National & International Observances — Key Dates

Why This Chapter Matters

Science and Technology questions in SSC MTS and CHSL split roughly into two buckets: static facts about scientists and inventions that never change, and current developments in space, defence, and digital India that shift every year. Papers usually carry two to four questions from this area, and the current-affairs side is exactly where a well-prepared aspirant pulls ahead of someone who only memorised old textbook facts. The good news is that you do not need to chase a hundred headlines. A handful of landmark achievements, repeated in every major exam cycle, cover almost all the questions asked.

The biggest mistake aspirants make is treating "current" science topics as unpredictable and skipping them entirely, or worse, memorising exact dates and version numbers that change every few months and getting confused during the actual exam. The smarter approach is to lock in the big, stable facts, the mission names, the "first" and "biggest" achievements, the names of scientists behind them, and phrase your understanding in a way that stays true even a year or two later. This chapter walks through India's space programme, defence technology basics, the digital India story including UPI, Aadhaar, and 5G, and finally the historical scientists whose work still gets asked about in every single paper.

1. India's Space Journey and Recent Achievements

The Indian Space Research Organisation (ISRO), headquartered in Bengaluru, is the nodal agency for India's space programme, founded in 1969 under the vision of Dr. Vikram Sarabhai, widely called the father of the Indian space programme. ISRO's story is a genuinely good one to understand rather than just memorise, because once you see the shape of it, individual facts fall into place on their own.

India's biggest space milestone in recent memory is Chandrayaan-3, which successfully landed near the south pole of the Moon on 23 August 2023. This made India the fourth country to achieve a soft landing on the Moon, after the United States, the erstwhile Soviet Union, and China, and importantly, the first country in the world to land near the Moon's south polar region specifically. The government later declared 23 August as National Space Day to mark this achievement every year. The lander module was named Vikram, after Dr. Vikram Sarabhai, and the rover was named Pragyan, meaning wisdom.

Exam trap: Do not confuse Chandrayaan-2 with Chandrayaan-3. Chandrayaan-2, launched in 2019, had its lander crash during descent, though its orbiter continued working and still circles the Moon today collecting data. Chandrayaan-3 corrected the earlier mistakes and achieved the soft landing.

Another landmark mission is Aditya-L1, India's first dedicated mission to study the Sun, launched in September 2023. It was placed in a halo orbit around a gravitationally stable point called Lagrange Point 1 (L1), about 1.5 million kilometres from Earth, from where it can observe the Sun continuously without any eclipse or occultation blocking the view. Aditya-L1 studies the Sun's outer layers, the corona, and solar wind, helping scientists understand solar storms that can affect satellites and power grids on Earth.

ISRO is also working toward Gaganyaan, India's first human spaceflight mission, which aims to send Indian astronauts into low Earth orbit using an Indian-made rocket and spacecraft. Uncrewed test flights have been carried out as preparation, and once achieved, India will join a very short list of nations that have sent humans to space using their own indigenous launch capability.

For everyday reference, remember that ISRO uses two workhorse rocket families: the Polar Satellite Launch Vehicle (PSLV), reliable for launching satellites into polar orbits and famous for placing 104 satellites in a single mission in 2017, and the Geosynchronous Satellite Launch Vehicle (GSLV), used for heavier payloads placed into geostationary orbit. India's Mangalyaan, or Mars Orbiter Mission, launched in 2013, also deserves a mention because it made India the first Asian nation to reach Martian orbit, and it did so in a single attempt, at a strikingly low cost that drew global attention.

Memory hook: Think of ISRO's big missions as chapters of one story: Mangalyaan reached Mars first attempt, Chandrayaan-2 stumbled at the final step, Chandrayaan-3 stuck the landing at the Moon's south pole, Aditya-L1 turned to study the Sun next, and Gaganyaan is the next chapter still being written, aiming to send Indians into space on an Indian rocket.

