In the last post here i showed an illustration of the spectral sensitivities of current earth observation satellites. I like to comment this a bit more in detail separately here.
The list of satellites is not meant to be complete, in particular not listed are military or otherwise secret systems, older geostationary weather satellites and also various systems with unclear operational status. Except for Landsat 5 (no more) and GCOM-C (not yet) i only included operational systems – Sentinel-3 however is not yet producing data for the public.
Satellites are grouped into three groups:
- At the bottom the commercial and limited access systems
- The center group with brighter background are the higher resolution open data systems
- On top the lower resolution continuously recording systems
I also listed the revisit and global coverage intervals. Revisit is somewhat ill defined for satellites with pointing capability but is generally considered to be 1-6 days for a single satellite with small field of view – depends somewhat on the orbit of course.
Global coverage is only specified for those satellites which regularly record a global or near global coverage. Several commercial operators claim this but there is no reliable data to verify those claims. Landsat 5 and 7 have both in the past been used to produce global image collections over the course of several years. Landsat 8 now usually records all land surfaces within its coverage area in the 16 day revisit cycle with only occasional gaps. The lower resolution polar orbiting systems (MODIS/VIIRS/Sentinel-3) all have a well defined global coverage interval since they are capable of continuously recording. AVHRR is meant – using several satellites – to achieve a 6 hour revisit frequency and of course geostationary systems can record their area of view in much higher frequency. DSCOVR EPIC finally – by not being a real satellite – has its own special recording scenario.
Apart from DSCOVR EPIC and the geostationary satellites nearly all systems shown are in a sun synchronous orbit, they record earth at approximately the same time of the day locally. The only exception are the Planetscope satellites in ISS orbit.