Space technology: previous-year questions
71 real UPSC Prelims questions (2011–2026) with the official answer and a clear explanation. 28 of them came in the last five papers.
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Consider the following statements with regard to involvement of private entities in India’s space programme :
- 1. The Indian National Space Promotion and Authorisation Centre (IN-SPACe) is an autonomous agency formed to facilitate participation of private entities.
- 2. Agnikul Cosmos launched the world’s first flight using 3D-printed rocket engine.
- 3. Skyroot Aerospace has developed liquid fuel for GSLV.
Which of the statements given above is/are correct ?
Answer (c) & explanation
Statements 1 and 2 are correct (c). Statement 1 is right: IN-SPACe (2020) is the single-window, autonomous body under the Department of Space that authorises private space activity. Statement 2 is right: Agnikul's Agnibaan SOrTeD (May 2024) flew on the world's first single-piece 3D-printed semi-cryogenic engine. Statement 3 is wrong: Skyroot builds its own Vikram rockets; it does not make fuel for ISRO's GSLV. So options (a), (b) and (d) fail.
Notice Skyroot's milestone: Vikram-S (2022) was India's first privately built rocket to reach space. The Indian Space Policy, 2023 opened all space activities to private firms, and 100% FDI is allowed in parts of the sector. NSIL is ISRO's commercial arm.
Answer as per the official UPSC answer key.
Which of the following statements with regard to drone swarms is/are correct ?
- 1. They use Terahertz band of frequency to communicate with the command centre.
- 2. Individual drones in the swarm can communicate with other drones in the swarm.
- 3. GPS Spoofing is a commonly used technique to counter drone swarm attack.
Select the answer using the code given below :
Answer (b) & explanation
Statements 2 and 3 are correct (b). Statement 2 is right: in a swarm, the drones talk to each other and share tasks, so the group keeps working even if some are lost. Statement 3 is right: defenders often jam or spoof GPS to send them off course. Statement 1 is wrong: swarms usually use ordinary radio bands; terahertz links are still experimental and short-range. So options (a), (c) and (d) fail.
Notice other counters: laser weapons, like DRDO's directed-energy systems, anti-drone guns and net systems. India showed a 75-drone swarm at the 2021 Army Day parade. Drone wars in Ukraine and during Operation Sindoor (2025) showed how cheap drones can overwhelm costly defences.
Answer as per the official UPSC answer key.
Which of the following statements with regard to the National Quantum Mission (NQM) is/are correct ?
- 1. It aims at developing intermediate-scale quantum computers with 50-1000 physical qubits.
- 2. Its implementation includes setting up of four Thematic Hubs (T-Hubs) in academic and national R&D institutes across India.
Select the answer using the code given below :
Answer (c) & explanation
Both statements are correct (c). Statement 1 is right: the National Quantum Mission (2023, under the DST) aims at quantum computers of 50–1,000 physical qubits within eight years. Statement 2 is right: it has four T-Hubs: computing at IISc Bengaluru, communication at IIT Madras, sensing and metrology at IIT Bombay, and materials and devices at IIT Delhi. So options (a), (b) and (d) fail.
Notice the budget: about ₹6,000 crore from 2023-24 to 2030-31. The mission also aims at secure quantum communication over 2,000 km between cities, and satellite-based quantum links. India joined a handful of nations, like the USA, China and France, with such a dedicated mission.
Answer as per the official UPSC answer key.
Which of the following statements with regard to India’s Deep Ocean Mission is/are correct ?
- 1. It was launched by the Ministry of Ports, Shipping and Waterways, Government of India.
- 2. Matsya-6000 has been designed to carry 3 people for deep sea exploration.
- 3. Samudrayaan is a project under this mission.
Select the answer using the code given below :
Answer (b) & explanation
Statements 2 and 3 are correct (b). Statement 2 is right: Matsya-6000 is a submersible designed to take three people to a depth of 6,000 metres. Statement 3 is right: Samudrayaan is the project under the mission that is building it. Statement 1 is wrong: the Deep Ocean Mission (2021) belongs to the Ministry of Earth Sciences, not the shipping ministry. So options (a), (c) and (d) fail.
