UPSC Essentials brings to you its initiative of subject-wise quizzes. These quizzes are designed to help you revise some of the most important topics from the static part of the syllabus. Attempt today’s subject quiz on Science and Technology to check your progress. Click Here to read the UPSC Essentials magazine for June 2026. Share your views and suggestions in the comment box or at manas.srivastava@indianexpress.com1. It is an orbit where satellites match the planet’s rotation and remain fixed over the same location.2. This orbit is ideal for low-latency telecommunications and microgravity research.3. This orbit contains more space debris than the Low Earth Orbit.Which one of the following conclusions based on the above statements is correct?(a) All three statements are correct.(b) There are two correct statements, that include statement 1.(c) There is only one correct statement.(d) There is no correct statement.Story continues below this adRelevance: Geostationary Orbit (GEO) is a high-priority Science & Technology topic because UPSC frequently asks about satellite orbits (LEO, MEO, GEO, polar and Sun-synchronous orbits), their applications, and associated concepts such as space debris, communication satellites, navigation systems, and Earth observation missions.Explanation— A new study has uncovered a hidden cloud of small space debris in geostationary orbit, one of the most valuable regions around Earth used by communications, weather, and broadcasting satellites. Researchers warn that these tiny fragments could pose a growing collision risk to spacecraft operating there.— Geostationary orbit sits around 36,000 kilometres above Earth, where satellites match the planet’s rotation and remain fixed over the same location. This unique position makes geostationary orbit ideal for television broadcasting, internet connectivity, weather forecasting, and Earth observation. However, the new research suggests the orbital region contains far more debris than earlier surveys detected. Hence, statement 1 is correct and statement 2 is not correct.— Low Earth orbit (LEO) has the highest concentration of space debris due to the presence of the majority of operating satellites, expended rocket stages, and collision pieces. Geostationary Orbit (GEO) also contains debris, but the overall density is far lower than in LEO. Hence, statement 3 is not correct.Therefore, option (c) is the correct answer.QUESTION 2Consider the following statements:Story continues below this ad1. Exhaust gases from lunar landers could pollute ancient ice deposits that have remained largely undisturbed for billions of years.2. The Moon has virtually no atmosphere; methane molecules would travel in ballistic hops across the surface instead of dispersing through the air.Which one of the following is correct in respect of the above statements?(a) Both Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation for Statement 1.Story continues below this ad(b) Both Statement 1 and Statement 2 are correct and Statement 2 is not the correct explanation for Statement 1.(c) Statement 1 is correct but Statement 2 is incorrect.(d) Statement 1 is incorrect but Statement 2 is correct.Relevance: This topic is relevant under Science and Technology (Space Technology). UPSC has increasingly focused on lunar exploration, permanently shadowed regions (PSRs), lunar ice, space missions (Artemis, Chandrayaan), and the scientific challenges of planetary exploration, making such conceptual questions highly probable in Prelims.Explanation— Future crewed missions to the Moon could unintentionally erase some of the oldest chemical evidence linked to the origins of life on Earth, according to a new study that raises concerns about contamination from spacecraft landings. Researchers say exhaust gases from lunar landers could pollute ancient ice deposits that have remained largely undisturbed for billions of years.— The study focuses on permanently shadowed craters near the Moon’s poles, where temperatures are cold enough for ice to survive indefinitely. Scientists believe this ice contains material delivered by asteroids and comets during the early history of the solar system, including prebiotic organic molecules — the building blocks that may have contributed to the emergence of life on Earth. Hence, statement 1 is correct.Story continues below this ad— Using computer simulations, researchers found that methane, a major component of rocket exhaust from planned lunar landers, could spread rapidly across the Moon after a landing. Because the Moon has virtually no atmosphere, methane molecules would travel in ballistic “hops” across the surface instead of dispersing through the air. Hence, statement 2 is correct.Why Statement 2 explains Statement 1: Because the Moon lacks a large atmosphere, exhaust molecules can move ballistically over its surface before becoming locked in cold, permanently shadowed craters containing ancient ice. Thus, spaceship exhaust can contaminate these otherwise clean ice formations.Therefore, option (a) is the correct answer.QUESTION 3The ‘Soyuz MS-29 mission’ is a joint mission of:1. National Aeronautics and Space Administration2. Japan Aerospace Exploration Agency3. Roscosmos4. European Space AgencySelect the correct answer using the codes given below:(a) 1 and 2 only(b) 1 and 3 only(c) 2 and 4 only(d) 3 and 4 onlyRelevance: The Soyuz MS-29 mission is relevant under the Science and Technology section, particularly space technology, international space cooperation, and the International Space Station (ISS). UPSC frequently asks questions on recent space missions, participating space agencies and collaborative programmes.ExplanationStory continues below this ad— Nasa astronaut Anil Menon and Russian cosmonauts Pyotr Dubrov and Anna Kikina are launched to the International Space Station (ISS) aboard Russia’s Soyuz MS-29 spacecraft. The mission was lift off from the Baikonur Cosmodrome in Kazakhstan.— The mission marks the first spaceflight for Anil Menon, who was selected as part of Nasa’s 2021 astronaut class. Before joining Nasa, Menon worked as SpaceX’s first flight surgeon, helping support commercial human spaceflight missions.