Comment on Pens in Space
blackbrook@mander.xyz 2 months agoCan we still buy one of the special space pencils? Were they low-dust or something?
Pens are dust-free as is, the problem with a regular ballpoint or felt tip pen is that both inking mechanisms rely on gravity. When you’re in 0g the ballpoint won’t work at all and the felt will stop working after a point when there’s no gravity to pull more ink to the tip.
You could probably spin a felt until it rewets but you’d be liable to make a mess as well.
Don’t felt tip pens work by capillary action?
That do. The failure comes if the spacecraft use lower air pressure, then the ink is pushed out of the pen by the pressurised gas in the ink
The same thing causes some pens to leak in aeroplanes.
You’re just raising the question about why the pencils cost over $100 if all pencils are dust free. What was so special about them when the special pens were so cheap?
Pens are dust-free, pencils are not. Dust-free pencils are special and expensive because it’s a lot of chemistry and testing to ensure that. How do you cleanly sharpen a pencil for example? Special pens are special but cheap because the components to make them are still relatively simple, the ink is still standard. More expensive than standard pens by a fair bit but a lot cheaper and more practical than the pencils.
I misread you as saying pencils are dust free.
jaybone@lemmy.zip 2 months ago
Yeah, what’s the story with these pencils?
Also don’t felt tip pens write upside down?
sqw@lemmy.sdf.org 2 months ago
they will for a bit
jqubed@lemmy.world 2 months ago
I don’t know if anyone still makes the pencils. IIRC they used a special formulation for the graphite that reduced the dust and risk of breakage, but I don’t think there’s much market for that outside the space program since that’s about the only place the dust would float and be hazardous. The pens were in development even before the space program because there’s a market for pens that can write in unusual orientations. I’m sure the marketing of it being a pen used in space helps expands that market some, but the market would exist regardless. It’s supposed to be a nice pen to write with also, although I don’t know how much of that is kind of a placebo to justify spending $10-20+ on a pen. I’m sure it’s nicer than a 50¢ pen, though.
Felt pens can be prone to leakage, especially in lower atmospheric pressure. This can be a problem even in airliners, and definitely not what you want in space. There’s nothing in the pen mechanism to seal the ink in when not in use. A properly made ballpoint pen actually seals the ink in when not in use. That was Bíró’s big selling point over earlier technologies like fountain pens; the pen still writes even if you leave it uncapped and the ink doesn’t dry out. The Bic pen was revolutionary for creating a manufacturing process that could produce them cheaply.
jaybone@lemmy.zip 2 months ago
Good reply. Thanks! You know a lot about pens.