Numerous satellite Earth observation missions have been undertaken since the first Landsat satellite was launched in 1972. Each one of these has built on the previous mission, with the radiometric, spatial and temporal capabilities of the systems being continually improved.
We are currently in a period of unprecedented growth in the number of active missions, making this a very exciting time for the users of remotely sensed and spatial data.
Alongside the technological improvements of the sensors is a concomitant improvement in the software used to manage and process the data collected by the satellite systems. The inclusion of spatial data into many different applications is well under way and new innovations in how software is provided mean that more and more people will be able to process satellite data. Access to data has never been more open. Missions such as those provided by Landsat and Sentinel mean that data can be disseminated to a greater number of potential users.
Such temporal datasets allow us to undertake change detection studies. We can map and monitor the effects of the human population on the global environment, and the locality around us. Helping with this task is the fact that satellite collected imagery is calibrated and can be used alongside other similar data from different platforms. The bullets below indicate the longevity of different missions (most of which implement a number of satellites over that timespan):
- Landsat: > 40 years
- AVHRR: > 30 years
- GOES: > 35 years
- IKONOS: > 15 years
- SPOT: > 28 years
With the coverage provided by these systems and (many) more, remotely sensed datasets really do have the potential to provide a window into the recent past, for any location on the planet.