict the extraordinary discoveries in the sedimentary strata at Meridiani. In other words, "in situ" exploration resulted in significant revision of ALL previously proposed hypotheses, which validates the strategy of performing in situ exploration. It is highly likely that "sampling," returning samples to Earth-based labs from sites that have been previously explored in situ, will result in a similar revolution in thinking about the history of a site. Thus, sample return missions should remain a high priority in the exploration strategy. Finally, the mission success of MER is the direct result of the hard work and dedication of one of the most well-integrated science-engineering teams in space exploration history. The value of team integration to maximizing the success of MER is perhaps the most enduring legacy of the mission to the exploration community. As we move forward returning humans to the Moon, then on to Mars and beyond, we should continue to strive for the integration of scientists and engineers into unified exploration teams.