The ninth planet from the primary star of the Nivenia System, A9 is a colony of the Nivenian Empire. It is a non-differentiated body, so the ice and rock are mixed fairly evenly throughout the object. A9 is a large source of magnesium and strontium in the Nivenian Empire, and contains large amounts of platinum as well. As such, much of the planet's industry is dedicated to mining, with the only other major industry being the refining of the minerals extracted.
A9 is home to the largest computer built in Nivenian history, which houses the very first artificial intelligence, Bob. Bob's purpose is doing research to streamline processes for mining, and to possibly figure out how to extract carbon directly from white dwarfs.
A9 has a lower gravity than would be acceptable for long-term Nivenian colonization, so large, slightly distorted O'Neill cylinders were built to maintain a higher gravity environment, not unlike the methods used on A2.