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To the question If mice escaped on the International Space Station, could they live and thrive? both the answer and comments point out that while mice escaped from an experiment might survive a while if they could find food and water, their chewing on insulation and and seals could cause tremendous problems and endanger the lives of the crew.

It would then be absolutely critical to capture the mice as soon as possible.

How might a mousetrap for use in space work? How might it differ from terrestrial 1 g mousetraps?

"Mousetrap" may be generalized somewhat. Remember that the goal is to rid the station of the dangers posed by the mice.

enter image description here

Screenshot from Mice aboard the International Space Station

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    $\begingroup$ Is it possible to seal off a section & pump enough air out to suffocate them? $\endgroup$ – Dan Pichelman Apr 17 at 16:07
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    $\begingroup$ @DanPichelman I recommend posting that as an answer. I'll clarify the question to allow for non-conventional solutions. $\endgroup$ – uhoh Apr 17 at 16:22
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    $\begingroup$ A great variation on "build a better mousetrap" $\endgroup$ – ben Apr 17 at 22:09
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    $\begingroup$ Cats? $\endgroup$ – A C Apr 18 at 7:29
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    $\begingroup$ The space is one giant mousetrap. $\endgroup$ – hey_you Apr 19 at 8:42
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Other suggestions here for trap mechanisms may have incorporated consideration of zero gravity on the operation of the trap, but not upon the mouse itself. In zero gravity, searching for a mouse is no longer an effectively 2-dimensional search of and behind surfaces. The moment a mouse escaped its enclosure and tried to walk along a surface, the very act of locomotion (by exerting force upon the surface) would propel its small mass away from the surface and into the three dimensional volume of the station.

One wouldn't need to be searching hiding places for the mouse, but simply scanning the air space. Catching it would be a simple manual process of plucking it out of the air. No matter how fast it tried running, its legs would be cycling uselessly and it would simply be drifting at relatively constant velocity until it collided with another surface, whereupon it would very quickly unintentionally launch itself back into the air.

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    $\begingroup$ Note that here on Earth, mice don't live on a 2-dimensional floor, they almost always move along the 1-dimensional line that joins the floor and wall. A trap in the middle of a floor, or even only a foot away from a wall, will seldom catch anything. To be effective, traps have to be placed perpendicular to the wall, with the bait end touching the wall. So even with 3 dimensions to work with, mice will still try to stay at the edges of any room. (How successful they'll be I don't know. It would make an interesting experiment though. $\endgroup$ – Ray Butterworth Apr 18 at 1:34
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    $\begingroup$ @RayButterworth Yes, that's a nice way to characterise constraints on their behaviour in their natural terrestrial environment. I think they would instinctively try to do the same thing in a large microgravity environment, but fail to do so (because they would need to use a strategy of using their paws in an alternating fashion to grasp surfaces rather than use standard quadripedal locomotion). They would lack a human's cognitive ability to use alternate forms of movement strategy (e.g. using handgrips, or propelling oneself intentionally through the air to a destination). $\endgroup$ – Michael MacAskill Apr 18 at 1:42
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    $\begingroup$ Exactly what I was thinking. Mice ARE very intelligent, but it's so foreign, I think you'd have quite a while while they're floating around helplessly. $\endgroup$ – user27163 Apr 18 at 2:43
  • $\begingroup$ @RayButterworth that is true, except that for terrestrial mouse traps you don't need any bait at all if you put them in the correct place as you indicated. Amusingly, one hardware store chain in the UK now sells old-style spring traps where the pressure pad is a piece of yellow plastic shaped to look like a piece of cheese, instead of the traditional bit of wood with a pin to hold the bait. They work just fine, even though real cheese is a very poor bait for mouse traps - they much prefer chocolate in my experience. $\endgroup$ – alephzero Apr 18 at 12:07
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    $\begingroup$ @user27163 I disagree. Rats are very intelligent (and hard to catch because of that) but mice are terminally stupid. $\endgroup$ – alephzero Apr 18 at 12:09
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There are many types of mousetraps, the traditional "snap trap" is unlikely to work well because it is dependent on pressure. Lethal traps like snap traps would be undesirable:

  • Humane concerns
  • Dead mice are a health concern in a closed environment
  • You want the mice alive for experimentation

So that leaves you with non-lethal traps, the two that come to mind are: Catch and Release traps: enter image description here

These traps are all variations on a theme, mice come in to get the bait and the door closes behind them. There are simple mechanical ones and electronic ones, I'd assume the electric ones are better again because you don't want to be reliant on pressure sensing.

Glue traps: these are really just sheets of very sticky glue with bait in the middle. A mouse gets stuck to the glue, it's that simple. These aren't perfect as it can be difficult to get the mouse off in one piece, and you'd be introducing solvents into the atmosphere from the glue. But, they'd be useful for some hard to reach places. Some have pointed out that glue traps can also be lethal, and they have a point. There's probably types that mitigate that and ways they could be used to reduce the risk.

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    $\begingroup$ It does, in my answer I say an electronic one with a sensor would be better @JCRM, I just couldn't find a decent picture of one. $\endgroup$ – GdD Apr 17 at 16:39
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    $\begingroup$ No probs @JCRM. $\endgroup$ – GdD Apr 17 at 16:51
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    $\begingroup$ Glue traps are, in general, death traps because most of the times the rodent get its nose stuck in the glue $\endgroup$ – jean Apr 18 at 11:04
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    $\begingroup$ Wouldn't the spring-action of a snap trap still work in zero g? $\endgroup$ – cr0 Apr 18 at 13:43
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    $\begingroup$ @cr0 The spring would work, but the pressure-based trigger is less likely to do so... $\endgroup$ – Chronocidal Apr 18 at 13:52
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A solution that comes to mind is to seal off one section of the ISS at a time and depressurize it.

