On 8 and 9 October 2026, a row broke out over satellite internet. SpaceX's chief executive alleged on social media that its Starlink service was being blocked in India by "certain oligarchs". The Ministry of Communications replied that India's authorisation framework for satellite communication is "fair and non-discriminatory", that no applicant has yet been cleared to launch services, and that a security assessment is under way for all three licensees: Starlink, the Bharti-backed Eutelsat OneWeb, and Jio Satellite Communications. After that assessment, a licensee may seek the assignment of spectrum. The Ministry said the three are "at broadly the same regulatory stage" and called the charge of unfairness "baseless and misconceived". Each holds a GMPCS licence (Global Mobile Personal Communication by Satellite) from the Department of Telecommunications; Starlink has also received (in July 2025) the authorisation of IN-SPACe, the Department of Space's body for private space activity. The papers reported a worry about foreign operators bypassing Indian gateways, and that Jio is planning its own low-orbit constellation of about 1,600–1,650 satellites.
The same morning, an article in The Hindu on stubble burning explained that the official count of farm fires uses NASA's MODIS and VIIRS sensors on polar-orbiting satellites, whose daytime passes over India fall only between about 10:30 a.m. and 1:30 p.m. A study led by ISRO scientists using a geostationary satellite found that farmers had shifted burning to the evening, to avoid the polar satellites. Two stories, one lesson: a satellite's orbit decides what it can see, when it can see it, how fast it can talk to you, and how many satellites you need. A satellite-internet company chooses a low orbit for speed; a weather service chooses a high one for a constant view; a fire counter on a sun-synchronous orbit sees the same hour every day, and a clever farmer can learn that hour. That is today's concept: orbits.
Concept Booster · Officer's Lens · Science, Tech & Health · Class 1
Why can't one satellite do everything? Orbits (LEO, GEO, sun-synchronous and polar) through a satellite-internet row and a farm fire that hides from the sky
एक उपग्रह सब कुछ क्यों नहीं कर सकता? कक्षाएँ (निम्न भू, भूस्थिर, सूर्य-तुल्यकाली और ध्रुवीय): एक उपग्रह-इंटरनेट विवाद और आकाश से छिपती पराली की आग के सहारे
KnowWhat keeps a satellite up, why height decides speed and period, and what LEO, MEO, GEO, sun-synchronous, polar and transfer orbits are and what each is good for.
LinkHow one idea ties satellite internet, cyclone warnings, crop-fire counts, NavIC, launch sites, spectrum law and space debris into a single question: which orbit for which job?
FeelThe nurse in a hill clinic with a frozen video call, the farmer who learns when the satellite passes, the fisherman waiting for a cyclone alert: orbits are lived on the ground.
DecideThe note an officer writes when a vendor, a department and a citizens' group all want "satellites" and each means a different orbit.
1The file on your desk
URGENT · FOR DECISION
To: Secretary, Information Technology and Disaster Management, a State government
Subject: "Use satellites": four proposals, one Cabinet meeting
It is the second week of October. The Chief Minister wants a single note before Monday's Cabinet. Four papers are on your table.
(1) A private vendor offers a "pre-booking agreement" for low-orbit satellite broadband for 300 remote schools and health centres that have no fibre and weak mobile signal. The provider it names holds a licence but has not yet been cleared by the Union government to start service. The vendor wants a State order this month.
(2) The Health Department: telemedicine calls from some sub-centres run on old satellite (VSAT) links through a geostationary satellite. Doctors complain that voices overlap, "as if the other side is always half a second late".
(3) The Agriculture Department: official satellite counts of crop-residue fires in two districts are far lower than last year, and the Department wants to announce a success. Block officers write that fires are "still happening, only later in the day".
(4) A citizens' forum petitions the State to "ban foreign satellites from flying over our State" for security reasons.
