<p>When a spacecraft flys past a planet eg. Jupiter , its heliocentric energy increases dramatically allowing it to go further away. How is this possible without using any more rocket fuel?</p>

CC BY-SA 4.0
2019-02-28T14:23:59.063Z
As [Wikipedia](https://en.m.wikipedia.org/wiki/Gravity_assist) says, the energy is taken from the planet's orbital energy.
PM 2Ring
CC BY-SA 4.0
2019-02-28T20:23:21.080Z
Are you sure "heliocentric energy" has any meaning?  Do you mean kinetic energy in the rest frame of the sun?
Carl Witthoft
<orbital-mechanics>
Energy conservation in Interplanetary orbit transfer
Danish 
# Energy conservation in Interplanetary orbit transfer

(Asked by: username_0 on 2019-02-28)

When a spacecraft flys past a planet eg. Jupiter , its heliocentric energy increases dramatically allowing it to go further away. How is this possible without using any more rocket fuel?

**Tags:** orbital-mechanics

> **Comments:**
> **username_1**: As [Wikipedia](https://en.m.wikipedia.org/wiki/Gravity_assist) says, the energy is taken from the planet's orbital energy.  
> **username_2**: Are you sure "heliocentric energy" has any meaning?  Do you mean kinetic energy in the rest frame of the sun?  

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## 0 answers

