Extended human space travel through biolationby Steve Hoeser
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| Are there practical near-term methods to improve space transport human system design factors that could allow us to create more cost-efficient spaceships and improve the safety to passengers and crew during these long voyages? |
We cannot do anything about the physical distances, nor can we expect much more performance out of current chemical rockets for projected near-term transports within the solar system. While there are projected improvements in velocity in the future through introduction of fission propulsion, fusion-drive rockets, or other exotic space transport engines, space travel will continue to require long transit times. Even if one is able to exploit velocity-enhancing tricks like gravity-assist planetary flybys, deep space trips to, say, mineral-rich asteroids in the main belt will still be measured in years.
So, for transporting people around our solar system, the fundamental question has and continues to be whether anything practical can be done about adjusting the impacts for the humans on board. More precisely, are there practical near-term methods to improve space transport human system design factors that could allow us to create more cost-efficient spaceships and improve the safety to passengers and crew during these long voyages?
If we were able to actually reduce those human factor system impacts, engineers could produce smaller and more efficiently designed spaceships. Smaller ships with reduced complexity normally have less mass, which means a faster velocity from the engines propelling it. These system and operating factors should reduce the transport costs. This could, in turn, stimulate an accelerated opening our solar system and possibly lead to realistic consideration of interstellar space transit without resorting to multi-generational starships.
However, when considering traditional methods for reducing the human factor system impacts, there are few options for people living normal lives. The food, water, and air needed for normal human metabolic processing requires not only these consumables but also means to process their human waste products. All of these consumables, and the spaceship volume and systems needed for such metabolic processing, add mass and spaceship design complexity. When one adds in the negative sociological and psychological considerations of extended journeys, designing spaceships for humans on long space missions spirals into a costly, negative system design cycle.
A method to address this issue would be a means to dilate the human impacts of long space journeys. When investigating this time dilation of the human life processes, in a biological sense, science fiction often resorts to several speculative alternatives. One is called stasis. Stasis would provide a means of totally stopping all human body functions and suspending animation, not to mention stopping aging. Then, once the ship is close to the destination, the passengers and crew would be brought out of stasis and resume their normal lives.
| This concept of biological time dilation was dubbed “biolation” by the late rocket ship engineer Maxwell W. Hunter. |
Another approach speculated is cryo-sleep. Cryo-sleep systems would be based on efforts to date in the world of cryogenics. Termed cryonics, some people have paid large sums of money to be cryogenically frozen quickly after their death in the dim hopes of a future body repair and a resumption of life. Unfortunately, cryonics processes have been shown to cause destructive damage to the cells in complex organisms like people. To date, no practical means to “re-animate” people frozen using cryonics has been devised.
There are, however, other, less severe, ways to achieve biological time dilation, specifically through forms of hibernation. There exists in nature at least two classes of hibernation: one in which aging continues at its normal rate and one in which aging slows while hibernating. It is the latter that is of particular interest for extended human space travels. This concept of biological time dilation was dubbed “biolation” by the late rocket ship engineer Maxwell W. Hunter.
Achieving practical crew hibernation with even moderate biolation promises impressive reductions of the human factors driving the design of interplanetary space ships. With a large fraction—perhaps the entire compliment—of crew and passengers in a state of induced hibernation, there would be no need for the added space for multiple individual crew living accommodations, mess halls, recreation facilities, or extensive food stores, water, and atmospheric processing systems.
For interplanetary spaceships, the savings in mass of consumables and reduction in needed power and habitable volume would reduce the complexity and mass of space transports. These reductions also allow consideration of more efficient design alternatives to spaceship radiation shielding, providing better protection for the passengers and crew. Most of al, the resulting smaller deep space transport ships would have considerably less mass, and thus require less fuel to move them to their destinations. All these complimenting factors would translate into lower design, manufacturing, and operating costs for future commercial space transport companies and, perhaps just as important, a potentially less distressing ride for the paying passengers on board.
As it turns out, there have already been preliminary investigations into ways to practically induce hibernation-like low metabolic torpor states in future space travelers. Torpor is a state of decreased physiological activity in an animal, usually through a reduced body temperature and metabolic rate. In nature, animals like bears use this method to help get them through the winter while expending minimal energy.
