The question What makes smartphones tilt-sensitive? Will they retain this ability in zero-gravity conditions? brought to mind the video of astronaut Steven Swanson's detailed tour of the ISS, in which he frequently referred to external images of the ISS using an iPad throughout the tour.

Do the iPads use their camera to judge the orientation of the user and rotate the frame accordingly, or do they rotate randomly, or is the "up" sensing function manually disabled and the orientation locked, or does iOS automatically lock the display orientation in the absence of a well-defined ~ 1g signal? (In other words, did they already think of this?)

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    $\begingroup$ I imagine they'd have to be orientation locked. $\endgroup$ – Russell Borogove May 13 '17 at 3:04
  • $\begingroup$ @RussellBorogove thinking again, I've just added a fourth possibility. $\endgroup$ – uhoh May 13 '17 at 3:08
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    $\begingroup$ They just fly te iPad back to earth when they need to change the orientation, then lock it. $\endgroup$ – Antzi May 13 '17 at 15:33
  • $\begingroup$ @Antzi on-demand small payload quick return? ;) $\endgroup$ – uhoh May 13 '17 at 15:42

According to Robert Frost, Flight Controller at NASA:

The onboard iPads are configured with the mute switch acting as the rotation lock. Should a crew member want to change the screen orientation, they toggle the mute switch and then jerk the iPad to impart a force that will change the orientation. They then reactivate the rotation lock.

So not only is it using the lock like the other answers have said, but they can change the orientation by turning off the lock and giving it a quick jerk to simulate gravity.

  • $\begingroup$ +1 This is great, thanks! An official NASA source with just the info I was looking for. So do you know if this is a special OS configuration for the ISS, or is this a normal (but perhaps hidden) feature within the OS, for everyone? $\endgroup$ – uhoh Jun 9 '17 at 16:05
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    $\begingroup$ It's a normal feature. I have my iPad set up that way, too. It's in settings, general, "Use Side Switch to..." and select "Lock Rotation". It's only on the iPad, though, the iPhone doesn't have that feature. $\endgroup$ – Kevin Fee Jun 9 '17 at 17:00
  • $\begingroup$ @KevinFee The iPhone can lock into always-portrait orientation, which is useful for reading while laying on your side. It used to be a rotation lock like the iPad; I have no idea why they changed to portrait-only locking. $\endgroup$ – Russell Borogove Mar 20 at 5:36
  • $\begingroup$ @RussellBorogove You can lock the iPhone rotation using the "swipe up" control center. But it lacks the "Use Side Switch to..." feature that NASA has configured to "Lock Rotation". That's what I was talking about. $\endgroup$ – Kevin Fee Mar 21 at 19:13

It doesn't use the camera. There's no way it can know where is up as someone have already explained in the question you linked. Auto rotation has been manually disabled. You can see the rotation locked icon at 1:25, in the top right corner.

Rotation locked

Rotation locked icon in google images, for comparison: https://www.google.es/search?q=rotation+locked+ios&source=lnms&tbm=isch&sa=X&ved=0ahUKEwih6unh8-vTAhWJoRQKHZofDqEQ_AUICygC&biw=1919&bih=880#imgrc=fQpvfhSyQKxHaM:

The interface of the app he is using is in landscape mode because is coded to show only in that way.

  • $\begingroup$ Excellent detective work! What about when that particular app is not being used? I've kept the wording of the question general, and not app-specific. $\endgroup$ – uhoh May 13 '17 at 3:41
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    $\begingroup$ Thanks! With rotation locked, and if the current app it's not forcing the orientation of the interface, it will always be in portrait mode, but that's probably more of a question about iOS than about space ;) $\endgroup$ – vistaero May 13 '17 at 3:53
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    $\begingroup$ I've heard crew members complain about the iPad display just spinning around because of that exact problem. $\endgroup$ – Tristan May 13 '17 at 14:32
  • $\begingroup$ @Tristan would be fantastic if it were caught on video! $\endgroup$ – uhoh May 13 '17 at 16:46

For excellent technical explanations on how these sensors work see What makes smartphones tilt-sensitive? Will they retain this ability in zero-gravity conditions? as is linked in the question.

Your question is more specific by asking about the iPad. The OS/UI framework on iPhone and iPad does distinguish between device orientation and user interface orientation. This is required for example to handle laying your iPad flat on a table: which way should the user interface be oriented when "up" is perpendicular to the display? In this case the previous user orientation is retained. Apps can even restrict and thus "enforce" a user interface orientation (for example, they can restrict that an app or even single views may only be shown in horizontal orientation).

You can lock the user interface orientation on iOS which I guess might be very handy in such an environment: after all, if you move the device it might confuse the acceleration with "gravity" and thus "down" and start to rotate the user interface. This won't happen with the rotation lock. I'm not sure whether the camera is also using the user interface orientation for its orientation, though (the one that gets written to the EXIF metadata and determines how to display the image later on).

  • $\begingroup$ I like your answer a lot. I'd originally thought there might be an "I am in outer space and here is no gravity" detection within the OS, but according to the comment by @Tristan there may not be. $\endgroup$ – uhoh May 16 '17 at 23:11

It won't work in space, but probably uses a component inside like the one listed below. It uses a tiny enclosed space, where heat rises and then a measurement is made of the variation of conductivity of hot air compared to cold air, and then creates an output telling the circuit which way is up.


Tilt sensor

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    $\begingroup$ No. The iPad uses accelerometers to determine orientation. $\endgroup$ – Hobbes May 13 '17 at 7:55
  • $\begingroup$ No. The iPad uses gyros and accels to determine orientation: specifically Apple's "Coremotion" software systems, use heuristics to guess at orientation, using the raw inputs from both of those physical devices, not to mention the hall effect compass even. $\endgroup$ – Fattie May 15 '17 at 11:00

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