SATELLITE SYSTEMS The invention of satellites that orbit Earth capturing images and collecting data has transformed the way cartographers map the physical world The Soviet Union launched the first artificial satellite Sputnik into space in 1957 It orbited or circled Earth 358 miles 577 km above the planet surface The first satellite to take images was Landsat launched by the United States in 1972 The images gave geographers a new view of the planet the view from space In 1976 photographs from Landsat 1 revealed an uninhabited or empty island off the coast of Canada Cartographers named it Landsat Island This image from Landsat 8 shows the location of tiny Landsat Island northeast of Labrador in Canada Landsat Island 1 mi 4
Today around 2,200 satellites orbit Earth at different heights They take many thousands of images collecting data on subjects as varied as how household aerosols interact with the ozone layer to smoke pollution caused by crop burning The View from Space Since its launch in 1972 NASA’s Landsat program has been continually mapping Earth It has mapped growing urbanization melting ice caps deforestation and coastal erosion The program helps cartographers map things that are difficult to see from the ground such as shrinking coral reefs Landsat images have also revealed unknown details such as the head of the Lambert Glacier in Antarctica the world’s largest glacier Landsat 8 was launched in 2013 and was scheduled to stay in service until 2021 Landsat 8 was launched in February 2013 The large solar panels generate energy to power the satellite’s scientific instruments Maps and Me My Changing Town How has your town changed over the years Ask if your local library has old maps of the town Compare how it looks on a map today with how it looked 10 20 or even 100 years ago Has it gotten bigger Can you figure out why any new construction was located where it is 5
How Does Landsat Work Landsat satellites orbit 438 miles 705 km above Earth They take 99 minutes to complete one orbit If they traveled slower they would crash back to Earth The satellite’s orbit takes it above a different strip of Earth each time as the planet rotates It completes 14 orbits a day The way the satellite’s orbit varies means it can photograph the whole surface of the planet every 16 days What has Landsat Seen By using images Landsat has taken of the same places over more than 40 years cartographers have made multi-layered maps of how Earth is physically changing They have divided the entire surface of the globe into square cells each of which has sides 820 feet 250 m long The cartographers use Geographic Information Systems GIS to combine Landsat information about each cell called ecological land units into layers that can be displayed on a map The maps might contain information about soil climate elevation vegetation and land use On each orbit Landsat photographs a 115-mile 185-km strip of Earth’s surface as seen in this combined image of the United States It takes 233 orbits or 16 days to cover the whole of Earth Did You Know GIS are computer programs that collect data and convert it so it can be shown in map form Information is displayed on many different layers Experts choose which layers they want to use to create a specific map 6
SATELLITE SYSTEMS In the Real World Acting on Information Today flooding occurs more regularly around the world than it did in the past Many countries use evidence from past floods to produce digital maps that show the potential future flood risks of rivers and other bodies of water These maps also show where homes are at the greatest risk of damage from flooding The individual maps created for each ecological land unit can then be combined digitally into larger maps Cartographers use Landsat maps to compare small areas to the same area on earlier maps Such comparisons can lead to change in the real world because cartographers can provide information about environmental changes and assess the risk for disasters For example Landsat photographs of the destruction of the Amazon rainforest convinced the Brazilian government to take action to stop illegal logging or cutting down trees to sell On a global scale satellite evidence that the ice caps are melting and sea levels rising helped to persuade nations to take steps to reduce global warming such as signing the Paris Agreement in 2016 This satellite map shows flooding in the Philippines in 2011 The flooded areas blue are along two rivers dark blue The size of the blue circles indicates how many people live in each region 7
