Nylon fishing Dry cells- Ball L a m p Spring Lower contact L a m p
-<HL
Spring • Dry cells — Switch C o n t a c t sExperiments with
Weightlessness
46
comes on again, then everything is all right. Otherwise we will need to m a k e another spring: change its diameter or wire thickness.
A f t e r the test, install the device on a prepared b o a r d 2 metres in length and 15 centimetres in width. A t the end of the b o a r d m a k e a loop so that it can be hanged vertically on a wall, and at the other end glue on a rubber ball. A l o n g the board, by-passing the ball, stretch two taut nylon fishing lines and secure them at the top. The lines must be separated by a distance equal to the diameter of the device and passed through the wire loops on both sides. W h e n raised, the device should not touch the board.
W e now proceed to p e r f o r m the experiment. Raise the device to the top with the lamp on. The glowing lamp implies that the objects suspended f r o m the spring (the dry cells) have weight. Lower the device. When the device falls we have weightlessness. The dry cells stop pulling the spring. The lower contact separates a n d the lamp goes out. W h e n the device strikes the shock absorb- ing ball, the weightlessness state ceases and the lamp turns on again. F o r the lamp not to glow unnecessarily put a switch o n the side of the cylinder-wall. Then the l a m p can be lit during an experi- ment only.
In our device weightlessness manifests itself by the fact that the lamp goes out. But, if you wish, the opposite can be m a d e to o c c u r : the lamp will go on when weightlessness sets in.
W E I G H T L E S S N E S S A R O U N D US. Under terrestrial conditions we often come across the p h e n o m e n a of, if not complete, then par- tial loss of weight. But on E a r t h it lasts for a very short time.
Surely you have gone down in a lift. The weight loss is especially noted at the start.
A n d swings? When these go down, there is also a partial loss of weight.
In high diving or trampolining, when the sportsman flies t h r o u g h the air, his weight is completely lost, and weightlessness occurs. P e r h a p s you have seen acrobats flying under the circus cupula a n d
47
Weightlessness Around U sj u m p i n g into a stretched net. E a c h j u m p is several seconds of weightlessness.
Free-fall drops of parachute divers, when they are still falling with an acceleration, is a f u r t h e r example of weightlessness.
But the most prolonged state of periodic weight loss occurs in a storm on a ship. W h e n the ship rolls the deck moves away under feet a n d weight is partially lost, some people have trouble with this a n d get sea-sick.
Thus weightlessness shows up in free fall. A space vehicle orbit- ing the E a r t h is in a state of free fall. It is subject to the E a r t h ' s attraction, and hence it falls incessantly. But it has such a velocity that it cannot hit the ground a n d keeps on flying in its Earth-orbit, one turn after another.
A n d everything inside the ship is also attracted by the E a r t h , but- does n o t exert any pressure on supports because of the weightless- ness. Therefore, for the a s t r o n a u t it is immaterial whether he sits in a chair or flies about the c o m p a r t m e n t . Y o u have seen m a n y times on television pens, writing-blocks and other unsecured objects floating inside the ship.
It takes prolonged training to get used to weightlessness. A n d not only to get used to it, but also to work for days on end.
Experiments with Heat
HEAT, THE BASIS OF LIFE. Life on Earth exists thanks to the radiant energy of the Sun, and the atmosphere. The Earth is inha- bited with an infinite variety of plants and animals, and they have adapted to temperatures ranging from + 5 8 ° C to — 70° C, in certain regions the temperature drops even lower.
A good example of the adaptation of living things to bitter frost is furnished by penguins. In the Antarc- tic penguins even hatch their young at extremely low temperatures.
Experiments with
But no living creature would survive 'n the cosmic cold, or on the surface ofVenus where the temperature can be as high as several hundred degrees centi- grade.
When astronauts travel through the cosmic wastes, where there is nothing to be heated by the Sun, or to catch and reflect solar rays, and thus most bitter cold is possible, all possible measures must be taken to have the ship heated adequately.
Inside a spaceship or orbital station the air is maintained at the same pressure and composition as on Earth, and the temperature is maintained at a comfortable level. This is all provided by devices that automatically control the composition, humidity, temperature, and pressure of the tiny atmosphere inside the craft.
It is only the weightless state that makes astronauts feel that they are not on Earth, but on a tiny artificial planet created by human genius, rushing along at terrific speed through dead empty space...
HOT RAYS T H R O U G H COSMIC EMPTINESS. Thus, all the living things on Earth owe their existence to the Sun. What is this mighty source of life?
The Sun is a hot gaseous sphere. The scientists say that in its bowels, at enormous temperatures and pressures, continually occurs the thermonuclear reaction of conversion of hydrogen into helium.