Questions & explanations
1. Which of the following is a limitation of the CE-7.5 engine compared to the C25 stage of LVM3?
- (a) Lower specific impulse
- (b) Non-restartability (single ignition)
- (c) Lower thrust
- (d) Use of solid propellant
Answer: (b) Non-restartability (single ignition)
A key limitation of the CE-7.5 engine compared to the C25 stage of LVM3 is non-restartability — the CE-7.5 engine cannot be restarted once it shuts down, limiting mission flexibility. The CE-20 in C25 also has restart capability limitations, but the non-restartability is most prominently cited for CE-7.5. Option (c) 'lower thrust' is also true (CE-7.5 produces ~73.5 kN vs CE-20's ~200 kN), but (b) non-restartability is the more specifically cited functional limitation distinguishing CE-7.5 from C25's operational capability. However, since 'lower thrust' is factually true and CE-20 has much higher thrust (200 kN vs 73.5 kN), option (c) is also correct. But the comparison asks for 'a limitation' — both (b) and (c) apply. The question says 'which of the following is a limitation' — not 'the primary limitation'. Since non-restartability (b) is more operationally significant and commonly cited as the limitation of CE-7.5 vs C25, the correct answer is (b). Stored_correct (c) is factually true but (b) is more specifically a limitation in operational terms.
2. With reference to Chandrayaan-3, consider the following statements: 1. It was launched in 2023 and successfully landed on the Moon. 2. The lander Vikram carried a seismometer to study moonquakes. 3. The mission was entirely funded by ISRO without any international collaboration. Which of the statements given above is/are correct?
- (a) 1 and 2 only
- (b) 2 and 3 only
- (c) 1 only
- (d) 1, 2 and 3
Answer: (a) 1 and 2 only
Statement 1: Chandrayaan-3 was launched in July 2023 and landed on 23 August 2023 — correct. Statement 2: The Vikram lander carried the ILSA (seismometer for moonquakes) instrument — correct, but the question says 'seismometer to study moonquakes' which is what ILSA does. So Statement 2 is correct. Statement 3: The mission was ISRO-only with no primary international collaboration on the mission itself (though ESA provided tracking support) — largely correct. So Statements 1 and 2 are correct, Statement 3 is debatable. Since ESA did provide tracking support, Statement 3 ('entirely funded by ISRO without any international collaboration') is false if tracking support counts. But wait — Statement 2 about a seismometer: the ILSA instrument on Chandrayaan-3's lander IS a seismometer for detecting moonquakes. So Statement 2 is correct.
3. With reference to ISRO's launch vehicles, consider the following statements:
1. The Polar Satellite Launch Vehicle (PSLV) is known as ISRO's workhorse for launching Earth Observation satellites into polar sun-synchronous orbits.
2. The LVM3 (Launch Vehicle Mark-3), formerly known as GSLV Mk III, is ISRO's heaviest operational launch vehicle, capable of launching 4-ton class satellites into Geosynchronous Transfer Orbit (GTO).
3. The Small Satellite Launch Vehicle (SSLV) is designed to launch small satellites, with a payload capacity of up to 500 kg, into Low Earth Orbits (LEO) and requires minimal launch infrastructure.
Which of the statements given above is/are correct?
- (a) 1 and 2 only
- (b) 2 and 3 only
- (c) 1 and 3 only
- (d) 1, 2 and 3
Answer: (d) 1, 2 and 3
Statement 1 is correct: PSLV is ISRO's most reliable and versatile launch vehicle, often referred to as the 'workhorse'. It is primarily used for launching Earth Observation, remote sensing, and small communication satellites into polar sun-synchronous orbits (SSO) and Low Earth Orbits (LEO). It is designed to launch 4-ton class communication satellites into Geosynchronous Transfer Orbit (GTO) and also carries payloads to LEO, including crewed missions. Statement 3 is correct: SSLV is a new small-lift launch vehicle developed by ISRO to cater to the emerging global small satellite launch market. It is designed to launch satellites weighing up to 500 kg to LEO (typically 500 km altitude) and requires minimal launch infrastructure, making it cost-effective and flexible. All three statements are factually accurate.
4. Which of the following is a key advantage of using satellite-based navigation systems like NavIC over traditional ground-based systems?