2. Defence Technology Basics

The Defence Research and Development Organisation (DRDO), headquartered in Delhi, is India's premier defence research agency, responsible for developing missiles, aircraft systems, and other military technology domestically rather than relying entirely on imports.

India's missile programme is best remembered through its major families. The Agni series are long-range ballistic missiles, with Agni-V capable of striking targets thousands of kilometres away, giving India strategic deterrence capability. The Prithvi series are shorter-range ballistic missiles developed earlier in the programme. The Akash missile is a surface-to-air missile designed to intercept aerial threats like enemy aircraft, and it has been inducted into both the Army and the Air Force. BrahMos, developed jointly by India and Russia, is a supersonic cruise missile named by combining the Brahmaputra and Moskva rivers, and it is considered one of the fastest cruise missiles in active service anywhere in the world.

On the aviation side, Tejas is India's indigenously developed light combat aircraft, built by Hindustan Aeronautics Limited (HAL), and its induction into the Air Force is often cited as a milestone for India's "Atmanirbhar Bharat," or self-reliant India, push in defence manufacturing.

India's naval strength includes INS Vikrant, the country's first indigenously built aircraft carrier, commissioned in 2022, built at Cochin Shipyard Limited in Kerala. Its commissioning made India one of a small group of nations capable of designing and constructing an aircraft carrier domestically. India also operates nuclear-powered submarines under the Arihant class, developed as part of its nuclear triad, the ability to launch nuclear weapons from land, air, and sea.

Exam trap: Students often mix up Agni (ballistic missile family, long range, India-developed) with BrahMos (cruise missile, supersonic, jointly developed with Russia). A ballistic missile follows a high arcing trajectory and re-enters the atmosphere to hit its target, while a cruise missile flies close to the ground or sea for most of its journey. If a question mentions "India-Russia joint venture," the answer is almost certainly BrahMos.

3. Digital India: UPI, Aadhaar, and 5G

The Digital India initiative, launched by the Government of India in 2015, aims to transform the country into a digitally empowered society, and several of its outcomes are now tested regularly in exams because they touch nearly every Indian's daily life.

Aadhaar, managed by the Unique Identification Authority of India (UIDAI), is a twelve-digit unique identity number issued to Indian residents based on their biometric and demographic data, and it has become the backbone for identity verification across government schemes, banking, and telecom services. It remains the world's largest biometric identity programme by number of people enrolled.

UPI, or Unified Payments Interface, developed by the National Payments Corporation of India (NPCI), launched in 2016, allows instant money transfer between bank accounts using a mobile phone, without needing to share bank account details each time. UPI transformed India's digital payments landscape so thoroughly that it now handles billions of transactions every month, and its success has made it a model that other countries have shown interest in adopting or linking with, including cross-border UPI arrangements with select nations. Think of UPI as replacing the old habit of carrying exact change; instead of counting coins at a shop, a scan of a QR code settles the payment in seconds.

5G, the fifth generation of mobile network technology, was rolled out commercially in India starting October 2022, offering significantly faster data speeds and lower latency than 4G, which supports technologies like high-quality video streaming, remote surgery trials, and smart city applications. Rollout has continued expanding to more cities and towns since then, though exact coverage figures shift often, so remember the core fact, that 5G brings dramatically faster and more responsive mobile internet, rather than any specific speed number.

Other digital India pillars worth knowing: DigiLocker, a cloud-based platform for storing digital versions of documents like driving licences and educational certificates, verified directly from issuing authorities; CoWIN, the portal built for scheduling and tracking COVID-19 vaccination across the country, which became a global reference model for vaccine rollout at scale; and Jan Dhan Yojana, launched in 2014, which brought banking access to millions of previously unbanked citizens by opening zero-balance bank accounts, later linked with Aadhaar and mobile numbers, a combination often called the JAM trinity (Jan Dhan, Aadhaar, Mobile).

