This plan will consist of three parts:
An orbiter, which would also deposit one probe onto the icy surface to test chemical composition and slight tremors (location is irrelevant). This orbiter would test for more convincing signs of an ocean below the icy surface, chemical composition, and, hopefully, with the use of advanced RADAR, geological activity. It might be possible to also test the possibility of water coming up to the surface in the case of an ocean positive (unlikely, yet possible). Various possible results would include:
Positive for ocean, positive for major geological activity, high amount of organic material in chemical composition, positive for water at the surface. This is the most optimistic scenario, almost guaranteeing life. It would even be reasonable to skip the second part of the plan, and proceed directly to depositing probes into the areas where the water is at the surface. This scenario is, however, highly unlikely.
Positive for ocean, positive for major geological activity, positive for organic molecules, negative for surface water. There is still a high probability of life as we know it, and the measurements of geological activity would allow us to highlight areas with highest probability of hydrothermal vents, and it might again be a good idea to proceed directly to sub-surface probes, though these would have to be long lived because they would first have to find exactly where the vents are.
Positive for ocean, positive for major geological activity, negative for organics in surface chemistry, positive for surface water. This scenario would necessitate the second part of the plan, as the near absence (we cannot call quits quite yet: it may be that there are trace amounts of organics in different locations which we missed) of organic material would indicate that life either doesn't exist or is a very rare phenomenon. Only after thorough exploration could we pinpoint where life is most likely to be (and pinpointing is necessary, as life would be a rare phenomenon). The packages would not have to be as complete, however, as in scenario 5 and further down.
Positive for ocean, positive for major geological activity, negative for organics in surface chemistry, negative for surface water. As life would still have to be a rare thing, the difference between the existence or nonexistence of surface water would not make any major difference, and we would proceed in the same way as with 3 in part two, but we would require a more advanced, ice penetrating sub-surface probe in part three (if there will be a part three).
Positive for ocean, negative for major geological activity, positive for organics, positive/negative for surface water (the difference would be the same as between 1 and 2: different penetrative probes, and different minimum life-span of the probes). This would require a thorough second part, as it is possible that a couple of hydrothermal vents eluded our attention.
Negative for ocean, positive for major geological activity, positive for organics, positive/negative for surface water. This would require a very thorough part two, as it is still possible that there is life: hydrothermal vents could create small domes which would have liquid water in small quantities. The bubble would steadily rise due to the deposit of the vent, but it could also move sideways due to geological activity, thus not necessitating the rise of the bubble to the surface.
Negative for ocean, positive for geological activity, negative for organics. Finding the locations of the possible bubbles would require a thorough part two. A there are no organic materials detected, it might also be a good chance to abandon the project, as there is a fairly large chance that there is no life whatsoever.
Positive for ocean, negative for major geological activity, negative for organics, positive/negative for surface water. This would require an even more thorough part two. However, it is also an option at this stage to abandon the plan, as the chances of life are very slim, as there is no evidence for it but the ocean.
Full negative: abandon project
Exploration packages. In result cases 3 and 4 we would require knowledge of geological hot- spots for vent locations, hence a seismograph would be necessary. We would also need to know where the temperatures would be right for life, hence we need the infra-red instrument package, as well as the seismograph to accurately pinpoint where the vents are most likely to be. The RADAR/SONAR is not necessary, as we already know that the ocean exists, and do not need to be reassured of its presence. We do not need such a strong battery as we would surely have needed, as finding major tremors is far easier than small ones, and we would already have an outline of what to do. The instruments would not have to be as acute as in further result cases. In result case 5 we would need an acute seismograph in order to find tremors, but we would not need extremely acute infrared sensors, and the density measuring equipment would not be necessary once again. In result case 6, 7, and 8, we would need a complete set.
Penetrative probes. It is essential that these probes be completely rid of any bacteria, for fear of contaminating the ocean, and perhaps effectively killing whatever life there may be. There are several ways to do this: either letting out plumes of poisonous material every few seconds, which would also kill the bacteria, assuming it exists only in trace amounts, so we would not be able to detect trace amounts of lifeforms, although we would be able to see if it was teeming with life of different kinds; liquid nitrogen just beneath the surface, forcing the water around to immediately freeze, and hence keep our bacteria from contaminating theirs, although this would limit movement, and perhaps force the water probe to only rise and fall by being suspended on a cord, and that would force all movement it would be capable of to be infinitesimal, such as opening and closing a single hatch, and perhaps pull in a sample of the surrounding water through vacuum suction; or each part could undergo a complex quarantine process in which it would be heated, frozen, and exposed to extremely harmful radiation repeatedly, and thus assuring that there are no lifeforms still attached. This would create the most unbiased experiment, and would allow the highest freedom of movement, but would be the most expensive. It is also not guaranteed to completely destroy all the bacteria. I prefer the second alternative, as it allows us to photograph, as well as to collect samples, and even move (to a certain extent).
This is a slow plan, and would take roughly a decade, as it requires three launches. I do not know if the second part of the plan is necessary, as I am do not even vaguely know the accuracy of the orbiter. There is also a possibility of one massive launch. Once in orbit, the satellite would act as the orbiter. If results are negative, the rest can be shut down. Then it could deploy the instrumental packages, then the probes, and different parts of the probes could be shut down depending on the result. That would expensive and difficult, however.