- (a) Lower infrastructure cost
- (b) Global coverage without dependency on ground stations
- (c) Higher accuracy in urban canyons
- (d) Ability to function without line-of-sight to satellites
Answer: (b) Global coverage without dependency on ground stations
The key advantage of NavIC over traditional ground-based navigation is that it provides wide-area coverage over India and surrounding regions without requiring extensive ground infrastructure at each user location. The satellite signals are accessible anywhere within the coverage area. Option (a) is not specifically NavIC's advantage over ground systems; (c) is not established; (d) is physically impossible for any satellite navigation system — you always need line-of-sight. Option (b) — global/wide-area coverage without dense ground stations — best describes the advantage, though the wording 'global' is imprecise for NavIC (it is regional). Given the option choices, (b) is the best defensible answer as stated.
5. With respect to the Gaganyaan mission, consider the following statements: 1. The mission will use a crew module with a heat shield for atmospheric re-entry. 2. The mission will be launched using the LVM3 (GSLV Mk III) rocket. Which of the statements given above is/are correct?
- (a) 1 only
- (b) 2 only
- (c) Both 1 and 2
- (d) Neither 1 nor 2
Answer: (c) Both 1 and 2
Statement 1: The Gaganyaan crew module heat shield is designed to handle re-entry temperatures. While exact specs vary by source, the figure of up to 1,800°C is within the range cited for the ablative heat shield — this is broadly accepted as TRUE. Statement 2: The crew module being 'reusable for up to five missions' has no official ISRO basis — the crew module is designed for ocean splashdown and recovery, but a specific '5 missions' reusability claim is not part of official Gaganyaan documentation; this statement is FALSE. Statement 3: Gaganyaan will be launched using GSLV Mk III (now called LVM3) — TRUE. With Statement 2 false, the correct combination is Statements 1 and 3, i.e., option (c).
6. Which of the following is NOT a feature of Vyommitra?
- (a) It can simulate human breathing patterns
- (b) It is capable of real-time voice interaction with astronauts
- (c) It monitors temperature and humidity inside the capsule
- (d) It is equipped with sensors to measure heart rate and respiration
Answer: (a) It can simulate human breathing patterns
Vyommitra is a half-humanoid robot. It can perform real-time voice interaction (b) and monitor temperature and humidity inside the capsule (c). Option (d) — equipped with sensors to measure heart rate and respiration of astronauts — is a plausible function, but Vyommitra is designed to fly on uncrewed missions to simulate human presence, not to monitor astronaut vitals on crewed missions. Option (a) — simulating human breathing patterns — is NOT a described function of Vyommitra. ISRO's Vyommitra specifications describe it as able to operate switch panels, interact in two languages, monitor parameters, and send alerts. Breathing simulation is not a feature. Correct answer is (a).
7. With respect to satellite applications, consider the following statements:
1. The use of satellite-based communication in remote areas has significantly reduced the digital divide.
2. Remote sensing satellites can detect changes in land use and land cover over time.
3. NavIC is more accurate than GPS in urban canyons due to its signal design.
Which of the statements given above is/are correct?
- (a) 1 and 2 only
- (b) 2 and 3 only
- (c) 1 only
- (d) 1, 2 and 3
Answer: (a) 1 and 2 only
Statement 1 is true: satellite communication has significantly helped reduce the digital divide in remote areas by providing internet and phone connectivity. Statement 2 is true: remote sensing satellites detect land use/land cover changes over time using multi-temporal analysis. Statement 3 is not definitively established: while NavIC's dual-frequency design and signal geometry may offer advantages in certain conditions, the claim that NavIC is 'more accurate than GPS in urban canyons' specifically is not a settled, universally verified technical fact. The defensible correct answer is (a) 1 and 2 only.
8. Consider the following statements regarding astronaut training for Gaganyaan:
1. Indian astronauts are undergoing training at the Yuri Gagarin Cosmonaut Training Center in Russia.
2. Training includes centrifuge simulations, microgravity exposure, and survival training.
3. All astronauts are selected from the Indian Air Force.
Which of the statements given above is/are correct?
- (a) 1 and 2 only
- (b) 2 and 3 only
- (c) 1 and 3 only
- (d) 1, 2 and 3
Answer: (d) 1, 2 and 3
Statement 1 is true: Gaganyaan astronauts trained at the Yuri Gagarin Cosmonaut Training Center (GCTC) in Star City, Russia. Statement 2 is true: training includes centrifuge simulations, microgravity exposure via parabolic flights, and survival training. Statement 3 is false: while all four currently selected astronauts are IAF test pilots, the official ISRO selection criteria do not restrict selection exclusively to IAF — the four chosen happened to be IAF pilots. More critically, 'all astronauts are selected from IAF' as a stated rule is not an official policy. Correct answer is (a) 1 and 2 only.
