Tapping Into Earth's Satellite Systems

Russia launched three navigation satellites into space from a base in Kazakhstan on Wednesday, December 25, 2003, military officials announced.

The satellites will join the GLONASS satellite navigation system of the Russian military. This system was developed during the 1970s and originally included 24 satellites. Over the years, their number has dwindled.

The three new satellites launched last week will bring the system strength up to 12, according to the ITAR-Tass news agency. Even so, the system needs 15 to18 satellites to operate normally, they added.

The upgraded GLONASS, a Russian acronym for Global Navigation Satellite System, will operate like the satellite network created and used by the United States, called the Global Positioning System, or GPS.

You might already know about some of the practical uses of the GPS and other satellite projects. Government agents, scientists and the general public tap into these systems in varying degrees and for various reasons. Uses range from monitoring global climate change to pinpointing one's real-time location in the forest or in a car.

In this week's lesson, you'll find out how the GPS and other satellite systems work, and what undiscovered characteristics of planet Earth people are discovering as they explore the world with orbiting network of machines.

What is GPS?

Since you may have heard of both GPS and GIS, an acronym for Geographic Information System, let's start the investigation by finding out the difference between the two and how they relate to each other.

Begin at the KanGIS website, GIS for Schools. As you read the introductory paragraph, you'll learn how GIS is a "tool for spatial data analysis." See how the layers represent distinct systems, and read how data is turned into visualizations. Also read through the What is GIS? section, clicking Next at the bottom to move through the pages. As you browse, you'll discover how some K-12 students have used GIS to create maps and find patterns of relationships.

How does the 2-Dimensional image compare to the 3-Dimensional ones? What are choropleth and isarithmic maps? How do you think this kind of information, presented in these customizable and comprehensible forms, impacts agencies, scientists, students and other citizens? What types of things can they do now that they couldn't do before?

Now visit the What is GPS? section from the KanGIS home page. Here, you'll learn how GPS is a project funded and controlled by the U. S. Department of Defense. How does the number of satellites compare with that of Russia's GLONASS? How do the satellite signals get to handheld receivers? How does the 3-D data system work? For what types of uses was GPS originally created?

Check out the in-depth GPS Primer at The Aerospace Corporation website next. Start off at the Welcome to the Global Positioning System (GPS) page, and click on Forward at the top or bottom of the page to continue.

How is GPS just one more step in our ever-evolving navigation technologies? Can we receive signals from all 24 satellites all of the time? What are the three parts, or segments, of GPS, and how do they relate to each other? When were the first and last GPS satellites launched? How does the system measure distance and translate that data into pinpointing exact locations?

Make sure to go all the way to the end of the primer to read about Military Uses for GPS and GPS Uses in Everyday Life.

How do those abilities affect how people investigate issues and relationships between spatial and temporal elements? How has GPS technology contributed to keeping people safe?

Scoping Out the Bigger Picture

Navigation satellites, like those of the GPS and GLONASS, are not the only type of satellites gathering and transmitting data about the planet's properties. What are referred to as "remote sensing" satellites see the world in ways we can't, like with infrared vision and the ability to measure aerosol concentrations in the atmosphere.

No place is better to get the scoop on these satellites than at NASA's Earth Observatory. From here, go to Mission Control, where you'll find a gallery of eight satellites. Mouse over the thumbnail listing of them to display a brief overview about each one. Click to each satellite's Fact Sheet or Home Page for more information about that satellite's sensory equipment, capabilities and the amazing images it produces.

Compare a few of the satellites. For example, what are some of the differences between the TRMM, Landsat-7 and EOS Terra projects? In what ways do the images they produce vary from each and why? How does what they measure contribute to scientists' understanding of how different components of the Earth's systems work and affect each other?

The Earth Observatory site also has some cool Features to browse. Check out Why the EOS Matters to All of Us, Tracking Clouds, Mapping the Decline of Coral Reefs, Prospecting From Orbit, Power to the People!, or choose a few of the others listed that interest you. In each case, how do our satellite system technologies make each project possible?

How do you think the GPS and the remote sensing satellites can be used together as a powerful combination for understanding complex planetary systems more thoroughly? How might this understanding influence certain decisions, like where best to mine metal ores or where to ban industrial development to keep local watersheds healthy? Can you describe some the limits on what these satellites can do?

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