using satellites and computers

satellite orbits

Satellites orbit high above the Earth in several ways. Different orbits are important for viewing different things about the planet.

what satellites can do

To understand what satellites can do, lets look at an example. One of the deadliest hurricanes in United States history hit Galveston, Texas in 1900. The storm was first spotted at sea on Monday, August 27th , 1900. It was a tropical storm when it hit Cuba on September 3rd . By September 8th , it had intensified to a hurricane over the Gulf of Mexico. It came ashore at Galveston (Figure 2.34). Because there was not advanced warning, more than 8000 people lost their lives. Today, we have satellites with many different types of instruments that orbit the Earth. With these satellites, satellites can see hurricanes form at sea. They can follow hurricanes as they move from far out in the oceans to shore. Weather forecasters can warn people who live along the coasts. These advanced warning give people time to prepare for the storm. They can find a safe place or even evacuate the area, which helps save lives.

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polar orbit

Another useful orbit is the polar orbit (Figure 2.35). The satellite orbits at a distance of several hundred kilometers. It makes one complete orbit around the Earth from the North Pole to the South Pole about every 90 minutes. In this same amount of time, the Earth rotates only slightly underneath the satellite. So in less than a day, the satellite can see the entire surface of the Earth. Some weather satellites use a polar orbit to see how the weather is changing globally. Also, some satellites that observe the land and oceans use a polar orbit.

geostationary orbit

A satellite in a geostationary orbit flies above the planet at a distance of 36,000 km. It takes 24 hours to complete one orbit. The satellite and the Earth both complete one rotation in 24 hours. This means that the satellite stays over the same spot. Weather satellites use this type of orbit to observe changing weather conditions over a region. Communications satellites, like satellite TV, use this type of orbit to keep communications going full time.

global positioning system

In order to locate your position on a map, you must know your latitude and your longitude. But you need several instruments to measure latitude and longitude. What if you could do the same thing with only one instrument? Satellites can also help you locate your position on the Earths surface. By 1993, the United States military had launched 24 satellites to help soldiers locate their positions on battlefields. This system of satellites was called the Global Positioning System (GPS). Later, the United States government allowed the public to use this system. Heres how it works. You must have a GPS receiver to use the system (Figure 2.38). You can buy many types of these in stores. The

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scientific satellites

The National Aeronautics and Space Administration (NASA) has launched a fleet of satellites to study the Earth (Figure 2.36). The satellites are operated by several government agencies, including NASA, the National Oceano- graphic and Atmospheric Administration (NOAA), and the United States Geological Survey (USGS). By using different types of scientific instruments, satellites make many kinds of measurements of the Earth. Some satellites measure the temperatures of the land and oceans. Some record amounts of gases in the atmosphere, such as water vapor and carbon dioxide. Some measure their height above the oceans very precisely. From this information, they can measure sea level. Some measure the ability of the surface to reflect various colors of light. This information tells us about plant life. Some examples of the images from these types of satellites are shown in Figure 2.37.

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thinking critically

  1. What would have happened if there had been satellites during the time of the 1900 Galveston earthquake? 6. What would have happened if there had been no satellites when hurricane Katrina struck the Gulf of Mexico coast in 2005?

computergenerated maps

Prior to the late 20th and early 21st centuries, mapmakers sent people out in the field to determine the boundaries and locations for various features for maps. State or county borders were used to mark geological features. Today, people in the field use GPS receivers to mark the locations of features. Map-makers also use various satellite images and computers to draw maps. Computers are able to break apart the fine details of a satellite image, store the pieces of information, and put them back together to make a map. In some instances, computers can make 3-D images of the map and even animate them. For example, scientists used computers and satellite images from Mars to create a 3-D image of Mars ice cap (Figure 2.39). The image makes you feel as if you are looking at the ice cap from the surface of Mars. When you link any type of information to a location, you can put together incredibly useful maps and images. The information could be numbers of people living in an area, types of plants or soil, locations of groundwater or levels of rainfall. As long as you can link the information to a position with a GPS receiver, you can store it in a computer for later processing and map-making. This type of mapping is called a Geographic Information System (GIS). Geologists can use GIS to make maps of natural resources. City leaders might link these resources to where people live and help plan the growth of cities or communities. Other types of data can be linked by GIS. For example, Figure 2.40 shows a map of the counties where farmers made insurance claims for crop damage in 2008. Computers have improved how maps are made. They have also increased the amount of information that can be displayed. During the 21st century, computers will be used more and more in mapping.

