Satellites — Set 2

Correct Answer: D. INSAT

• **INSAT system** = multipurpose Indian satellites for telecom and weather forecasting. • **Disaster management** — enables warning systems and search-and-rescue operations. • 💡 Wrong-option analysis: A (GSAT): communication satellites but not meteorological focus; B (Oceansat): ocean/biological monitoring; C (Cartosat): earth mapping/remote sensing.

Correct Answer: C. A device that receives and retransmits signals

• **Transponder function** = receives, amplifies, and refrequencies signals for retransmission. • **Data traffic handler** — core component for satellite communications; one satellite carries dozens. • 💡 Wrong-option analysis: A (fuel tank): stores propellant for maneuvering; B (heat shield): thermal protection; D (camera lens): for imaging only.

Correct Answer: A. Medium Earth Orbit

• **MEO altitude** = 2,000–35,786 km region; GPS at ~20,200 km. • **Optimal balance** — provides broad coverage with strong signals for navigation. • 💡 Wrong-option analysis: B (LEO): too low for global coverage; C (GEO): stationary orbit, not navigation; D (Polar): doesn't provide global continuous coverage.

Correct Answer: C. High-resolution Earth mapping

• **Cartosat series** = ISRO's Indian Remote Sensing satellites for mapping. • **High-resolution imagery** — supports urban planning, resource management, disaster assessment. • 💡 Wrong-option analysis: A (TV broadcasting): INSAT handles comms; B (atmospheric): research satellites; D (ocean study): OceanSat's role.

Correct Answer: D. Gravitational force

• **Gravity provides centripetal force** = pulls satellite inward while velocity curves its path. • **Orbital equilibrium** — balance between inward pull and outward inertia maintains stable orbit. • 💡 Wrong-option analysis: A (magnetic): too weak in space; B (nuclear): not applicable to orbital mechanics; C (friction): causes orbital decay, not maintenance.

Correct Answer: C. The functional instruments on the satellite

• **Payload definition** = mission-specific instruments (cameras, sensors, transponders). • **Distinct from bus** — payload performs mission; bus provides power and structure. • 💡 Wrong-option analysis: A (rocket weight): refers to launch vehicle; B (mission cost): overall expense; D (launch fuel): rocket propellant, not satellite.

Correct Answer: C. India

• **EDUSAT (GSAT-3)** = India's first educational satellite (2004). • **Distance learning** — interactive satellite education for rural areas; unique space-for-education mission. • 💡 Wrong-option analysis: A (USA): developed Landsat for earth observation; B (Russia): supplied space station modules; C (China): launched first after India.

Correct Answer: A. Space debris accumulation

• **Kessler Syndrome** = cascading collisions from high-density LEO debris. • **Space sustainability threat** — debris belt could make spaceflight impossible for generations. • 💡 Wrong-option analysis: B (battery failure): technical issue, not cascade effect; C (solar flares): radiation damage; D (signal interference): frequency issue.

Correct Answer: C. ISRO

• **Bhuvan geo-portal** = ISRO's 2D/3D Earth visualization platform. • **Thematic maps** — water, agriculture, land cover data for national planning. • 💡 Wrong-option analysis: A (NASA): manages Landsat; B (ESA): operates Copernicus; D (DRDO): defense research, not geo-portal.

Correct Answer: D. Monitoring Earth's entire surface over time

• **Polar orbit characteristics** = passes over North and South Poles; maps entire Earth over time. • **Global coverage** — used for weather, reconnaissance, environmental monitoring. • 💡 Wrong-option analysis: A (DTH TV): GEO requirement; B (deep space): inter-planetary; C (fixed telecom): GEO only.