Would suction cups work in space?

Apytele@sh.itjust.works to Ask Lemmy@lemmy.world – 137 points –

You know like the kind that go on a window or bathroom mirror or on the wall or in the shower. They need the atmosphere pushing down on them to work, right?

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Yes. They won't work because they operate on a difference in air pressure providing a force. No air? No force. Same reason an airplane wing won't provide lift in the upper atmosphere.

But, compare to a rocket engine that does NOT need an atmosphere to push against.

Phrases I did not expect to think this early in the morning: "what's the rocket engine of suction cups?”

Velcro, or maybe Van Der Waals force, or maybe whatever the hell makes gauge blocks stick to each other.

I like the gauge block notion. A (quick) search says that it's a combination of surface tension from the oils they're coated in, suction (gone for us), and the super flat surfaces slightly exchanging electrons and bonding in close proximity.

I'm a fan of the surface tension angle as the "rocket of suction cups", since it's got that "non-binding force" element, where welding or glue feels different, and Velcro feels like a tangle.
It's "pull-y" where suction is "push-y".

Now the question is would surface tension grab something in a vacuum the way it does outside of one. I know you'd have water sublimate off, so it's questionable to me.

If it's metal, just rub a bit of it against another piece of metal and it will cold weld/fuse to it.

This only works on "virgin" metal iirc - if it's been exposed to Earth's atmosphere, it won't work. If you shave off some from the surface I believe it works again.

Like I said- "rub it". The oxidized layer on metal is very, very, thin. It doesn't take much at all to get rid of it.

I didn't realize that the layer was thin enough to rub away with minimal friction. I'd learned about this years ago so I could be misremembering things, but the source I read made it out as if it wasn't a major concern with space exploration because it took substantial effort to cold weld things that had been exposed to air.

Selotape? It'd have to be something that sticks on it's own

Just a technicality, but the Casimir effect would still provide some adhesive force. It would be greatly reduced vs a suction cup in an atmosphere, but it wouldn't be 0 force.

Though in microgravity, it might be enough to stick something to a surface, as long as it's not getting bumped or jostled. And don't expect it to stay in place if you need to do a maneuvering burn.

Edit: fixed word