Biogas Propulsion
February 26, 2020 5:39 AM   Subscribe

Can a fart propel you in zero g? I ask two aerospace engineers to find out. (SLImgur)
posted by Johnny Wallflower (48 comments total) 19 users marked this as a favorite
 
Wallflower! You’re... skating... on thin ice!
posted by GenjiandProust at 5:43 AM on February 26, 2020 [1 favorite]


I believe Dr. Griffin McElroy had a similar proposition that has not yet been tested
posted by Countess Elena at 5:54 AM on February 26, 2020 [3 favorites]


I thought tweet threads were the worst way to read a blog post, but I am no longer sure.
posted by timdiggerm at 5:57 AM on February 26, 2020 [8 favorites]


Those computations assume the fart gas is ejected as propellant, rather than being trapped with you in your space suit. You'd actually get a small displacement while the gas had nonzero average momentum, then come to stop once all the gas had interacted with your suit and your closed system had zero momentum again. The odor would make you remember how to vent your suit, which would make a much better propulsion system than farting anyway.

Noobs.
posted by fantabulous timewaster at 6:02 AM on February 26, 2020 [10 favorites]


“I suppose we'll need to determine the capabilities of the human anus to withstand explosive forces.”
There are some sentences that you just don't ever expect to read and yet here we are.
posted by Fizz at 6:02 AM on February 26, 2020 [14 favorites]


Chris Hadfield addressed this in an interview:

Hadfield observed that he experienced increased flatulence in orbit — "because it's impossible to burp when weightless (the gas, liquid and solid in your stomach all mix together)," he wrote. "As an experiment, try standing on your head and burping."

Alas, releasing this gas didn't give him an additional way of getting around the space station. "We all tried it," he wrote, but the farts were "too muffled, not the right type of propulsive nozzle."

posted by bondcliff at 6:04 AM on February 26, 2020 [30 favorites]


Hold on, we're not talking about naked astronauts, are we?

Wouldn't an astronaut wearing pants mostly just momentarily propel themselves relative to the backside of those pants, before both pants and astronaut snap elastically back, given that they would remain attached to their undergarments? I would imagine that our intrepid explorer would only change their overall inertia relative to their spaceship based on a much less focused and much less powerful emission from the pants. For example, imagine that we wrapped the space shuttle and Mobile Launcher Platform together in a giant asbestos pair of underwear, the shuttle might move some relative to the Earth, but it would move back.
posted by Blasdelb at 6:07 AM on February 26, 2020 [1 favorite]


Even naked astronauts can't ignore air resistance.
posted by hat_eater at 6:12 AM on February 26, 2020


not the right type of propulsive nozzle

Sounds like an untapped market opportunity!
posted by mrgoat at 6:15 AM on February 26, 2020 [2 favorites]


Hold on, we're not talking about naked astronauts, are we?

I mean, you could just cut a hole.
posted by Rock Steady at 6:15 AM on February 26, 2020


Who will be voted OFF the International Space Station?
posted by sammyo at 6:18 AM on February 26, 2020 [4 favorites]


untapped

I see what you did there...
posted by notsnot at 6:18 AM on February 26, 2020 [2 favorites]


This is the quality content I come here for
posted by sugar and confetti at 6:21 AM on February 26, 2020 [6 favorites]


Best of the web, indeed. I really mean this.
posted by NoMich at 6:23 AM on February 26, 2020 [1 favorite]


I believe this counts as "an excellent and inventive suggestion with just two tiny drawbacks."

Just remember that you might be weightless but this analysis only works in a zero-drag environment and untroused - i.e. if you're bare-assing it in deep space. (Probably for the best, since in space no-one can hear you fart.)
posted by ptfe at 6:25 AM on February 26, 2020 [2 favorites]


If you like daft science, I heartily recommend the British TV show Brainiac: Science Abuse. There's a lot of it on YouTube; my favourite is probably the clip of reality TV star Jon Tickle walking on custard. If I remember right, virtually every episode ended with a caravan being exploded.

(Warning: it's very much of its time, and some of the experiments, e.g. the Naked Job Interview, are mildly NSFW.)
posted by Cardinal Fang at 6:25 AM on February 26, 2020 [2 favorites]


Good example of let the force be with you. Providing you have pants woven of aerodynamic-cross-section threads, and a few other precautions and preparations (dare I mention Jerusalem artichokes?).
posted by Namlit at 6:37 AM on February 26, 2020


I wonder if you could propel yourself by expelling air out of your mouth. Seems much more likely to work and be more controllable than attempting to fart your way across the space station. But you'd have to point your mouth "up" so it would be aimed away from your center of mass, otherwise you'd mostly spin.
posted by smcameron at 6:38 AM on February 26, 2020 [1 favorite]


Came in to see if "nut in space" had been mentioned, was not disappointed.
posted by saladin at 6:56 AM on February 26, 2020


There was a documentary on this very subject a few years ago. Based on my viewing, the science seems pretty sound #notascientist.
posted by Ashwagandha at 6:56 AM on February 26, 2020 [1 favorite]


There was a documentary on this very subject a few years ago. Based on my viewing, the science seems pretty sound #notascientist.

