Melange

The most essential and valuable commodity in the universe, melange is a geriatric drug that gives the user a longer lifespan, greater vitality, and heightened awareness; it can also unlock prescience in some subjects, depending upon the dosage and the consumer's physiology. This prescience-enhancing property makes interstellar travel possible. Melange comes with a steep price however: it is addictive, and withdrawal can be a fatal process.