NASA Science
Satellite constellation
Many satellites flown as one system, so that at least one is always overhead.
A single low satellite is only in view of a given place for minutes. A constellation arranges enough of them in enough planes that coverage is continuous — GPS needs 24 to guarantee four in view anywhere, and broadband constellations need thousands because they are far lower. The consequences reach the ground: they have transformed connectivity, and they have also filled the sky with moving points that streak long-exposure images and interfere with radio astronomy.
Where it has come up lately
Related terms
Sun-synchronous orbit
A near-polar orbit that crosses the equator at the same local time every day.
Geostationary orbit
The one orbit where a satellite appears to hang motionless over a fixed point.
Kessler syndrome
The runaway scenario where collisions in orbit generate debris that causes more collisions.
Low Earth orbit
Everything from about 160 to 2,000 km up, where almost all spacecraft and all people are.
Questions
What is Satellite constellation?
Many satellites flown as one system, so that at least one is always overhead.
Why does it matter?
A constellation arranges enough of them in enough planes that coverage is continuous — GPS needs 24 to guarantee four in view anywhere, and broadband constellations need thousands because they are far lower. The consequences reach the ground: they have transformed connectivity, and they have also filled the sky with moving points that streak long-exposure images and interfere with radio astronomy.