1. UNIT 2 – MODULE 6: Earth Resource Satellites *

2. INTRODUCTION This chapter emphasizes satellites operating in the UV, visible, near, mid & thermal infrared portions of the EM spectrum. At these energy levels, lenses & mirrors can be used to refract & reflect these spectrum portions. * Credit: NASA

3. RECALL ORBIT SELECTION End-user requirements determine orbit selection. Several different orbits: – Low Earth Orbit (LEO) – Sun-Synchronous Orbit – Polar Orbit – Medium Earth Orbit (MEO) – High Earth Orbit (HEO) – Geosynchronous Orbit (GEO) – Geostationary Orbit (GEO) – Highly Elliptical Orbit (HEO) Advantages & disadvantages to each. Credit: www.swiftutors.com Credit: ESA Credit: www.mpoweruk.com

4. ORBITAL ELEMENTS Altitude – the height of a satellite in relation to sea level or ground level. Orbit – the type of path a satellite takes around an object. Orbital Period – the time taken for a satellite to make one complete orbit around an object. Global Coverage Period – the time taken for a satellite to completely view an object (i.e. the time a satellite takes to cover/image or move across all of an object’s surface.

5. LOW EARTH ORBIT Altitude: 160 km to 200 km. Orbital Period: 88 minutes to 127 minutes. Advantage: can visit often. Requires less energy to put satellite into orbit. Disadvantage: atmospheric drag on satellites. Cannot spend long periods of time over a given area. Examples: ISS, Hubble Credit: www.swiftutors.com Credit: NASA

6. SUN-SYNCHRONOUS ORBIT A low-Earth, near-polar orbit that matches the rate at which the Earth moves about the Sun. Allows a satellite to pass over a section of Earth at the same time each day. Altitude: 200-1000 km. Orbital Period: 96-100 minutes. Advantage: Can compare images from the same season over several years. Disadvantage: low coverage repetition and small coverage area. Example: Landsat 7 & 8 * Credit: CCRS / CCT Credit: ESA

7. POLAR ORBIT A satellite operating in a sun- synchronous orbit in which it crosses over both poles on each revolution. Altitude: 700-1700 km. Orbital Period: 100 minutes. Advantage: reconnaissance and high-resolution images for Earth observation/mapping. Provides a more global view. Disadvantage: cannot view a particular spot on Earth's surface continuously. Example: CryoSat 2 Credit: www.globalmicrowave.org Credit: Natural Resources - Canada

8. MEDIUM EARTH ORBIT The region between LEO and geostationary orbit. Altitude: 2,000-36,000 km. Orbital Period: 2-24 hours. Advantage: larger coverage area than LEO. Good for communications. Disadvantage: high levels of space radiation. Example: GPS Credit: www.swiftutors.com

9. HIGH EARTH ORBIT A geocentric orbit that has an apparent retrograde motion (i.e. orbital velocity is less than Earth’s rotational speed). Altitude: 36,000 km or more. Orbital Period: > 24 hours Advantage: Fewer satellites needed for global coverage. Disadvantage: not easily accessed. Longer signal delays. Example: Vela 1A Credit: The Air University

10. GEOSYNCHRONOUS ORBIT A circular orbit that matches the Earth’s rate of spin, while moving North & South of the equator. Altitude: 36,000 km. Orbital Period: 24 hours. Advantage: can study large- scale weather (e.g. cyclones & hurricanes). Also good for communications. Disadvantage: poor resolution and pole monitoring difficulty. Example: WGS-5 Credit: www.mpoweruk.com Credit: www.quora.com

11. GEOSTATIONARY ORBIT A geosynchronous orbit that that follows the plane of the equator. Altitude: 36,000 km Orbital Period: Equal to Earth’s rotational period. Advantage: Remains stationary on a fixed position. Good for communications & weather monitoring. Disadvantage: high altitude increases radio signal delays. Example: GOES, AMC-18 Credit: www.mpoweruk.com Credit: Wikipedia/Lookang *

12. HIGHLY ELLIPTICAL ORBIT An elliptical orbit with a long dwell time at apogee and short dwell at perigee. Altitude: 500-50,000 km. Orbital Period: 6-24 hours. Advantage: Good for communications satellites and observing large swaths of Earth over long periods of time. Disadvantage: limited to one area of coverage. Example: Sirius Satellite Radio Credit: Iowa State University Credit: Tech Museum of Innovation

13. EARLY HISTORY OF SPACE IMAGING

14. TIROS-1 (1960) The first successful low- Earth orbit weather satellite. Carried two six-inch cameras. One camera had a wide- angle lens that could view an 800 mile-wide area. Credit: NASA

15. MA-6 (1962) Part of NASA’s Project Mercury. The third human spaceflight mission. Mission piloted by John Glenn, who performed three orbits (LEO) around Earth. Glenn took color pictures of Earth with a hand-held camera. Credit: NASA

16. GEMINI 4 (1965) Part of NASA’s Gemini program. The first photographic experiment was conducted. Specifically directed at geology. Vertical, overlapping photos led to new discoveries in tectonics, volcanism & geomorphology. Credit: NASA

17. APOLLO 9 (1969) Part of NASA’s Apollo program. The first controlled experiment involving multispectral photography. Photos were produced using panchromatic film with green & red filters, black & white IR film, and color film. Credit: NASA

18. SKYLAB (1973-1979) The first space station operated by NASA. Astronauts took over 35,000 Earth images with the Earth Resource Experiment Package (EREP). The EREP included: a six-camera multispectral array, 13-channel multispectral scanner, and more. Demonstrated the complimentary nature of photo & electronic imagery from space. Credit: NASA