Monsoon rains failed this year, a strong El Niño is forecast, and the cyclone season on the coast is not over. The Secretary wants one page: what the State does now, what it waits for, what it asks of the Centre, and what it cannot do. You have 24 hours.
To: Secretary, Information Technology and Disaster Management, a State government
Subject: "Use satellites": four proposals, one Cabinet meeting
It is the second week of October. The Chief Minister wants a single note before Monday's Cabinet. Four papers are on your table.
(1) A private vendor offers a "pre-booking agreement" for low-orbit satellite broadband for 300 remote schools and health centres that have no fibre and weak mobile signal. The provider it names holds a licence but has not yet been cleared by the Union government to start service. The vendor wants a State order this month.
(2) The Health Department: telemedicine calls from some sub-centres run on old satellite (VSAT) links through a geostationary satellite. Doctors complain that voices overlap, "as if the other side is always half a second late".
(3) The Agriculture Department: official satellite counts of crop-residue fires in two districts are far lower than last year, and the Department wants to announce a success. Block officers write that fires are "still happening, only later in the day".
(4) A citizens' forum petitions the State to "ban foreign satellites from flying over our State" for security reasons.
Monsoon rains failed this year, a strong El Niño is forecast, and the cyclone season on the coast is not over. The Secretary wants one page: what the State does now, what it waits for, what it asks of the Centre, and what it cannot do. You have 24 hours.
The file is a composite for teaching; no real office, vendor or person is described.
2The story
3The skeleton: physics, orbits, law and institutions
3a. Why a satellite does not fall (or rather, keeps falling and missing)
Newton's thought experiment: from a high mountain, fire a cannonball so fast that the ground curves away beneath it as quickly as it falls. It never lands. That is an orbit: free fall with enough sideways speed, about 7.8 km per second near the Earth (escape velocity, to leave the Earth altogether, is about 11.2 km/s).
• Gravity weakens with height, so a higher satellite needs less speed and has a longer path: the higher the orbit, the slower the satellite and the longer its period (Kepler's third law: the square of the period is proportional to the cube of the orbit's size). The satellite's own mass does not matter.
• Inclination is the angle between the orbit's plane and the Equator: 0° is equatorial, 90° is polar, above 90° means moving against the Earth's rotation (retrograde).
Rule of thumb: height decides period and speed; inclination decides which parts of the Earth the satellite flies over.
• Gravity weakens with height, so a higher satellite needs less speed and has a longer path: the higher the orbit, the slower the satellite and the longer its period (Kepler's third law: the square of the period is proportional to the cube of the orbit's size). The satellite's own mass does not matter.
• Inclination is the angle between the orbit's plane and the Equator: 0° is equatorial, 90° is polar, above 90° means moving against the Earth's rotation (retrograde).
Rule of thumb: height decides period and speed; inclination decides which parts of the Earth the satellite flies over.
