Landsat 4 (TM)
In addition to the MSS sensor, Landsat 4 carried a new scanning sensor with improved spectral and spatial resolution. These high-resolution scanners have seven spectral bands that cover an area of 185 x 185 km. The Thematic Mapper (TM) scanner has the ability to observe a wider (and more scientifically-tailored) portion of the electromagnetic spectrum and view the ground in greater detail. The instrument had seven spectral bands, collecting data from the blue, green, red, near-infrared, mid-infrared (2 bands) and thermal infrared portions of the electromagnetic spectrum.
In 1983, Landsat 4 lost two solar panels and both of its direct downlink transmitters. Hence, the downlink of data was not possible until the TDRS (Tracking and Data Relay Satellite) system became operational. In that case Landsat 4 could transmit data to TDRS using its Ku-band transmitter. TDRS could then relay this information to its ground stations. Landsat 4 remained in orbit for standby and data tracking until it was decommissioned on June 1st, 2001, at which point it was placed into a disposal orbit to reduce collision risk with other resident space objects.
|Site||Vandenberg Air Force Base, California|
|Scene size||170 km x 185 km (106 mi x 115 mi)|
|Design life||Minumum of 3 years|
|Sensor||Band number||Band name||Wavelength (μm)||Resolution (m)||Band Applications|
|TM||Band number1||Band nameVisible Blue||Wavelength (μm)0.45 – 0.52||Resolution (m)30||Band ApplicationsBathymetric mapping, distinguishing soil from vegetation, and deciduous from coniferous vegetation|
|TM||Band number2||Band nameVisible Green||Wavelength (μm)0.52 – 0.60||Resolution (m)30||Band ApplicationsEmphasizes peak vegetation, which is useful for assessing plant vigor|
|TM||Band number3||Band nameVisible Red||Wavelength (μm)0.63 – 0.69||Resolution (m)30||Band ApplicationsDiscriminates vegetation slopes|
|TM||Band number4||Band nameNIR||Wavelength (μm)0.76 – 0.90||Resolution (m)30||Band ApplicationsEmphasizes biomass content and shorelines|
|TM||Band number5||Band nameSWIR 1||Wavelength (μm)1.55 – 1.75||Resolution (m)30||Band ApplicationsDiscriminates moisture content of soil and vegetation;|
|TM||Band number6||Band nameThermal||Wavelength (μm)10.40 – 12.50||Resolution (m)120||Band ApplicationsThermal mapping and estimated soil moisture|
|TM||Band number7||Band nameSWIR 2||Wavelength (μm)2.08 – 2.35||Resolution (m)30||Band ApplicationsHydrothermally altered rocks associated with mineral deposits|