Memory hook: Picture the JAM trinity as three legs of a stool: Jan Dhan gives you a bank account, Aadhaar gives you an identity, and Mobile gives you the device to connect the two instantly. Remove any one leg and the digital payments system, especially UPI, would not stand.

4. Notable Indian Scientists and Their Contributions

Static science-history questions have not gone away just because current affairs gets more attention; if anything, they appear even more reliably because the facts never change. Here are the names that come up again and again.

Sir C.V. Raman won the Nobel Prize in Physics in 1930 for discovering the "Raman Effect," which describes how light changes wavelength when it scatters off molecules, a phenomenon with wide use in analysing chemical structures. He remains the first Asian and the first non-white person to win a Nobel Prize in any science category. National Science Day is celebrated on 28 February every year to mark the day he announced this discovery in 1928.

Dr. Homi J. Bhabha is called the father of India's nuclear programme, founder of the Tata Institute of Fundamental Research (TIFR) and the driving force behind the Atomic Energy Commission of India.

Dr. Vikram Sarabhai, as mentioned earlier, founded ISRO and is remembered as the father of the Indian space programme, and India's rocket launch centre at Thumba, and later the Vikram Sarabhai Space Centre, carry his name.

Dr. APJ Abdul Kalam, often called the Missile Man of India, played a leading role in developing India's missile technology, including the Agni and Prithvi programmes, and served as India's eleventh President from 2002 to 2007. He also contributed significantly to India's Pokhran-II nuclear tests in 1998 as a key figure at DRDO.

Sir Jagadish Chandra Bose was a pioneering physicist and biologist who demonstrated that plants have life and respond to stimuli much like animals do, using an instrument he invented called the crescograph, and he is also credited with early experiments in wireless radio communication, some of which predate Marconi's famous demonstrations.

Srinivasa Ramanujan was a self-taught mathematical genius from Tamil Nadu who made extraordinary contributions to number theory, infinite series, and continued fractions, despite having almost no formal training, and his collaboration with British mathematician G.H. Hardy at Cambridge remains one of the most remarkable stories in the history of mathematics. His birthday, 22 December, is observed as National Mathematics Day.

Har Gobind Khorana, born in undivided Punjab, won the Nobel Prize in Physiology or Medicine in 1968 for research explaining how genetic code controls protein synthesis in cells.

Dr. Salim Ali, often called the Birdman of India, was the country's most influential ornithologist, whose detailed field studies gave India its foundational body of knowledge on bird species and their habitats.

Sir M. Visvesvaraya, a celebrated civil engineer, designed major irrigation and flood-control systems including automatic sluice gates for dams, and his birthday, 15 September, is observed as Engineer's Day across India.

Exam trap: Aspirants often mix up who won which Nobel Prize. Remember: C.V. Raman (Physics, 1930) for light scattering, and Har Gobind Khorana (Physiology or Medicine, 1968) for genetic code research. No Indian scientist working purely within India has won a Nobel Prize in Chemistry as of now, so do not invent one under exam pressure.

5. Other Useful Science and Technology Facts

A handful of standalone facts round out this chapter and appear frequently enough to be worth memorising directly rather than as part of a bigger story.

The Bhabha Atomic Research Centre (BARC), located in Mumbai, is India's premier nuclear research facility, originally established as the Atomic Energy Establishment, Trombay, and renamed in honour of Homi Bhabha after his death. Pokhran, in Rajasthan, is the site of India's nuclear tests, first in 1974 under the codename "Smiling Buddha," and again in 1998 under "Operation Shakti," after which India was formally recognised as a nuclear weapons state by its own declaration.

The Council of Scientific and Industrial Research (CSIR) is India's largest research and development organisation, running numerous national laboratories across disciplines from chemistry to oceanography. The Indian Council of Agricultural Research (ICAR) coordinates agricultural research nationally and was central to the Green Revolution's scientific backbone in the 1960s, alongside the contribution of agricultural scientist Dr. M.S. Swaminathan, often called the father of India's Green Revolution.