Notice the mission's other parts: deep-sea mining of polymetallic nodules in the Central Indian Ocean Basin, ocean biodiversity, and climate advisory services. The National Institute of Ocean Technology in Chennai builds Matsya. Only a few countries, such as the USA, China, Japan and France, have crewed deep-sea vehicles.
Answer as per the official UPSC answer key.
Which of the following statements about DHRUV64 is/are correct ?
- 1. It is the third chip fabricated under the DIR-V Programme with an overall aim to enable the creation of microprocessors for India.
- 2. It is India’s first homegrown 1.0 GHz, 64-bit dual-core microprocessor.
Select the answer using the code given below :
Answer (c) & explanation
Both statements are correct (c). Statement 1 is right: DHRUV64, announced in December 2025 by C-DAC, is the third chip fabricated under the Digital India RISC-V (DIR-V) programme, after THEJAS32 and THEJAS64. Statement 2 is right: it is India's first homegrown 1.0 GHz, 64-bit dual-core microprocessor. So options (a), (b) and (d) fail.
Notice the technology: RISC-V is an open-source instruction set, so India can design chips without paying licence fees to owners of ARM or x86 designs. DHRUV64 targets 5G equipment, industrial automation, automotive and IoT uses. Next in line are the Dhanush chips. The India Semiconductor Mission (2021) supports the wider fab and assembly ecosystem.
Answer as per the official UPSC answer key.
Which one of the following pairs of semiconductor plants in India and their locations is not correctly matched ?
Answer (c) & explanation
The pair HCL-Foxconn : Madhya Pradesh is wrong (c). The HCL–Foxconn joint venture India Chip Ltd. was approved in 2025 near Jewar in Uttar Pradesh, close to the new airport, not in Madhya Pradesh. Option (a) is correct: CG Power with Renesas and STARS is building at Sanand, Gujarat. Option (b) is correct: Tata's assembly and test unit is at Jagiroad, Assam. Option (d) is correct: SiCSem's silicon carbide fab is in Odisha.
Notice the anchor project: Tata and PSMC of Taiwan are building India's first big fab at Dholera, Gujarat, and Micron's assembly unit is at Sanand. These come under the India Semiconductor Mission (2021), which offers about 50% fiscal support.
Answer as per the official UPSC answer key.
Which of the following statements with regard to India’s indigenous new high resolution weather model, the ‘Bharat Forecast System,’ is/are correct ?
- 1. Its objective is to generate forecasts at the Panchayats cluster level.
- 2. It was developed by IIT Delhi.
Select the answer using the code given below :
Answer (a) & explanation
Only statement 1 is correct (a). Statement 1 is right: the Bharat Forecast System (BFS), launched in May 2025, runs at about 6 km resolution, fine enough for forecasts at the level of panchayat clusters. Statement 2 is wrong: it was developed by the Indian Institute of Tropical Meteorology (IITM), Pune, and runs on the Arka supercomputer, not at IIT Delhi. So options (b), (c) and (d) fail.
Notice the advance: earlier global models ran at about 12 km, so BFS gives much sharper local forecasts of heavy rain and cyclones. It is among the world's highest-resolution operational models. IITM works under the Ministry of Earth Sciences, alongside the IMD. Better forecasts help farmers and disaster management.
Answer as per the official UPSC answer key.
Which of the following statements regarding the features of blockchain technology are correct ?
- 1. Records stored in the database may be made visible to relevant stakeholders without risk of alteration.
- 2. Copies of the entire database are stored on multiple computers on a network, syncing within seconds.
- 3. Consortium blockchain is a blend of public and private blockchains allowing selective data access.
- 4. Mathematical algorithms make it impossible to change or delete any data once recorded and accepted.
Select the answer using the code given below :
Answer (c) & explanation
Statements 1, 2 and 4 are correct (c). A blockchain is a shared record of transactions copied across many computers. Statement 1 is right: records can be shown to stakeholders without risk of alteration. Statement 2 is right: copies of the whole ledger sit on many nodes and sync quickly. Statement 4 is right: cryptographic hashing links each block to the last, so accepted data cannot be changed or deleted. Statement 3 is wrong: a blend of public and private is a hybrid blockchain; a consortium blockchain is run by a group of organisations. So options (a), (b) and (d) fail.
