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Payload imaging sensor

The Moderate Resolution Imaging Spectroradiometer (MODIS) is a satellite based sensor used for earth and climate measurements. There are two MODIS sensors in Earth orbit: one on board the Terra (EOS AM) satellite, launched by NASA in 1999; and one on board the Aqua (EOS PM) satellite, launched in 2002. MODIS has now been replaced by the VIIRS, which first launched in 2011 aboard the Suomi NPP satellite. The MODIS instruments were built by Santa Barbara Remote Sensing. They capture data in 36 spectral bands ranging in wavelength from 0.4 μm to 14.4 μm and at varying spatial resolutions (2 bands at 250 m, 5 bands at 500 m and 29 bands at 1 km). Together the instruments image the entire Earth every 1 to 2 days. They are designed to provide measurements in large scale global dynamics including changes in Earth's cloud cover, radiation budget and processes occurring in the oceans, on land, and in the lower atmosphere. Support and calibration is provided by the MODIS characterization support team (MCST).

With its high temporal resolution although low spatial resolution, MODIS data are useful to track changes in the landscape over time. Examples of such applications are the monitoring of vegetation health by means of time series analyses with vegetation indices, long term land cover changes (e. g. to monitor deforestation rates), global snow cover trends, water inundation from pluvial, riverine, or sea level rise flooding in coastal areas, change of water levels of major lakes such as the Aral Sea, and the detection and mapping of wildland fires in the United States. The United States Forest Service's Remote Sensing Applications Center analyzes MODIS imagery on a continuous basis to provide information for the management and suppression of wildfires.

Specifications Orbit 705 km, 10:30 a. m. descending node (Terra) or 1:30 p. m. ascending node (Aqua), Sun synchronous, near polar, circular Scan rate 20.3 rpm, cross trackSwath2330 km (cross track) by 10 km (along track at nadir) DimensionsTelescope17.78 cm diam. off axis, afocal (collimated), with intermediate field stopSize1.0 × 1.6 × 1.0 mWeight228.7 kgPower162.5 W (single orbit average)Data rate10.6 Mbit/s (peak daytime); 6.1 Mbit/s (orbital average)Quantization 12 bitsSpatial resolution250 m (bands 1–2) 500 m (bands 3–7) 1000 m (bands 8–36)Temporal resolution1–2 days Design life6 years

MODIS utilizes four on board calibrators in addition to the space view in order to provide in flight calibration: solar diffuser (SD), solar diffuser stability monitor (SDSM), spectral radiometric calibration assembly (SRCA), and a v groove black body. MODIS has used the marine optical buoy for vicarious calibration.

BandWavelength(nm)Resolution(m)Primary use1620–670250Land/cloud/aerosolsboundaries2841–8762503459–479500Land/cloud/aerosolsproperties4545–56550051230–125050061628–165250072105–21555008405–4201000Ocean color/phytoplankton/biogeochemistry9438–448100010483–493100011526–536100012546–556100013662–672100014673–683100015743–753100016862–877100017890–9201000Atmosphericwater vapor18931–941100019915–9651000BandWavelength(μm)Resolution(m)Primary use203.660–3.8401000Surface/cloudtemperature213.929–3.9891000223.929–3.9891000234.020–4.0801000244.433–4.4981000Atmospherictemperature254.482–4.5491000261.360–1.3901000Cirrus cloudswater vapor276.535–6.8951000287.175–7.4751000298.400–8.7001000Cloud properties309.580–9.8801000Ozone3110.780–11.2801000Surface/cloudtemperature3211.770–12.27010003313.185–13.4851000Cloud topaltitude3413.485–13.78510003513.785–14.08510003614.085–14.3851000