3b. The family of orbits
| Orbit | What it is, and what it is used for |
|---|---|
| Low Earth Orbit (LEO) | Roughly up to 2,000 km; one circuit in about 90 to 120 minutes (the space station, at about 400 km, goes round about 16 times a day). Sharp pictures, short signal delay, cheaper launches. But each satellite sees a small patch for a few minutes, so continuous service needs a constellation of hundreds or thousands with hand-overs. Uses: satellite broadband (Starlink, OneWeb), the space station, many imaging satellites. |
| Medium Earth Orbit (MEO) | Between LEO and GEO. The US GPS satellites fly at about 20,200 km and circle twice a day. Uses: global navigation (GPS, GLONASS, Galileo, part of BeiDou). |
| Geostationary Orbit (GEO) | About 35,786 km above the Equator, in its plane, moving eastward once per sidereal day (23 h 56 min), so it seems fixed in the sky and a dish never has to move. One satellite sees about two-fifths of the Earth. The cost is delay: the signal travels at least about 72,000 km up and down, about a quarter of a second one way, half a second for a question and its answer (from about 550 km up, only a few milliseconds). Uses: TV, VSAT links, weather watching (INSAT-3D series), part of NavIC. |
| Geosynchronous Orbit (GSO) | Any orbit with the one-sidereal-day period. If tilted, the satellite traces a figure-of-eight over the same longitude instead of standing still. NavIC uses both GEO and inclined GSO satellites. |
| Polar Orbit | Inclination near 90°: the satellite passes near both poles while the Earth turns beneath it, so over days it sees the whole globe. Uses: mapping, weather sounding, reconnaissance. |
| Sun-Synchronous Orbit (SSO) | A near-polar LEO, usually about 600–800 km high and tilted about 98° (slightly retrograde). The Earth's equatorial bulge turns the orbit's plane by about 1° a day, matching the Earth's yearly journey round the Sun, so the satellite crosses a given latitude at the same local solar time on every pass: comparable light and shadows, season after season. Uses: earth observation (Cartosat, Resourcesat, Oceansat; the satellites carrying NASA's MODIS and VIIRS). |
| Highly Elliptical Orbit (HEO) | Egg-shaped: close at perigee, far at apogee, where the satellite lingers. The Russian Molniya type (about 63.4°, 12-hour period) serves high latitudes that GEO sees only near the horizon. |
| Geosynchronous Transfer Orbit (GTO) | A road, not a home: an ellipse with its high point near GEO height. The GSLV or LVM3 drops a communication satellite here; the satellite's own engine then raises it to GEO. |
| Beyond Earth orbit | Lagrange points, where the pulls of the Sun and the Earth balance a spacecraft's motion: Aditya-L1 circles L1, about 1.5 million km away. |
3c. The legal and institutional frame
| Provision or body | What it does for this concept |
|---|---|
| Union List Entry 31; Article 73 | "Posts and telegraphs; telephones, wireless, broadcasting and other like forms of communication" is a Union subject. Space as such is named in no List; the Union runs it through its executive power. |
| Outer Space Treaty, 1967 (India a party) | Article II: no nation can claim outer space by sovereignty, use or occupation. Article VI: states bear international responsibility for national space activities, including those of private companies, which need "authorization and continuing supervision". Article VII: liability for damage (with the Liability Convention, 1972, and the Registration Convention, 1975). Article 51(c) of our Constitution asks the State to foster respect for such treaty obligations. |
| International Telecommunication Union (ITU) | The UN agency whose Radio Regulations govern how countries file and coordinate frequencies and orbital positions, including GEO "slots", so satellites do not jam one another. |
| ISRO, Department of Space, NSIL, IN-SPACe | ISRO (1969) builds and launches; the Department of Space and Space Commission (1972) set policy; NewSpace India Limited (2019) sells launches and capacity; IN-SPACe (2020) promotes and authorises private space activity, which is the Article VI duty in Indian form. The Indian Space Policy, 2023 sets their roles. |
| Department of Telecommunications; MHA | The DoT grants the service licence (for satcom, GMPCS) with security conditions and assigns spectrum; the Telecommunications Act, 2023 (Section 4(4) read with the First Schedule) provides for spectrum for certain satellite services to be assigned administratively rather than auctioned. The Home Ministry examines security conditions such as Indian gateways and lawful interception. |
3d. How satellite internet actually flows
Your user terminal (a small dish) talks to a satellite, which talks to a gateway earth station that joins the internet. In GEO, one satellite and a few gateways can serve a country. In LEO, the satellite overhead keeps changing, so the network needs many gateways or laser links between satellites that carry traffic across the sky before bringing it down. That is the heart of today's security worry: traffic that lands at a gateway outside India is beyond Indian lawful interception and data rules.
Rule of thumb: orbit decides physics; the gateway decides jurisdiction.
Rule of thumb: orbit decides physics; the gateway decides jurisdiction.
