Yuri Gagarin, who made man’s first-ever sojourn in space, ‘waxed eloquent’ as to how different things were up there without the comforting force of gravity. It is actually a sort of `falling-elevator’ sensation — one result of which is that the spine in zero-gravity expands temporarily. This leads to disconcerting backaches. What’s more, astronauts come home from space a few inches ‘taller’ than when they left, most gaining as much as 2.75 inch during a space trip. You’d think of such a paradigm as a fascinating non-surgical ‘technique’ to increase one’s height, albeit the ‘extension’ is simply momentary and, unfortunately, painful.
This is not all. Astronauts returning home from space have demonstrated other changes both bizarre and complex, no less — from bones that have become lighter and blood cell chemistry gone askew, primarily because of ‘distorted’ immune function, cardiac arrhythmia and also ‘reduced’ size of the heart itself. Though there is no precise explanation of the process of such changes related to such deviations, space physiologists cite the varied phenomena as being due to prolonged exposure to a state of zero-gravity ‘sponsored’ weightlessness in space. While it is agreed that the basic causes of such physiological changes have been studied and deciphered exhaustively, what is not exactly known is the essential role of the whole mechanism — the deep mystery within.
The most important ‘cosmic’ malady of space travel is motion sickness, or ‘space adaptation syndrome.’ Its primary symptoms are nausea, sweating, headache, appetite loss, lethargy, dizziness, notoriously forceful vomiting spells and cold fingers. With such a spectre being the song of one’s burden in space, it is, indeed, valiant of astronauts to be able to generate cheerful smiles and enthusiastic thumbs-up signs just before take-off, and also landing, as shown on numerous television channels!
While the precise source of motion sickness could be physical — owing to latent feelings of nervousness inside a sealed pressure suit — space scientists infer the queasy malady could be a fall-out of a state of chaos in the inner ear’s vestibular system, or the Organ of Corti, the body’s balancing apparatus. The tiny part in the inner ear, they suggest, probably tells the brain that the body is tilting, while the senses of sight and touch say it is not. On earth, or terra firma, the constant tug of gravity tells us of the ‘up-and-down’ sides of things without any riddle or uncertainty attached. In zero-gravity state, or when there is no pull downwards by gravity, such a sense of subtle perception is often lost. This axiom does not, of course, hold good for those exhilarating rides in the amusement park, where gravitational cues get befuddled.
Motion sickness for most astronauts usually dissipates in a few days’ time, as the brain adapts itself to conditions of zero-gravity. However, other effects of the state don’t disappear with ease. This is what happens. On earth, blood and body fluids pool marginally in the legs and lower torso under the effect of gravity, even though the dissipation is unequal. This is something which nature has ordered the body to expect and adapt to. During space travel, the fluids spread more effectively into the upper extremities. As a result, there is a strange sensation of fullness in the head, juxtaposed by puffed-up eyes and stuffy sinuses.
Muscle-wasting is also common after a trip into the wild blue yonder. The legs, for example, shrink palpably. Most annoyingly, there is fluid shift with fluid loss through amplified urination, because the pressure monitoring sensors in the chest take note of surplus fluid and shunt it away. Blood volume too drops within hours of take-off, leading to dehydration. As one NASA physiologist puts it, “The body’s baroreceptors, the pressure-monitoring nerves in the arteries of the chest and neck say, ‘Hey, there’s too much of fluid in here. We’ve got to dump the excess.’”
So far, no enormously negative effects from fluid shift have resulted from a voyage in space. However, the transition back to gravity does have a bearing. Once on earth, astronauts often suffer from sudden changes in blood pressure levels. In space, such fluctuations can impair the body’s blood-pressure-regulating reflex, causing variations identical to those that occur in ‘earth-bound’ individuals prior to heart attacks. With lack of blood, the heart is not always in a position to pump enough oxygen-carrying fluid to the brain. The outcome is severe vertigo and fainting spells, as the newly returned astronaut tries to take his, or her, first few ‘faltering’ steps, or rise from bed. One simple solution that works is taking large quantities of water and salt tablets before re-entry — to increase blood volume by 15 per cent. However, this uncomplicated solution is effective only for short-term missions — not in extended space projects, or space walk.
Man’s ingenuity has, of course, found some means to dealing with such complexities — to foster the cause of scientific advancement. Space physiology has become increasingly sophisticated —coalescing ideas of novelty with technological progress. New exciting projects are nothing short of the astounding — they have made space endeavours all the more exciting, while expanding on augmented safety parameters vis-à-vis one’s health and wellness.
To cull one example — picture a NASA ‘gadget’, special and practical, in the form of lower body negative pressure device [LBNP]. The unit is a sort of reverse iron-lung system, which applies a partial vacuum to the astronaut’s lower torso and limbs, so much so that it sucks fluid back down from the head and chest, redistributing it more normally through the body. Astronauts often use this handy ‘space suit’ in simulators and, at intervals, during space flights, just to remind the body of earth and its gravity. All is well that has begun well.
So far, so good. Yet, the problem area is still the circulatory system. It may be fairly easy to correct fluid pressure, but not the body’s natural pump — a weightless astronaut’s cardiac system would never be able to work as forcefully and articulately as it does on earth. Without gravity, the heart begins to relax, adapting to its lowered work load and more shrivelled existence. Fortunately, the dilemma of reduced heart size is, more or less, self-correcting, once the astronaut returns to his natural dwelling. A majority of astronauts regain their pristine cardiac mass within 2-3 months of their return to planet earth.
Cardiac arrhythmia too adds ‘grist’ to the wide-ranging perplexity the human system experiences in space. On earth, the anomaly is often caused by stress, or excessive levels of stimulants such as coffee. While some physiologists label stress in space as the trigger factor for arrhythmias, there are several other theories doing the rounds in research laboratories. No one, as yet, knows how exactly arrhythmia is caused, although the likely triggers suggested are electrolyte imbalance, hormone shift, or fluid-volume changes.
Paradoxically, however, a major dilemma is now ‘weighted’ on the positive side. No astronaut has, so far, displayed any major illnesses related to a weakened immune system. Small wonder then that Nostradamus purportedly prophesied that an explicit cure for AIDS would emerge from a laboratory located in outer space! Well, the fact also is research is now underway, in space, to determine the role of specific antigens in combating illness — from allergies to diseases, big and small — as a first step. What’s more, NASA is now ‘sculpting’ new tools, despite a fall in its budgetary allocations, including the formulation of an ‘artificial gravity’ spaceship. What does this connote? That with emerging new cutting-edge technology, it won’t take too long to crack some of space physiology’s most labyrinthine puzzles on solid ground.