BharatNotes S&T has ranged from 4 to 14 questions per paper (2019-2025 average approximately 8-9 questions). It is the most current-affairs-dependent subject — about 70 percent of S&T questions are from the last 12-18 months of developments. Key themes for 2025-26: ISRO missions (SpaDeX docking, NVS-02, NISAR), Gaganyaan programme, AI/semiconductor policy, defence R&D (DRDO), and biotechnology.
Science and Technology is the subject that most resembles a lottery in UPSC Prelims — not because it is random, but because the question count varies more dramatically than any other subject. Post-exam analyses from 2019-2025 show S&T ranging from approximately 4 questions (2023) to 13-14 questions (2021, 2025), with most years falling between 7 and 10. This variance makes it uniquely difficult to optimise: too much time spent on S&T in a 4-question year is a poor allocation; too little in a 14-question year costs you 28 marks.
The strategic response to this variance is to cover S&T efficiently through current affairs rather than through static books. Unlike Polity or Geography, where static foundations dominate, approximately 60-70 percent of S&T Prelims questions in recent years have been directly triggered by current affairs — a mission launched, a policy announced, a technology tested. This means that a candidate with excellent daily current affairs habits and a moderate S&T conceptual base outperforms a candidate who has read every physics and chemistry NCERT but skipped The Hindu Science page for six months.
Key S&T themes for Prelims 2026 (verified 2024-2026 developments):
Space policy and ISRO missions: The most exam-relevant ISRO developments of the 2024-2026 cycle:
- SpaDeX (Space Docking Experiment): PSLV-C60 launched both SDX01 and SDX02 spacecraft on December 30, 2024. India successfully completed in-space docking on January 16, 2025, making India the fourth country in the world (after USA, Russia, China) to achieve space docking capability. This is a foundational technology for Chandrayaan-4 (lunar sample return) and the Indian Space Station.
- NVS-02: Launched January 29, 2025 aboard GSLV-F15. The 100th mission from ISRO's Sriharikota spaceport. Second satellite in the NavIC (Navigation with Indian Constellation) new generation.
- NISAR (NASA-ISRO Synthetic Aperture Radar): Launched July 30, 2025. A joint NASA-ISRO Earth observation satellite studying surface changes related to earthquakes, landslides, glaciers, forests, and agriculture. The largest-ever science collaboration between ISRO and NASA.
- Gaganyaan programme: The programme involves a series of uncrewed test flights before India's first crewed mission (currently targeted for 2027). Gaganyaan developments are tracked in PIB regularly and are high-frequency Prelims material.
AI and semiconductor policy: The IndiaAI Mission (launched 2024) aims to build India's AI ecosystem through compute infrastructure, datasets, and startup support. The India Semiconductor Mission focuses on building domestic chip manufacturing capability (Tata Electronics fab in Dholera, Micron plant in Sanand). Questions on these typically test the nodal ministry (MeitY), the associated Mission name, and the budgetary allocation.
Defence R&D: DRDO's key 2024-25 developments include successful tests of long-range hypersonic missile (December 2024), Agni-V MIRV capability, and the Light Combat Aircraft Tejas Mark 2 programme. The iDEX (Innovations for Defence Excellence) framework and the Atmanirbhar Bharat Defence Production policy are also exam-relevant.
Biotechnology: The Biological Diversity Amendment Act 2023 (which came into force 2024) significantly changed how traditional knowledge and biological resources are accessed under India's framework. Gene therapy approvals and mRNA vaccine technology (from COVID era) remain tested topics. The National Biotechnology Development Strategy 2021-2025 is a policy document worth reviewing.
How to study S&T for Prelims: Three sources are sufficient. First, NCERT Class 9 and 10 Science for static fundamentals (materials, disease, electricity, environment-science interface). Do not go beyond Class 10 Science for static study — Class 11-12 Science is not tested in Prelims at the specific depth those textbooks go into. Second, Science Reporter (CSIR monthly magazine) for cutting-edge S&T in Indian context. Third, PIB releases tagged under 'Science & Technology' and 'Space' — these are the primary source for ISRO, DRDO, and biotech announcements. With these three sources and consistent daily reading, you can cover the realistic S&T Prelims universe in approximately 45 minutes per day during the CA reading phase of preparation.