19. LANDSATS: PROGRAM OVERVIEW Originally called the Earth Resource Technology Satellites (ERTS). A series of Earth-observing satellites. New landsats continue to be developed. All data is collected with an “open skies” principle, meaning anyone can access the data anywhere in the world. * Credit: NASA

20. LANDSAT 1-3 (1972, 1975, 1978) Altitude: 917 km Orbit: Sun-Synchronous Orbital Period: 103 minutes Global Coverage Period: 18 Days Sensors: – Return Beam Vidicion, or RBV (captured visible & near-infrared photos). – Multispectral Scanner, or MSS, with four spectral bands: Band 4 Visible Green (0.5 to 0.6 µm) Band 5 Visible Red (0.6 to 0.7 µm) Band 6 Near-Infrared (0.7 to 0.8 µm) Band 7 Near-Infrared (0.8 to 1.1 µm) Credit: NASA

21. LANDSAT-1 IMAGERY Credit: NASA/USGS

22. LANDSAT-2 IMAGERY Credit: NASA/USGS

23. LANDSAT-3 IMAGERY Credit: NASA/USGS

24. LANDSAT 4-5 (1982, 1984) Altitude: 705 km Orbit: Sun-Synchronous Orbital Period: 99 minutes Global Coverage Period: 16 Days Sensors: – MSS with the same four spectral bands as Landsat I/II. – Thematic Mapper, or TM, with seven spectral bands, including a thermal band: Band 1 Visible (0.45 - 0.52 µm) Band 2 Visible (0.52 - 0.60 µm) Band 3 Visible (0.63 - 0.69 µm) Band 4 Near-Infrared (0.76 - 0.90 µm) Band 5 Near-Infrared (1.55 - 1.75 µm) Band 6 Thermal (10.40 - 12.50 µm) Band 7 Mid-Infrared (IR) (2.08 - 2.35 µm) Credit: NASA/USGS *

25. LANDSAT-4 & 5 IMAGERY Credit: NASA/USGS

26. LANDSAT-6 (1993) Was launched in 1993 but failed to reach orbit. Resulted in Landsat-4 & Landsat-5 being used well beyond their expected lifespan. Landsat-6 had an enhanced thematic mapper (ETM), which would later be deployed with Landsat-7. Credit: NASA

27. LANDSAT-7 (1999) Altitude: 705 km Orbit: Sun-Synchronous Orbital Period: 99 minutes Global Coverage Period: 16 Days Sensor: – Enhanced Thematic Mapper (ETM) Plus, or ETM+, with eight spectral bands, including a panchromatic & thermal band. Credit: NASA/USGS

28. LANDSAT-7 BAND APPLICATIONS Credit: Journal of the Geological Association of Canada

29. LANDSAT-7 IMAGERY Credit: NASA/USGS

30. LANDSAT-8 (2013) Altitude: 705 km Orbit: Sun-Synchronous Orbital Period: 99 minutes Global Coverage Period: 16 Days Sensor: – Thermal Infrared Sensor, TIRS, with two spectral bands. – Operational Land Imager, OLI, with nine spectral bands, including a panchromatic band. Credit: NASA/USGS *

31. LANDSAT-8 SPECTRAL BANDS Credit: USGS

32. LANDSAT-8 IMAGERY Credit: NASA/USGS *

33. ADDITIONAL EARTH RESOURCE SATELLITES There are many additional satellites used to monitor/manage Earth’s resources. We will review a few: – OrbView-2 – Terra – Aqua – NOAA-19 Credit: NASA

34. ORBVIEW-2 (1997) A marine-observing, imaging satellite. Altitude: 705 km Orbit: Sun-Synchronous Orbital Period: 99 minutes Global Coverage Period: 16 Days Sensor: SeaWiFs Credit: NASA

35. SEAWIFS SPECTRAL BANDS Credit: NOAA

36. SEAWIFS IMAGERY Credit: NASA

37. TERRA (1999) NASA’s flagship satellite studying the interactions of Earth's atmosphere, lands, oceans, and radiant energy. Altitude: 705 km Orbit: Sun-Synchronous Orbital Period: 99 minutes Global Coverage Period: 14 Days Sensors: – Advanced Spaceborne Thermal Emission & Reflection Radiometer (ASTER) – Clouds & Earth’s Radiant Energy System (CERES) – Multi-Angle Imaging Spectroradiometer (MISR) – Moderate Resolution Imaging Spectroradiometer (MODIS) – Measurements of Pollution in the Troposphere (MOPITT) Credit: NASA

38. TERRA IMAGERY Credit: NASA

39. AQUA (2002) Altitude: 705 km Orbit: Sun-Synchronous Orbital Period: 99 minutes Global Coverage Period: 14 Days Sensors: – Moderate Resolution Imaging Spectroradiometer (MODIS) – Advanced Microwave Scanning Radiometer-EOS (AMSR-E) – Advanced Microwave Sounding Unit (AMSU) – Atmosphere Infrared Sounder (AIRS) – Humidity Sounder for Brazil (HSB) – Clouds & the Earth’s Radiant Energy System (CERES) Credit: NASA

40. MODIS IMAGERY Credit: NASA

41. TERRA & AQUA SENSORS Credit: Remote Sensing & Image Interpretation – Lillesand, Kiefer, Chipman - 2008

42. NOAA-19 (2009) The fifth & last in a series of polar-orbiting weather satellites. Altitude: 870 km Orbit: Sun-Synchronous Orbital Period: 102 minutes Global Coverage Period: 14 Days Sensors: – Advanced Very High Resolution Radiometer (AVHRR) – High Resolution Infrared Radiation Sounder (HIRS) – Several others. Credit: NOAA

43. AVHRR SPECTRAL BANDS Credit: NOAA

44. NOAA-19 IMAGERY Credit: NOAA