Wednesday, October 10, 2012

Smoking in Space: Literature, Technology, and Physiology

In constructing a science fiction tale, authors often find it useful to employ gimmicks—constructs employing technical or physical impossibilities—as devices to propel the story into new settings and inject it with certain qualities. Such commonly understood gimmicks include superluminal flight, artificial gravity, and time travel (arguably a subset of faster-than-light travel.) One such gimmick may seem a minor detail, but has much room for technical discussion: the activity of smoking while on-board a spacecraft. It has occurred in many forms of science fiction media from early to recent. The current technical consensus on the matter rules the act as an impossibility. However, examination of the pertinent literature reveals that this may be a technical impossibility rather than a physical one, implying a potential future possibility for the practicality of smoking in space. Literary, technical, and physiological aspects of space smoking shall be considered.
The problems presented by smoking in space have understandably not been overcome or even attempted by present or prior generations of astronauts. Smoking is an inherently recreational act (excepting a sharp minority of medicinal cases) with what are typically considered neutral to negative physiological effects upon the participant, depending on the plant matter in question. It requires continuous combustion, which in turn draws on finite oxygen supplies, releases pollutants into a closed-air environment, and presents a fire risk. Given the current government-operated spacefaring regimes' collective emphases on mission safety and astronaut health, such questions were not likely to arise (at least to be taken with any seriousness.) However, as the 21st century has witnessed the birth of viable privatized spaceflight, the aspirations of private residence and pleasure travel in space seem near at hand. Private individuals, and not solely government employees, will begin entering space for their own purposes. Questions pertinent to the creature comforts of these future private spacefarers will inevitably arise. There has never been a better time to have a serious discussion about the prospect of smoking in space.
Robert Heinlein provided one of the earliest science fiction explorations of smoking in space in his 1939 short story Misfit, wherein a character affixes a “smoke filter” to his face prior to lighting his cigarette. No further description of the device is given, but Heinlein here presented the idea that the problem of smoking in a sealed spacecraft could be solved in some fashion via a specialized device. As it was used by the smoker and not other passengers, it is perhaps implicit that this device confined the smoke to the user's person and the apparatus. Containing the cigarette, the combustion, and the smoke in a face-affixed apparatus may be a viable—however unwieldy—solution, given the invention of such a device. It would need to be capable of sealing in the smoke produced as a byproduct, and then either filter or otherwise dispose of both the secondary smoke and the primary exhalation from the user. Efficient filtration of smoke may be a simpler technical matter in microgravity environments than it is under the influence of terrestrial gravity, for reasons discussed below.
The probability of dangerously rapid combustion of any hydrocarbon ignition upon a spacecraft was once a gravely prohibitive risk for smoking in space. Early spacecraft environment systems, such as those of the Apollo era, used low-pressure atmospheres composed predominantly of oxygen with some water vapor and carbon dioxide. Keeping atmospheric pressure low by leaving out common buffer gases like nitrogen and argon allowed for a lighter, more airtight spacecraft. However, the absence of buffer gases and high oxygen concentration created such a deadly fire hazard that all modern pressurized spacecraft use nitrogen-buffered atmospheres of approximately terrestrial pressure (Friedman, 1999.) Thus, the risk of runaway combustion reactions from cigarette ignition or smoking is negligible for modern spacecraft.
Barring the implementation of an unwieldy containment vessel for the combustion (or presuming its inefficiency in containment,) the pollutants in smoke must be addressed with respect to their effects on the environment. Smoking produces such pollutants as carbon monoxide, hydrogen sulfide, butadiene, benzene, and styrene (Huber, 1989 and Moir, 2008.) No direct observation of dried plant matter burning in a microgravity environment has been made, but analogs can be found in paper and candle smoke observed in smoke detector experiments on board the International Space Station. Smoke of the sort produced by paper, candles, and cigarettes is of a sooty nature. In the ISS experiment, soot particles condensed to more than twice their average terrestrial size due to an absence of the buoyancy effects that typically draw smoke particles quickly from their high-temperature formation zone (Urban, 2005).
The ISS presently uses lithium hydroxide canisters containing activated charcoal in the air revitalization subsystem of its Environmental Control and Life Support System for removing carbon dioxide and biogenic or trace contaminants (Dumoulin, 1988.) Were such filters increased in number relative to the habitat size (or concentrated in an airlock-segregated designated smoking area), they could filter cigarette smoke with a safe level of efficiency. Such filters would likely be used in such settings as the Zion torus space station from William Gibson's 1986 novel Neuromancer, an entire space colony of ganja-smoking Rastafarians. Such cannabis smoke, especially in the concentrations a colony of space Rastafarians would likely produce, would quickly become toxic under normal conditions. In terrestrial filtration schemes micropore density in the activated charcoal filter would need to be increased above that of typical filters in order to address the smallness of cigarette soot particles, but the size change that microgravity endows soot would likely negate this need.
It is worth noting that the carcinogenicity of tobacco smoke is a function of the heterogeneity of smoke particle deposition within the respiratory tract, which in turn is a function of particle size (Balásházy, 2003.) Whether this makes smoking in space safer or more dangerous may be the subject of future study, but that a difference should exist one way or the other makes this a potentially significant subject of scientific inquiry. Future smokers may find their lifestyle choice more or less deleterious to their health depending on the gravity of their setting.
Smoking in space presents a technical challenge for spacefaring pleasure-seekers, but it is far from an impossibility. Given adequate safety and health precautions, technological development, and perhaps a bit of preliminary clinical research, spacecraft can become a relatively safe environment for smoking. Future astronauts may not need to altogether shirk their earthly pleasures in order to set off for the stars.

Works Cited
Balásházy, I. (2003). Local particle deposition patterns may play a key role in the development of lung cancer. Journal of Applied Physiology, 94(5), 1719-1725. Retrieved from http://jap.physiology.org/content/94/5/1719.short
Dumoulin, J. National Aeronautics and Space Administration, (1988). NSTS 1988 news reference manual. Retrieved from Kennedy Space Center website: http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/stsref-toc.html
Friedman, R. National Aeronautics and Space Administration, (1999). Fire safety in the low-gravity spacecraft environment. Glenn Research Center. Retrieved from: www.asi.org/adb/04/03/14/spacecraft-fire-safety.pdf
Gibson, W. (1986). Neuromancer. Ace Publishing.
Heinlein, R. (1939, November). Misfit. Astounding Science Fiction.
Huber, G. L. (1989). Physical, chemical, and biologic properties of tobacco, cigarette smoke, and other tobacco products. Seminars in Respiratory Medicine, 10(4), 297-332.
Moir, D. (2008). A comparison of mainstream and sidestream marijuana and tobacco cigarette smoke produced under two machine smoking conditions. Chemical Research in Toxicology, 21(2), 494-502. Retrieved from http://pubs.acs.org/doi/full/10.1021/tx700275p
Urban, D. (2005). Detection of smoke from microgravity fires. International Conference On Environmental Systems, doi: 10.4271/2005-01-2930



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