Notice uses in India: land records, supply chains, and the RBI's e-rupee pilots. Bitcoin (2009) was the first public blockchain.
Consortium and hybrid both sound like a mix. Consortium means many owners; hybrid means a mix of public and private.
Answer as per the official UPSC answer key.
Which of the following statements with regard to Large Language Models (LLMs) used in machine learning is/are correct ?
- 1. LLMs assign probabilities to the next possible words and then pick the one with the highest probability.
- 2. LLMs process data through mathematical optimization to minimise prediction errors.
- 3. LLMs produce unbiased outputs.
Select the answer using the code given below :
Answer (b) & explanation
Statements 1 and 2 are correct (b). Statement 1 is right: a Large Language Model predicts the next word, or token, by giving every candidate a probability, and then picks a likely one. Statement 2 is right: it learns by optimisation, adjusting billions of weights to reduce prediction error on its training text. Statement 3 is wrong: because it learns from human text, it can repeat human bias. So options (a), (c) and (d) fail.
Notice the related risks: hallucination, where an LLM confidently gives false facts, and deepfakes made by generative AI. India's IndiaAI Mission backs Indian-language models such as BharatGen and Sarvam. The "T" in GPT stands for Transformer, the design behind modern LLMs.
Answer as per the official UPSC answer key.
Which of the following statements with regard to stealth technology is/are correct ?
- 1. Stealth objects have a very small radar cross-section and are coated with Radar Absorbing Material.
- 2. Stealth objects can be detected using specific frequencies.
- 3. Stealth objects are coated with metamaterials to increase the scattering of electromagnetic radiation.
Select the answer using the code given below :
Answer (c) & explanation
Statements 1 and 2 are correct (c). Statement 1 is right: stealth aircraft cut their radar cross-section through shape and radar-absorbing material (RAM). Statement 2 is right: they are tuned against common radar bands, so low-frequency radars, such as VHF, can still pick them up. Statement 3 is wrong: metamaterial coatings are meant to absorb or bend waves away, reducing the echo, not increasing scattering. So options (a), (b) and (d) fail.
Notice examples: the US F-35 and B-2, China's J-20, and Russia's Su-57. India's AMCA fifth-generation fighter is planned to be stealthy. Stealth also cuts infrared heat and noise signatures. Other counters include passive radar and multi-static radar networks.
Statement 3 uses a real term, metamaterials, but gives them the opposite purpose.
Answer as per the official UPSC answer key.
Which of the following statements with regard to Black Boxes used in modern aircrafts is/are correct ?
- 1. They carry a beacon emitting red light pulses to facilitate underwater detection.
- 2. They record both the cockpit voice and flight data.
- 3. Their memory units are made using either stainless steel or titanium.
Select the answer using the code given below :
Answer (b) & explanation
Statements 2 and 3 are correct (b). Statement 2 is right: the "black box" is really two orange recorders, the cockpit voice recorder and the flight data recorder. Statement 3 is right: their crash-survivable memory sits in stainless steel or titanium shells. Statement 1 is wrong: under water, the locator beacon sends out ultrasonic pulses, about 37.5 kHz, not red light. So options (a), (c) and (d) fail.
Notice why they are orange: to be easy to spot in wreckage. The beacon works for about 30 to 90 days. Black boxes were key in probing the Air India Ahmedabad crash (June 2025); India's AAIB read its data at a new lab in Delhi. Newer rules call for 25-hour voice recording.
Answer as per the official UPSC answer key.
With reference to Unmanned Aerial Vehicles (UAVs), consider the following statements :
- I. All types of UAVs can do vertical landing.
- II. All types of UAVs can do automated hovering.
- III. All types of UAVs can use battery only as a source of power supply.
How many of the statements given above are correct?
Answer (d) & explanation
None of the statements is correct (d). Each statement says "all types", which is the trap. Statement I is wrong: multi-rotor drones land vertically, but fixed-wing UAVs, such as most military drones, need a runway or a net. Statement II is wrong: fixed-wing UAVs cannot hover; they must keep moving forward. Statement III is wrong: large UAVs run on fuel engines, and some use solar power or hydrogen. So options (a), (b) and (c) fail.
