Chandrayaan-2 Finds Evidence of Subsurface Ice on the Moon

Overview

Previous Year UPSC-CSE Questions By the end you will be able to draft model answers for the following UPSC questions. Each question carries a collapsible framework showing how to approach it in the exam.

  1. UPSC Prelims 2025Consider the following space missions:
    1. Axiom-4
    2. SpaDeX
    3. Gaganyaan

    How many of the space missions given above encourage and support microgravity research?

    1. a Only one
    2. b Only two
    3. c All the three
    4. d None
    How to approach this Prelims question

    Question type: multi-statement

    Approach: Check whether each mission involves microgravity research.

    Trap to watch: All three support microgravity research; the trap is to exclude one, such as SpaDeX, which is a docking experiment with research uses.

    Key facts to recall:

    • Axiom-4 carried research in microgravity aboard the space station.
    • Gaganyaan is India's human spaceflight programme enabling microgravity experiments.
    • SpaDeX demonstrates space docking, supporting future research platforms.

    Answer signal: All three encourage microgravity research. Correct answer: All the three.

  2. UPSC Mains 2023 GS-IIIWhat is the main task of India's third moon mission which could not be achieved in its earlier mission? List the countries that have achieved this task. Introduce the subsystems in the spacecraft launched and explain the role of the 'Virtual Launch Control Centre' at the Vikram Sarabhai Space Centre which contributed to the successful launch from Sriharikota.
    How to structure the answer in the exam

    Directive verb: Explain · Approach: State the main task, name the countries, and describe the spacecraft subsystems and the launch-control role.

    Introduction: Open with Chandrayaan-3's goal of a soft landing near the lunar south pole, which Chandrayaan-2 narrowly missed.

    Body (sub-themes to develop):

    • Main task: a soft landing on the Moon, achieved by Chandrayaan-3.
    • Countries that soft-landed earlier: the United States, the erstwhile Soviet Union and China.
    • Subsystems: the propulsion module, lander (Vikram) and rover (Pragyan).
    • Virtual Launch Control Centre: monitoring and control supporting the launch.
    • Significance: India as the first to land near the south pole, the region of the ice finding.

    Conclusion: Conclude that the south-pole focus links the landing to the search for lunar water ice.

Chandrayaan-2 is India's second lunar mission, whose orbiter has continued to study the Moon since 2019. Its Dual Frequency Synthetic Aperture Radar (DFSAR), which uses L-band and S-band microwaves, has found evidence of subsurface ice in the Moon's south polar region. The finding, from a study led by the Physical Research Laboratory, focused on permanently shadowed craters where sunlight never reaches and temperatures stay extremely low. It strengthens the case that the lunar poles hold water ice below the surface, a resource for future exploration.

Why the Chandrayaan-2 finding is in focus

Radar evidence of ice beneath the south pole

A study using Chandrayaan-2 radar data found evidence of subsurface ice near the Moon's south pole. The orbiter's radar detected signatures consistent with ice buried beneath the surface of shadowed craters.

Subsurface ice is frozen water lying below the lunar soil, or regolith. Unlike surface frost, it is shielded from sunlight, so it can survive in cold traps over long periods.

The finding came from the orbiter's Dual Frequency Synthetic Aperture Radar, which uses microwaves that penetrate the surface. The study was led by the Physical Research Laboratory and focused on permanently shadowed craters.

The headline elements of the finding are:

  • Instrument: the Dual Frequency Synthetic Aperture Radar, in L-band and S-band.
  • Location: permanently shadowed craters near the lunar south pole.
  • Finding: radar signatures consistent with subsurface ice.
  • Lead: a study led by the Physical Research Laboratory.

Why the finding matters

Water as the key to lunar exploration

Water is the single most valuable resource for exploring the Moon. Carrying it from Earth is hugely expensive, so finding ice in place could transform what missions can do.

Subsurface ice is especially useful. Because it sits below the surface in cold traps, it is more stable than surface frost, so it is a more reliable target for future extraction and study.

The finding also showcases Chandrayaan-2's instruments. Years after launch, the orbiter's radar is still producing front-rank science, underlining the value of long-lived space assets.

How the radar finds buried iceDFSAR microwaves penetrate the lunar surfaceOrbiter radarDFSAR sends L-bandand S-band microwaves.→Through the regolithMicrowaves penetrate thesoil of shadowed craters.→Ice signatureReturns consistent withsubsurface ice.Two radar frequencies probe different depths, helping locate buried ice.Radar can see what cameras cannot, beneath permanently dark craters.Figure 1. Microwaves out, ice signatures back.ISRO, Chandrayaan-2 DFSAR study.Digitally LearnCopyright (c) 2026. All Rights Reserved.

