JoAnn Jackson, age 13, of Rome, N.Y., for her question:
HOW DOES A COMMUNICATIONS SATELLITE WORK?
A communications satellite is an artificial earth satellite that is used to send radio, television, telephone or other electronic communications to any part of the world.
Rockets launch the satellites into earth orbits. Then transmitting stations on the ground beam signals to the satellites by means of special antennas. The satellites next send the signals back to earth. The signals can be picked up by receiving stations that may be a third of the distance around the world from the transmitting station.
A communication satellite is placed in a synchronous orbit 22,000 miles above the earth’s equator. At this distance the satellite completes one orbit every 24 hours. If we could see the satellite with the naked eye it would appears as a bright non moving object in the sky, but it is moving in its own orbit. A satellite at this distance can provide communications services for one third of the earth’s surface.
Communication by satellite is much more reliable than by ordinary short wave radio and it also has better quality. Communications satellites also carry a wider range of radio frequencies or wave lengths than short wave radio can. ,
Ruth Basham, age 9, of Scottsdale, Ariz., for her question:
WHY ARE SOME PEOPLE PUT IN QUARANTINE?
Quarantine means to isolate or shut off from others. Sometimes people, animals or places are quarantined because of the possibility that they carry the danger of infection.
International quarantine is held in three types of stations: maritime, aircraft and border places of entry.
Ships coming in from foreign areas are always subject to quarantine. The officer in charge must give the port inspection officer a statement of the health status of crew and passengers.
If a ship is free from infectious disease, the ship is allowed to dock. If disease is present, however, the ship must stay in the harbor flying a yellow flag until it completes a period of quarantine. Heavy penalties result from false statements or concealing facts about disease.
The word quarantine comes from the Latin quadraginta, meaning 40. In early times, officials held a ship outside of port for 40 days if they suspected that it carried infection among its passengers or freight.
In the United States, the Public Health Service controls the quarantine service. The United States maintains a quarantine over Asiatic cholera, yellow fever, smallpox, typhus fever, leprosy, parrot fever, plague and anthrax.
Subject to certain quarantine laws are states, cities, small communities, single households and even individuals. Officials enforce these laws to prevent the spread of contagious diseases. Often officials post notices on houses where infectious diseases are known to be present.
Sometimes doctors and nurses must remain isolated with patients with infectious diseases or take special measures of disinfection to prevent carrying germs.
Quarantine laws have proved effective in reducing death rates and limiting epidemics.
In the past, harmful insect pests have been brought into the United States and Canada by diseased plants and animals. Officials of both governments now provide inspections. Strict laws make it possible to keep out infected animals and plants.
Some states have quarantines to keep out diseased plants and animals or insect pests. Local areas may also be quarantined occasionally to prevent the spread of such animal diseases as foot and mouth disease, which affects livestock.
Aircraft quarantine differs from maritime quarantine because of the swiftness of air transport. Passengers are allowed to go to their destinations when they arrive by air, but health officials keep them under check until it is certain that they do not have any infectious disease.
Air travelers must also provide health certification.