Satellite Observation Systems for Earth: Landsat, TIROS, AVHRR, ERTS

1. ÖNCEL AVCIKADİR 110020915

2. LANDSAT OBSERVATİON SATELITE SYSTEM Landsat satellites have been collecting images of the Earth's surface for more than thirty years. NASA launched the first Landsat satellite in 1972, and the most recent one, Landsat 7, in 1999. Instruments onboard the satellites have acquired millions of images of the Earth. These images provide a unique resource for people who work in agriculture, geology, forestry, regional planning, education, mapping, and global change research

3. TIROS • The Television Infrared Observation Satellite Program (TIROS) • The TIROS Program (Television Infrared Observation Satellite) was NASA's first experimental step to determine if satellites could be useful in the study of the Earth. At that time, the effectiveness of satellite observations was still unproven. Since satellites were a new technology, the TIROS Program also tested various design issues for spacecraft: instruments, data and operational parameters. The goal was to improve satellite applications for Earth-bound decisions, such as "should we evacuate the coast because of the hurricane?". • The TIROS Program's first priority was the development of a meteorological satellite information system. Weather forecasting was deemed the most promising application of space-based observations. • TIROS proved extremely successful, providing the first accurate weather forecasts based on data gathered from space. TIROS began continuous coverage of the Earth's weather in 1962, and was used by meteorologists worldwide. The program's success with many instrument types and orbital configurations lead to the development of more sophisticated meteorological observation satellites

9. AVHRR • ADVENCED VERY HIGH RESOLUTION RADİOMETER • The Advanced Very High Resolution Radiometer (AVHRR) provides four- to six-band multispectral data from the NOAA polar-orbiting satellite series. There is fairly continuous global coverage since June 1979, with morning and afternoon acquisitions available. The resolution is 1.1 kilometer at nadir. • Visible, NIR, Thermal • 1.1 km Resolution - local area coverage (LAC) • 4 km Resolution - global area coverage (GAC) • Used for meteorological studies • Vegetation pattern analy

10. LANDSAT (ERTS) - Earth Resources Technology Satellite. • The Earth Resources Technology Satellite (ERTS) mock-up in a space chamber test at General Electric's Space Division. The ERTS program represented a concentrated effort to observe and monitor the limited resources of the Earth, in order to best conserve and utilize the resources in support of a burgeoning world population. The first ERTS was launched in 1972 and was later named Land Remote-Sensing Satellite (Landsat), to better represent the civil satellite program's prime emphasis on remote sensing of land resources. Multiple sensors survey and relay back masses of data in various ways from the Landsat. NASA has built 7 Land Remote Sensing Satellites, which have helped agricultural experts pick up underutilized land areas and new prospects for land use through irrigation. It has also assisted in pinpointing the spread of crop disease and in charting new uses of the sea for oceanographers. • Visible, NIR spectral bands (Landsats 1,2,3), and MIR and Thermal (Landsats 4 and 5)

11. Sensors • Multispectral scanner (MSS)The MSS instrument has operated on the first five Landsat spacecraft. Although the basics of scanning spectroradiometric sensors were reviewed earlier in this Section, because of MSS's important role in these missions which extended over 31 years some of this information is repeated and expanded on this page. A simplified model of this optical-mechanical sensor appears in the next figure. • On Landsats 1,2,3,4,5 • 60 meter resolution • 128 brighness values (radiometric resolution) • 4 spectral bands • Green, Red, and 2 NIR • 570 mile orbit (for Landsat 1,2,3) • Oscillating mirror design • One swath = 185 km x 474 meters • Each spectral band has 6 detectors • 474 Meters / 6 Detectors = 79 Meter ground resolution

12. This data set consists of a series of Landsat Multispectral Scanner scenes. Small regions have been selected from full scenes over the capital cities in Australia

17. Thematic mapper (TM) • The Multispectral Scanners (MSSs) were the first Thematic Mapper (TM). Based upon the success of the Multispectral Scanner, the Thematic Mapper, a second-generation sensor for monitoring Earth's resources, was developed for Landsats 4 and 5. The MSS was also carried on these spacecraft to provide data continuity. The TMs on Landsats 4 and 5 have better spatial, spectral, and radiometric resolution and extend spectral coverage into the blue, the short-wavelength infrared, and the thermal infrared. These instruments have continued to operate for years beyond their design-life goals. The Landsat 4 TM operated for more than 11 years, while the Landsat 5 instrument has more than 13 years of successful operation, as of this writing. The Enhanced Thematic Mapper was launched as the sole instrument on Landsat 6 on October 5, 1993. The ETM, developed for Landsat 6, had the same bands as the other TMs and also a panchromatic band with 15-meter resolution. Increased redundancy was incorporated into the instrument configuration to increase its lifetime, and the redesigned monolithic prime focal plane offered improved band-to-band registration. The data acquired by the Landsat 4 and 5 Thematic Mappers have enhanced knowledge of Earth in the fields of agriculture, geology, forestry, cartography, hydrology, oceanography, and bathymetry and have been used for environmental monitoring, disaster assessment, land-use and regional planning, range management

18. On Landsat 4,5 • 30 meter resolution reflected / 120 meter emitted. • 256 brightness values • 7 spectral bands • Blue/Green, Green, Red, NIR, MIR, MIR, Thermal • 423 mile orbit • Oscillating mirror design acquires data with each sweep in both directions • One swath = 185 km x 474 meters • Each spectral band has 16 detectors except for the thermal band which has 4 detectors.

19. SPOT • SPOT is the French government sponsored civil Earth observation program, with support from Belgium and Sweden. A single SPOT satellite provides complete coverage of the Earth every 26 days. Image products from SPOT are handled by a commercial entity, SPOT-Image Corp. Spacecraft: 3-Axis stabilised to 0.1 deg using momentum wheels. Single solar arrays generates 1000 W (BOL) power. Downlink at 8 GHz and 2 x 25 Mbps. Hydrazine propulsion system provides orbit maintenance. Payload: The HRV (High Resolution Visible) imaging payload provides 20 meter resolution multispectral imagery and 10 meter panchromatic imagery using push-broom sensors. HRV covers the following spectral bands: 0.5 - 0.59 µ m, 0.61 - 0.68 µ m, 0.79 - 0.89 µm; in addition to the panchromatic band: 0.51 - 0.73 µ m. The field of view is 4.13 deg in both modes (multispectral and panchromatic) with 3000 pixels per multispectral line and 6000 pixels per panchromatic line. The observed strip is 60 km wide (swath width). On-board recorder capacity is 22 minutes for both modes. The HRV mass is 250 kg. The spacecraft carries two identical HRVs to provide a total of 117 km swath (with 3 km overlap).

20. 22 February 1986 SPOT 1 Spacecraft: SPOT-1-2-3. Mass: 1,830 kg. Launch Site: Kourou . Launch Vehicle: Ariane 1. • 22 January 1990 SPOT 2 Spacecraft: SPOT-1-2-3. Mass: 1,870 kg. Launch Site: Kourou . Launch Vehicle: Ariane 4. • 26 September 1993 SPOT 3 Spacecraft: SPOT-1-2-3. Mass: 1,907 kg. Launch Site: Kourou . Launch Vehicle: Ariane 4. • 24 March 1998 SPOT 4 Spacecraft: SPOT-4. Mass: 2,755 kg. Launch Site: Kourou . Launch Vehicle: Ariane 4 • 04 May 2002 SPOT 5 Spacecraft: SPOT-5A-5B. Mass: 3,000 kg. Launch Site: Kourou . Launch Vehicle: Ariane 42P.