Fig. 1. Left: Konstantin Edvardo- vich Tsiolkovsky (1857–1935), an almost deaf mathematics teacher in provincial Russia but a remark- able space visionary (from Tass- Sovfoto). Right: sketch of a space- craft made by Tsiolkovsky in 1883 (from Ref. 14).
and takes off. We have the sensation of terrible heavi- ness. My weight has increased tenfold. I am knocked down to the floor, severely injured and perhaps have even been killed—can there be any talk of observa- tions? There are ways of standing up to this terrible weight, but only in a, so to say, compact form or being submerged in a liquid. [Volunteers have now tolerated 30 G during water immersion (4).]
Even when submerged in liquid we will hardly be inclined to observe anything outside. Be all that as it may, the gravity in the rocket has apparently increased tenfold since takeoff. We would be informed of this by a spring balance or a load gauge by the accelerated swinging of a pendulum (some 3 times faster) [the period of a pendulum is inversely proportional to the square root of G], by the faster fall of bodies, by the diminished size of droplets (their diameter decreasing tenfold), by all things carried aboard the rocket becom- ing heavier, and many other phenomena.
way. For this reason there is no difference in the motion of the rocket and the bodies in it. They are carried along by the same stream, the same force, and, as far as the rocket is concerned, there is no gravity.
There are many things that convince us of this. All objects in the rocket, that were not attached, have left their places and are hanging in the rocket’s air, out of contact with anything; and if they touch something, they do not exert any pressure on each other or on the support. We ourselves do not touch the floor and can have any position and be in any direction: we can stand on the floor, on the ceiling or on the wall; we can stand perpendicularly or have an inclined attitude; we float in the middle of the rocket like fish but without any effort whatsoever, and we do not come in contact with any- thing; no object exerts pressure on any other if they are not pressed together.
Water does not pour from a decanter, a pendulum does not swing and hangs to the side. An enormous
Tsiolkovsky gave an equally imaginative account of the sensation of weightlessness that he predicted would occur when the spacecraft reached orbit and the
engines were turned off (Ref. 7, p. 100).
The awful gravity that we experience will last until the explosion and the noise come to an end. Then, as dead silence sets in, the gravity pull will diminish instantaneously, just as it appeared. We are now out beyond the limits of the atmosphere at an altitude of 575 km. The gravity pull did not only diminish in force but vanished completely without a trace; we no longer even experience the terrestrial gravitation that we are accustomed to just as we accustomed to the air, though it is not at all so necessary as the latter. The altitude of 575 km is very little, it is almost at the surface of the Earth, and the gravity should have diminished ever so slightly. And that actually is the case. But we are dealing with relative phenomena, and for them there is no gravity.
The force of terrestrial gravitation exerts its influ- ence on both the rocket and bodies in it in the same
mass hung from the hook of a spring balance does not make the spring taut—it always indicates zero. Lever scales are also useless: the balance beam takes up any
position, quite irrespective of and indifferent to the equality or inequality of the weights in the pans. Gold cannot be sold by weighing its mass. Conventional ways of measuring mass cannot be employed here.
Subsequent to Tsiolkovsky’s theoretical studies, sev- eral rocket pioneers were active in the 1920s and 1930s. In 1926, the American Robert Hutchings God- dard (1882–1945) launched the first liquid-propelled rocket at his Aunt Effie’s farm in Auburn, Massachu- setts, having previously published his classical treatise A Method of Reaching Extreme Altitudes in 1919 (3). However, many of his ideas were ridiculed in the New York Times and other quarters, and he largely retired from the public eye to work on his ideas in relative seclusion. Although he offered his ideas to the military in World War II, there was little interest and he worked on jet-assisted take-off devices for aircraft.
J Appl Physiol • VOL 91 • OCTOBER 2001 • www.jap.org
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