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Is it true that astronauts can't use ball point pens in space? The mechanical contact of a ball point with the paper should make the pen write but I am not sure if it's true. Any clarification will be greatly appreciated.

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    $\begingroup$ FYI, "in space" is ambiguous. When somebody asks a question about "...in space," they often are asking about either one of two environments; They may be asking about microgravity (a.k.a., "free-fall", a.k.a., "zero-g"), or they may be asking about in vacuum. Less frequently, they may be asking about other conditions that are encountered in space missions such as, extreme temperatures, extreme temperature changes, or radiation. $\endgroup$ – Solomon Slow Jun 29 at 13:28
  • $\begingroup$ Related questions (suggested by DrSheldon): space.stackexchange.com/questions/1712/… space.stackexchange.com/questions/36178/… $\endgroup$ – David Z Jun 30 at 19:24
  • $\begingroup$ Wasn't there a pen manufacturer that advertised in the 60's or 70's that they were used by Apollo astronauts? $\endgroup$ – Barmar Jul 1 at 14:33
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    $\begingroup$ This is applicable to both physics and space exploration. If it had been originally asked here, it would've probably just been migrated to the physics site instead. Things like this migration are just a waste of time and effort. $\endgroup$ – Panzercrisis Jul 2 at 14:30
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    $\begingroup$ @Panzercrisis well, a Physics mod deliberately migrated this to here, so even if it had been originally asked here, migrated to there, then it'd probably be closed again and the migration bounce back to here again. $\endgroup$ – Andrew T. Jul 3 at 13:27
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They can and they do use regular ballpoint pens. And normal pencils, mechanical pencils, grease pencils, felt-tip markers ("Sharpies"), and pressurized "space pens".

ESA astronaut Pedro Duque comments on ballpoint pens in his 2003 diary.

I am writing these notes in the Soyuz with a cheap ballpoint pen. Why is that important? As it happens, I've been working in space programmes for seventeen years, eleven of these as an astronaut, and I've always believed, because that is what I've always been told, that normal ballpoint pens don't work in space.

During my first flight I took with me one of those very expensive ballpoint pens with a pressure ink cartridge, the same as the other Shuttle astronauts. But the other day I was with my Soyuz instructor and I saw he was preparing the books for the flight, and he was attaching a ballpoint pen with a string for us to write once we were in orbit. Seeing my astonishment, he told me the Russians have always used ballpoint pens in space.

...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.

Ballpoint pens do not work through gravity, rather they work through capillary action. If you hold a ballpoint pen upside down on Earth it will stop writing because the capillary action is insufficient against the force of gravity. In orbit there is no "upside down", no force of gravity to work against capillary action. In orbit, capillary action is sufficient.

And astronauts can do what we do on Earth, shake the pen.

Here is a repeat of Phillip's experiment but writing horizontally with the paper against the wall to negate the force of gravity. As you can see, but perhaps not read because of my handwriting, the pen works. I've used a Pilot G-2 gel ink ballpoint pen which retails for about $2 US.

a photo of a piece of lined paper; transcription below

Writing facing down

Just to demonstrate the pen works.

Writing against a wall

Writing with the paper flat against a wall to simulate 0 gravity. The pen continues to write because it works by capillary action. My handwriting remains as terrible as ever. More writing. Lorem ipsum etc. This is a pilot G-207. A good pen.

Writing upside down

The pen is having trouble now. And this is very awkward. It still works. (Ed: The ink is becoming faint in the last sentence.) A simple shake and it's back. A good pen will write upside down for a while. (Ed: Becoming faint again.) A shake brings it back.

Here we see Scott Kelly on STS-133 with what appears to be a space pen and a marker in his pocket, plus several mechanical pencils attached to the console.

And here is Cosmonaut Oleg Artemyev with the wide variety of writing implements used on the ISS.

Oleg Artemyev positioned in front of a wall with several notepads clipped to it, holding a tablet computer and a marker pen to write on one of those pads.

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  • $\begingroup$ Presumably the only reason it had any trouble writing upside down is that he did that test last? $\endgroup$ – Luke Sawczak Jul 1 at 18:41
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    $\begingroup$ @LukeSawczak It isn't, but good spot of an experimental flaw! I should have done another horizontal pass to rule the possibility out. Try it yourself. $\endgroup$ – Schwern Jul 1 at 18:50
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    $\begingroup$ I think the horizontal test is not quite equivalent to microgravity. When fluids are blocked from moving downward in a gravity well, they tend to spread outward, if possible. In this case, I would think the pen tip would fit as an outward direction. In other words, the ink is still getting some help from gravity. Still, fascinating answer! $\endgroup$ – 8bittree Jul 1 at 21:52
  • $\begingroup$ Shaking will also work differently in microgravity. On Earth, shaking mainly causes the fluid to move towards the direction of gravity. In space, you could hold the pen from one end and shake the tip from side to side, to make centrifugal action move the ink towards the tip. $\endgroup$ – jpa Jul 3 at 11:38
  • $\begingroup$ @8bittree: You're correct but the experiment wasn't quite intended for that level of precision. Just moving the pen around during writing is going to introduce fluctuations (literally of the ink, and figuratively of the simulation of microgravity). However, since tilting it up means being helped by gravity and tilting it down means fighting gravity, there should logically be a "sweet spot" on the tilt where you neither get helped by nor fight gravity. If you could gradually change the tilt as you write, you would eventually find it (assuming perfect dexterity). $\endgroup$ – Flater Jul 3 at 11:53
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EDIT: While I always believed this to be true, it looks like @Schwern has shown me otherwise! The link in their answer (which is the correct one) shows that ballpoint pens do indeed work in space.

