  A simple, heuristic formula with parallels to the Drake Equation is
introduced to help focus discussion on open questions for the origins of life
in a planetary context. This approach indicates a number of areas where
quantitative progress can be made on parameter estimation for determining
origins of life probabilities. We also suggest that the probability of origin
of life events can be dramatically increased on planets with parallel
chemistries that can undergo the development of complexity, and in solar
systems where more than one planet is available for chemical evolution, and
where efficient impact ejecta exchange occurs, increasing the effective
chemical search space and available time.