Notice India's drone push: the Drone Rules, 2021, the PLI scheme for drones, and Namo Drone Didi, giving drones to women's self-help groups for spraying crops. India is buying US MQ-9B drones, and drones were widely used in Operation Sindoor (2025).
"All types" in every statement is the clue. One counter-example, the fixed-wing drone, breaks all three.
Answer as per the official UPSC answer key.
Consider the following statements :
- I. It is expected that Majorana 1 chip will enable quantum computing.
- II. Majorana 1 chip has been introduced by Amazon Web Services (AWS).
- III. Deep learning is a subset of machine learning.
Which of the statements given above are correct?
Answer (c) & explanation
Statements I and III are correct (c). Statement I is right: Majorana 1 (February 2025) is a quantum chip built on "topological" qubits, expected to make quantum computing more stable. Statement III is right: deep learning, which uses many-layered neural networks, is a subset of machine learning, itself part of AI. Statement II is wrong: Majorana 1 is Microsoft's chip; Amazon's quantum chip is called Ocelot. So options (a), (b) and (d) fail.
Notice Google's quantum chip, Willow (2024). India's National Quantum Mission (2023) aims to build quantum computers with 50–1,000 qubits. A qubit can be 0 and 1 at once (superposition), which gives quantum computers their power.
Big tech firms announced quantum chips within weeks of each other in 2025: Microsoft (Majorana 1), Amazon (Ocelot) and Google (Willow).
Answer as per the official UPSC answer key.
Consider the following space missions :
- I. Axiom-4
- II. SpaDeX
- III. Gaganyaan
How many of the space missions given above encourage and support micro-gravity research?
Answer (b) & explanation
Two of the missions support microgravity research (b). Item I is right: Axiom-4 (2025) took Shubhanshu Shukla to the International Space Station, where he ran Indian microgravity experiments, such as on sprouting seeds and muscle loss. Item III is right: Gaganyaan is designed to carry microgravity experiments on its crewed and uncrewed flights. Item II is not counted in UPSC's key: SpaDeX was a docking technology demonstration, though it did carry some small payloads.
Notice SpaDeX's importance: in January 2025 India became the fourth country to dock two satellites in space, after the USA, Russia and China. Docking is needed for the planned Bharatiya Antariksh Station and the Chandrayaan-4 sample return.
Answer as per the official UPSC answer key.
GPS-Aided Geo Augmented Navigation (GAGAN) uses a system of ground stations to provide necessary augmentation. Which of the following statements is/are correct in respect of GAGAN?
- I. It is designed to provide additional accuracy and integrity.
- II. It will allow more uniform and high quality air traffic management.
- III. It will provide benefits only in aviation but not in other modes of transportation.
Select the correct answer using the code given below.
Answer (d) & explanation
Statements I and II are correct (d). GAGAN, built by ISRO and the Airports Authority of India, corrects GPS signals using ground stations and geostationary satellites. Statement I is right: it adds accuracy and integrity. Statement II is right: it allows more uniform, high-quality air traffic management and safer aircraft approaches. Statement III is wrong: its signal is also used for railways, shipping, fishing alerts and surveying. So options (a), (b) and (c) fail.
Notice the difference: GAGAN improves GPS, while NavIC (IRNSS) is India's own independent regional navigation system. India was the third country, after the USA and Europe, with such an aviation-grade satellite-based augmentation system.
Answer as per the official UPSC answer key.
Consider the following statements :
Statement-I : Giant stars live much longer than dwarf stars.
Statement-II : Compared to dwarf stars, giant stars have a greater rate of nuclear reactions.
Which one of the following is correct in respect of the above statements ?
Answer (d) & explanation
Statement I is wrong but Statement II is correct (d). Statement II is right: giant, massive stars have much hotter, denser cores, so their nuclear reactions run far faster than in small dwarf stars. Statement I is wrong: because they burn fuel so fast, giant stars live shorter lives. A very massive star may last only a few million years, while a small red dwarf can shine for trillions of years. More fuel does not mean a longer life: the faster burn rate wins.
