Early Satellites and Their Orbits
Amanda N. / Physics 336 / 17 April 1997
An artificial satellite's orbit is the path it traces out around the
Earth or a particular heavenly body. Once a rocket or shuttle has carried
a satellite to its determined altitude, it is then put in an orbit. When
a satellite is in orbit, it is circling the earth at the correct speed,
so that the satellite does not immediately fall back into the earth's atmosphere.
Generally, the orbits of artificial satellites are elliptical, however
other types of orbits are used.
Sputnik 1
The earliest artificial satellite had an elliptical orbit. On October
4, 1957 the Soviet Union launched the very first artificial satellite,
Sputnik 1. Sergei Korolev designed it in such a way that the satellite
rolled as it orbited the earth in an egg shape. Its orbit was low which
allowed Sputnik to get as close to the earth's surface as 142 miles (228
km.) and as far from it as 589 miles (947 km.). Sputnik 1 was able to complete
a single orbit in 96 minutes and 17 seconds. The success of Sputnik was
a great accomplishment for the Soviet Union. It is because of this success
that the United States quickly attempted to launch their first artificial
satellite. ". . . the Soviets had claimed the lead in space technology
and posed a clear threat to U. S. national security . . ." (Lewis,
77).
The Soviet Union
Launches a Second Satellite
Unfortunately before the United States could successfully launch the
Explorer 1 the Soviet Union had launched their second satellite, Sputnik
2. The United States' failure to launch a satellite was embarrassing since
Russia already had two orbiting the earth (Vogt 6). Sputnik 2 is known
for its development in satellite technology. It was on November 3, 1957
that Sputnik 2 carried a female dog named Lakia ("barker") (Lewis
77) into orbit. Lakia was the first living creature to orbit the Earth.
Sputnik 2's orbit pattern was elliptical, similar to that of the first
Sputnik.
The Explorer 1
Finally after several failed attempts to launch a satellite the United
States received their first break. On January 31, 1958, about four months
after Sputnik 1 was launched, Explorer 1 was successfully put into orbit
Explorer1 was developed by a team of scientists at the University of Iowa
under the direction of Professor James Van Allen. Explorer's design was
pencil-shaped, which allowed it to spin like a bullet as it orbited. The
spinning helped the satellite maintain stability in its orbit. Explorer
was able to reach 529 miles (2,460 km) (Lewis, 79) and was able to descend
to about 224 miles (360 km) (Vogt 7). Explorer's elliptical orbit decayed
in 1967. After Explorer 1 the United States continued their technological
developments and launched a series of Explorers.
Conclusion
Most artificial satellites orbit the Earth in an elliptical, or egg-shaped
patter. The earliest satellites also shared this characteristic. Even at
a time when satellites were very experimental, scientists took a major
step when they discovered that a elliptical orbit would prevent satellites
from crashing back into the earth's surface.
References
Luis, Cathleen S., Neal Valerie, Winter Frank H. "Spaceflight."
Smithsonia Guides. New
York: Prentice Hall Macmillion Company, 1995.
Magill's Survey of Science Space Exploration Series. vol. 1
Pasadena: Salem Press, 1989.
Oberright, John E. "Artificial Satellite." The World Book
Encyclopedia. 1996 ed.
"Satellite." New Encyclopedia of Science. Milwaukee:
Raintree Publishers, 1982.
Vogt, Gregory. Space Satellites. New York: Franklin Watts Inc.,
1987.