4The fine print — what separates a topper from the rest
1. Every geostationary orbit is geosynchronous; not every geosynchronous orbit is geostationary. GEO needs three things together: a one-sidereal-day period, a circular orbit and zero inclination. Tilt it and you get an inclined GSO, which wanders north and south of the Equator each day. NavIC's four inclined GSO satellites do exactly this, which improves the geometry of the position fix over India.
2. "Sun-synchronous" is an Earth orbit, not a solar one. It is synchronised with the Sun's apparent position, not orbiting it. It works only because the Earth's equatorial bulge drags the orbit's plane round; that is why SSOs are slightly retrograde (about 97°–99°), "near-polar" rather than polar. Not every polar orbit is sun-synchronous. A "dawn–dusk" SSO rides the line between day and night, keeping its solar panels in constant sunlight, which suits radar satellites.
3. Faster is lower, slower is higher. A GEO satellite moves at about 3 km/s, far slower than the space station's 7.7 km/s, yet it "stays over" one place because its circle is huge. To catch up with a satellite ahead of you in the same orbit, you first slow down to drop lower, where you go round faster. Examiners love the counter-intuitive version.
4. The orbit sets a timetable, and people can read timetables. A sun-synchronous satellite crosses Punjab at roughly the same clock hour every day; burn after the overpass and the fire vanishes from the count. A geostationary sensor watches all day but with coarser detail. Good policy combines both, plus ground checks. The lesson travels: any fixed-time inspection invites people to work around its timing.
5. Low orbit is not simply "better". LEO gives speed and sharp images, but needs thousands of satellites, many gateways and frequent replacement (drag pulls low satellites down within years), and adds to crowding and collision risk. GEO gives wide, steady coverage with few satellites, but with delay, weak coverage near the poles and costly launches. MEO is the compromise that navigation chose.
6. Space is not territory. A country's sovereignty covers its airspace (the Chicago Convention, 1944), but outer space cannot be appropriated (Outer Space Treaty, Article II). In 1976 eight equatorial countries issued the Bogotá Declaration claiming the GEO segment above their territory; the claim found no acceptance. There is no treaty boundary between air and space; about 100 km (the "Kármán line") is a common convention. So a State, or even India, cannot "ban" foreign satellites from flying overhead. What a country controls is service on its soil: licences, terminals, spectrum, gateways.
7. GEO slots are scarce and contested. There is only one ring over the Equator, and satellites on the same frequencies must be spaced apart; developing countries have long argued that early ITU filers gained an unfair head start. A dead GEO satellite is pushed a few hundred kilometres higher into a "graveyard orbit" to free its slot.
8. Spectrum is a public resource, and how it is given is a constitutional question. In Secretary, Ministry of I&B v. Cricket Association of Bengal (1995), the Supreme Court held that airwaves are public property to be used for public good. In Centre for PIL v. Union of India (2012, the 2G case), it cancelled licences given on a first-come basis and favoured auction; but in the Natural Resources Allocation Presidential Reference (2012), it held that auction is not a constitutional mandate for every resource: any method that is fair, transparent and serves the common good can be valid. The 2005 Antrix–Devas deal for satellite S-band spectrum was annulled in 2011, and in 2022 the Supreme Court upheld the winding-up of Devas for fraud.
5How the idea grew
1609 → 1687Kepler's laws of planetary motion (the third in 1619); Newton's Principia (1687) explains orbits by universal gravitation.
1945Arthur C. Clarke's article "Extra-Terrestrial Relays" proposes three satellites in the 24-hour orbit to relay signals across the world. The GEO ring is still called the "Clarke belt".
1957The Soviet Union launches Sputnik 1 (4 October) into low orbit: the space age begins.
1962 → 1969INCOSPAR is formed under Vikram Sarabhai (1962); the first sounding rocket rises from Thumba (21 November 1963); the Outer Space Treaty (1967); ISRO is formed (15 August 1969).
1975 → 1976Aryabhata, India's first satellite, is launched by the Soviet Union (19 April 1975). The Satellite Instructional Television Experiment (SITE) uses a NASA satellite to beam educational TV to about 2,400 villages.
