Geostationary Satellites Quiz

1. What is the approximate altitude of a geostationary orbit above Earth's surface?

2,000 km
10,000 km
35,786 km
100,000 km

Correct Answer: c) 35,786 km
A geostationary orbit must be approximately 35,786 km above Earth's surface to match Earth's rotational period of 24 hours.

2. What is the primary advantage of geostationary satellites for communication?

Lowest latency
Fixed position relative to ground stations
Lowest cost to launch
Best for polar coverage

Correct Answer: b) Fixed position relative to ground stations
The main advantage is that ground antennas don't need to track the satellite, as it appears stationary in the sky.

3. How many geostationary satellites are theoretically needed for complete global coverage (excluding polar regions)?

1
3
6
12

Correct Answer: b) 3
Three properly spaced geostationary satellites can cover most of the Earth's surface (except near the poles).

4. What is the approximate round-trip time delay for signals to a geostationary satellite?

10 ms
120 ms
250 ms
500 ms

Correct Answer: c) 250 ms
The round-trip delay is about 250 ms due to the high altitude (signal travels ~72,000 km up and down at speed of light).

5. Which frequency band is NOT commonly used for geostationary satellite communications?

C-band
Ku-band
Ka-band
VHF-band

Correct Answer: d) VHF-band
VHF (30-300 MHz) is generally not used for GEO communications; C (4-8 GHz), Ku (12-18 GHz), and Ka (26-40 GHz) bands are standard.

6. What is the primary reason for station-keeping maneuvers in GEO?

To change coverage area
To compensate for orbital perturbations
To increase transmission power
To cool down the satellite

Correct Answer: b) To compensate for orbital perturbations
Station-keeping counters gravitational effects from the Moon, Sun, and Earth's oblateness that would otherwise move the satellite.

7. What is the typical orbital velocity of a geostationary satellite?

1.5 km/s
3.07 km/s
7.8 km/s
11.2 km/s

Correct Answer: b) 3.07 km/s
The orbital velocity is about 3.07 km/s, calculated using v = √(GM/r) where r ≈ 42,164 km from Earth's center.

8. Which of the following is NOT a characteristic of a geostationary orbit?

Circular orbit
Zero inclination
24-hour period
Altitude of 2,000 km

Correct Answer: d) Altitude of 2,000 km
GEO requires 35,786 km altitude. 2,000 km is typical for LEO (Low Earth Orbit) satellites.

9. What is the main limitation of geostationary satellites for real-time communications?

Low bandwidth
High latency
Limited coverage
High power consumption

Correct Answer: b) High latency
The 250 ms round-trip delay makes GEO unsuitable for real-time applications like voice/video calls without echo cancellation.

10. What is the primary cause of north-south drift in geostationary satellites?

Solar radiation pressure
Gravitational pull of the Moon
Atmospheric drag
Earth's magnetic field

Correct Answer: b) Gravitational pull of the Moon
The Moon's gravity causes inclination changes of about 0.85° per year, requiring north-south station-keeping maneuvers.