Astrochemistry is not only a fascinating and active field of research. It is also a computational chemist’s dream. Why? Because of all the unusual molecules and reactions that occur in this environment. One example of a project we are pursuing is the reaction of He+ with CO. This reaction is very rare in any planetary atmosphere because He+ will typically react with the first molecule with which it collides. If the density is relatively high, the He+ will become He in a matter of nanoseconds. In the vacuum of interstellar space the lifetime of He+ will be much longer and this high energy ion may react with several different molecules. The He+ + CO reaction is challenging to model because there are many electronic states to consider (that is, there are many Lewis Structures and electron configurations). We are using multi-reference electronic structure calculations to compute the potential energy surfaces for the various electronic states of the system as a first step towards modeling the reactions.