A return fab now rehab

Two American astronauts Sunita Williams of Indian origin and Butch Wilmore landed on Earth to much relief and celebrations on Wednesday morning One could actually hear the world exhale as the astronauts returned pictorials showing the space capsule deploying its parachute before a splashdown in the ocean off the coast of Florida There was joy as the spirited twosome were helped out of the capsuleThe duo who visited the International Space Station ISS on what was supposed to be a oneweek stay in the first week of June 2024 on a test mission found their stay inordinately delayed as the spaceship that took these two astronauts developed a technical snag As a concerned world looked on that stay stretched for a nervy nine monthsGforceSpace travel is inherently dangerous to the human body and the microgravity environment affects astronautsrsquo physiology When a rocket carrying astronomers lifts off it reaches a speed of 28000 kilometres per hour At that speed astronauts experience intense Gforces severe cockpit vibrations and loud rocket engine noise This leads to physiological changes in the astronauts like increased heart rate possible loss of hearing and body fluid redistribution which can cause dizziness and swelling However the time from liftoff to the designated orbit takes about 10 minutes Once the spaceship reaches its orbit astronauts regain their normal senses It can take a few hours to a day for the spaceship to dock with the ISS In their spaceship astronauts start sensing the effect of nearzero gravityMass lossThe human body is a highly complex system of bones and muscles with a highly evolved brain The brain continuously monitors all the bodyrsquos activities and signals its parts to take corrective action if necessary or to adjust to the local environment The body realises there is no gravity to pull it down and allows astronauts to float effortlessly Initially the brain does not view this as a significant issue However as the astronomersrsquo stay in this near zerogravity environment prolongs the brain recognises that the function of muscles needed on the surface of the Earth is no longer necessary As a result muscles begin to lose mass The same occurs with bones To prevent significant muscle loss astronomers exercise for more than two hours daily in a gym designed for the Station We had periodic reports about these astronauts working out in space to arrest muscle and bone mass loss as much as possibleHowever muscle and bone mass loss are inevitable with a prolonged stay in this environmentBack homeAfter landing on Earth astronauts experience ldquogravity sicknessrdquo This is because their bodies need to readjust to the planetrsquos gravity The process of readjustment leads to dizziness nausea difficulty with balance and coordination and potential muscle and bone soreness Depending upon their stay in space astronomers can take from a few days to weeks to acclimatise their bodies to the gravity of the Earth The effects of bone and muscle loss are seen immediately Earlier Sunita Williams had spoken about the difficulties she is expected to face when back She had said that due to the muscle loss in her body she would find it difficult to do something as simple as lifting a pencilWe saw as both these intrepid astronauts landed they needed to be assisted to get out Now they will need time and rehabilitation to rebuild muscle tissuesLimb movementThe other physiological aspect is the coordination of limbs hands and legs Our inner ear has sensors that detect the posture of our body This sensor and brain constantly monitor our body and take necessary action under adverse conditions if one is about to fall Then the needed action is taken to maintain the balance Due to the lack of gravity in space the use of this sensor for checking body balance was not needed However after returning to Earth it takes considerable time for the sensor to readjust to the gravity here resulting in dizziness nausea and difficulty with balance and coordinationVision worriesOn Earth body fluids are constantly pulled down But in space extra fluid can reach the eyes causing swelling and structural changes This can lead to vision problems in astronauts Facial swelling tight hamstrings and calves have been noticed These problems remain upon returningto EarthLastly but importantly it has been suggested that astronauts experience a temporary decline in cognitive efficiency such as thinking learning and judgement after returning to EarthWe have seen astronauts performing cuttingedge science experiments in space but even after returning to Earth they would provide valuable information about physiological changes in spaceThe columnist is the director of the Nehru Planetarium Mumbai