SPACE – THE NEW FRONTIER
By UDITA JAHAGIRDAR M.D., F.A.C.O.G.
The launch of a spaceship over at the coast of Central Florida is a site to behold. The anticipatory throng of humanity, the pulse quickening countdown growing into a chant, then the lift off – a flash of fire on a bed of white cloud of smoke, a rumble turning into a roar as the spacecraft hurtles skyward riding a plume of fire as the scaffolding tears away, a thunderous applause with every eye straining to get a last glimpse of the fiery speck in the sky, and finally crowds dispersing with a universal murmur of obeisance to the marvels of science and human endeavor on their lips. As if this is not enough, one has the dazzling spectacle of a night launch and recent mind-boggling precision return to target landings of the reusable SpaceX booster rockets.
Commercial space travel or space tourism is now a certainty. NASA has now allowed private astronauts to go on the International Space Station with the use of Elon Musk’s Crew spacecraft and Boeing’s Starliner, priced at $ 35,000 per day. A Japanese businessman Yusaku Maezawa has paid a substantial deposit for a Moon loop flight on Space X. Virgin Galactic founder Sir Richard Branson has booked more than 600 tourists at $250,000 apiece on a 6 passenger SpaceShipTwo for a 3-4 hour sub orbital flight. There is a huge thrust to monetize space programs. Knowing AAPI members penchant for exotic travel we may well see our very own physicians in orbit soon.
With this growing realism, one may wonder about the effects of space on human body. Obviously, the impact depends on whether it is a brief space jaunt or a Mars mission. The risks are grouped into FIVE categories: Gravity Fields, Isolation/Confinement, Hostile/Closed Environment, Space Radiation and Distance from Earth. Space Medicine is a developing medical practice to discover how long people can survive extreme conditions in space and how fast they can readapt to the earth’s environment and the preventive and palliative measures to be undertaken.
The long term effects on the body were best studied by NASA’s trail blazing Twin study which compared retired astronaut Scott Kelly while he was in the International Space Station for 340 days to his identical twin brother Mark Kelly, also an astronaut, who remained back on earth. There were changes in his telomere length, gene expression, gut microbiome, body mass and vitamin levels, increased carotid artery thickening, ocular changes and cognitive functions. Overall, there was a return to preflight levels upon return to earth demonstrating the robustness and resilience of the human body.
As of now, there are no rules requiring space companies to set or meet any health criteria for accepting passengers- they just need to sign a statement that they understand the risks of such a flight and are able to pay the hefty amounts charged. Initial short duration flights will probably be a gentle low G- ride up, a few minutes of weightlessness at 100 km, an incredible view of earth, followed by a thrilling reentry and landing – perhaps only with some associated nausea and vomiting – far different from a long Mars mission.
A brief evaluation of the challenges and hazards of space travel is as follows:
Ascent and Reentry: force or gravitational acceleration force – an untrained person can withstand 3G but may blackout at 4 to 6G because blood flows away from brain and eyes, especially with a vertical ascent and can cause loss of vision then loss of consciousness. This is mitigated by G- force training and a G- suit which constricts the body to keep more blood in the head. Most spacecrafts keep G- forces within comfortable limits.
Weightlessness has deleterious effects on muscle mass and bone density. Short term exposure causes Space Adaptation Syndrome, a self-limiting condition caused by derangement of the vestibular system and otoliths, resulting in motion sickness, lethargy, malaise, vertigo, and can reduce aerobic capacity and slow down the cardiovascular system. Without the pull of gravity, fluids distribute into upper half of body causing the round-faced puffiness, seen in astronauts, balance disorders, decreased performance, increased intracranial pressure on optic nerves, distorted vision and loss of taste and smell. There is accelerated bone loss from normal 3% cortical bone loss every decade to 1% every month, an increased osteoclastic activity in the pelvic region with increased serum calcium levels and a potential to form kidney stones. In a weightless environment muscles atrophy rapidly and without regular exercise astronauts can lose 20% of muscle mass in 5 to 11 days The International Space Station has treadmills, stationary bikes and weight training equipment.
Isolation and Confinement cause behavioral, cognitive and psychiatric conditions with decline in mood, morale and interpersonal interaction. Loss of circadian rhythm causes sleep disorder, depression and may impact performance of a mission. Lack of fresh food may further contribute to nutritional deficiencies – morale and motivation may decrease three quarters of a way into a mission. NASA is developing LED technology to help align circadian rhythms and methods to assess performance fatigue.
Hostile/Closed environments: Microbes can change characteristics in space and microorganisms can be easily transferred from person to person. Illnesses like Epstein Barr may be reactivated as stress hormones are elevated and immune system is altered
Space Radiation: On the space station which sits just within earth’s magnetic field astronauts still receive over 10 times the radiation occurring on earth where we are protected by earth’s magnetic fields and atmosphere. There is lowered immunity from damage to lymphocytes experienced by astronauts and a higher incidence of cataracts. Cosmic rays may accelerate the onset of Alzheimer’s while solar flares may give a lethal dose of radiation in minutes. A vehicle travelling to Mars would need significant yet undetermined shielding.
Distance from earth: The moon is 0.239 million miles away, while Mars is 140 million miles away. Imagine the challenges of communication, equipment failure and skills needed to endure.
As humans, we are poised to take this giant leap into the unknown. How far are we going to succeed? – only time will tell.