1980 → 1983SLV-3 places Rohini in orbit from Sriharikota (July 1980). APPLE, India's first experimental communication satellite, reaches GEO (1981). INSAT-1B (1983) begins the INSAT system for telecom, TV and weather.
1988 → 1994IRS-1A, India's first remote-sensing satellite, goes into a sun-synchronous orbit (1988, Soviet launch). The PSLV, named for its ability to reach polar and sun-synchronous orbits, succeeds for the first time (October 1994).
2001 → 2013The GSLV, built to reach GTO, makes its first flight (2001). IRNSS-1A, the first NavIC satellite, is launched (2013).
2019 → 2020Mission Shakti (27 March 2019): India destroys one of its own satellites in LEO with an anti-satellite missile. NSIL is set up (2019); the space sector is opened to private enterprise and IN-SPACe is created (June 2020).
2022 → 2023ISRO's LVM3 launches 72 OneWeb broadband satellites to LEO in two missions (October 2022, March 2023). The Indian Space Policy, 2023 is approved; Aditya-L1 is launched towards the L1 point (September 2023). The Telecommunications Act, 2023 is passed.
2024 → 2025INSAT-3DS, a geostationary weather satellite, is launched (February 2024). The DoT grants Starlink a GMPCS licence (June 2025) after a wait of about three years; IN-SPACe's authorisation follows (July 2025).
October 2026The licensing row: the Ministry says all three satcom licensees are under security assessment and none is cleared to launch. The same week, the finding that farm fires shifted to evenings to dodge polar satellites enters the stubble debate.
6One issue, six lenses
Polity & law
Satellite communication is a Union subject (Entry 31); private space activity needs authorisation because Article VI of the Outer Space Treaty makes India answerable for it; spectrum is public property (Cricket Association of Bengal) to be given fairly (2G, the 2012 Reference).Carry: the sky above is no one's, but the service on the ground is India's to licence.
Social justice
Fibre and towers reach dense, paying areas first. Islands, mountains, deserts and forests need satellites most, and can least afford a costly terminal.Carry: the right orbit can close the digital divide; the wrong price can widen it.
Governance
Earth observation from SSO drives crop insurance, flood mapping, forest cover and stubble counts; GEO feeds cyclone warnings. A measuring tool with a blind hour can make a policy look successful when it is not.Carry: know your instrument's blind spots before you announce your results.
Economy
LEO constellations cost billions and need scale; GEO capacity is mature. Launch services (LVM3 for OneWeb) earn foreign exchange; competition among licensees should lower prices.Carry: the orbit sets the business model: many cheap satellites or a few costly ones.
Ethics
Fair rules applied equally, reasons for delay given, no shortcut for the loudest voice. Space is a commons: dead satellites left in a crowded orbit harm everyone after.Carry: impartiality to every applicant, and responsibility to every future user of the sky.
Citizen & nation
A child in a remote hamlet deserves an online class; the nation deserves to know where its data lands. Security and access are both national interests, and a good regulator serves both without letting either become an excuse.Carry: connect every citizen, but on terms India can supervise.
7From paper to village — the implementation chain
1
International filing: the satellite's frequencies and orbit are filed and coordinated through the ITU; the operator's home country registers the object. Breaks if: filings are delayed or slots are occupied by others first.
2
Space authorisation: IN-SPACe authorises the space segment that serves India, under the Space Policy, 2023. Breaks if: rules are unclear or slow, and private investment waits.
3
Service licence and security: the DoT's GMPCS licence; security conditions (Indian gateways, lawful interception, data handling) checked with the MHA. Breaks if: the assessment has no timeline or reasons, and a fair process looks unfair.
4
Spectrum: assigned to the cleared licensee, with a price and conditions. Breaks if: the method or price is opaque, inviting the suspicion that history (2G, Antrix–Devas) has taught.
