At least in the US, if we urgently needed to send something to the moon in 8 years, we would not be able to do it. Between politically making it happen, deciding who spends the money on it, choosing a contractor that represents the right disadvantaged special interest group, years of contract negotiation, town hall discussions, environmental impact studies, project management failures, budget overruns, pork barrel carve-outs and jobs programs for various congresspeople's districts, etc. it would take way more than 8 years.