Landsat 9 has completed its post-launch assessment and begun its operational phase. Launched from the Vandenberg Space Force Base in California on 27 September 2021, Landsat 9 is a joint venture between Nasa and the US Geological Survey (USGS). The Landsat programme has been running since the 1970s and will pass its 50th anniversary of unbroken images of Earth from orbit later this year. Landsat 1 was launched on 23 July 1972 and was initially called the Earth Resources Technology Satellite. Landsat 8 was launched on 11 February 2013. To prepare Landsat 9 for operations, it has been working in tandem with its predecessor, taking simultaneous images of the Earth so the datasets can be compared and the instruments calibrated to give identical readings to each another. This allows the data to be used as a seamless timeline in environmental and climate research studies. Nasa led the commissioning phase, and the USGS will handle operations, archiving and distribution of the data. Landsat 9 carries two instruments. The Operational Land Imager 2 takes images at visible and certain infrared wavelengths. It covers the entire Earth’s surface every 16 days. In tandem, the Thermal Infrared Sensor 2 measures the land surface temperature at two infrared wavebands.