5
Gateways and terminals: earth stations built in India; user terminals imported or made here, certified and sold. Breaks if: terminals cost more than a family earns in a month.
6
State and district: States connect schools, health centres and panchayat offices; the district disaster cell keeps satellite phones and uses GEO weather alerts and SSO flood maps. Breaks if: equipment sits in a store, untested, until the cyclone arrives.
7
The village: a teacher, a nurse, a fisherman, a farmer using the link or the alert. Breaks if: no one local knows how to fix the dish, or the subscription lapses after the launch photograph.
8Who wants what
| Stakeholder | Wants | Fears | Their fair point |
|---|---|---|---|
| Foreign LEO operator | Quick approval to sell service | Endless delay while rivals catch up | It has invested heavily and holds licences; it says it serves areas others do not. |
| Indian licensees and telecom firms | A level field and time to build their own constellations | A foreign giant with thousands of satellites taking the market first | The same rules must apply to all; national capacity matters. |
| Security agencies | Traffic that lands in India and can be lawfully intercepted | Services that bypass Indian gateways | Satellite links have been used in crises and conflicts; control over a network is not a formality. |
| Remote users (schools, clinics, islands, armed forces posts) | Fast, affordable, reliable internet now | Being forgotten while the big players argue | They have waited longest for fibre and towers. |
| Scientists and earth-observation users | More satellites, more orbits, open data | Bright constellations and debris spoiling observations and orbits | Space is a shared commons that needs rules for everyone. |
| Farmers and the Agriculture Department | Help to manage straw, and fair counting | Being blamed or fined on one partial measure | Fires counted by a single satellite timetable miss the full picture. |
9The human side — EQ, citizen first, nation first
The people behind the file. A nurse in a hill sub-centre holds a feverish child up to a webcam; the doctor's reply arrives half a second late, they talk over each other, and she gives up and sends the family on a five-hour bus ride. A small farmer in Punjab has no machine to clear the straw before wheat sowing; neighbours say the satellite "comes before lunch", so he waits until evening. A fisherman's family on the coast waits for the cyclone bulletin.
An officer with emotional intelligence sees that each is acting rationally. The nurse needs a lower-delay link, not a lecture on bandwidth. The farmer needs a machine, a fair price for straw and a measure he cannot dodge, not just a fine. The fisherman's family needs the geostationary satellite's steady watch, turned into a warning in their language. She does not mock the forum that wants to "ban satellites"; she explains that outer space belongs to no country and India's real control lies in licences, gateways and spectrum.
Citizen first: connect the school and the clinic with the best service lawfully available today, and count fires honestly even if the number is unwelcome. Nation first: insist that every operator, Indian or foreign, meets the same security conditions, and build India's own capacity in launchers, satellites and orbits, so that the nation's connectivity never depends on one company's goodwill.
An officer with emotional intelligence sees that each is acting rationally. The nurse needs a lower-delay link, not a lecture on bandwidth. The farmer needs a machine, a fair price for straw and a measure he cannot dodge, not just a fine. The fisherman's family needs the geostationary satellite's steady watch, turned into a warning in their language. She does not mock the forum that wants to "ban satellites"; she explains that outer space belongs to no country and India's real control lies in licences, gateways and spectrum.
Citizen first: connect the school and the clinic with the best service lawfully available today, and count fires honestly even if the number is unwelcome. Nation first: insist that every operator, Indian or foreign, meets the same security conditions, and build India's own capacity in launchers, satellites and orbits, so that the nation's connectivity never depends on one company's goodwill.
10The concept web — where this sits in your mind
Launch vehicles — PSLV for polar and sun-synchronous orbits, GSLV and LVM3 for GTO, SSLV for small LEO payloads; why the orbit decides the rocket (scitech-002). Darpan Lens: horizon.
Communication satellites — GEO broadcasting and VSAT, high-throughput satellites, LEO broadband constellations (scitech-004).
