Chandrayaan

1. Programme and scientific significance

Chandrayaan, meaning Moon craft, is ISRO’s robotic lunar exploration programme. Its progression illustrates increasing technological complexity: observing the Moon from orbit, attempting a controlled landing, operating instruments on the surface and developing sample-return capability. The missions combine planetary science with technologies relevant to navigation, propulsion, autonomous control, deep-space communication and precision landing. They should not be confused with Gaganyaan, India’s human-spaceflight programme, or Aditya-L1, a solar observatory mission.

The Moon preserves evidence of early Solar System impacts and planetary evolution because it lacks Earth-like plate tectonics and extensive atmospheric weathering. Its surface is covered by regolith, a layer of fragmented rock and dust. Lunar studies investigate mineral composition, crustal structure, thermal properties and the distribution of volatiles. Water and hydroxyl are scientifically important because they help explain interactions among solar-wind particles, minerals and externally delivered material.

Polar exploration is especially valuable because some crater interiors remain permanently shadowed and extremely cold, potentially trapping water ice. Such ice could eventually support drinking water, oxygen production and propellant manufacture, although extracting it economically remains a major challenge. A landing in southern high latitudes does not automatically imply landing inside a permanently shadowed crater or directly detecting accessible ice.

2. Chandrayaan-1: orbital exploration and water-related discoveries

Chandrayaan-1 was launched from the Satish Dhawan Space Centre, Sriharikota, on 22 October 2008 using PSLV-C11. It entered lunar orbit in November 2008 and carried 11 scientific instruments from India and international partners. Its objectives included three-dimensional terrain mapping and chemical and mineralogical investigation. Initially operating in an approximately 100-km polar orbit, it provided repeated coverage of different lunar regions as the Moon rotated beneath its orbital path.

Indian instruments included the Terrain Mapping Camera, Hyper Spectral Imager and Moon Impact Probe. The probe deliberately impacted the Moon on 14 November 2008 while collecting observations during descent. This was an impact experiment, not a soft landing: a soft landing requires sufficiently controlled deceleration to leave the spacecraft operational on the surface. Communication with Chandrayaan-1 ended in August 2009, earlier than its planned two-year mission.

NASA’s Moon Mineralogy Mapper, carried aboard Chandrayaan-1, detected spectral signatures attributable to water and hydroxyl in lunar surface materials. The findings, announced in 2009 alongside complementary observations, transformed understanding of the Moon’s hydration. The Mini-SAR radar also found signatures consistent with water ice in north-polar craters. For examination purposes, distinguish evidence of molecular hydration from directly sampling bulk ice; different instruments measure different physical properties and carry different interpretive limitations.

3. Chandrayaan-2: an orbiter, lander and rover mission

Chandrayaan-2 launched on 22 July 2019 aboard GSLV Mk III-M1, the launch-vehicle family subsequently designated LVM3. It comprised an orbiter, the Vikram lander and the Pragyan rover. Vikram was named after Vikram Sarabhai, a foundational figure in India’s space programme; Pragyan means wisdom. The mission sought to expand lunar remote sensing while demonstrating soft landing and rover mobility in the southern high latitudes.

During the September 2019 landing attempt, Vikram did not complete the planned controlled descent and made a hard landing. Consequently, Pragyan could not undertake its surface mission. The orbiter, however, remained operational and continued scientific observations. Describing Chandrayaan-2 as a complete failure therefore obscures the distinction between its successful orbital component and unsuccessful surface component.

The orbiter’s instruments included the Orbiter High Resolution Camera, Terrain Mapping Camera-2, Imaging Infrared Spectrometer and Dual Frequency Synthetic Aperture Radar. They supported studies of surface morphology, mineralogy, elemental composition and polar terrain. Radar is an active sensor that transmits electromagnetic signals and analyses their return; optical imaging largely depends on reflected sunlight. Chandrayaan-2 imagery also supported the assessment of terrain for subsequent landing operations.

4. Chandrayaan-3: soft landing and surface experiments

Chandrayaan-3 launched on 14 July 2023 using LVM3-M4. It consisted of a propulsion module, Vikram lander and Pragyan rover, rather than a full scientific orbiter comparable to Chandrayaan-2. Its three objectives were to demonstrate safe soft landing, demonstrate rover movement and conduct in-situ scientific experiments. Improvements included stronger landing legs, enhanced sensing, greater operational margins and expanded testing of possible failure conditions.

On 23 August 2023, Vikram landed near 69.37°S and 32.35°E. India became the first country to land in this southern high-latitude region and the fourth to soft-land anywhere on the Moon. The site was named Shiv Shakti. Popular descriptions of a south-pole landing require qualification: the geographic pole is at 90°S, and the landing site is not a permanently shadowed polar crater. Surface operations were designed for approximately one lunar day, or about 14 Earth days.

Vikram carried ChaSTE to examine near-surface thermal properties, ILSA to measure seismic vibrations and RAMBHA-LP to study the local plasma environment. A NASA Laser Retroreflector Array supported laser-ranging applications. Pragyan carried LIBS and APXS for elemental analysis. LIBS provided unambiguous in-situ confirmation of sulphur in the investigated area. The propulsion module carried SHAPE to observe Earth’s spectral and polarimetric characteristics, providing information relevant to studies of potentially habitable exoplanets.

5. Mission engineering, future direction and examination relevance

Chandrayaan missions used staged Earth-orbit raising and translunar transfer rather than a direct launch-to-landing trajectory. Lunar-orbit insertion requires a carefully timed braking manoeuvre to achieve capture. Landing then demands major velocity reduction, altitude and speed estimation, hazard assessment and controlled touchdown. Because the Moon has no substantial atmosphere, parachutes cannot provide effective landing deceleration; propulsion performs the principal braking task.

A communications delay and rapidly changing descent conditions make onboard autonomy essential. Navigation must also contend with rugged terrain, while surface systems face abrasive dust, severe temperature variation and limited solar-power availability. Orbital remote sensing provides broad geographical coverage; landers and rovers provide local measurements with greater contextual detail. Neither substitutes completely for laboratory analysis of returned samples.

In September 2024, the Union Cabinet approved Chandrayaan-4, intended to develop technologies for returning lunar samples to Earth. Its challenges include lunar ascent, docking, sample transfer and safe Earth re-entry. Approval is distinct from mission completion. For UPSC, track demonstrated achievements separately from proposed capabilities, and connect lunar exploration with scientific cooperation, technological self-reliance and responsible use of outer space.

Previous year questions

No source-linked PYQ is available here yet. Use the practice questions below.

Practice questions