Finding and removing dead mice may be somewhat easier than finding and removing live ones that are actively avoiding capture.

(I fully agree with the comments - removing the dead mice would be a major problem)

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    $\begingroup$ I have to disagree with that fundamentally, mice are amazing at working their way into things, you don't want a rotting mouse corpse stuck behind a console where the crew can't reach! $\endgroup$ – GdD Apr 17 at 16:42
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    $\begingroup$ @GdD Agreed. I once had a mouse die in the heating vents of my car, and the car was old enough where taking it apart to find it would've exceeded the value of the car. Even with the windows open it stank for months. $\endgroup$ – ceejayoz Apr 17 at 16:45
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    $\begingroup$ That's nasty @ceejayoz! I had one die behind a range once, couldn't get the landlord to send someone to get it out and I wasn't allowed to move it contractually. Pretty unpleasant! $\endgroup$ – GdD Apr 17 at 16:53
  • $\begingroup$ You'd certainly want to seal all the hatches. Search each compartment section by section so that you can be sure you've got them all. $\endgroup$ – Ruadhan2300 Apr 18 at 11:10
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    $\begingroup$ @Ruadhan2300: Sounds like a plan that Dallas and Ripley tried. $\endgroup$ – dotancohen Apr 18 at 16:11
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I believe that funnel traps should work in zero-gravity. They are not active, do not use gravity or springs. Gravity may help the mouse fall in for those with opening at the top but imho that is not strictly needed as other designs use openings on the sides.

A trap Image source Little Green Shop

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    $\begingroup$ I like this one. $\endgroup$ – Organic Marble Apr 17 at 23:13
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    $\begingroup$ ah, those ones. We had those in our chicken coops when I was little. Couldn't use regular mouse traps as the chickens would step on them and trigger the mechanism with their feet. $\endgroup$ – jwenting Apr 18 at 4:02
  • $\begingroup$ I'm impressed that mice never figure out how to escape this. $\endgroup$ – Joshua Apr 18 at 18:42
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    $\begingroup$ @Joshua the metal rods are quite sharp, so easy to move against one way but very difficult to go the other way $\endgroup$ – Richard Tingle Apr 19 at 12:57
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Modern problems require modern solutions!

You can't rely on gravity. what you want is a modified vacuum cleaner. Essentially a suction device with a metal grill to catch the mouse (nobody wants to puree a rodent!) Given that the mouse is essentially guiding itself along the wall, it doesn't have anything to cling to, and gravity is a non-factor. So the suction should draw it in without issue!

You'd place food or a similar lure in an easily accessed location, use light-sensors or similar to trigger it, then power up your vacuum cleaner. Assuming enough suction, your rodent will immediately be caught on the metal grill inside the mouth of the vacuum cleaner, unable to pull itself free of a hurricane-strength suction.

The noise should attract the astronauts, who immediately bag the rodent and put it back in the cage none-the-worse for wear.

Reset the trap and await the next mouse!

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Same as on Earth, just get a cat!

I venture to speculate that the felonaut has the advantage in microgravity. Once a cat holds on to something with its claws, and while waiting there detects a mouse floating in open air without steering, it should be able to jump straight at it and catch it.

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  • $\begingroup$ There are some extra problems with this, first off, you'd need to get a kitten and train it from the outset for microgravity. Cats don't naturally do very well in space. Secondly, you'd have problems of blood and random mouse-parts drifting around, cats are not prone to tidiness. $\endgroup$ – Ruadhan2300 Apr 23 at 8:07
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How might a mousetrap for use in space work? How might it differ from terrestrial 1 g mousetraps?

Most of mouse traps don't rely on gravity. classic trap At least, the classic, spring-loaded, killing traps. They rely on a sensitive trigger on which the bait is fixed, and by twiddling with the bait, mouse sets the mechanism off. A problem could be in positioning the mouse - without gravity the lever may hit the mouse mid-air, which again may or may not be enough for the rodent to come out of it alive. Positioning is a problem even here on Earth. Enter the over-400 years old design that positions the mouse perfectly before garrotting it: 400 years old design This design is infallible down here, and it would work exactly same on a space station. The victim positions itself through a mouse-sized hole and the mechanism is set off by chewing on the string with a bait. video of trap in action

The biggest consideration will be how mice move around without gravity. The video in question shows one floating helplessly and another one running thanks to centrifugal effect - but that's peculiar to a small, coffined space. However, setting a mouse trap always involves analysis of mouse movement and choosing appropriate location, so on ISS would be not fundamentally different than here.

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You dont want to kill the mice as they can be used for experimentation purposes, and the regular snap traps wont work because of the need of pressure for them to work, and that will kill the mouse. They would use a catch a release trap, there are electronic and mechanical traps, however electronic ones would be more effective.

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  • $\begingroup$ Interesting. Can you expand on that a little bit? Why would electronic traps be better for use in Space? I've never heard of electronic catch-and-release mouse traps, so maybe a sentence or two explaining how they operate would be helpful as well. Thanks! $\endgroup$ – uhoh Apr 18 at 11:59

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