(Also, I'm embarrassed to not have tried their simple extension to my experiment, by writing horizontally against a wall, which would have immediately shown me I was wrong.)

The more you know...


Ballpoint pens need gravity to push the ink onto the ball point that in turn transfers it to the paper when it rotates. As a result, they won't work in space. In fact, you don't need to go that far: they won't work when you're trying to write upside down, either!

I can't believe I never tried this before, but I just did a little experiment: I wrote a passage on paper, and then tried to write the same passage lying on my back in bed. You'll notice that there's still some ink on the point, so a couple of words do come out, but it stops very quickly. I then tried to write "normally" again, and you'll notice that it takes some time for the ink to flow back down to the point, but once it does, writing's back to normal again!

enter image description here

EDIT: My little experiment only shows that the capillary force is easily countered by gravity, not that ballpoint pens need gravity to work.

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    $\begingroup$ This has nothing to do with physics, but there is an interesting story that NASA spent millions to develop a ball-point pen that would work in zero-gravity. The Russians gave their kosmonauts good old pencils. $\endgroup$ – Oбжорoв Jun 29 at 11:54
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    $\begingroup$ I remember laughing a lot at this when I was younger: turns out that it's more a myth than anything else, sadly! $\endgroup$ – Philip Jun 29 at 12:01
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    $\begingroup$ @Oбжорoв On the other hand, pencils cause problems of their own, what with graphite flaking off. And then the Russians went and bought some of the zero-g pens, anyways. $\endgroup$ – fyrepenguin Jun 29 at 19:17
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    $\begingroup$ @Oбжорoв, short version: it wasn't NASA who spent the millions, it was Fisher (pen manufacturer), and selling to NASA was a publicity stunt to get the attention of their real intended customer: the US military. $\endgroup$ – Mark Jun 29 at 21:21
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    $\begingroup$ What you've demonstrated is Earth gravity is sufficient to act against the capillary action of a ballpoint pen, but there is no upside-down in orbit. Ballpoint pens do work in space. $\endgroup$ – Schwern Jun 29 at 22:09
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Yes, ball-point pens can be used in space. NASA even has a web page specifically about the Fisher Space Pen:

Fisher developed his space pen with no NASA funding. The company reportedly invested about \$1 million of its own funds in the effort then patented its product and cornered the market as a result.

Fisher offered the pens to NASA in 1965, but, because of the earlier controversy, the agency was hesitant in its approach. In 1967, after rigorous tests, NASA managers agreed to equip the Apollo astronauts with these pens. Media reports indicate that approximately 400 pens were purchased from Fisher at $6 per unit for Project Apollo.

The Soviet Union also purchased 100 of the Fisher pens, and 1,000 ink cartridges, in February 1969, for use on its Soyuz space flights. Previously, its cosmonauts had been using grease pencils to write in orbit.

Both American astronauts and Soviet/Russian cosmonauts have continued to use these pens.

The Apollo equipment stowage lists shows each mission launched with 3 Fisher ("data recording") pens, 3 felt-tipped markers, and 3 pencils. Each astronaut launched with one of each writing instrument in their spacesuit. The Apollo 11 manifest is included below:

pens in Apollo 11 stowage

Buzz Aldrin famously used a pen to fix a broken circuit breaker.

The Apollo astronauts often wrote notes directly on the spacecraft walls. Photographs and analysis of Apollo 11 "graffiti" is on this NASA webpage. Most of the writing appears to be in pencil, followed by felt-tipped marker. However, there is also the presence of pen writing:

pen-based graffiti in Apollo 11

This answer has a photograph with writing on a spacecraft in Russian, using pen.

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  • $\begingroup$ In Carrying the Fire Collins says he wrote that graffiti when they were in quarantine. $\endgroup$ – adam.baker Jul 3 at 8:08
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In space? Certainly. Aboard a rotating space station or a spacecraft undergoing velocity change - or any other circumstances that provided a force that moved the ink "downward" onto the paper.

The more interesting question is whether a ballpoint pen would work in zero (net) gravity. As ink moves from the pen to the paper there will be a miniscule reduction in pressure at the ball which could theoretically cause the ink to feed in that direction, but other effects are likely to be greater. The short answer is that standard designs of ballpoint pen rely on gravity to feed the ink to the ball when writing.

Alternatively, the pen could be redesigned so the ink was subject to another force pushing it towards the ball. The Fisher Space Pen used gas pressure for this.

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    $\begingroup$ Fisher "uses" nitrogen -- pens and refills still available. $\endgroup$ – Paul_Pedant Jun 29 at 19:08

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