On computing and internet milestones, India's first supercomputer, PARAM, was developed indigenously by the Centre for Development of Advanced Computing (C-DAC) in Pune, first launched in 1991, a significant achievement at a time when advanced computing technology was largely restricted from export to India.

Bharat Net, a government project, aims to connect rural India with high-speed broadband internet through optical fibre networks reaching gram panchayats across the country, forming part of the larger Digital India push to close the urban-rural digital divide.

When you see a "recent achievement" question in an SSC paper, anchor your answer to the biggest, most widely reported facts rather than obscure technical details. Examiners writing for a foundational-level paper almost always test whether you know the headline fact, not the fine print.

6. Historical Indian Inventions and Scientific Firsts

A short list of "firsts" rounds out the static side of this subject, and these tend to be asked as standalone one-liners rather than wrapped in a story, so treat them as flashcards.

Aryabhata, the ancient Indian astronomer-mathematician who lived in the fifth century CE, calculated the value of pi to a remarkably accurate approximation for his time and explained that the Earth rotates on its own axis, causing day and night, at a time when most civilisations still believed the sky moved around a stationary Earth. India's first satellite, launched in 1975 with Soviet assistance, was named Aryabhata in his honour, a fitting tribute linking ancient and modern Indian science.

Sushruta, an ancient physician often called the father of surgery, is credited with describing surgical techniques, including early forms of plastic surgery, in his text the Sushruta Samhita, centuries before such methods were documented elsewhere. The concept of zero as a number, essential to modern mathematics and computing, is credited to ancient Indian mathematicians, with Brahmagupta in the seventh century CE providing some of the earliest formal rules for arithmetic with zero.

In more recent history, Jagadish Chandra Bose's wireless signalling demonstrations in Kolkata in 1895 are cited by many historians as happening before Guglielmo Marconi's more famous public demonstrations in Europe, though Marconi is the one who commercialised the technology and is popularly credited with inventing radio. This is a useful fact to know precisely because exams sometimes test the nuance: Bose demonstrated the science first, but did not patent or commercialise it the way Marconi did.

Satyendra Nath Bose, a physicist who collaborated with Albert Einstein, gave his name to an entire class of subatomic particles called bosons, following his statistical work in quantum physics during the 1920s, a rare instance of an Indian scientist's name becoming a permanent part of the vocabulary of physics itself.

On the applied and industrial side, India's first fully indigenous car, the Hindustan Ambassador, rolled off assembly lines in the 1950s, built by Hindustan Motors, and became a familiar sight on Indian roads and in government use for decades. Verghese Kurien, known as the father of the White Revolution, transformed India from a milk-deficient country into the world's largest milk producer through the cooperative dairy model pioneered at Amul in Gujarat, a scientific and organisational achievement that changed rural livelihoods across the country.

7. How Digital India Technologies Connect to Daily Life

It helps to see how the digital India pieces fit together rather than memorising each in isolation, because SSC questions increasingly test this connected understanding rather than pure definitions.

Consider a small shopkeeper in a town today. Her identity is verified through Aadhaar. Her bank account, opened free of cost under Jan Dhan Yojana, is linked to that Aadhaar number and to her mobile number, completing the JAM trinity. When a customer buys something, payment happens instantly through UPI, scanned via a QR code generated by her bank or a payment app, with the transaction settling in seconds without any cash changing hands or any card being swiped. Her business records and licences might be stored securely in DigiLocker, verifiable instantly by any authority that needs to check them, without carrying physical paperwork.

This chain, identity, bank account, mobile connectivity, and instant payment, is what officials mean when they describe India's digital public infrastructure as a model watched by other countries. It did not happen through a single scheme but through several technologies launched separately over roughly a decade, from Aadhaar's rollout starting 2009-10, to Jan Dhan in 2014, to UPI in 2016, converging into the ecosystem visible today. Recognising this layered history helps you answer questions that ask which scheme came first, rather than treating all of Digital India as one single, undated block.