From the Thunderpants IMDB summary:
An 11-year-old boy's amazing ability to break wind leads him first to fame and then to death row, before it helps him to fulfill his ambition of becoming an astronaut.
There's so much happening in this sentence, it's difficult to process it all.
posted by Fizz at 7:02 AM on February 26, 2020 [12 favorites]


My new definition of flatulence: More of a valve action phenomena from an already pressurized vessel...
posted by jim in austin at 7:07 AM on February 26, 2020


> I mean, you could just cut a hole.

Anything goes through the hole in the suit.
posted by davelog at 7:16 AM on February 26, 2020


"Thunderbird 3, engage ButtThrusters!"

(Alan Tracey unzips jumpsuit)
posted by CynicalKnight at 7:27 AM on February 26, 2020 [1 favorite]


There's so much happening in this sentence, it's difficult to process it all.

I can assure you, it is an emotional roller coaster.
posted by Ashwagandha at 7:28 AM on February 26, 2020 [1 favorite]




People. You obviously have to light it. It’s flames that do the pushing.
posted by njohnson23 at 8:23 AM on February 26, 2020 [1 favorite]


This is why I carry two cans of Bianca during EVA.
posted by clavdivs at 8:40 AM on February 26, 2020


so how do you turn around, once you get to your destination?
posted by They sucked his brains out! at 8:46 AM on February 26, 2020


so how do you turn around, once you get to your destination?

You eat more cruciferous vegetables.
posted by Fizz at 9:06 AM on February 26, 2020 [1 favorite]


So this does nothing to clarify the burp vs. fart issue.
posted by bonehead at 9:29 AM on February 26, 2020


Pop rocks and 7-Up might help with reverse thrust issues.
posted by They sucked his brains out! at 10:45 AM on February 26, 2020


Those computations assume the fart gas is ejected as propellant, rather than being trapped with you in your space suit.

Reminds me of a hoodie I have. It's long enough to cover my ass and made of heavy fleece. If I fart with the hood up the vapor cloud becomes concentrated around my head and slowly leaks out around my face in what would be long-term fart odor extravaganza, if not for the fact that I then yank the hoodie off my body in the sort of blind panic that might make an onlooker assume that it had somehow become filled with bees.
posted by Serene Empress Dork at 10:58 AM on February 26, 2020 [4 favorites]


Your body is a thunderland
posted by sugar and confetti at 11:25 AM on February 26, 2020 [6 favorites]


Farting in the space station. No way to get past it. Or you could say, I dunno, it was like that when I got here. Or maybe just own it, and suggest that we all play musical toots after lunch.
posted by mule98J at 11:32 AM on February 26, 2020


it had somehow become filled with bees.

Farting bees!
posted by Greg_Ace at 11:44 AM on February 26, 2020 [1 favorite]


Farting bees, each one wearing its own little hoodie for concentration purposes.
posted by flabdablet at 2:21 PM on February 26, 2020 [2 favorites]


What's the latest buzz on the street? Fart hoodies for bees!
posted by Greg_Ace at 2:30 PM on February 26, 2020 [2 favorites]


Metafilter: you'd still need drastically increased fart force to get there in a reasonable time
posted by numaner at 3:35 PM on February 26, 2020


The engineers, IMO, are neglecting the potential here: a human fart is a fairly low specific force (the 0.2 N mentioned) but a relatively large dissipation of kinetic energy and noise—because there's heaps of energy wasted in expelling gases. So the application of some kind of turbine to drive a propeller, or a fart turbocharger, might give a more efficient basis to move in [pressurised, atmospheric] zero G than simple explosive reaction.
posted by Fiasco da Gama at 7:03 PM on February 26, 2020 [2 favorites]


ALL THESE WORLDS ARE YOURS
EXCEPT EUROPA
DONT NOBODY GO IN THERE
FOR ABOUT 35, 45 MINUTES
posted by RobotVoodooPower at 7:59 PM on February 26, 2020 [13 favorites]


Titan might be a bit iffy as well
posted by flabdablet at 9:42 PM on February 26, 2020 [1 favorite]


Seems you really need to have a butt trumpet sort of nozzle to create laminar flow and reduce impedance mismatch between the fast moving gas and the stationary air. Else you lose most of the energy in turbulence.
posted by zengargoyle at 10:08 PM on February 26, 2020 [2 favorites]


Threads like this are why I love MeFi so much. <3
posted by xedrik at 6:30 AM on February 27, 2020


Humans have been going into orbit for nearly six decades. I guarantee you someone has tried this.

Granted, space isn't big on privacy, and you wouldn't want to try it with other people around.

But what do you think Mike Collins was doing while Armstrong and Aldrin were on the moon? He had a whole 24 hours for the scrubbers to dissipate it.

Maybe he still didn't want to chance it - but Ken Mattingly had three days alone on Apollo 16! Eating space rations! What are you gonna do?
posted by automatronic at 8:37 AM on February 27, 2020


I suspect that if you're in a shared, air-filled space, the currents created by all the other astronauts frantically waving their hands in front of their faces and rushing to the other side of the room would dominate any noticeable effect.

The question I now want to know is what sort of boost you can get from a mouth full of alkaseltzer tablets and a kazoo. (I think I've just found a new, very silly homework problem.)
posted by eotvos at 11:26 AM on February 27, 2020


a mouth full of alkaseltzer tablets and a kazoo

Which is also your secret sockpuppet name, right?
posted by Greg_Ace at 12:29 PM on February 27, 2020




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