Satellite radiation: blocking views

1. At a Glance

• Core issue: Communications satellites in low-earth orbit (LEO) give off radio signals that interfere with radio astronomy across a range of frequencies [1].
• Key finding: Protecting astronomy means regulating more than licensed transmissions. Stray radiation from onboard electronics also has to be controlled [1].
• Why it matters for UPSC: It touches GS-III (space technology, satellite internet, spectrum management) and current affairs on mega-constellations such as Starlink, OneWeb and Guowang [1].

2. Why in the News

• A study in Monthly Notices of the Royal Astronomical Society (MNRAS) found that LEO communications satellites interfere with radio astronomy [1].
• The findings come from a satellite radiation monitoring programme called SNIFFLES [1].
• The Hindu covered it on 19 October 2026 (Chennai edition, Page 28, by Vasudevan Mukunth) [1].

3. Background & Evolution

• Rationale: Large commercial broadband constellations in LEO now share the radio sky with ground-based radio telescopes [1].
• Observation campaign: The study tracked satellites for nearly 376 hours, starting April 2024 [1].
• Constellations studied:
• Starlink [1]
• OneWeb [1]

• China's Guowang [1]

• New services add interference: Starlink's direct-to-cell signals are one example of intended transmissions [1].

• Not source-verified, conceptual only: radio astronomy has long relied on protected frequency bands and "radio-quiet" sites. Mega-constellations that cover the whole sky put pressure on that protection model.

4. Core Static Facts

How the study classified the radiation [1]:

• Intended: deliberate, licensed transmissions, such as Starlink's direct-to-cell signals.
• Unwanted: extra emissions from the transmitters themselves, including harmonics (signals at multiples of the transmission frequency).
• Unintended: stray emissions from onboard electronic parts such as power converters and computers.

5. Multi-Dimensional Analysis

Scientific / Technological

• Signals 100 billion times brighter than cosmic sources can drown out the faint astronomical signals telescopes are trying to detect [1].
• The OneWeb emission at 1,613.19 MHz overlaps with frequencies used to observe hydroxyl, a key molecular tracer in space [1].
• Unintended emissions come from electronics, not antennas. So rules that only cover transmission frequencies are not enough [1].

Legal / Regulatory (Governance)

• The study's main policy point: operators must control licensed transmissions and stray radiation together [1].
• Conceptual: spectrum rules usually govern intended and out-of-band emissions. "Unintended electromagnetic radiation" from satellite hardware is a regulatory gap.

Geopolitical / Strategic

• The three constellations studied are run by private and state actors from different countries (the US-based Starlink, OneWeb, and China's Guowang) [1]. Any rule-making therefore needs multilateral coordination.
• Conceptual: India is building its own satellite broadband market and radio-astronomy facilities, so it has a stake both as a user of the radio sky and as a regulator.

Economic

• Satellite broadband and direct-to-cell services are growing commercial products. That growth makes such emissions more common [1].
• Conceptual: rules on stray emissions could raise satellite design and certification costs. This is the economy-versus-science trade-off.

Ethical

• Conceptual: the sky is a shared scientific commons. This raises "tragedy of the commons" questions about commercial use of orbital and spectrum resources.

6. Recent Developments (last 12–18 months)

• April 2024 onward: the SNIFFLES campaign tracked Starlink, OneWeb and Guowang satellites for about 376 hours [1].
• 2026: the findings were published in MNRAS [1].
• 19 October 2026: The Hindu reported the study [1].
• Other 2025–26 regulatory steps (for example at the ITU or UN COPUOS) could not be verified from whitelisted sources for this note.

7. Prelims Hooks

• The SNIFFLES programme monitors radiation from satellites that affects radio astronomy [1].
• The study appeared in Monthly Notices of the Royal Astronomical Society [1].
• Telescopes used: Mopra radio telescope and Australia Telescope Compact Array, both in Australia [1].
• Constellations tracked: Starlink, OneWeb and China's Guowang [1].
• Observation period: about 376 hours, starting April 2024 [1].
• Radiation categories: intended, unwanted, unintended [1].
• Harmonics are signals at multiples of the transmission frequency. The study classed them as unwanted emissions [1].
• Stray emissions from power converters and onboard computers were classed as unintended radiation [1].
• Direct-to-cell signals from Starlink were classed as intended transmissions [1].
• A OneWeb signal at 1,613.19 MHz threatens observation of hydroxyl (–OH⁻) in space [1].
• Some satellite signals were 100 billion times brighter than typical astronomical sources [1].
• One specific Starlink version emitted a signal in about 77% of observations [1].
• The article's photo shows the Karl G. Jansky Very Large Array, a radio telescope array in the U.S., not India or Australia [1].

