Writing in Space with a Cheap Ballpoint Pen 298
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.
Sometimes there is pressure, I understand. (Score:3, Informative)
The ink cartridges in some pens is pressurized.
Re:gravity doesn't matter? (Score:4, Informative)
Why wouldn't capillary action work in space? (Score:5, Informative)
It's the surface tension propteries of the ink, commonly known as capillary action [google.com].
But pencils are still cool... (Score:2, Informative)
Ofcourse, one can also break a pencil in two, and voila: TWO pencils, you colleague astronaut has one too now...
Third option, that a pen doesn't normally provide, is the fact that a pencil can be erased more easily without nasty chemicals. Easy if you want to wipe out the last log-entry in which you were a little drunk and have written down nasty things about the flight-captain.
When you need to draw a very fine line, one can sharpen the pencil to make it so. I don't see them sharpening a pen
Concluding: regardless of the truth of the "pen doesn't work in space but pencil does" story, it is still a much more versatile tool than a pen, so it "works" better....
NASA spent $2.95 per pan for 400 pens (Score:4, Informative)
Fisher just developed the pens to be helpfull.
Of course having NASA use his pens was great advertising and did give them a great run in the comercial sector.
Re:Amazing Technology (Score:5, Informative)
I think this is the explanation. (Score:5, Informative)
The reason for using pressure in pens, it seems, is that surface tension alone may not be enough to pull a long column of ink through a narrow tube. If there is a little bubble in the column of ink, the surface tension is broken, and there is no way to pull ink past the bubble.
The problem of a bubble in the column of ink happens on land, too, not just in space. People deal with it by just throwing the pen away. Since cheap pens cost less than 15 cents, someone may develop the habit of throwing away pens without noticing what he is doing. If a bubble develops, it is usually after the pen has had considerable use, so there is little complaint.
In situations of varying temperature and outside air pressure, unpressurized pens may develop a bubble more easily. Pressurized ink cartridges are a little more reliable, and cost the manufacturer only a little more.
Re:gravity doesn't matter? (Score:5, Informative)
Because gravity is still in action on the ink when the pen is horizontal, at a guess. Writing with the pen held horizontally isn't the same as writing in microgravity - in microgravity the stickiness of the ink is more than capable of pulling more ink towards the ball as it writes, whereas with the pen held horizontally in normal G it still has to pull ink "uphill" against gravity towards the top of the ball.
It'a another example of how nearly impossible it is to extrapolate what happens in space or on the Moon from our experiences on Earth - for more examples, check out Bad Astronomy on the Apollo "Hoax" [badastronomy.com]
Re:Movie quote (Score:2, Informative)
http://www.snopes.com/business/genius/spacepen.asp / [snopes.com]
Re:Amazing Technology (Score:2, Informative)
(Granted, it would be an issue today if pencils are used in space, but in those days, it wasn't.)
Re:gravity doesn't matter? (Score:3, Informative)
The pen works perfectly well upside down, I've tried. Probably doesn't cost as much as a pressurized pen either
Re:Be fair (Score:3, Informative)
Its not liquid or gas is it?
Re:And what I really wonder... (Score:3, Informative)
Re:And what I really wonder... (Score:2, Informative)
Yup [nasa.gov]. That's about right. [nasa.gov]
Re:I think this is the explanation. (Score:3, Informative)
It that seal were airtight, the pen wouldn't work. If you look close you'll see that the little seal is a fibrous material that lets air pass through. It's harder to blow-pressurize, but you can still do it. I survived an English exam like that in high school. The little tuft won't let the ink paste through, so your pen won't "bomb" on you.
BTW the Pilot EasyTouch I'm writing this with (blue, medium point) has no such seal. Just as well because the blobs of ink tend to come from the front of this pen rather than the back.