21. "' Landsat 8 "'is an American Earth observation satellite launched on February 11, 2013. 22. He also photographed Mexico and Mexico City as part of the mission's Earth observations . 23. Usually, Earth observation satellites have three or more radiometers ( Landsat has seven ). 24. Earth observation footage from the camera also appeared in the 1991 film Blue Planet.25. Prism spectrometers are ideal for Earth observation because they measure wide spectral ranges competently. 26. International Institute for Geo-information Science and Earth Observation , Enschede. 27. Most Earth observation satellites carry instruments that should be operated at a relatively low altitude. 28. Dozens of scientists attempted experiments in disciplines ranging from medicine and biotechnology to Earth observation . 29. Such orbits are desirable for many Earth observation missions such as weather, imagery, and mapping. 30. Several operators of Earth observation satellites, such as GeoEye and Spot Image, provide images commercially.