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instructional diagrams

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questions

Which best describes a geostationary orbit?

a. A satellite orbit that can see the entire Earth in about 24 hours

b. A satellite orbit that is used to accurately pinpoint a location using radio signals

-->  c. A satellite that stays above one location

d. A satellite orbit that is very high above the Earth and collect data on a single geographic point on the

Scientific satellites can be used

a. by NOAA, NASA and USGS

b. to detect things such as the ocean levels

c. to carry instruments that allow for measurements such as temperatures or atmospheric gas levels

-->  d. all of the above

Which of the following is not true of GPS?

a. it stands for Global Positioning System

b. it was first used by the U.S. military, but is now available to the general public

-->  c. it makes use of travel times of infrared waves in order to know distances

d. it relies on both a GPS receiver at the point of interest and satellites

In which way can a satellite be used to help with safety?

a. satellites can better predict weather to warn people of severe storms or hurricanes

b. satellites keep people from getting lost when they use GPS

c. satellites can communicate important information to television stations to warn of a dangerous situation

-->  d. all of the above

Computer maps

-->  a. are often able to display more information than traditional maps

b. cannot put multiple pieces of satellite data together

c. are not more accurate, but are often more visually pleasing

d. all of the above

Satellites can be used to track the paths of hurricanes.

-->  a. true

b. false

All satellites orbit Earth from east to west.

a. true

-->  b. false

Communications satellites have polar orbits.

a. true

-->  b. false

A polar orbit is a shorter orbit than a geostationary orbit.

a. true

-->  b. false

Some weather satellites have geostationary orbits.

-->  a. true

b. false

GPS can only be done with a minimum of 4 satellites.

-->  a. true

b. false

Polar orbits are closer to Earth than geostationary orbits.

a. true

-->  b. false

Satellites in polar orbits always remain over Earths north or south pole.

a. true

-->  b. false

GIS stands for Geostationary Information System.

a. true

-->  b. false

Satellites identify vegetation by the color of light it reflects.

-->  a. true

b. false

Computers increase the accuracy of maps made from satellite images and satellite data.

-->  a. true

b. false

The higher above Earth that a satellite orbits the smaller the view it is able to see.

a. true

-->  b. false

Satellites can help you locate your precise position on Earths surface.

-->  a. true

b. false

A GPS receiver detects lines of latitude and longitude.

a. true

-->  b. false

Any type of information that can be linked with locations can be used to make a map.

-->  a. true

b. false

U.S. government agency that has launched a fleet of scientific satellites

a. geostationary orbit

b. GPS receiver

c. polar orbit

d. satellite

e. GIS

-->  f. NASA

g. GPS

type of orbit that allows a satellite to see all of Earths surface in less than a day

a. geostationary orbit

b. GPS receiver

-->  c. polar orbit

d. satellite

e. GIS

f. NASA

g. GPS

artificial body that orbits Earth

a. geostationary orbit

b. GPS receiver

c. polar orbit

-->  d. satellite

e. GIS

f. NASA

g. GPS

system of satellites used to locate exact positions on Earths surface

a. geostationary orbit

b. GPS receiver

c. polar orbit

d. satellite

e. GIS

f. NASA

-->  g. GPS

device that detects radio signals from satellites to determine its position on Earths surface

a. geostationary orbit

-->  b. GPS receiver

c. polar orbit

d. satellite

e. GIS

f. NASA

g. GPS

type of orbit that allows a satellite to stay over the same location on Earths surface

-->  a. geostationary orbit

b. GPS receiver

c. polar orbit

d. satellite

e. GIS

f. NASA

g. GPS

system that links GPS information with other types of information

a. geostationary orbit

b. GPS receiver

c. polar orbit

d. satellite

-->  e. GIS

f. NASA

g. GPS

A weather satellite with a geostationary orbit could be used to observe

a. changes in weather all over Earths surface.

-->  b. changing weather conditions over one location on Earths surface.

c. a cold front moving across the North American continent.

d. a hurricane moving across the Atlantic Ocean.

A satellite with a polar orbit maintains a distance from Earths surface of

a. 3,600 kilometers.

-->  b. 36,000 kilometers.

c. 90,000 kilometers.

d. several hundred kilometers.

U.S. government agencies that use scientific satellites to gather information include

a. NASA.

b. NOAA.

c. USGS.

-->  d. all of the above

Information gathered by scientific satellites includes

a. land temperatures.

b. ocean water levels.

c. global vegetation.

-->  d. all of the above

To use GPS to find your location on Earths surface, you need radio signals from at least

a. 1 satellite.

b. 3 satellites.

-->  c. 4 satellites.

d. 24 satellites.

Maps that link information on natural resources with GPS positioning information are created by

-->  a. computers.

b. GPS receivers.

c. GIS satellites.

d. GPS satellites.

Satellites could be used to study global warming by measuring the

a. amounts of gases in the atmosphere.

b. temperatures of ocean water.

c. sizes of polar ice caps.

-->  d. all of the above

diagram questions

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