— The mission will be the second spaceflight for both Dubrov and Kikina. Dubrov previously spent nearly a year aboard the ISS between 2021 and 2022, while Kikina flew to the station on SpaceX’s Crew-5 mission in 2022, becoming the first Russian cosmonaut to travel on a private American spacecraft.— The Soyuz MS-29 mission continues the long-running cooperation between Nasa and Roscosmos, allowing astronauts from both agencies to fly on each other’s spacecraft as part of seat-swap agreements that help maintain continuous operations aboard the International Space Station.Therefore, option (b) is the correct answer.QUESTION 4Consider the following statements:Story continues below this ad1. For every molecule of petrol burnt versus every molecule of ethanol burnt, the carbon dioxide levels would be lesser as the ethanol blend increases.2. Ethanol also has a very high octane number, which has made it a preferred fuel component for high-performance ICEs.3. Ethanol and ethanol-based fuels have historically been used in sports cars because of their superior anti-knock characteristics.How many of the statements given above are correct?(a) Only one(b) Only two(c) All three(d) NoneRelevance: This topic is relevant under Science and Technology and Environment, covering alternative fuels, ethanol blending, octane rating, internal combustion engines, and India’s Ethanol Blended Petrol (EBP) Programme.ExplanationStory continues below this ad— Ethanol is what is called a carbon chain two, that is C2H5OH, whereas petrol being used at the pumps is somewhere much higher in the range in terms of the carbon content — from between C8 and C12. So, for every molecule of petrol burnt versus every molecule of ethanol burnt, the carbon dioxide levels will be necessarily lesser as the ethanol blend increases. Hence, statement 1 is correct.— Ethanol also has a very high octane number, so it can result in a cleaner burn inside an internal combustion engine than pure petrol. It is a fact that ethanol’s exceptionally high-octane number (approximately 108 RON, or Research Octane Number) has made it a preferred fuel component for high-performance ICEs. Hence, statement 2 is correct.— Ethanol and ethanol-based fuels have historically been used in sports cars because of their superior anti-knock characteristics, better power potential and cooling effect stemming from their high latent heat of vaporisation. Most turbocharged and high-compression engines worldwide do rely on ethanol blends to realise higher performance, while simultaneously reducing emissions. Hence, statement 3 is correct.Therefore, option (c) is the correct answer.QUESTION 5With reference to Stuxnet, consider the following statements:1. It is regarded as the world’s first known cyber weapon.2. It was designed mainly to steal financial data from banking institutions.Which of the statements given above is/are correct?(a) 1 only(b) 2 only(c) Both 1 and 2(d) Neither 1 nor 2Relevance: This topic is important for Science and Technology, Internal Security, and Cyber Security. UPSC has increasingly focused on critical infrastructure, emerging technologies, AI, cybersecurity, and strategic affairs, making concepts such as SCADA, PLCs, ICS, Operational Technology (OT), cyber weapons, and AI-assisted cyber warfare highly relevant for both Prelims and Mains.Explanation— The proliferation of artificial intelligence is rapidly transforming warfare, with military applications spanning intelligence, autonomous systems and cyber operations. AI models such as Fable and Anthropic’s Mythos present the latest evolution of cyber warfare.— Stuxnet, which was discovered in 2010, was the world’s first known cyber weapon, demonstrating that malicious code could inflict physical destruction on critical infrastructure rather than merely stealing data or disrupting networks. This marked a turning point in cyber warfare, with its technical innovations paving the way for offensive cyber capabilities. Hence, statement 1 is correct.— Though Stuxnet was first identified in June 2010 by Belarusian malware expert Sergey Ulasen, it entered the global spotlight on July 15, 2010, when investigative journalist Brian Krebs revealed its existence. State-sponsored cyber operations have been part of national security strategies since the 1990s, with campaigns such as Moonlight Maze, Titan Rain and Operation Aurora carrying out espionage, data theft and disrupting networks.— Stuxnet remains the most complex targeted malware the tech community has ever witnessed. It was the first known malicious code designed to cross the cyber realm into the physical world and inflict real damage on a country’s critical infrastructure, in this case nuclear centrifuges at Iran’s Natanz. Hence, statement 2 is not correct.— The malware initially infected the Microsoft operating system, but its precision target was Siemens industrial software such as STEP7, WinCC, and PCS 7 etc — used to programme and monitor PLCs (Programmable Logic Controller which controls motors and valves etc) and SCADA (Supervisory Control and Data Acquisition, a central control system).— After gaining access to the PLCs controlling the centrifuges, Stuxnet remained silent for days while recording normal operations. It then launched planned sabotage cycles by periodically altering valve pressure and centrifuge speed, thereby disrupting the uranium enrichment process.Therefore, option (a) is the correct answer.Previous Daily Subject-Wise-QuizDaily Subject-wise quiz — History, Culture, and Social Issues (Week 159)Daily subject-wise quiz — Polity and Governance (Week 171)Daily subject-wise quiz — Science and Technology (Week 170)Daily subject-wise quiz — Economy (Week 170)Daily subject-wise quiz — Environment and Geography (Week 170)Daily subject-wise quiz – International Relations (Week 170)Subscribe to our UPSC newsletter and stay updated with the news cues from the past week.Stay updated with the latest UPSC articles by joining our Telegram channel – IndianExpress UPSC Hub, and follow us on Instagram and X.