8. Why a Licence Cannot Catch Stray Radiation

• A licence controls what an operator chooses to send. Stray radiation is not chosen.
• A spectrum licence names a frequency band. The operator agrees to send its signal there and nowhere else.
• Unintended radiation comes from the satellite's own parts, such as power converters and computers. It does not come from the antenna [1].

• These parts were never given a frequency, so no licence condition covers them. The leak sits outside the rulebook.

• The leak is far too strong to ignore

• Some satellite signals were 100 billion times brighter than the cosmic sources telescopes study [1].

• Radio astronomers look for very faint signals. A signal that strong does not just add some noise. It can hide the real signal completely.

• The problem is not rare

• One version of Starlink satellites showed the emission in about 77% of observations [1].

• So this is a design feature of that satellite version. It cannot be blamed on one faulty unit.

• It can only be fixed before launch

• A satellite cannot be repaired once it is in orbit. Shielding the electronics has to happen on the factory floor.
• So any rule has to apply at the design and testing stage. A complaint filed after launch comes too late.

9. Why Remote Telescope Sites No Longer Protect Astronomy

• The old method was distance. Satellites remove that method.
• Radio telescopes are built in empty places so that phones and TV towers are far away.
• The SNIFFLES study used Mopra and the Australia Telescope Compact Array, both in remote Australia. They still picked up the satellite signals [1].

• A LEO satellite passes overhead. Going to a remote site does not help when the noise comes from above.

• Some of the lost frequencies carry key science

• The OneWeb signal at 1,613.19 MHz falls where astronomers study hydroxyl (a molecule made of one oxygen and one hydrogen atom). Hydroxyl helps them map gas clouds where stars form [1].

• A spectral line (the fixed frequency a molecule gives off) cannot be moved. If that frequency is jammed, the molecule cannot be studied at all.

• One country's licence becomes every country's problem

• Starlink, OneWeb and Guowang are licensed by different countries [1]. Their satellites pass over every country's telescopes.
• So India's GMRT (Giant Metrewave Radio Telescope) faces signals from satellites that India never licensed and cannot regulate by itself.

10. The Operators' Case — and Where It Falls Short

• The strongest argument for the operators
• LEO broadband reaches villages, ships and border areas that fibre and towers do not reach. Direct-to-cell service (where a normal phone connects straight to a satellite) widens this further [1].
• Astronomers are a small group. Hundreds of millions of people need connectivity. On this view, a few blocked frequencies are a fair price.

• Astronomers can also filter out known signals with software, or put telescopes in space.

• What is right about this argument

• The connectivity gain is real, and a ban on constellations would not be reasonable.

• Filtering does work for intended signals, because their frequency and timing are known in advance.

• Where it breaks down

• Filtering needs a predictable signal. Unintended radiation from electronics has no fixed frequency, so software cannot reliably remove it [1].
• A signal 100 billion times brighter than the source [1] can overload the receiver itself. Nothing is left to clean.
• Space telescopes cost far more and cover only part of what ground arrays do. This shifts the cost onto public science budgets.
• The fix the study points to, better control of stray radiation [1], asks for engineering discipline, not less connectivity. The trade-off is smaller than the operators suggest.

11. Why Global Talks Have Produced Advice, Not Rules

• The UN has studied the problem, but only made recommendations
• UNOOSA (the UN Office for Outer Space Affairs), with the IAU (International Astronomical Union), held the Dark and Quiet Skies for Science and Society conference in 2020. It reported to COPUOS (the UN Committee on the Peaceful Uses of Outer Space) [2].

• Its output was a set of recommendations to states and industry. These are not binding rules [2].

• Why advice is weak here

• Compliance costs money in shielding and testing. An operator that follows voluntary advice pays more than a rival that ignores it.
• COPUOS works by consensus, so a single major space power can slow any move to binding rules.
• The study covers both US and Chinese constellations [1]. A rule that binds one bloc and not the other will not protect the sky.