Notice the endings: massive stars die in a supernova, leaving a neutron star or black hole. Sun-like stars swell into red giants and end as white dwarfs. The Chandrasekhar limit (about 1.4 solar masses) sets the maximum mass of a white dwarf.
Answer as per the official UPSC answer key.
Consider the following activities :
- 1. Identification of narcotics on passengers at airports or in aircraft
- 2. Monitoring of precipitation
- 3. Tracking the migration of animals
In how many of the above activities can the radars be used ?
Answer (b) & explanation
Radars can be used in two of the three (b). Item 2 is right: Doppler weather radars track rain, hail and storms, and help forecast cyclones; India's IMD runs a growing radar network, expanded under Mission Mausam (2024). Item 3 is right: the same radars pick up flocks of birds, bats and swarms of insects such as locusts on migration, and scientists use this to study them. Item 1 is wrong under UPSC's key: narcotics on passengers are found with X-ray and body scanners, chemical trace detectors and sniffer dogs, not radar.
Notice that radar stands for Radio Detection and Ranging. It bounces radio waves off objects, and the Doppler shift in the echo shows speed and direction.
Answer as per the official UPSC answer key.
Which one of the following words/phrases is most appropriately used to denote “an interoperable network of 3D virtual worlds that can be accessed simultaneously by millions of users, who can exert property rights over virtual items” ?
Answer (c) & explanation
This describes the metaverse (c). The metaverse is a persistent, shared, interoperable network of 3D virtual worlds that millions of users can enter at the same time, through VR/AR headsets or screens. Users can own virtual land and items, often recorded on blockchains as NFTs. Option (a) is wrong: big data analytics studies huge data sets for patterns. Option (b) is wrong: cryptography is the science of secure codes. Option (d) is wrong: "virtual matrix" is not a standard term.
Notice that the word comes from Neal Stephenson's 1992 novel Snow Crash. Facebook renamed itself Meta in 2021 to bet on it. The question's wording follows a widely cited definition by investor Matthew Ball.
Answer as per the official UPSC answer key.
Consider the following actions :
- 1. Detection of car crash/collision which results in the deployment of airbags almost instantaneously
- 2. Detection of accidental free fall of a laptop towards the ground which results in the immediate turning off of the hard drive
- 3. Detection of the tilt of the smartphone which results in the rotation of display between portrait and landscape mode
In how many of the above actions is the function of accelerometer required?
Answer (c) & explanation
An accelerometer is needed in all three (c). An accelerometer, usually a tiny MEMS chip, senses changes in speed and the direction of gravity. Action 1 needs it: in a crash, it detects the sudden deceleration and fires the airbags within milliseconds. Action 2 needs it: when a laptop is in free fall, the sensor feels near-zero gravity and parks the hard drive heads to avoid damage. Action 3 needs it: it measures the tilt of a phone against gravity to switch the screen between portrait and landscape.
Notice its partners: a gyroscope measures rotation, and a magnetometer works like a compass. Together they power step counters, games and navigation when GPS drops. Smartwatches also use them for fall detection.
Answer as per the official UPSC answer key.
Consider the following pairs :
| Objects in space | Description
| 1. Cepheids | Giant clouds of dust and gas in space
| 2. Nebulae | Stars which brighten and dim periodically
| 3. Pulsars | Neutron stars that are formed when massive stars run out of fuel and collapse
How many of the above pairs are correctly matched?
Answer (a) & explanation
Only one pair is correct (a). Pair 3 is right: pulsars are fast-spinning neutron stars, left when a massive star runs out of fuel and collapses in a supernova; they send out beams of radio waves like a lighthouse. Pairs 1 and 2 are swapped. Cepheids are pulsating stars that brighten and dim regularly; their period shows their true brightness, so they are used to measure cosmic distances. Nebulae are giant clouds of dust and gas, where new stars are born.
Notice that Henrietta Leavitt found the Cepheid period-brightness rule, and Edwin Hubble used it to show the universe is expanding. India's GMRT near Pune helps study pulsars, which act as precise cosmic clocks.
Answer as per the official UPSC answer key.