But what if there could be a compromise? I spoke with a colleague yesterday who suggested that perhaps what was necessary was a planetary parks system. Under this scheme, some sensitive areas would be set aside for preservation while others could be opened up to study. It's an intriguing idea. You could, for instance, restrict landings to some gullies on Mars, but not all gullies. That way, you could begin to study the gully ecosystem today with cheaper, ready-to-go technologies, while preserving much of the occurrences of this land form for future study or complete preservation.
This is not dissimilar to the way in which returned samples are curated. Current protocols divide any such sample into four pieces, one of which remains untouched, awaiting more sophisticated future analysis. In the context of a park system, similar gradations could be applied. This would lead to a multi-tiered system in which concentric boundaries could mark areas in which landers with successively more stringent decontamination could be placed. This would allow for early and cheap study of these interesting regions, while preserving areas for future study.
In the process we could learn more about the potential for life in these areas. If these early spacecraft show a high astrobiological potential, this increases the chances that an adequately sterilized, expensive and highly sensitive mission will be sent to the parks area. In contrast, today's system of restricting all landings on type-IV special regions, actively discourages missions from visiting these areas.
My colleague also suggested an added benefit of such a policy. Defining the limits and extent of the areas would become a mission objective in and of itself. A good parallel is the scientific bonanza which has resulted from Canada's desire to map the arctic continental shelf for economic and political reasons. As a former engineering student, I see no issue with doing Science in support of a practical goal.
Unfortunately, the parks scheme doesn't solve everything. The liquid water subsurface of Europa, which likely mixes, is not easily subdivided into park-like zones. Thus areas like these should still be off-limits to all but the most sterile spacecraft. However, the parks system strikes a good balance between an open free-for-all, and complete preservation.