Dr Ryan Anderton, the CAA’s medical lead for flight, told The Times that “physiological responses are likely to be benign for most passengers” but older people usually have slightly “stiffer arteries” which could lessen the pooling of blood away from the brain.
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“For the vast majority of people, even older people, that’s not necessarily going to present a problem and there isn’t a detrimental effect long-term,” Anderton said.
“What we’re trying to do in research is determine which individuals might be more susceptible and what we might have to screen them for.”
The study placed 24 healthy people aged from 32 to 80 in an RAF centrifuge at Cranwell to recreate the G-forces felt during the launch and descent of suborbital rocket and spaceplane flights.
The research found that G-forces could reach four times the usual force of the Earth’s gravity for 20 to 30 seconds during ascent and peak at six times, or 6G, during descent for 10 to 15 seconds.
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These forces, the paper said, could create a heavy sensation on the chest, making it more difficult to breathe, and can reduce the intake of oxygen, affect the rhythm of the heart and lead blood to pool away from the brain.
The study noted a rise in heart rate and blood pressure, a dip in blood oxygen and some “greying out” of peripheral vision during periods of high G-force, but found these quickly return to normal.
One participant briefly lost consciousness, but with no lasting ill effects. The effects were reduced when the chair was tilted back slightly.
Dr Ross Pollock, from King’s College London, said a suborbital traveller could lose consciousness during take-off and landing but would otherwise be fine during the flight.
“By changing the position of the chair you change the direction the G goes through the body. When the chair is upright, you get a lot of G-force going from the head to the feet,” he said.
“This in effect pushes the blood away from your head and eyes down towards your legs, therefore, you do not have enough oxygen reaching those parts of the body and your vision changes and potentially you can lose consciousness.”
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