Remote sensing & fires — SSO imaging, revisit time, resolution versus coverage, and today's stubble-fire counting gap (scitech-006; GS3 environment and agriculture).
NavIC — three GEO and four inclined GSO satellites over India and the region around it (scitech-005).
Space debris & OST — crowded LEO, collision cascades, graveyard orbits, Mission Shakti and the treaty duties (scitech-012, scitech-013). Darpan Lens: global.
IN-SPACe reforms — authorisation, NSIL, private launchers and satellites, the Space Policy, 2023 (scitech-011).
Spectrum & telecom — the Telecommunications Act, 2023, administrative assignment versus auction, the 2G and Natural Resources cases (scitech-033; GS2 governance).
Lagrange points — where Earth orbits end and Aditya-L1's halo orbit begins (scitech-009).
On the website, each of these opens its own class as the library grows. Each new class adds lines to this web.
11Your decision — back to the file
You are the Secretary. Choose the line you will send to the Chief Minister:
The note an officer would write
1. "Use satellites" means different orbits for different jobs: geostationary (GEO) for steady wide coverage and weather; low-earth orbit (LEO) for low-delay broadband; sun-synchronous orbit (SSO) for regular imaging at a fixed local time.
2. Connectivity: schools and health centres to be connected now through services already authorised for India, upgrading GEO links where possible. A technology-neutral tender to be framed: any operator may bid once it holds the DoT licence, IN-SPACe authorisation, security clearance and assigned spectrum. No pre-booking with an operator not yet cleared. Telemedicine sites to get low-delay links first when available.
3. Farm fires: the lower count comes from polar satellites whose daytime passes come about 10:30 a.m.–1:30 p.m.; field reports suggest burning has moved to the evening. No announcement until counts from polar and geostationary data and field verification agree. Enforcement to be paired with machines and straw-purchase support.
4. Cyclone season: GEO weather imagery and bulletins to reach coastal villages in the local language; satellite phones in each coastal block to be tested this week.
5. The forum's petition: outer space cannot be appropriated by any country (Outer Space Treaty, Art. II); India regulates service on its soil through licences, gateways and spectrum. A plain-language reply to be sent.
6. Request to the Union: share timelines for the security assessment and spectrum assignment; consider affordable terminals for public institutions.
7. What the State will not do: sign with an uncleared provider, issue an order it has no power to issue, or publish a number it knows is incomplete.
8. Submitted for approval.
12How the exam asks it
| Paper | How this concept serves you |
|---|---|
| Prelims | Heights and periods of LEO, MEO and GEO; GEO versus GSO; why SSOs are retrograde and near-polar; why polar satellites suit mapping; GTO; which Indian satellites use which orbit (INSAT, Cartosat, NavIC); Lagrange points; the Outer Space Treaty; IN-SPACe and NSIL. |
| GS3 — Science & Technology | "Awareness in the fields of IT, Space, Computers, robotics, nano-technology, bio-technology and issues relating to intellectual property rights"; "Science and Technology — developments and their applications and effects in everyday life"; "Achievements of Indians in science & technology; indigenization of technology and developing new technology." |
| Essay | "What we measure is what we manage, and what we cannot see we cannot fix"; "The sky belongs to no one, the service belongs to everyone." |
| Interview | "If you were Collector of a remote island district, would you wait for fibre or connect by satellite? Which orbit, and why?" |
Trap: "A geostationary satellite does not move." — False; it moves at about 3 km/s, eastward, in step with the Earth's rotation. It only appears still from the ground.
Trap: "A sun-synchronous orbit is an orbit around the Sun." — False; it is an Earth orbit whose plane keeps a fixed angle to the Sun, so it passes each place at the same local solar time.
Trap: "Satellites in higher orbits move faster because they need more energy to stay up." — False; higher orbits are slower and have longer periods (Kepler's third law), though reaching them takes more energy from the rocket.