5G technology adds a further layer on top of this foundation, since faster and more reliable mobile internet makes services like video-based bank verification, telemedicine consultations in rural areas, and real-time government service delivery far more practical than they were under 3G or early 4G networks. Combined, these layers explain why India's digital payments volumes are among the highest in the world today, a fact regularly referenced in current-affairs sections of SSC papers.

Quick Revision — One-Line Facts

• ISRO is headquartered in Bengaluru; founded in 1969 by Dr. Vikram Sarabhai.
• Chandrayaan-3 landed near the Moon's south pole on 23 August 2023; that date is now National Space Day.
• India is the fourth country to soft-land on the Moon and the first to land near its south pole.
• The Chandrayaan-3 lander is named Vikram; the rover is named Pragyan.
• Aditya-L1 is India's first Sun-observation mission, placed near Lagrange Point 1.
• Gaganyaan is India's planned first human spaceflight mission.
• Mangalyaan made India the first Asian nation to reach Mars orbit, on its first attempt.
• PSLV and GSLV are ISRO's two main launch vehicle families.
• DRDO is India's premier defence research organisation.
• The Agni series are long-range ballistic missiles; BrahMos is a supersonic cruise missile developed with Russia.
• Tejas is India's indigenous light combat aircraft, built by HAL.
• INS Vikrant, commissioned in 2022, is India's first indigenously built aircraft carrier.
• UIDAI manages Aadhaar, India's biometric identity system.
• UPI was developed by the National Payments Corporation of India (NPCI), launched in 2016.
• 5G services were commercially rolled out in India starting October 2022.
• The JAM trinity stands for Jan Dhan, Aadhaar, and Mobile.
• DigiLocker stores verified digital copies of official documents.
• C.V. Raman won the Nobel Prize in Physics (1930) for the Raman Effect; National Science Day is 28 February.
• Homi J. Bhabha founded TIFR and is called the father of India's nuclear programme.
• APJ Abdul Kalam, the Missile Man of India, was India's eleventh President.
• Jagadish Chandra Bose proved plants respond to stimuli using the crescograph.
• Srinivasa Ramanujan's birthday, 22 December, is National Mathematics Day.
• Har Gobind Khorana won the Nobel Prize in Physiology or Medicine (1968).
• Salim Ali is known as the Birdman of India.
• M. Visvesvaraya's birthday, 15 September, is Engineer's Day.
• India's nuclear tests took place at Pokhran, in 1974 and 1998.
• BARC, located in Mumbai, is India's premier nuclear research centre.
• M.S. Swaminathan is called the father of India's Green Revolution.
• India's first indigenous supercomputer, PARAM, was built by C-DAC, Pune.
• Bharat Net aims to connect rural gram panchayats with broadband internet.

Memory Tables

Key ISRO Missions

Mission	Focus	Key Fact
Mangalyaan (2013)	Mars orbit	First Asian nation to reach Mars, on first attempt
Chandrayaan-2 (2019)	Moon landing attempt	Lander crashed; orbiter still functional
Chandrayaan-3 (2023)	Moon south pole landing	Successful soft landing; 23 August is National Space Day
Aditya-L1 (2023)	Sun observation	Positioned near Lagrange Point 1
Gaganyaan (upcoming)	Human spaceflight	India's first crewed space mission

Scientists and Their Key Contributions

Scientist	Known For
C.V. Raman	Raman Effect; Nobel Prize in Physics, 1930
Homi J. Bhabha	Father of India's nuclear programme; founded TIFR
Vikram Sarabhai	Father of Indian space programme; founded ISRO
APJ Abdul Kalam	Missile Man of India; 11th President
Jagadish Chandra Bose	Proved plant response to stimuli; crescograph
Srinivasa Ramanujan	Number theory; self-taught mathematical genius
Har Gobind Khorana	Nobel Prize in Physiology or Medicine, 1968
Salim Ali	Birdman of India; ornithology
M. Visvesvaraya	Civil engineering; Engineer's Day, 15 September
M.S. Swaminathan	Father of India's Green Revolution

