Minimalist IAS
Science & technology

Prelims · Science & technology · 22 questions

Space technology

Every UPSC Prelims question on this topic, 2016–2026, newest first. Tap an option to check yourself; the answer and explanation open below it.

Space technology questions per year: 2016: 2, 2017: 2, 2018: 3, 2019: 2, 2020: 1, 2021: 0, 2022: 1, 2023: 2, 2024: 2, 2025: 2, 2026: 2 Asked in 10 of 11 years · most in 2018 (3)

UPSC syllabus: “General Science.” See the full syllabus →

Prelims 2018 · Q55

Easy

In which of the following areas can GPS technology be used?

  1. 1.Mobile phone operations
  2. 2.Banking operations
  3. 3.Controlling the power grids

Select the correct answer using the code given below:

Answer & explanation

Answer: (d) 1, 2 and 3

GPS is used for far more than finding locations: its satellite signals carry very precise atomic-clock time, and that timing is used to synchronise mobile networks, banking and financial systems, and power grids. So all three areas are correct.

  • ✓ 1. Wireless and communications networks use GPS time to synchronise their operations and to use limited radio spectrum efficiently.
  • ✓ 2. Financial networks use GPS time to synchronise systems and to put traceable time tags on financial transactions and billing.
  • ✓ 3. Power grids depend on GPS timing for precise synchronisation across the network.

Remember · GPS gives position and precise time. Precise time is used to synchronise communications, financial networks and power grids.

Sources

Question and answer: UPSC's official GS Paper I (2018, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2018 · Q61

Medium

With reference to the Indian Regional Navigation Satellite System (IRNSS), consider the following statements:

  1. 1.IRNSS has three satellites in geostationary and four satellites in geosynchronous orbits.
  2. 2.IRNSS covers entire India and about 5500 sq. km beyond its borders.
  3. 3.India will have its own satellite navigation system with full global coverage by the middle of 2019.

Which of the statements given above is/are correct?

Answer & explanation

Answer: (a) 1 only

Only statement 1 is correct: IRNSS (now called NavIC) has seven satellites, three in geostationary orbit and four in inclined geosynchronous orbit. It is a regional system that reaches about 1,500 km beyond India's boundary, not 5,500 sq. km, and India has announced no global-coverage system for 2019.

  • ✓ 1. ISRO describes a seven-satellite constellation: three satellites in geostationary orbit and four in inclined geosynchronous orbit.
  • ✗ 2. The primary service area is India plus the region up to 1,500 km from its boundary. The statement gives 5,500 sq. km, which is a wrong figure and the wrong kind of unit for a distance.
  • ✗ 3. IRNSS is 'an independent regional navigation satellite system', meant for India and its neighbourhood. ISRO's own description names no plan for global coverage by 2019.

Remember · IRNSS/NavIC: 7 satellites (3 geostationary + 4 inclined geosynchronous); primary service area is India plus 1,500 km beyond its boundary; regional, not global.

Sources

  • ISRO: Satellite Navigation Services (NavIC) ↗ “Three satellites of the constellation are placed in geostationary orbit, at 32.5°E, 83°E and 129.5°E respectively, and four satellites are placed in inclined geosynchronous orbit”
  • ISRO: IRNSS Programme ↗ “IRNSS is an independent regional navigation satellite system being developed by India. It is designed to provide accurate position information service to users in India as well as the region extending up to 1500 km from its boundary”

Question and answer: UPSC's official GS Paper I (2018, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2018 · Q95

Medium

With reference to India’s satellite launch vehicles, consider the following statements:

  1. 1.PSLVs launch the satellites useful for Earth resources monitoring whereas GSLVs are designed mainly to launch communication satellites.
  2. 2.Satellites launched by PSLV appear to remain permanently fixed in the same position in the sky, as viewed from a particular location on Earth.
  3. 3.GSLV Mk III is a four-staged launch vehicle with the first and third stages using solid rocket motors; and the second and fourth stages using liquid rocket engines.

Which of the statements given above is/are correct?

Answer & explanation

Answer: (a) 1 only

Only statement 1 is correct. PSLV is ISRO's workhorse for earth-observation (remote-sensing) satellites in low, sun-synchronous polar orbits, while GSLV's main job is communication satellites for geosynchronous transfer orbit. GSLV Mk III has three stages, not four.

  • ✓ 1. Government of India's science portal says PSLV is designed mainly to deliver earth-observation or remote-sensing satellites, and VSSC says GSLV places INSAT and GSAT communication satellites into geosynchronous transfer orbit.
  • ✗ 2. A satellite looks fixed in the sky only if it is in geostationary orbit, about 35,786 km up. PSLV mainly puts satellites in polar orbits at 600-900 km, which sweep across the sky.
  • ✗ 3. GSLV Mk III (LVM3) is a three-stage vehicle: two solid strap-on motors (S200), a liquid core stage (L110) and a cryogenic upper stage (C25). It has no fourth stage.
  • • Since then ISRO now names this rocket LVM3 (GSLV Mk III); the configuration described on ISRO's LVM3 page is the same three-stage design.

Remember · PSLV: earth-observation satellites into polar sun-synchronous orbits. GSLV: communication satellites into geostationary transfer orbit. GSLV Mk III (LVM3): three stages.

Sources

Question and answer: UPSC's official GS Paper I (2018, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

The same topic in Mains

More in Science & technology