Satellite constellation
Also called: Inter-satellite link · Topic: Remote Sensing, GIS and GNSS · NCERT: Beyond NCERT
Meaning
A satellite constellation is a group of satellites that work together as one system. A single satellite sees a place only when it passes overhead, and then it moves on. With many satellites spread out in orbit, one of them is over a given spot much more often. This gives wider coverage and better temporal resolution (how soon the same area is seen again). Many constellations use inter-satellite links, which are direct radio or laser connections between satellites. These links let the satellites share data and act as one network. Constellations matter because they get around a basic trade-off: sensors with finer detail usually see a narrower strip of ground and come back less often.
Example
India's NavIC was planned as a constellation of seven satellites: three in geostationary orbit and four in inclined geosynchronous orbit. Working together, they give positioning signals over India and about 1,500 km around it. One satellite alone could not do this. The US GPS is a global example, with about 31 operational satellites in medium earth orbit, about 20,200 km up.
Don't confuse with
- Inter-satellite link: this is only the connection between two satellites. The constellation is the whole group of satellites, which these links can tie together.
- Satellite orbit (for example, sun-synchronous or geostationary): an orbit is the path one satellite follows. A constellation is many satellites, sometimes placed in several different orbits, as in NavIC.