Free Astronomy Magazine November-December 2021

38 NOVEMBER-DECEMBER 2021 ASTRO PUBLISHING exerts on bodies at the surface of our planet (9.8 ms -2 ). (Attention here: “g”, constant defined specific to the Earth, should not be con- fused with “G”, universal gravita- tional constant) The acceleration to which a military pilot can be subjected can exceed 10 g. For an astronaut at vertical take-off with a rocket, the acceler- ation can reach 16 g, a force that is bearable only if it is suffered along the transverse axis, which is why the astronauts are lying down during launch. The main harmful effects of a vio- lent acceleration are the so-called “black outs” or “black visions,” and the loss of consciousness caused by the accumulation of blood in the lower part of the body, which de- prives the brain of blood and there-