Or maybe press the timer and let it float...

or sticky-tape it to the window.

d5 has an actual shutter yeah? not mirrorless? I think the shutter moving will spin the camera.

I haven’t looked at the manual but it likely has the ability to flip and keep the mirror up for direct capture on the sensor without the mirror flipping up and down between exposures.

I would love to see the effect of the mirror's effect on the motion of the camera in a weightless environment. I bet it's enough to measurably affect the picture, especially on a long exposure. Net torque of it opening and then closing should be near (but probably not exactly) zero, but while it's open the camera should spin a tiny amount.

Bad idea, shutter speed was 1/4 apparently (https://news.ycombinator.com/item?id=47632457), even the small rotational inertia everything in zero gravity gets from a human "dropping" it would probably be enough to be annoying, you'd get a better shot holding it.