In a BBC news article celebrating 60 years of the Biro/ballpoint pen, the trivia listed a claim that ballpoints work in outerspace. I was always under the impression that you needed the gas in the ink cartridge of a Space Pen (tm and all that) to push the ink out, otherwise the sticky ink wouldn’t make it out of the pen. Hence a Biro on Earth won’t work upside down.
Now, is this true or another not-quite-fact put forward by the QI quiz show (also shown by the BBC.) I should have perhaps made the thread about that TV show, they made another claim that I queried here and found to be false.
Gel pens (the most common type of biro) feed by liquid cohesion, not gravity feed. I would expect them to work–as well as the work at all–in a freefall environment as on Earth. Ditto for most modern well-ink pens which have spring-pressurized ink reservoirs. Fancy nitrogen-pressurized “space pens” are strictly a gimmick for the rubes.
I’ve not got my gel ink pens to hand, but two biros, a normal tip and a fine tip, worked for a second and a few seconds respectively upside down before stopping. I’ll try a gel ink pen later.
Mum got me a space pen for a birthday a few years back. The pen worked intermittently in all advertised environments (except outer space!) before the tip leaked heavily and the ink clotted outside the pen :dubious:
Trying to write with a biro upside down on earth is not a fair test of how a ballpoint responds in microgravity.
A biro works generally works by capillary motion and surface tension, not gravity. The rotating ball picks up ink with surface tension and wipes it off on to the writing surface. As ink in the nib is used up, a pressure differential is created that sucks (via surface effects) the ink down from the barrel of the pen. The trick to ballpoint pens is having an ink of the correct properties to seal the nib/ball without leaking, and that will draw down (and not flow out the other end of the barrel when lying down) and won’t dry out.
In zero gravity, capillary action is all that matters. On earth, holding a pen upside down means that gravity works against the capillary action, and so the pen may not work. The best test down here is to hold the pen horizontal and write on a vertical surface. This tests pure capillary effects. Most ballpoints will work like this, and thus probably will in space.
It wasn’t. NASA never ordered development of a “Space Pen”. Fisher developed it on their own and offered free samples to astronauts, no doubt for the promotional value. (They also provided some to the Soviets back in the day, as a goodwill gesture, a la Hewlettt Packard.) And as you noted, they aren’t always the most reliable pens, even on Earth. (The claims that they can be used underwater, et cetera, seem pretty spurious to me. What would you write on that the ink would stick to? All of the underwater writing I’ve ever done or seen involved using lead or grease pencil and plastic slate.)
The u.l. about the Soviets having the “simple but brilliant” solution to the problem of writing in space by using $0.10 lead pencils rather than million-dollar Space Pens is bullshit, too. The graphite and shaving from a lead pencil would be both a contamination and fire hazard, especially in the high oxygen fraction environments in early spacecraft, The Soviets used grease pencils.
