What Chandrayaan-3 found at the Moon’s south pole

Chandrayaan-3 made India the fourth country to land softly on the Moon and the first to land so close to its south pole. Its scientific haul, published in journals since 2024, is substantial: the first direct measurement of sulphur near the pole, soil that supports the idea that the young Moon was covered by an ocean of molten rock, the first temperature profile measured in the ground at high latitude, and more than 250 seismic signals. The landing site turns out to be about 3.7 billion years old and to sit inside a buried crater some 160 km wide.

The main findings, instrument by instrument

1. Sulphur, measured on the spot (LIBS)

Pragyan’s laser-induced breakdown spectroscope fires a laser at the soil and reads the light from the tiny spark. On 29 August 2023 ISRO announced that it had confirmed sulphur near the south pole “unambiguously”, along with aluminium, calcium, iron, chromium, titanium, manganese, silicon and oxygen. Sulphur was already known from Apollo samples, but this was the first measurement made on the surface at high southern latitude. How much sulphur is there awaits fully calibrated results.

2. Soil from a magma ocean (APXS)

The rover’s alpha particle X-ray spectrometer measured the soil’s chemistry at 23 spots near the landing point. The results, published in Nature in August 2024, show fairly uniform soil made mostly of ferroan anorthosite, a pale rock that floats to the top as a sea of molten rock cools. That supports the lunar magma ocean idea: that the young Moon was covered by molten rock hundreds of kilometres deep, whose lightest minerals formed the crust. The soil also carries more magnesium-rich minerals than that idea alone predicts. The authors suggest they were dug up from deeper down by the impact that made the giant South Pole–Aitken basin.

3. A hot slope, and where ice might hide (ChaSTE)

ChaSTE pushed a probe with ten temperature sensors about 10 cm into the ground, the first such profile taken at high lunar latitude. In a paper in Communications Earth & Environment in 2025, the team reported a peak surface temperature of 355 K, about 82 °C, on a slope of about 6 degrees facing the Sun, against about 332 K, 59 °C, measured on flat ground roughly a metre away. Their modelling suggests that at high latitudes, slopes facing away from the Sun at more than about 14 degrees could stay cold enough to keep water ice just a few centimetres down, which would make ice easier to reach than in permanently shadowed craters. With one site, they caution, they cannot say how much ice there is.

4. More than 250 seismic signals (ILSA)

ILSA, the first seismometer on the Moon since the Apollo era and the first in the polar region, recorded about 190 hours of data. A study in the journal Icarus counted more than 250 distinct signals. About 200 match known activity, such as the rover driving or instruments working. About 50 could not be linked to anything on the lander or rover; the authors suggest small nearby meteorite impacts, heating effects in the soil or in the lander itself.

5. A thin plasma (RAMBHA-LP)

A probe on Vikram made the first measurement of the charged gas just above the surface near the south pole. ISRO reported it to be sparse, with roughly 5 to 30 million electrons per cubic metre. That matters for future landers and radio communications.

6. Ancient ground

Two studies by scientists at the Physical Research Laboratory in Ahmedabad have dated the site. One, reported by ISRO in September 2024 and published in Icarus, used Pragyan’s navigation camera and the Chandrayaan-2 orbiter’s high-resolution camera to show that Vikram landed inside a heavily degraded crater about 160 km across, buried under debris from later impacts and probably older than the South Pole–Aitken basin itself. Another, from early 2025, used crater counts to date the surrounding plains to about 3.7 billion years.

Our check: why the slope ran 23 degrees hotter

The gap between 355 K on the slope and 332 K on flat ground a metre away looks large. Simple geometry explains most of it. At 69 degrees south the noon Sun is only about 20 degrees above the horizon. A slope tilted 6 degrees towards the Sun meets the sunlight at about 26 degrees instead, and the sine of the angle sets how much energy each square metre receives: sin 26.6° ÷ sin 20.6° is about 1.27, or 27 percent more sunlight.

Airless lunar soil heats until it radiates away what it absorbs, and radiated energy rises with the fourth power of temperature. So the temperature should rise by the fourth root of 1.27, about 6 percent: 332 K × 1.06 is about 353 K. That is within 2 K of what ChaSTE measured. A small tilt matters enormously when the Sun is low, which is exactly why slopes facing away from the Sun near the poles can stay cold enough to hold ice.

Engineering results

• The hop: on 3 September 2023 Vikram fired its engines, rose about 40 cm and landed 30 to 40 cm away, a test of techniques for a future sample-return mission.
• The propulsion module came home: with fuel left over, ISRO moved it out of lunar orbit and back to an orbit around Earth in late 2023.
• A permanent marker: NASA’s Lunar Reconnaissance Orbiter bounced a laser off a small reflector on Vikram on 12 December 2023, making the lander a fixed reference point near the south pole.

Chandrayaan-2 and Chandrayaan-3: the difference

Chandrayaan-2, launched in 2019, carried an orbiter, a lander and a rover. The orbiter still works; the lander crashed during descent in September 2019. Chandrayaan-3 carried no new orbiter. It was a lander, a rover and a propulsion module, built with sturdier legs, wider landing margins and more fuel, and it relied on the Chandrayaan-2 orbiter for communications.

What comes next

In September 2024 the Union Cabinet approved Chandrayaan-4, which aims to bring lunar samples back to Earth, and India is working with Japan on a joint lander, LUPEX, to look for ice near the south pole. India’s longer aim is to put its own astronauts on the Moon by 2040, a goal tied to the Gaganyaan human spaceflight programme. For how the Moon moves through our own sky, see our guide to this winter’s closest full moons.

How we worked this out

Mission facts are from ISRO. Scientific results are from the peer-reviewed papers and ISRO releases listed below; where coverage disagreed, we used the paper or ISRO’s own statement. The slope calculation is ours: we took a noon Sun elevation of 20.6 degrees, which follows from the site’s latitude of about 69.4 degrees, applied the 6 degree slope reported by the ChaSTE team, and assumed the surface is in radiative balance. It is a simplified model that ignores heat flow into the ground, so close agreement should be read as a sense check, not a result.

Sources

• ISRO: Chandrayaan-3
• Vadawale et al. (2024), Nature: Chandrayaan-3 APXS elemental abundance measurements at lunar high latitude
• Durga Prasad et al. (2025), Communications Earth & Environment: ChaSTE temperature measurements
• ISRO: first in-situ temperature measurement near the lunar south pole
• Vijayan et al. (2024), Icarus: Chandrayaan-3 landing site evolution by South Pole–Aitken basin and other impact craters
• ISRO: discovery of a buried crater on the Moon
• Business Standard: Moon’s seismic activity likely linked to past meteorite impacts (on the ILSA study)