Practice MCQs

Q1. Where is ISRO headquartered? (a) Chennai (b) Bengaluru (c) Thiruvananthapuram (d) Hyderabad

Q2. Chandrayaan-3 achieved a soft landing near which part of the Moon? (a) North pole (b) Equator (c) South pole (d) Dark side

Q3. Which date is now observed as National Space Day in India? (a) 15 August (b) 23 August (c) 2 October (d) 5 September

Q4. What was the name of the Chandrayaan-3 rover? (a) Vikram (b) Pragyan (c) Mangal (d) Aryabhata

Q5. Aditya-L1 is India's mission to study which celestial body? (a) Moon (b) Mars (c) Sun (d) Venus

Q6. Which organisation developed UPI? (a) RBI (b) UIDAI (c) NPCI (d) SEBI

Q7. Aadhaar is managed by which authority? (a) NPCI (b) UIDAI (c) TRAI (d) SEBI

Q8. The JAM trinity stands for Jan Dhan, Aadhaar, and which third element? (a) Money (b) Mobile (c) Market (d) Machine

Q9. BrahMos, a supersonic cruise missile, was jointly developed by India and which country? (a) United States (b) France (c) Russia (d) Israel

Q10. INS Vikrant, commissioned in 2022, is significant because it is India's first what? (a) Nuclear submarine (b) Indigenous aircraft carrier (c) Guided missile destroyer (d) Stealth frigate

Q11. C.V. Raman won the Nobel Prize in Physics for discovering what? (a) Theory of relativity (b) Raman Effect (c) Radioactivity (d) X-rays

Q12. Who is known as the Missile Man of India? (a) Homi Bhabha (b) Vikram Sarabhai (c) APJ Abdul Kalam (d) C.V. Raman

Q13. National Mathematics Day, 22 December, marks the birthday of which mathematician? (a) Aryabhata (b) Srinivasa Ramanujan (c) C.R. Rao (d) Satyendra Nath Bose

Q14. Har Gobind Khorana won the Nobel Prize in which field? (a) Physics (b) Chemistry (c) Physiology or Medicine (d) Peace

Q15. Tejas, India's indigenous light combat aircraft, is built by which organisation? (a) DRDO alone (b) Hindustan Aeronautics Limited (c) ISRO (d) BEL

Answer Key

Q	Answer	Reason
1	(b) Bengaluru	ISRO's headquarters and main command centre are based here
2	(c) South pole	India became the first country to land near this region
3	(b) 23 August	Date of Chandrayaan-3's successful landing in 2023
4	(b) Pragyan	Vikram was the lander; Pragyan was the rover, meaning wisdom
5	(c) Sun	Placed near Lagrange Point 1 for uninterrupted solar observation
6	(c) NPCI	National Payments Corporation of India built UPI in 2016
7	(b) UIDAI	Unique Identification Authority of India issues Aadhaar numbers
8	(b) Mobile	Mobile links the bank account and identity for digital transactions
9	(c) Russia	Named after the Brahmaputra and Moskva rivers
10	(b) Indigenous aircraft carrier	Built at Cochin Shipyard Limited, commissioned 2022
11	(b) Raman Effect	Describes scattering of light causing wavelength change
12	(c) APJ Abdul Kalam	Central to Agni and Prithvi missile development at DRDO
13	(b) Srinivasa Ramanujan	Self-taught genius in number theory, born 22 December 1887
14	(c) Physiology or Medicine	Awarded in 1968 for genetic code research
15	(b) Hindustan Aeronautics Limited	HAL manufactures the Tejas light combat aircraft