Landsat 1 was launched exactly 40 years ago today. This has been the longest continuously running satellite land monitoring program around.

Check out the greatest hits from the Nasa Goddard Space Flight Center.

As NASA explains;

Throughout the decades, the Landsat satellites have given us a detailed view of the changes to Earth’s land surface. By collecting data in multiple wavelength regions, including thermal infrared wavelengths, the Landsat fleet has allowed us to study natural disasters, urban change, water quality and water usage, agriculture development, glaciers and ice sheets, and forest health.

Little known, but Landsat 1 was the first sensor based satellite series which took digital images to be sent back to earth. Prior satellites such as the Corona series took images on film which was then ejected from the satellite and either landed on earth or were caught by flying aircraft as the canisters descended to earth.