We had a launch party today at 1:02pm EST, as NASA and USGS successfully launched the Landsat Data Continuity Mission (LDCM) spacecraft aboard an Atlas-5 rocket, from Vandenberg Air Force Base in California. After launch, LDCM became Landsat 8, continuing in the the Landsat data series legacy, which has provided beautiful imagery of the Earth to the scientific community and the general public since 1972. Thanks to the U.S. Government’s investments in remote sensing and technology, and ongoing commitment to open data, we have unprecedented time-series imagery of the entire globe, for several decades. We are really excited to start using this data.
Launch party @MapBox HQ in DC
Landsat 8, while designed to continue the data series, is powered by new technologies never before available to previous Landsats. I’m going to run through the two instruments onboard the spacecraft.
Operational Land Imager (OLI)
The Operational Land Imager (OLI) - LDCM VIS/IR Instrument, Credit: NASA/GSFC/Landsat
The OLI instrument will measure reflected visible light, near infrared, and shortwave infrared across 8 bands, each with a spatial resolution of 30 meters per pixel and a swath of 185km. The panchromatic band has a spatial resolution of 15 meters per pixel, and measures all visible light. Unlike previous Landsat images which had whiskbroom sensors, Landsat 8 utilizes a “push-broom” sensor, which is more sensitive (with over 7,000 detectors per band) and has fewer moving parts.
Landsat 8’s OLI instrument retains 7 of the 8 mutispectral bands of Landsat ETM+, omitting the thermal infrared band, for which Landsat 8 has a dedicated instrument, Thermal Infrared Sensor (TIRS), to measure. The OLI instrument will provide two additional new bands: band 1, which is sensitive to ocean color near land coasts; and band 9, a shortwave-infrared band, designed to aid in cloud detection.
Relationship of Landsat 8 to ETM+
Thermal Infrared Sensor(TIRS)
The Cryocooler —Part of the LDCM Thermal Infrared Sensor (TIRS), Credit: NASA/GSFC/Landsat
Continuing in the tradition of Landsat 5’s Thematic Mapper and Landsat 7’s Enhanced Thematic Mapper-Plus, Landsat 8 will provide precide measurements of the Earth’s thermal infrared radiation. Unlike other Landsat models, Landsat 8 has a dedicated instrument for thermal infrared raditation, TIRS, which has two thermal bands.
Landsat 8’s TIRS instrument utilizes a pushbroom sensor like OLI and has a resolution of 100 meters per pixel. The TIRS instrument pioneers a new technology – Quantum Well Infrared Photodetectors (QWIPs) – that uses the laws of quantum mechanics to measure the Earth’s thermal radiation.