Why are very-low Earth orbit (LEO) satellites generally not used alone for fixed satellite communications to a single ground user?

Introduction / Context:
Satellite communication architectures vary by orbit: GEO, MEO, and LEO. Coverage and contact time to a fixed user depend on orbital altitude and constellation size. This question targets why a single LEO cannot serve as a continuous link to one location on Earth.

Given Data / Assumptions:

• LEO altitude typically 500–2000 km.
• Orbital period is about 90–120 minutes.
• Ground station remains fixed; satellite moves rapidly across the sky.

Concept / Approach:

Due to their short orbital periods and low altitude, LEO satellites provide only brief visibility windows (a few minutes) to any fixed point per pass. Continuous service requires a constellation and seamless satellite handovers. In contrast, a geostationary satellite near 35,786 km altitude remains fixed in the sky relative to the observer, enabling continuous coverage within its footprint.

Step-by-Step Solution:

Verification / Alternative check:

LEO constellations (e.g., Iridium, Starlink) employ many satellites to ensure continuous coverage through overlapping footprints and handovers, confirming the limitation of single-satellite LEO links.

Why Other Options Are Wrong:

• Sonic booms and melting are irrelevant.
• Propagation through the atmosphere is generally reliable at designed frequencies.
• Ionospheric effects exist but do not categorically prohibit LEO use.

Common Pitfalls:

Confusing LEO advantages (low latency, lower path loss) with continuous-coverage capability from a single satellite.

Final Answer:

Because a single LEO does not provide 24-hour/day continuous contact to a fixed user