What the finding signifies

Resources, the south pole and India's space science

Three threads carry the weight: water as a resource, the value of the lunar south pole, and the strength of India's space science.

First, water as a resource. Lunar ice could be split into hydrogen and oxygen, supplying drinking water, breathable air and rocket fuel, the building blocks of a sustained presence on the Moon.

Second, the south pole. Its permanently shadowed craters act as cold traps that preserve ice, which is why space agencies, including India, target the region for landings and study.

Third, India's space science. A discovery drawn from an Indian orbiter's instrument, led by an Indian laboratory, shows India contributing front-rank planetary science, not only launches.

Distinguishing features of the finding

The finding at a glance

The table sets out the key facts of the study, so its instrument, location and lead are visible at a glance.

Feature Detail
Mission Chandrayaan-2 orbiter (operating since 2019)
Instrument Dual Frequency Synthetic Aperture Radar (DFSAR)
Frequencies L-band and S-band microwaves
Location Permanently shadowed craters near the south pole
Lead Physical Research Laboratory study

Three features that define the finding

Three elements make this finding notable:

  1. (i) Subsurface, not surface. The evidence points to ice below the regolith, which is more stable than surface frost.
  2. (ii) Radar, not cameras. Microwave radar can probe permanently dark craters that optical instruments cannot see into.
  3. (iii) From an ageing orbiter. The result comes from Chandrayaan-2, years after launch, showing the long life of its science payload.
What ice on the Moon can provideIn-situ resource utilisation from lunar waterLunar water icemined from the poles↓Drinking waterFor astronauts on longmissions and bases.OxygenBreathable air, splitfrom water.Rocket fuelHydrogen and oxygenas propellant.Using local resources cuts the cost of lifting supplies from Earth.Figure 2. Water, oxygen and fuel from lunar ice.ISRO; planetary-science literature.Digitally LearnCopyright (c) 2026. All Rights Reserved.

Observable outcomes

Three trackable outcomes

The finding translates into three developments to watch.

  1. (a) Target selection. The mapped craters can guide where future landers and rovers are sent to confirm and study the ice.
  2. (b) Mission planning. Evidence of accessible ice feeds into plans for sample return and longer-stay missions.
  3. (c) More radar science. Continued DFSAR observations can refine the depth and extent of the ice.

The evidence is of possible ice, not confirmed deposits. Direct measurements on the surface are still needed to prove how much ice exists and how accessible it is.

The finding in India's lunar programme

From Chandrayaan-1 to a global race for lunar water

The finding builds on India's lunar programme. Chandrayaan-1 first detected water signatures on the Moon, and Chandrayaan-3 landed near the south pole, the region now in focus.

It connects to a wider race for lunar water. The United States, China and others target the poles, because accessible water would anchor permanent bases and deeper space travel.

The result also strengthens the case for in-situ resource utilisation, the idea of living off local resources rather than carrying everything from Earth, central to the next phase of exploration.

India’s lunar programmeThe path to the subsurface-ice finding2008Chandrayaan-1:water signatures2019Chandrayaan-2:orbiter and radar2023Chandrayaan-3:south-pole landing2026Subsurface-iceevidenceEach mission deepened India’s search for water at the lunar poles.Figure 3. From water signatures in 2008 to subsurface-ice evidence in 2026.ISRO.Digitally LearnCopyright (c) 2026. All Rights Reserved.

UPSC relevance and exam focus

Where this fits in the UPSC-CSE syllabus

This topic maps to General Studies Paper III: developments in science and technology, and Indians' achievements in space, with a link to India's space programme.

For Prelims, hold the high-yield facts: Chandrayaan-2's DFSAR instrument, the L-band and S-band radar, permanently shadowed regions, and the lunar south-pole focus.

For Mains, two framings recur: India's achievements in space science and exploration, and the strategic value of lunar resources for the future.

Recurring linked concepts an aspirant should keep in working memory:

  • DFSAR: the Dual Frequency Synthetic Aperture Radar on the Chandrayaan-2 orbiter.
  • Permanently shadowed regions: polar craters that never receive sunlight and trap ice.
  • In-situ resource utilisation: using local resources, such as water, instead of carrying them.
  • Chandrayaan programme: Chandrayaan-1, Chandrayaan-2 and Chandrayaan-3.

