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## Question

I understand the dV map to get from Kerbin to LKO is 3400, another 950 gets me to the sun and then 90 more will get me to a fly-by Eve with another 80 to get into orbit and 1350 to circularize just over the atmo. So to get into orbit of Eve I would need 5850 (plus margin) to simply get to the orbit of Eve.

If I want to return from Eve to Kerbin what parts of that do I need to account for? Do I need to add the whole thing back or can I forget that 1330 that was used to circularize?

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You need the whole thing back. The only times you can ignore numbers are when you use a gravity assist to get somewhere, or an aerobraking pass to slow down. Otherwise the process of burning fuel to change your orbits is "reversible".

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The thing you don't need is the 3400 m/s that got you into Kerbin orbit.  You dispel the equivalent energy in the atmosphere when you re-enter.

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4 hours ago, JBMCW2010 said:

I understand the dV map to get from Kerbin to LKO is 3400, another 950 gets me to the sun and then 90 more will get me to a fly-by Eve with another 80 to get into orbit and 1350 to circularize just over the atmo. So to get into orbit of Eve I would need 5850 (plus margin) to simply get to the orbit of Eve.

If I want to return from Eve to Kerbin what parts of that do I need to account for? Do I need to add the whole thing back or can I forget that 1330 that was used to circularize?

Think of it this way. you burned 1330 (+ the 80) to circularize at Eve after coming in from Kerbin, so you need 1330 to "un-circularize" from Eve (just like you needed 950 to do the same from Kerbin) and another 80 to keep going out to Kerbin. After that (and a minor mid-course correction or two to intersect Kerbin's atmosphere) is all you need to come down safely. Assuming  your craft can handle the atmospheric re-entry heating. Which is by far not a given

Edited by 5thHorseman
typo

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