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#26 2015-02-03 08:14:02

JoshNH4H
Member
From: Pullman, WA
Registered: 2007-07-15
Posts: 2,546
Website

Re: Magnetic shoes/boots: How come NASA doesn't use them?

Rik, .3?  Masochist indeed.  I have some friends who are .5 snobs, just wait till they hear of you XD


-Josh

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#27 2015-02-03 15:53:01

Tom Kalbfus
Banned
Registered: 2006-08-16
Posts: 4,401

Re: Magnetic shoes/boots: How come NASA doesn't use them?

RobertDyck wrote:

Mechanical pencil. No wood shavings, and no ink so works in zero-G. Narrow lead so always sharp without wasting graphite by sharpening.
http://www.staples-3p.com/s7/is/image/Staples/s0110326_sc7%20?$search$ http://www.staples-3p.com/s7/is/image/Staples/s0084943_sc7%20?$search$

Have you ever tried jumping out of an airplane and jotting something down on a piece of paper? if ball point pens needed gravity to work, I don't think I would be able to write on the ceiling with them, as the ink would be fighting gravity in order to get to the ball point. I think a regular ball point pen would have no trouble working in zero gravity, as I don't have to hold them with the point down in order to write with them.

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#28 2015-02-03 16:27:08

JoshNH4H
Member
From: Pullman, WA
Registered: 2007-07-15
Posts: 2,546
Website

Re: Magnetic shoes/boots: How come NASA doesn't use them?

How long have you held your pen upside down before trying to write with it?


-Josh

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#29 2015-02-03 21:42:09

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,813
Website

Re: Magnetic shoes/boots: How come NASA doesn't use them?

Um, Tom, the text I wrote said "mechanical pencil". The images are two examples of mechanical pencil. They use a rubber sleeve to hold the graphite, and a clicking the button on the top of the pencil pushes the pencil lead down. A spring pushes the button back up when you release. Once the pencil lead extends beyond the steel sleeve, you write with it as you would a wooden pencil. It's a pencil, not a pen. No ink.

But if you think a normal pen will work, then try it. Hold a paper on the underside of a table, with you lying on the floor. Write at least one paragraph. I believe you will find the first word works fine, but once the ink immediately on the ball is used up, it can't write any more. Pens require gravity for ink to flow down the tube. That's why the space pen has a pressurized ink canister.

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#30 2015-02-04 00:46:38

Rxke
Member
From: Belgium
Registered: 2003-11-03
Posts: 3,669

Re: Magnetic shoes/boots: How come NASA doesn't use them?

RobertDyck wrote:

Pens require gravity for ink to flow down the tube.

Always puzzled me, thought it worked using capillary pressure, but probably the ink is too viscous for that to work.

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#31 2015-02-04 08:31:54

Terraformer
Member
From: Ceres
Registered: 2007-08-27
Posts: 3,821
Website

Re: Magnetic shoes/boots: How come NASA doesn't use them?

Oh, okay. I managed to write a sentence, but after that...

Is there such a risk from graphite floating around in modern spacecraft? I'm sure they're built to deal with a bit of dust in the cabin, nowadays. I suspect it was only a problem because the designs they used back then had electronics which weren't sealed against bits of graphite.


"I'm gonna die surrounded by the biggest idiots in the galaxy." - If this forum was a Mars Colony

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#32 2015-02-04 11:18:33

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 5,471
Website

Re: Magnetic shoes/boots: How come NASA doesn't use them?

Pencils,  plain or mechanical,  always break off pieces of the lead.  These are smaller,  harder-to-see-and-recover items with mechanical pencils,  even here on Earth.  In space in zero gee,  they float about the cabin,  not noticed.  Until it gets in your eye!

Even in a spacecraft with artificial gravity this will be a problem,  because every so often,  you have to go back to zero-gee.  All the debris becomes a hazard at that point,  including pencil lead bits. 

So,  all-in-all,  today the modern zero-gee pen is a better,  safer solution.  Early on,  the pencil (risks and all) was OK,  because that's all there was available. 

That being said,  I still admire "KISS" thinking (keep it simple,  stupid).

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#33 2015-02-05 18:26:25

JCO
Member
Registered: 2015-01-22
Posts: 35

Re: Magnetic shoes/boots: How come NASA doesn't use them?

Terraformer wrote:

Still, I'd like to develop a pencil that can be used in freefall, simply for any artists who decide to take a trip. Perhaps an ink consisting of graphite particles in suspension?

What you are talking about is called a grease pencil. Artist know it well. They also come in mechanical pencil varieties that would likely pass muster in space.

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