The radar instrument is DFSAR on the Chandrayaan-2 orbiter, not on the Chandrayaan-3 lander. Attributing the finding to the wrong mission is an easy error.

Do not overstate the result as confirmed ice. It is evidence of possible subsurface ice, which still needs direct surface measurement to confirm.

Prelims MCQ practice

Each question below tests one specific concept on the topic. Click to reveal the answer and a full option-wise explanation.

Q1. Consider the following statements regarding the 2026 Chandrayaan-2 finding:

  1. It found evidence of subsurface ice near the Moon's south pole.
  2. It used the orbiter's Dual Frequency Synthetic Aperture Radar.
  3. The radar operates in the L-band and S-band.

Which of the statements given above is/are correct?

  1. 1 and 2 only
  2. 2 and 3 only
  3. 1 and 3 only
  4. 1, 2 and 3
Show answer and explanation

Answer: 1, 2 and 3

Explanation.

All three are correct. The finding is of subsurface ice near the south pole, detected by the orbiter's DFSAR, which operates in the L-band and S-band. Hence 1, 2 and 3.

Q2. The DFSAR instrument that made the finding is carried on which one of the following?

  1. The Chandrayaan-3 lander
  2. The Chandrayaan-2 orbiter
  3. The Mangalyaan spacecraft
  4. The Aditya-L1 spacecraft
Show answer and explanation

Answer: The Chandrayaan-2 orbiter

Explanation.

Option (b) is correct. DFSAR is carried on the Chandrayaan-2 orbiter. The Chandrayaan-3 lander, Mangalyaan (Mars) and Aditya-L1 (Sun) are different missions. Hence option (b).

Q3. Why do permanently shadowed regions near the lunar poles trap ice?

  1. They receive intense direct sunlight
  2. They never receive sunlight, so they stay extremely cold and act as cold traps
  3. They are heated by the Moon's core
  4. They have a thick atmosphere
Show answer and explanation

Answer: They never receive sunlight, so they stay extremely cold and act as cold traps

Explanation.

Option (b) is correct. Permanently shadowed regions never receive sunlight, so they remain extremely cold and trap volatiles like water ice. The other options are false; the Moon has effectively no atmosphere. Hence option (b).

Q4. With reference to lunar water ice as a resource, consider the following potential uses:

  1. Drinking water for astronauts
  2. Breathable oxygen
  3. Hydrogen and oxygen as rocket propellant

Which of the above are potential uses of lunar water ice?

  1. 1 and 2 only
  2. 2 and 3 only
  3. 1 and 3 only
  4. 1, 2 and 3
Show answer and explanation

Answer: 1, 2 and 3

Explanation.

All three are potential uses. Lunar water can supply drinking water, be split into breathable oxygen, and yield hydrogen and oxygen as rocket propellant. Hence 1, 2 and 3.

Q5. Which Indian mission first detected water signatures on the Moon, paving the way for later studies?

  1. Chandrayaan-1
  2. Chandrayaan-3
  3. Mangalyaan
  4. Aditya-L1
Show answer and explanation

Answer: Chandrayaan-1

Explanation.

Option (a) is correct. Chandrayaan-1 first detected water and hydroxyl signatures on the Moon. Chandrayaan-3 landed near the south pole, Mangalyaan went to Mars, and Aditya-L1 studies the Sun. Hence option (a).

Q6. Consider the following statements about the finding:

  1. It points to ice below the lunar surface, not only surface frost.
  2. Radar can probe craters that optical cameras cannot see into.
  3. The finding is confirmed proof of large, accessible ice deposits.

Which of the statements given above is/are correct?

  1. 1 and 2 only
  2. 2 and 3 only
  3. 1 and 3 only
  4. 1, 2 and 3
Show answer and explanation

Answer: 1 and 2 only

Explanation.

Statements 1 and 2 are correct: the evidence points to subsurface ice, and radar can probe dark craters. Statement 3 is wrong: the result is evidence of possible ice, not confirmed proof of large accessible deposits. Hence 1 and 2 only.

Sources and Further Reading

Editorial Disclaimer

This article is compiled from the reference materials listed in the Sources section. It is an explainer for UPSC preparation and is not a substitute for primary documents (NCERTs, GoI ministry releases, IMD bulletins, RBI / CEA / MoEFCC publications, and Standing-Committee reports).