Such a constellation can be considered to be a number of satellites with coordinated ground coverage, operating together under shared control, synchronized so that they overlap well in coverage (the period in which a satellite or other spacecraft is visible above the local horizon). REF: COM-EN, based on: 'Satellite constellation'. Wikipedia, https://en.wikipedia.org/wiki/Satellite_constellation [22.3.2.17]
'SATELLITE CONSTELLATION The Sentinel-1 mission is designed as a two-satellite constellation. The identical satellites orbit Earth 180° apart and at an altitude of almost 700 km. This configuration optimises coverage, offering a global revisit time of just six days.'
