1. What is the typical altitude range for LEO satellites?
Correct Answer: a) 160-2,000 km
LEO satellites operate at altitudes between 160 km and 2,000 km above Earth's surface. This relatively low altitude provides advantages like lower latency and higher resolution for Earth observation.
2. What is the approximate orbital period of a LEO satellite?
Correct Answer: a) 90-120 minutes
Due to their low altitude, LEO satellites complete an orbit around Earth in about 90 to 120 minutes, traveling at speeds of about 7.8 km/s.
3. Which of these is NOT a typical application of LEO satellites?
Correct Answer: c) Direct-to-home television
Direct-to-home television is typically provided by GEO satellites because they remain fixed relative to Earth's surface. LEO satellites move quickly across the sky, making them unsuitable for this application.
4. What is the main advantage of LEO satellites compared to GEO satellites?
Correct Answer: a) Lower latency
The primary advantage of LEO satellites is their much lower latency (20-50ms) compared to GEO satellites (about 500ms) due to their proximity to Earth.
5. Why do LEO satellite constellations require many satellites?
Correct Answer: a) To compensate for their small individual coverage areas
Each LEO satellite covers a relatively small area of Earth's surface (about 500-1,000 km diameter) and moves quickly, so many satellites are needed to provide continuous global coverage.
6. What is the primary reason LEO satellites have shorter operational lifetimes than GEO satellites?
Correct Answer: a) Atmospheric drag
The thin upper atmosphere at LEO altitudes creates drag that gradually slows satellites, causing orbital decay. Most LEO satellites operate for 5-7 years before re-entering the atmosphere.
7. Which of these famous satellite constellations operates in LEO?
Correct Answer: a) Starlink
Starlink is SpaceX's LEO satellite constellation providing global broadband internet. The other options are GEO satellite operators.
8. What is the main challenge in designing communication systems for LEO satellites?
Correct Answer: a) Handover between satellites
The rapid movement of LEO satellites requires sophisticated handover mechanisms to maintain continuous service as satellites move in and out of view of ground stations or user terminals.
9. Which frequency bands are commonly used by LEO satellite systems?
Correct Answer: a) Ku and Ka bands
Modern LEO communication satellites primarily use Ku (12-18 GHz) and Ka (26-40 GHz) bands, which offer high bandwidth for data transmission while allowing reasonably sized antennas.
10. What is the primary reason for the increasing interest in LEO satellite constellations?
Correct Answer: a) Demand for low-latency global internet
The growing need for low-latency internet access in remote and underserved areas has driven investment in LEO constellations, which can provide global coverage with latency comparable to terrestrial networks.