Why is Jason dying?

Jason says that the replicators technology required another component, which was not mentioned by Wun Ngo Wen: a human element capable of acting as a catalyst for a different communications channel between the network of replicators and its point of origin. Jason offered Wun to become this communication entity. This was accomplished by injecting a new version of the Martian drug. Jason further explains that his real goal in life is a greater knowledge, as he could not imagine dying ignorant.