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Writing in Space with a Cheap Ballpoint Pen
Roland Piquepaille writes "Some days bring big surprises. Like many people, I always believed that it was impossible to write in space with ordinary pens because ink would not flow. So imagine my astonishment when I read Pedro Duque's diary from space this morning. Pedro Duque is an astronaut since 1992. Now, he's on board of the International Space Station (ISS) since October 18, 2003. And he's writing -- from space -- with a cheap ballpoint pen, like Russians apparently always did: 'So I also took one of our ballpoint pens, courtesy of the European Space Agency (just in case Russian ballpoint pens are special), and here I am, it doesn't stop working and it doesn't "spit" or anything.' Isn't it amazing? This summary contains more details and a photograph of Pedro Duque on board ISS." Note that NASA didn't go crazy developing a pen for space. Surface tension is the important factor for all pens, not gravity.
He's writing in a space station that's pressurized and kept at around 20C. The 'space pen' was designed to work in a vacuum in a temperature range of something like -100C to +200C, as experienced on the lunar surface: try doing that with a $0.50 plastic ballpoint.
would you trust your research to a pencil? i wouldn't. i'd have to write it in pen when i got home, so that when the pencil fades (like my physics notes from 3 years ago), i'd still have the pen copy.
I write code.
Surface tension is indeed the important factor, but what you're missing is this: although gravity is not needed for the pen to write, in space it's not working against you when you try to write upside down.
Don't they have a Zaurus each instead of pen & paper?
Of course graphite contaminant floting in the air and sooting up the entire station is of no concern to you.
;-)
Regarding graphite conduction, I'm sure that it would make ANY part misbehave. It would be better to use the metal shell of a pen
-------- -------- Support Wesley Clark for president!!!
Microgravity.
What happens to all the pencil shavings and eraser crumbs?
Chip H.
"the fact that a pencil can be erased more easily without nasty chemicals"
But it leaves all that rubber shit from the eraser floating around.:)
There's a growing sense that even if The Future comes,
most of us won't be able to afford it.
-- Lemmy
There has to be some force acting on the ink to get it to move at all. With a pen held upright, gravity and surface tension are acting in concert to get ink onto the ball. Invert the pen, and gravity is now opposing surface tension. At some critical value of g, the surface tension and gravity will be exactly equal and the ink will stay where it is. With stronger g, as on Earth, gravity will win over surface tension and the ink will be pulled away from the ball. With weaker g, surface tension will be stronger than gravity and the ink will flow normally.
Determining this critical value probably is the sort of thing likely to win you an Ig Nobel Prize
Je fume. Tu fumes. Nous fûmes!
It's not capillary action really... it is cohesion to the ball. The ball is rotated, and the ink would rather be on paper than the ball, so the ink leaves, thus creating a void which sucks in more ink.
There are some real space pens that don't use nitrogen pressure and can be used in both freezing cold and blistering heat because the ink is actually a near solid. The ball's friction tears off the ink as it goes, and the suction (the ball is mainly used as a valve in almost all ink pens) pulls ink in without letting air into the ink well.
There is a folk tale about ink pens and the cold war that I can't verify. It had to do with the US spending 5 million dollars or more in research to develop a pen that was cheap and would work in space while the Russians just used pencils. If anyone can find the origin of the folk tale, or actually find evidence for this story, I'ld love to read more.
Karma Clown