How does SpaceX get their rockets to stay vertical when hovering without tips over and eventually crashing into the ground? I don't mean the initial launch. I mean when its coming back down I feel like the gravity would take advantage of one tiny wobble and send it to the ground because the rocket is top heavy.

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    $\begingroup$ Hello callisto and welcome to the Space Exploration Stack Exchange. Your question needs some serious work on your part and may be closed by other contributors. To me, at least, it is not clear what you are asking, or what research effort you have done before. Please show us that you tried to answer this question on your own. Then we will gladly help you fill the gaps. $\endgroup$ – Rikki-Tikki-Tavi Feb 4 '16 at 15:36
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    $\begingroup$ This question is about launch rather than landing, but the answer is exactly the same: space.stackexchange.com/q/12093/195 $\endgroup$ – Russell Borogove Feb 4 '16 at 15:47

If you mean the Falcon 9 then that cannot hover. It has TWR >1 during the landing even when using just 1 of its 9 engines. But yes it can stay vertical during the descent by using thrust gimbal. The Grasshopper test rocket is able to hover that way. The nozzle of the engine can point a bit to the side to balance the long rocket - similarly as you can balance a stick on your finger.


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