Q30. The terms event horizon, singularity, string theory and Standard Model are associated primarily with what?
[UPSC CSE Prelims 2017]
(A) Understanding and observing the Universe
(B) Studying only eclipses
(C) Launching satellites around Earth
(D) Origin of life on Earth
Answer: (A) Understanding and observing the Universe
Explanation: Event horizons and singularities arise in gravitational theories of compact objects. String theory and the Standard Model investigate fundamental particles and interactions. Together these terms concern basic physical descriptions of the cosmos, not spacecraft launches alone.
Q29. What is the purpose of the evolved Laser Interferometer Space Antenna (eLISA)?
[UPSC CSE Prelims 2017]
(A) Neutrino detection
(B) Gravitational-wave detection
(C) Testing missile-defence effectiveness
(D) Studying only solar-flare effects
Answer: (B) Gravitational-wave detection
Explanation: eLISA was conceived as a space-based gravitational-wave observatory using laser interferometry between distant spacecraft. It targets tiny distortions in distance generated by massive accelerating systems such as black-hole binaries, beyond many frequencies accessible from Earth.
Q28. How many planets are recognised in the Solar System?
[SSC MTS, 21 September 2017, Shift 1]
(A) 8
(B) 10
(C) 9
(D) 7
Answer: (A) 8
Explanation: The International Astronomical Union recognises eight major planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Pluto was reclassified as a dwarf planet in 2006 because it had not cleared its orbital neighbourhood.
Q27. Which planet was explored by NASA’s Cassini mission, which ended in September 2017?
[UPSC CDS (II) 2017 – General Knowledge]
(A) Sun
(B) Neptune
(C) Saturn
(D) Jupiter
Answer: (C) Saturn
Explanation: Cassini spent over a decade studying Saturn, its rings, magnetosphere and moons after arrival in 2004. Its mission ended with a deliberate atmospheric plunge in 2017 to protect potentially habitable moons from accidental biological contamination.
Q26. Which country launched the Venus environmental-research microsatellite in August 2017?
[UPSC CDS (II) 2017 – General Knowledge]
(A) India
(B) Russia
(C) China
(D) Israel
Answer: (D) Israel
Explanation: Venus, short for Vegetation and Environment monitoring on a New Micro-Satellite, was a joint Israeli–French Earth-observation satellite. Israel launched the spacecraft in 2017 for environmental and vegetation imaging, despite its planetary-sounding name.
Q25. Which statements about Astrosat are correct?
1. Besides the USA and Russia, India is the only country to have launched such an observatory.
2. Astrosat weighs 2,000 kg and orbits at a height of 1,650 km.
[UPSC CSE Prelims 2016]
(A) 1 only
(B) 2 only
(C) Both 1 and 2
(D) Neither 1 nor 2
Answer: (D) Neither 1 nor 2
Explanation: Astrosat, launched in 2015, was India’s first dedicated multiwavelength space observatory. The claims about exclusivity and a 2,000-kilogram spacecraft at 1,650 kilometres are inaccurate. Other countries had also launched space observatories before India.
Q24. Consider Mangalyaan:
1. It is also called Mars Orbiter Mission.
2. India was the second country to orbit Mars after the USA.
3. India succeeded in orbiting Mars on its first attempt.
Which statements are correct?
[UPSC CSE Prelims 2016]
(A) 1 only
(B) 2 and 3 only
(C) 1 and 3 only
(D) 1, 2 and 3
Answer: (C) 1 and 3 only
Explanation: Mangalyaan is the Mars Orbiter Mission and reached Mars orbit on India’s first interplanetary attempt. Other space agencies had already orbited Mars before ISRO, so India was not the second country overall. Statements 1 and 3 are correct.
Q23. Which statement about ISRO’s reusable launch-vehicle technology demonstrator is NOT correct?
[UPSC CDS (II) 2016 – General Knowledge]
(A) The demonstration flight occurred in 2016
(B) It launched from Sriharikota
(C) It reached approximately 65 km altitude
(D) It was initially boosted by a liquid-fuel rocket
Answer: (D) It was initially boosted by a liquid-fuel rocket
Explanation: ISRO tested its winged Reusable Launch Vehicle–Technology Demonstrator in May 2016 using a solid booster from Sriharikota. It reached suborbital altitude before a controlled descent. The claimed initial liquid-fuel booster is the incorrect detail.
Q22. In astronomical news, what does the term Goldilocks Zone refer to?
[UPSC CSE Prelims 2015]
(A) A habitable layer above Earth
(B) Shale-gas regions inside Earth
(C) The search for potentially Earth-like planets around other stars
(D) Meteorites containing precious metals
Answer: (C) The search for potentially Earth-like planets around other stars
Explanation: The circumstellar habitable zone is the orbital region where surface liquid water could persist on a suitable planet. It depends on stellar luminosity and atmospheric conditions. Being in this zone does not by itself establish that a planet has life.
Q21. For which activities are Indian Remote Sensing satellites used?
1. Crop productivity assessment
2. Locating groundwater
3. Mineral exploration
4. Telecommunications
5. Traffic studies.
[UPSC CSE Prelims 2015]
(A) 1, 2 and 3 only
(B) 4 and 5 only
(C) 1 and 2 only
(D) All five
Answer: (A) 1, 2 and 3 only
Explanation: Indian Remote Sensing satellites image the Earth for agriculture, resource inventories and geological investigations. Telecommunications generally depend on communication satellites, and ordinary traffic-management functions do not define the core applications asked in this question.