Trap: "Every geosynchronous satellite is geostationary." — False; only the circular, zero-inclination one is. NavIC's inclined GSO satellites trace a figure-of-eight.
Mains practice 1 (GS3)
"The choice of orbit determines the purpose a satellite can serve." Explain with reference to communication, navigation and earth-observation satellites in India. (10 marks, 150 words)Model approach
Directive — Explain: make the cause-and-effect clear. Introduction: an orbit is free fall with sideways speed; height decides speed, period and view. Body: GEO (35,786 km) for constant wide coverage: INSAT/GSAT for TV, VSAT and weather; inclined GSO and GEO for NavIC's regional coverage; SSO (about 600–800 km, about 98°) for same-time imaging: Cartosat, Resourcesat; LEO constellations for low-delay broadband. Today's example: SSO overpass times and the evening shift in stubble burning. Conclusion: a mix of orbits, matched to the task, gives India complete and honest information.Mains practice 2 (GS3)
"Low-earth-orbit satellite constellations can bridge India's digital divide, but they raise questions of security, competition and space sustainability." Discuss. (15 marks, 250 words)Model approach
Directive — Discuss: both sides, then a view. Introduction: LEO broadband: low delay, needs thousands of satellites; three GMPCS licensees in India; the October 2026 row. Benefits: remote areas, disaster resilience, schools, telemedicine. Concerns: security (gateways, lawful interception) and the Outer Space Treaty's Article VI duty of supervision; competition and fair spectrum assignment (Cricket Association of Bengal; 2G; the 2012 Reference); affordable terminals; debris in LEO. Way forward: time-bound, reasoned security assessments applied equally; transparent spectrum terms; Indian constellations and launch capacity; deorbit rules. Conclusion: connect every citizen on terms India can supervise and the sky can sustain.13Check yourself
1. Why does a satellite in orbit not fall to the Earth?
Answer
It is always falling, but moves sideways so fast (about 7.8 km/s near the Earth) that the ground curves away beneath it as fast as it falls.2. State the relation between an orbit's height, speed and period.
Answer
The higher the orbit, the slower the satellite and the longer its period (Kepler's third law: the square of the period is proportional to the cube of the orbit's size). The satellite's own mass does not matter.3. What three conditions make an orbit geostationary?
Answer
A period of one sidereal day (about 23 h 56 min), a circular orbit (about 35,786 km above the Earth) and zero inclination (in the Equator's plane), moving eastward.4. Why is a sun-synchronous orbit slightly retrograde, and what does it achieve?
Answer
At about 98° inclination, the Earth's equatorial bulge turns the orbit's plane by about 1° a day, matching the Earth's motion round the Sun. The satellite then passes each latitude at the same local solar time, giving comparable lighting for images.5. Why do video calls through a geostationary satellite feel delayed?
Answer
The signal travels at least about 72,000 km up and down, about a quarter of a second one way and half a second for a question and its answer. From LEO the physical delay is a few milliseconds.6. How did the orbit of the fire-counting satellites affect stubble-burning figures?
Answer
The MODIS and VIIRS sensors are on polar, sun-synchronous satellites whose daytime passes over India come only around 10:30 a.m.–1:30 p.m. An ISRO-led study using a geostationary satellite found burning had shifted to the evening, so polar-only counts miss many fires.7. Can a State, or India, ban foreign satellites from passing overhead? What can India control?
Answer
No. Outer space cannot be appropriated by any nation (Outer Space Treaty, Article II). India controls service on its soil: the DoT licence, IN-SPACe authorisation, security conditions such as Indian gateways, spectrum and terminals.8. Which Indian rocket is named for an orbit, and which orbit does the GSLV aim at?
Answer
The PSLV (Polar Satellite Launch Vehicle), for polar and sun-synchronous orbits. The GSLV (and LVM3) place satellites in a geosynchronous transfer orbit, from which their own engines raise them to GEO.“Know it, link it, feel it, decide it.”
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