While playing KSP I came to realize how how counter-intuitive distances in space exploration are. Just because a planet is closer doesn't mean it's easier to get to. For example, I used to think that because a mission like Voyager escaped the solar system, and Voyager flew so far it needed huge amount of energy. After looking at the delta-v map, a mission like that is nothing compared to landing on a much closer Mercury for example.
This makes me wonder. Of all the missions we have flown and will fly, which ones require the biggest delta-v with huge rockets? (I'm guessing Moon landing is #1) In comparison, what are the missions that were optimized through gravity assists, aero-breaking and other ingenuity that even though they would normally need a huge rocket, in the end needed only a moderately sized one?
What I'm really trying to figure out is which missions are the "big ones". For example, when I hear on the news "a probe flew past Pluto", how does that compare with "a return sample mission from Moon" in terms of shear accomplishment and size. Which mission is bigger? And how much bigger? I'm trying to come up with a heuristic to use when thinking about how "big" a mission is:
- Distance is not helpful (as explained above)
- Cost is not helpful because some countries/companies are more frugal than others
- I'm left with delta-v ... or is there some better way to wrap one's head around this?
- Or maybe I should forget about delta-v (because it doesn't account for smarts like aerobraking and gravity assists) and simply ask for list of "biggest achievements" in space exploration? Maybe we got to a planet that would normally need 40Km/s with a 15Km/s budget?
Bonus: Is there a destination in our own solar system that is harder to get to (because of delta-v) compared to a mission to another solar system?