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so does NASA time it's launches to when it get's to 0.5 AU? you'd think we'd have expeditions to mars every 2 years by now.
by jlebrech 11y ago
so does NASA time it's launches to when it get's to 0.5 AU? you'd think we'd have expeditions to mars every 2 years by now.
- JoeAltmaier 11y agoIts never a direct ballistic route - its a dance of orbital slingshots. You launch from here, so when you get over there, that's where Mars is. And sometimes you do a carom off Venus or whatever, to add some energy that you couldn't afford to get by rocket fuel. So no, the fact that Mars is sometimes very close to the Earth is not really helpful. What'd be helpful is, if the max distance were not so great. But we're stuck with what nature gave us. It can help to try Kerbal Space Program, to get a feel for orbital mechanics. In fact, it may be the best way to get that feel.
- dzdt 11y agoSlingshots have never been used for Earth-Mars launches where Mars is the final destination. I am having trouble finding a reference as to whether a Venus flyby could even reduce the energy budget for a Mars mission, but in practice no one has ever decided to do that.
- JoeAltmaier 11y agoEarth-Venus-Jupiter has been proposed; I assumed that Earth-Venus-Mars would have some benefit. I stand corrected.
- snowwrestler 11y agoI think some Mars missions have used a Moon slingshot to Mars, but I've never heard of Venus.
- dzdt 11y agoIt does time the launches for short cruise time and lower energy required, but since the cruise time is significant that doesn't work out to launching at the moment of closest approach. See https://en.wikipedia.org/wiki/Human_mission_to_Mars https://en.wikipedia.org/wiki/Human_mission_to_Mars section "Travel to Mars" for some discussion.