Personally, a double launch on the same rocket is the way to go, especially with the Quasar. (unless the Galileo II required a Quasar to begin with...) It's a lower cost for the entire program by using a single, larger rocket instead of two smaller, but not quite lower cost, rockets. AKA the total cost of both smaller rocket launches is MORE than that of a single Quasar launch.
Also, maybe you could pack a second atmospheric probe atop Salviati for Jupiter, and use the one on Galileo II for Venus. :2cents:
Costs are an aspect considered in the developing of the FOI rockets, although only at a superficial level. For example, scalability and reuse of the same elements (stages, boosters) in different rockets are elements taken in account.
But i think that Quasar 452 could be VERY expensive in the real world, principally because of the dimensions of the core stage (manufacturing difficulties) and the very low flight rate, although some elements are low-cost (the RS-68 engine), others are Jarvis-derived (the upper stage), and still others are used in higher flight rate vehicles (Quasar 220 / Eridanus). Even the Jarvis M should be expensive for this task.
IMHO, the best low-cost superheavy is the Jarvis H, that is entirely made of elements from smaller rockets (and, individually, with an high flight rate).
Anyway... with a VEEGA trajectory (Venus-Earth-Earth Gravity Assist), a mere Jarvis E is sufficient for the Galileo II. For the Salviati probe (that, even with its carrier, is considerably lighter than Galileo II), the same launch can be achieved with an even smaller Jarvis C, with some margin.
A Jarvis H should be sufficient for a single launch of the two probes together.
