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Writing in space

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Writing in space

Notes on a map written with a felt-tip pen by Michael Collins while in orbit around the Moon

Several instruments have been used to write in outer space, including different types of pencils and pens. Some of them have been unmodified versions of conventional writing instruments; others have been invented specifically to counter the problems with writing in space conditions.

A common urban legend states that, faced with the fact that ball-point pens would not write in zero-gravity, NASA spent a large amount of money to develop a pen that would write in the conditions experienced during spaceflight (the result purportedly being the Fisher Space Pen), while the Soviet Union took the simpler and cheaper route of just using pencils. The Fisher Space Pen was actually developed independently and privately in the 1960s, NASA later purchasing 400 of the pens at $6 each.[1] The Soviets followed as well.[2]

Mission requirements

Space versus ground recordkeeping presents several serious issues:

Contamination control

As with submarines before them, space capsules are closed environments, subject to strict contamination requirements. Incoming material is screened for mission threats. Any shedding, including wood, graphite, and ink vapors and droplets, may become a risk. In the case of a manned capsule, the much smaller recirculating volume, combined with microgravity and an even greater difficulty of resupply, make these requirements even more critical.

Release of wood shavings, graphite dust, broken graphite tips, and ink compounds are a dangerous flight hazard. Lack of gravity makes objects drift, even with air filtration. Any conductive material is a threat to electronics, including the electromechanical switches in use during early manned space programs. Nonconductive particles may also hamper switch contacts, such as normally-open and rotary mechanisms. Drifting particles are a threat to the eyes (and to a lesser extent an inhalation threat), which may risk execution of a critical procedure. Personnel may don protective gear, but both ground and flight crews are more comfortable and more productive "in shirtsleeves". Paul C. Fisher of Fisher Pen Company recounts that pencils were 'too dangerous to use in space.'[3]

Even before the Apollo 1 fire, the CM crew cabin was reviewed for hazardous materials such as paper, velcro, and even low-temperature plastics. A directive was issued but poorly enforced. When combined with high oxygen content, the Apollo 1 cabin burned within seconds, killing all three crew.

Cosmonaut Anatoly Solovyev flew with Space Pens starting in the '80s and states "pencil lead breaks...and is not good in space capsule; very dangerous to have metal lead particles in zero gravity"[4]

See also: Apollo 1

Mission assurance and quality records

Strict documentation requirements accompany anything as complex as a large-scale aerospace demonstration, let alone a manned spaceflight. retention of engineering knowledge for later programs, and any incident investigations.

When the flight also has scientific or engineering science objectives, low-quality data may affect mission success directly.

Faced with these requirements, pencils or other non-permanent recordkeeping methods are unsatisfactory. The act of taking permanent, high-integrity documentation itself deters kludges, workarounds, and "go fever." The Apollo 1 investigation uncovered procedural and workmanship deficiencies in multiple areas, up to procedures on the pad.

See also: Life-critical system

See also: System engineering

Pressure and temperature

Temperature is moderated by a thick atmosphere. As air pressure falls, temperatures can swing more dramatically. Many early manned missions operated at below standard pressure, to decrease the stresses (and thus, mass) of their capsules. Many did not have separate airlocks, instead exposing the entire cabin to hard vacuum at times. Low pressures also exacerbate contamination issues, as substances acceptable at standard conditions may begin outgassing at lower pressures and/or higher temperatures. While the Soyuz spacecraft had a 14.7 psi design pressure, and could use its Orbital Module as an airlock, the Orbital Module would be deleted for planned lunar missions. In any case, a pen which was insensitive to pressure and temperature would eliminate the issue (including accidental depressurizations), provide margin, and allow the ability to record during extravehicular activities.

Pre-existing writing instruments

The wood pencil has been used for writing by NASA and Soviet space programs from the start. It is simple with no moving parts, except for the sharpener. But wood, graphite, and rubber (in the eraser) are all combustible and create dust. Graphite, in particular, burns to produce dust that conducts electricity.

The mechanical pencil has been used by NASA starting in the 1960s Gemini program. It can be made to be as wide as the width of astronauts' gloves, yet maintain its light weight. There are no wooden components which might catch fire and create dust. However, the pencil lead still creates graphite dust that conducts electricity.

Grease pencils on plastic slates were used by the Soviet space program as an early substitute for wood pencils. It is simple with no moving parts. The paper shroud is peeled back when needed. The disadvantage is that the paper wrapper has to be disposed of. Writing done with the grease pencil is also not as durable as ink on paper.

Ballpoint pens have been used by Soviet and then Russian space programs as a substitute for grease pencils as well as NASA and ESA. The pens are cheap, use paper (which is easily available), and writing done using pen is more permanent than that done with graphite pencils and grease pencils, which makes the ball point pen more suitable for log books and scientific note books. However, the ink is indelible, and depending on composition is subject to outgassing and temperature variations.

Felt-tip pens were used by NASA astronauts in the Apollo missions. However, wick-based instruments are designed around low viscosity, and thus operating temperature and pressure.

Writing instruments specifically intended for space writing

The Space Pen is a gas-charged ball point pen that is rugged and works in a wider variety of conditions, such as zero gravity, vacuum and extreme temperatures. Its thixotropic ink and vent-free cartridge release no significant vapor at common temperatures and low pressures. However, it is slightly more expensive than the aforementioned alternatives. It has been used by both NASA and Soviet/Russian astronauts on Apollo, Shuttle, Mir,[5] and ISS missions.

References

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