16. 9 NOTES
What are satellites and space probes?
Objective: Explain how artificial satellites and space probes are used to explore
space
A satellite is any object,
natural or artificial, that
follows a curved path around
another object in space. The
curved path of the object is
its orbit.
On October 4, 1967, the
Soviet Union launched the
first artificial satellite,
Sputnik. It circled Earth every
96 minutes.
There are four main orbits: CIRCULAR, POLAR, ECCENTRIC, and GEOSTATIONARY
Circular orbits are usually
about 25 km above
Earth’s surface.
Polar orbits are usually
above 800 km high.
An elliptical, or eccentric
orbit depends on where
the satellite is in its orbit
A geostationary orbit is 36,000 km above earth’s surface, staying above the same
spot on Earth. This is because it travels at the same speed as the planet rotates.
Artificial satellites collect information about Earth, the Sun, the stars, other
planets, comets, and other bodies in the solar system. The Global Positioning
System (GPS) is a radio navigation system of about 24 satellites operating in
circular orbits. GPS is used to:
1.
2.
3.
4.
5.
Locate places on earth’s surface in degrees of latitude and longitude
Monitor changes in earth’s crust cause by tectonic motion
Measure temperature and water content of the atmosphere
Map changes in Greenland’s ice sheet to help understand climate changes
Translate weather satellite data into current temperatures, pressures,
humidity readings, and wind speeds to create weather reports
Space probes do NOT carry people. They are used to explore the Moon and
other planets. The Galileo explored Jupiter in 1995. The Cassini was
launched in 1997 to explore Saturn. The Voyagers were sent to capture
images of the planet Neptune. The Voyager 2 is still in space. Scientists are
hoping to keep Voyager 2 in space until the year 2020. Space probes DO
NOT return to Earth. In fact, some have been sent to explore the outer
planets and have been sent out of the solar system. Others are destroyed
by temperature and/or pressure.