According to the United Nations Office for Outer Space Affairs (UNOOSA, 2016), there were 1419 operational satellites orbiting Earth in 2016 and around a quarter of these are Earth-observing.
Remote sensing arose with the development of flight and photography. The two together allowed for the balloonist G Tournachon to create the first aerial photographs of Paris in 1858. Along with this, there were several other methods deployed to produce aerial photographs, from pigeons to rockets, but these were quickly filtered out of practical use. Amongst many other technological developments, war acted as a catalyst to the development of Remote Sensing, with it becoming prolific in airborne surveillance and reconnaissance up until the Cold War. Figure 1 below shows how remote sensing was used in world war 1 to locate trenches for military use.
What I have come to realise is how recent remote sensing as a source of information actually is and how much has changed within such a short period of time, making me curious to where this course will lead and the opportunities remote sensing currently has and what it holds in the future.
References
UNOOSA (2017). UNOOSA. [online] Available at: http://www.unoosa.org/ [Accessed 23 May 2017].
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