Three Years on the Moon

I have only had time to see Moon, so far, so that is what I will be posting about this week. Alas, there is plenty to say.
As soon as the infomercial for Lunar Industries at the start concluded, and the heavy handed ominous music began, it was clear to me that something was amiss on the lunar base. The first moment I realized that Sam was probably never going home was when there was an obvious cut in the video communication with his wife, and Sam called out for GERTY to fix it, but he was too distracted to ultimately question what had gone wrong.
As the end of the film approached, it was my understanding that these Sam clones were designed to only have a three year life span, which is why the first Sam became increasingly ill over the final few days before he was 'scheduled to return home.' However, I read somewhere after the fact that his illness was due to overexposure to the atmosphere. Further, that even if the clones were healthy after three years, they were still executed, so that a new Sam could emerge and take over the human duties that need to be performed on the base, and live out his three years. I suppose it doesn't really make a difference as the clones have a three-year life span either way.
Before I begin discussing ideas about cloning and humanity, I had a minor moment of confusion that I am hoping someone can clear up. I understand that they had to call it 'a rescue mission' in order to maintain appearances for the newly awakened Sam, but when the 'rescuers' arrived at the crashed rover they said something along the lines of, "Well he's not going anywhere." Wouldn't that be a given since this Sam was at the end of his three year contract and was scheduled to be executed soon? Was that just an incidental comment, and the point of the rescue mission was to clear up damage from the crash?
Returning to the idea of these clones as having a three year life span--I thought it was very interesting how they kept the clones complacent. The idea of artificial memories being implanted in these clones reminded me immediately of Dollhouse and Total Recall. The Dollhouse's ability to manipulate memory is far more advanced than the manipulation in this film. It seems that the very need to implant these clones with a back- story and family life to enjoy, underscores their humanity. These are definitely not replicants that feel nothing but can perform human tasks -- they are real humans with complex emotional interiors. Of course, this film centers around a glitch in the smooth system of rotating in a new Sam every three years, so we see the whole system fall apart. What is revealed is a morally bankrupt corporation that is participating in the creation of life only to then engage in mass murder of the very lives created--there were many Sam clones waiting on the lower decks.
I liked that the film was couched in terms of energy, because the lack of energy resources on earth already causes such an immense amount of conflict-- wars, bloodshed, and death. It is interesting to see the way this film presents the deaths needed to meet the world's energy needs. Did anyone else think about the many deaths of Sam in the context of current energy crises?