The most important commodity in The Bary is Compound K5, known colloquially as Stardust. Stardust is a non-biological complex drug with nanoparticular properties. It is taken once every circadian cycle or at another regular interval: orally in greater quantities or intravenously in smaller quantities, suspended in a saline solution.
The primary benefit of Stardust consumption is that it almost entirely negates the physiological wasting that occurs on human beings in a microgravity environment. Stardust strengthens bones, regulates blood cell production and eryptosis, stops muscular atrophy, and has some milder immuno-supportive effects.
As analog gravity by means of thrust or rotation is the only way to impart a mass with weight, the discovery of Stardust has revolutionized space travel. Vessels no longer require bulky and expensive gravity rings, nor do they require their engines to be operational to keep their occupants healthy. (Stardust is not an anti-radiological drug; ships and their fusion engines still require radiation shielding.) Unlike cocktails of drugs used historically, Stardust is a permanent solution with zero side effects when fully refined.
Stardust is a synthesized drug and not particularly difficult to manufacture once the infrastructure and supply chain is in place. However, there are several issues and bottlenecks that affect and limit supply.
By the end of the Stardust novel, which tells the story of the drug’s discovery and the conspiracies surrounding it, the five Barystates have agreed to cooperate for mutual economic benefit. There are several active ingredients and precursors to fully manufactured Stardust, each of them exclusively held by one of the nations of The Bary. As a result, a serious political or technical disruption can shut down the supply chain and, after resource stores are depleted, all Stardust production. Black market procurement is one way around artificial scarcity in the short-term, as is the temporary use of the far less reliable and side-effect laden Compound K4.
However, Compound K’s usefulness drops, and its side effects increase exponentially with reduced refinement. Compound K5 is coveted and the end product of the full production line. Compound K1, which is a junkie drug that saw its first use in the Republic, is highly addictive and essentially lethal in withdrawal, with a low LD50.
After the discovery of Stardust, shipbuilders began to build more compact vessels without gravity rings or drop tanks. This lowered transport costs dramatically and increased public access to space. Older designs are still considered utilitarian in case of Stardust shortages, and for long voyages, as human physiology still prefers having an innate sense of “down.”