The hibernation investigations thus far were based on leveraging existing medical therapeutic hypothermic therapy (topor) and Total Parenteral Nutrition (TPN) methods. Topor has been a staple in certain medical critical care conditions since 2003. TPN provides the means to intravenously provide nutrition to feed the patient during the topor state. Applied to space travel, these methods could be used to make the long journey to places like Mars (and, by inference, the rest of the solar system) safer, less expensive, and far less taxing for crewmembers.
Through two rounds of funding from NASA Innovative Advanced Concepts (NIAC) one company, SpaceWorks Enterprises Inc. in Atlanta, Georgia, investigated just such a hibernation-like process several years ago. The SpaceWorks biolation approach leveraged the medical topor and TPN in their concepts. Their method for space application calls for lowering individuals’ body temperatures by about nine degrees Fahrenheit (five degrees Celsius). This would induce a “hypothermic semi-stasis” that cuts their metabolic rates by 50 to 70 percent.
With a crew of six in this hypothermic torpor state, it was estimated that the space transport living habitat space could be cut by a factor of 40. The resulting smaller crew habitat would weigh almost 70 percent less than if the crew remained in an active 24-hour lifecycle during the trip. In this topor biolation state, the crew’s consumption of nutrients could be more than cut in half (less maintenance fluids), not to mention the mass savings from reduction of prepared food packaging, storage, and human waste processing. More or less sleeping through the long space trek should also minimize the psychological and social challenges that as concerned human spacefaring nations (and navy submariners) for years.
While in the induced topor biolation, however, passenger’s lower metabolism will still require nutrition. The approach calls for the chilled sleeping crewmembers to be fed intravenously, bypassing the normal processes of eating and digestion. They would also need to be “lightly restrained” within the habitat to maintain safe conditions and to provide continuous automated health monitoring.
It is also well known that extended exposure to microgravity conditions has a variety of negative health effects. This ranges from muscle atrophy and bone weakening to vision problems. This would indicate that the torpid crewmembers may need to have their habitat produce some level of artificial gravity. In a reduced metabolic biolation state however, a simpler rotating system design should suffice to generate the yet-to-be-determined level of artificial gravity (see “Zero-g or why not?”, The Space Review, November 21, 2016).
| It is a reasonable hypothesis that reduction in the metabolic rates offered by a hibernation process can help address the key challenges of long space journeys. |
The SpaceWorks hypothermic torpor study for space travelers identified a number of development challenges before such a biolation method is ready for testing, let alone general use. One is that a cocktail of sedatives is currently needed for medical patients in therapeutic hypothermia to suppress the body’s natural shiver response to cold. Methods to provide automated monitoring and health response systems will be needed to deal with and remotely treat any medical conditions. Possible medical conditions noted included thromboembolism (blood clotting), unanticipated bleeding, infections, electrolyte imbalances, muscle atrophy, and development of fatty liver and other possible liver problems. Other identified potential complications of such long hypothermic torpor that will also need to be investigated include hypo/hyper glycaemia, bile stasis, and as-yet-undiscovered complications.
The use of torpor biolation will also likely create a crew perception of time dilation. For the crew this could be much akin to that lost time feeling experienced by patients under anesthesia. Depending on the torpid period, crewmembers will likely have a good deal of catching up to do when they “wake up.” It may also be possible that actual biolation-induced life extension from this metabolic reduction technique could occur, although the prospects of that remain unclear.
Regardless, hibernation using torpor biolation combined with TPN could clearly have a positive impact on future space transport system complexity, design, and operating costs, as well as increase both the viability and practicality of deep space travel. Additionally, the beneficial psychological impacts of such future long-duration space transport hibernation missions will require further sociologic and clinical studies to gain acceptance within the health and space communities.
It is a reasonable hypothesis that reduction in the metabolic rates offered by a hibernation process can help address the key challenges of long space journeys. The topor biolation methods presented in the SpaceWorks Enterprises hypothermic torpor concept study provide a real promise to address the negatives of space transport design and costs. In addition to these reasons, the terrestrial medical advancement potentials of such topor biolation processes deserve due consideration for future funding of additional investigations.