India's Chandrayaan Missions

A lander, a rover and a clear brief

ISRO built Chandrayaan-3 around a propulsion module, the Vikram lander and the Pragyan rover. Its mission page lists three objectives: to demonstrate a safe and soft landing on the lunar surface, to demonstrate a rover moving on the Moon and to carry out experiments on site. The same page gives the lander module a mass of 1,752 kilograms including the 26-kilogram rover, a rover power output of 50 watts and a mission life of one lunar day, about 14 Earth days. Those figures describe a focused mission, built first to prove that India could land and drive on the Moon, with its science designed around that goal.

What the Vikram lander measured

The lander was a science station in its own right. ISRO's mission page lists four payloads on Vikram: RAMBHA, which studied the plasma near the surface; ChaSTE, which measured the thermal properties of the soil; ILSA, which listened for lunar seismic activity; and a laser retroreflector array supplied by NASA. The page gives the prime landing area as a 4-kilometre by 2.4-kilometre zone centred at 69.367621 degrees south, 32.348126 degrees east, in the south polar region. Instruments that stay in one place can record how conditions change through the lunar day, complementing a rover that samples many spots briefly. Together they give a fuller picture of a single site than either could alone.

Pragyan's reading of the soil

According to ISRO's mission page, Pragyan carried two instruments for working out what the ground is made of: an Alpha Particle X-ray Spectrometer and a Laser Induced Breakdown Spectroscope. A 2024 paper in Nature led by Santosh Vadawale reported 23 APXS measurements near the landing site, the first in situ measurements of elemental abundances at the Moon's southern high latitudes. The authors found the local terrain fairly uniform and mainly made of ferroan anorthosite, a product of the crystallisation of the early lunar magma ocean, while a relatively higher magnesium content hinted at mixing with more mafic material. They describe this uniformity over a few tens of metres as ground truth for orbital remote sensing.

A buried crater beneath the landing site

Rover images can also say something about deep history. In September 2024 ISRO described research, published in the journal Icarus, suggesting that Chandrayaan-3 landed inside an old buried impact crater around 160 kilometres across and about 4.4 kilometres deep, likely older than the South Pole-Aitken basin. ISRO says Pragyan's navigation camera images showed groove-like structures possibly formed by distant impacts and a traverse free of boulders larger than a metre, consistent with typical highland terrain. ISRO puts the site about 350 kilometres from the rim of the South Pole-Aitken basin, whose ejecta later blanketed the area. A small rover on a short mission can still contribute to questions about the Moon's earliest history.

Sources and further reading

• Chandrayaan-3 Details — Indian Space Research Organisation (ISRO).
  ISRO's mission page: objectives, landing site, lander and rover masses, payloads and mission life.
• Chandrayaan-3 APXS elemental abundance measurements at lunar high latitude — Nature.
  Pragyan's X-ray spectrometer results: a uniform, anorthosite-rich soil that fits the lunar magma ocean idea.
• Discovery of a buried crater on the Moon: Chandrayaan-3 Vikram lander and Pragyan rover landed within it — Indian Space Research Organisation (ISRO).
  ISRO summary of research suggesting the landing site lies in an ancient buried crater near the South Pole-Aitken basin.

Common questions

How long did Chandrayaan-3's rover operate?

ISRO planned the surface mission around a life of one lunar day, roughly 14 Earth days, according to its mission page. The rover was designed for that daylight period, so its surface work was always meant to be short, while its data continues to feed published research.

Why did Chandrayaan-3 land so far south?

The south polar region interests scientists because of its cold, shadowed terrain and possible ice. ISRO's mission page places the prime landing area at about 69 degrees south, and the Nature APXS paper notes that Pragyan made the first in situ measurements of elemental abundances at southern high latitudes.