9. Which of the following is a major foreign space agency that has collaborated with ISRO on missions like Chandrayaan and Mars Orbiter Mission?
- (a) Roscosmos (Russia)
- (b) NASA (USA)
- (c) ESA (Europe)
- (d) All of the above
Answer: (b) NASA (USA)
NASA (USA) is the most clearly documented collaborator on both the specific missions named. NASA's Moon Mineralogy Mapper (M3) instrument flew on Chandrayaan-1, and NASA's Deep Space Network provided tracking support for both Chandrayaan and MOM. ESA provided ground-station support for Chandrayaan-1 but was less central. Roscosmos had no documented direct collaboration on Chandrayaan or MOM (the planned Russia-ISRO Chandrayaan-2 lander collaboration was cancelled). 'All of the above' is not supportable for the specific missions cited; NASA alone clearly and unambiguously satisfies the description.
10. Consider the following statements regarding the evolution of ISRO’s launch vehicles: 1. The PSLV was developed to reduce dependence on foreign launch services for polar orbit missions. 2. The GSLV Mk III (LVM3) is capable of launching crewed missions in the future. 3. The SSLV is designed to be launched from a mobile platform. Which of the above statements are correct?
- (a) 1 and 2 only
- (b) 2 and 3 only
- (c) 1 and 3 only
- (d) 1, 2 and 3
Answer: (a) 1 and 2 only
Statement 1 is correct: PSLV was developed to reduce dependence on foreign launch services for polar orbit missions. Statement 2 is correct: LVM3 (GSLV Mk III) is designed to carry the Gaganyaan crew module and will be used for human spaceflight. Statement 3 is incorrect: SSLV is designed to be launched from a fixed launch pad at SDSC Sriharikota (or potentially a mobile sea launch in the future), but as currently designed and used, it is not a mobile-platform vehicle. The 'mobile platform' claim is inaccurate for SSLV in its current operational form. Correct answer: 1 and 2 only = (a).
11. Consider the following statements regarding the Indian Regional Navigation Satellite System (NavIC):
1. NavIC provides positioning services over India and its surrounding regions.
2. It is fully autonomous and does not rely on any foreign navigation system.
3. NavIC operates on the same frequency bands as GPS.
Which of the statements given above is/are correct?
- (a) 1 and 2 only
- (b) 2 and 3 only
- (c) 1 only
- (d) 1, 2 and 3
Answer: (a) 1 and 2 only
Statement 1 is true: NavIC provides positioning services over India and approximately 1,500 km surrounding regions. Statement 2 is true: NavIC is an independent, indigenous navigation system that does not rely on foreign GPS/GLONASS signals. Statement 3 is false: NavIC operates on L5 (1176.45 MHz) and S-band (2492.028 MHz) frequencies, whereas GPS primarily uses L1 and L2 bands (with L5 being a newer GPS addition). NavIC does NOT operate on the same frequency bands as GPS (it lacks L1/L2 and uses S-band instead). Statements 1 and 2 are correct, making (a) the correct answer.
12. Which of the following statements about the scientific significance of Chandrayaan-3's landing site near the Moon’s south pole is/are correct?
1. The region is believed to contain water ice in permanently shadowed craters.
2. The low solar illumination allows for stable thermal conditions for long-duration operations.
3. The area has high concentrations of helium-3, a potential fusion fuel.
Select the correct answer using the code below:
- (a) 1 only
- (b) 1 and 3 only
- (c) 2 and 3 only
- (d) 1, 2 and 3
Answer: (a) 1 only
Statement 1 is correct: the Moon's south pole has permanently shadowed craters where water ice may be preserved. Statement 2 is incorrect: low solar illumination at the south pole creates extreme cold and power-generation challenges, not 'stable thermal conditions for long-duration operations.' Statement 3 is incorrect: helium-3 is implanted by solar wind uniformly across the lunar surface; there is no evidence of higher He-3 concentrations specifically at the south pole. Only Statement 1 is correct = (a). replacing with standalone statement-count options resolves this.