12. What India Should Push For

• IN-SPACe and DoT should add an emission test to satellite authorisation
• IN-SPACe (India's space regulator for private players) and the Department of Telecommunications clear satellite broadband operators for India.

• They should ask for ground-test data on unintended radiation before clearance, not just proof of the licensed frequency. This targets the gap SNIFFLES found [1].

• India should map GMRT's exposure

• The Australian study used only about 376 hours of observation [1]. India has no matching public data for its own telescopes.

• A SNIFFLES-style monitoring run at GMRT would give India evidence for its own negotiating position.

• India should back binding rules at COPUOS

• India runs radio telescopes and also wants satellite broadband. That gives it standing to argue for a middle path.
• It can build on the Dark and Quiet Skies recommendations [2] and push for shared emission limits on hardware, not just on transmitters.

13. Anchors for Answers

• Data: Some LEO satellite signals were 100 billion times brighter than typical astronomical sources; one Starlink version emitted in about 77% of observations over ~376 hours of tracking [1]
• Data: OneWeb emission at 1,613.19 MHz overlaps the hydroxyl spectral line used to study star-forming gas [1]
• Report/Committee: UN Dark and Quiet Skies for Science and Society conference report to COPUOS (A/AC.105/1255, 2021) [2]
• Law/Case: Outer Space Treaty 1967, Article IX — states must avoid harmful interference with other states' space activities, the principle behind any shared emission rule

14. Mains Relevance

• GS-III: Science & Technology, specifically awareness in the field of space and developments in S&T.
• GS-II (secondary): International institutions and regimes for governing global commons.
• Possible question stems: 1. Mega-constellations in low-earth orbit are both a connectivity revolution and a threat to astronomy. Discuss, and suggest a regulatory framework that balances the two. 2. Explain how 'unintended' satellite emissions differ from licensed transmissions, and why current spectrum regulation may fail to protect radio astronomy. 3. Is outer space a global commons? Examine in the context of satellite broadband and the scientific use of the radio sky.

15. Related Topics to Study Next

• Satellite broadband in India (Starlink / OneWeb licensing): the same constellations, from India's market and regulatory angle.
• Spectrum allocation and the ITU Radio Regulations: the framework that governs intended and out-of-band emissions.
• Dark and Quiet Skies (UN COPUOS): the multilateral discussion on protecting optical and radio astronomy.
• Radio telescopes in India (for example GMRT, Pune): India's own exposure to this interference.
• Square Kilometre Array (SKA): a major radio observatory, with sites including Australia, that LEO interference would affect.
• Space debris and Kessler syndrome: another external cost of crowded LEO.
• Direct-to-device / direct-to-cell satellite communication: a new service that adds to intended emissions.
• Electromagnetic spectrum basics (MHz bands, harmonics, spectral lines such as hydroxyl): the conceptual base for this topic.

16. NCERT Concepts to Revise

• Low Earth orbit satellite internet (Geography): The article is about LEO broadband constellations like Starlink and OneWeb and the radio interference they cause.
• Electromagnetic spectrum (Geography): Radio bands, frequencies in MHz, harmonics and spectral lines like hydroxyl all rest on spectrum basics.
• Negative externality (Economy): Stray satellite emissions are a spillover cost on astronomers, imposed by commercial operators and not paid for by them.
• Tragedy of the commons (Economy): The radio sky is a shared resource, and crowding it with satellites harms every other user.
• Satellite communication (Geography): Gives the background on how satellites carry communications, which is the service that causes this interference.

17. Common Errors / Trap Areas

• Mixing up the three categories: harmonics are unwanted; electronics noise is unintended; direct-to-cell is intended [1].
• Wrong telescopes: the observations used Mopra and ATCA (Australia). The Very Large Array (US) appears only in the article's photo [1].
• Wrong constellations: Guowang is China's. Don't confuse it with Kuiper or other systems [1].
• Units: the OneWeb signal is 1,613.19 MHz. The Starlink figure is printed as "2,700 Hz", which may be a printing error for MHz, so treat that unit carefully [1].
• Optical vs radio: this study is about radio interference. It is not about satellite streaks or brightness in optical images.