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In the Starship Launch Animation, first, a crewed Starship launches and reaches orbit. Then the fuel tanker Starship rendezvous with the former and docks like this for orbital re-fuelling.

enter image description here

It can be seen that the heat shields (windward side) of the ships face opposite sides. This can be inferred from the fact the two ships have slight variations near the landing legs and the backward actuator (or body flap). And also note the difference in reflection of light from the sun by the surfaces of two Starships.

Another view of the two ships in docked mode:

enter image description here

So, Why do two Starships dock in such a manner their heat shields face opposite sides? Is there any specific reason or something not to care much in an animation? I think there must be some kind of scientific reason for this type of docking.

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  • $\begingroup$ I note that in this configuration, the guidance systems of the two spacecraft agree on the meaning of +/- pitch and roll, but not yaw, while if their tops were aligned, they would agree on +/- yaw, but not pitch or roll. I don't know if that's relevant. $\endgroup$
    – Russell Borogove
    Commented Oct 16, 2019 at 17:41
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    $\begingroup$ This seems to me like the convenient orientation to fit in- and outlets of fuel and oxidizer together. I don't know how they are located exactly, but it seems reasonable if we assume both ships are identical from their internal structures. $\endgroup$
    – asdfex
    Commented Oct 16, 2019 at 18:02
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    $\begingroup$ An observation - this would make the bells of the vacuum engines line up with the aft cargo doors, assuming that the tanker configuration is the same. Does it make sense to fuel a Raptor through the bell? $\endgroup$
    – Chris B. Behrens
    Commented Oct 16, 2019 at 18:22
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    $\begingroup$ I don't think the September 2019 update gave us enough information to answer this. Both variants are still in development so all we can do is guess. I suggest we hold off answering this till we are given an explanation of some sort from SpaceX themself. $\endgroup$
    – Seth Kurkowski
    Commented Oct 16, 2019 at 19:02
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    $\begingroup$ It's a science demonstration; crazy CEO wants to make a giant Crookes radiometer $\endgroup$
    – uhoh
    Commented Oct 17, 2019 at 0:46

1 Answer 1

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I think it’s because they want to use the same pipe work they use for tanking on the ground in orbit. I imagine the Starship will have an LOX inlet/outlet on one side and a Methane inlet/outlet on the other and all Starship will be built in the same way.

If you back one Starship onto another with the heatshields pointing in the same direction the LOX pipe would face the methane pipe. In order for the LOX and methane pipes to align correctly one ship needs to be flipped over.

So Starship pipework must be arranged in a straight line that passes through the centre of the 9m diameter to facilitate this. There could be more than 2 pipes but the same logic applies with 4 fold or 6 fold symmetry.

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    $\begingroup$ Thanks for the answer. In the first paragraph, by "one side", are you referring to the left and right sides (or where the backward actuators are connected to the fuselage) or wind-facing and non-wind facing sides of starship? The latter works only when heatshields point the same direction whereas the former works only when heatshields point the opposite direction. $\endgroup$
    – Vishnu
    Commented Oct 18, 2019 at 1:38

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