Chandrayaan I

Chandrayaan I was India’s first lunar exploration mission, launched by the Indian Space Research Organisation (ISRO) on 22 October 2008. It marked India’s entry into the elite group of nations engaged in lunar exploration and represented a major milestone in the country’s space research and technological advancement. The mission aimed to study the Moon’s surface, mineral composition, and chemical characteristics, as well as to demonstrate India’s capability in deep space missions.

Background and Objectives

The Chandrayaan I mission was conceived in the late 1990s as part of ISRO’s long-term vision to expand beyond Earth’s orbit and explore celestial bodies. The word Chandrayaan derives from Sanskrit, meaning “Moon craft.”
Formally approved by the Indian government in 2003, the mission was designed to serve both scientific and technological purposes, strengthening India’s position in planetary science.
The main objectives of Chandrayaan I were:

• To prepare a detailed three-dimensional atlas of both the near and far sides of the Moon.
• To conduct chemical and mineralogical mapping of the lunar surface at high spatial resolution.
• To search for water or ice in the polar regions of the Moon.
• To test deep space communication and navigation systems for future interplanetary missions.

These goals aligned with ISRO’s broader vision of promoting space science research and advancing India’s indigenous spacecraft design capabilities.

Design and Configuration

Chandrayaan I was a 300-kilogram lunar orbiter designed and built by ISRO. It carried 11 scientific instruments, five of which were Indian, and six supplied by international partners including NASA (United States), ESA (European Space Agency), and the Bulgarian Academy of Sciences.
Key components of the spacecraft included:

• Propulsion System: A bipropellant system used for orbital manoeuvres and lunar insertion.
• Scientific Payload: Instruments for imaging, spectroscopy, and mineralogical analysis.
• Communication System: S-band telemetry and a Deep Space Network (DSN) for data transmission.
• Power System: Solar panels generating 700 watts of power, supported by lithium-ion batteries.

The orbiter was launched aboard India’s Polar Satellite Launch Vehicle (PSLV-C11) from the Satish Dhawan Space Centre, Sriharikota.

Mission Profile

The Chandrayaan I mission followed a multi-phase trajectory to reach lunar orbit:

1. Launch and Earth Orbit Phase: The spacecraft was launched into an initial Earth orbit of 255 x 22,860 kilometres.
2. Translunar Trajectory: Using a series of orbit-raising manoeuvres, it escaped Earth’s gravity and entered a translunar path.
3. Lunar Orbit Insertion: On 8 November 2008, Chandrayaan I successfully entered lunar orbit at approximately 100 kilometres altitude.
4. Operational Phase: The orbiter conducted scientific observations for nearly 10 months, orbiting the Moon at a polar inclination of 90 degrees.

A major highlight occurred on 14 November 2008, when the Moon Impact Probe (MIP), bearing the Indian tricolour, was released from the orbiter and impacted near the Lunar South Pole. This symbolic and scientific milestone marked India’s first contact with the lunar surface.

Scientific Instruments and Experiments

Chandrayaan I carried a suite of sophisticated instruments designed to study the Moon’s topography, mineralogy, and elemental composition.
Indian Instruments:

• Terrain Mapping Camera (TMC): Captured high-resolution 3D images of the lunar surface.
• Hyper Spectral Imager (HySI): Mapped the Moon’s mineral composition.
• Lunar Laser Ranging Instrument (LLRI): Measured lunar topography.
• High Energy X-ray Spectrometer (HEX): Detected radioactive elements.
• Moon Impact Probe (MIP): Collected atmospheric data during descent.

International Instruments:

• Mini-SAR (NASA): Radar instrument that identified evidence of water ice in the lunar polar regions.
• Moon Mineralogy Mapper (M³) (NASA): Detected water/hydroxyl molecules on the lunar surface.
• SARA (ESA/Sweden): Studied solar wind interactions.
• X-ray Spectrometer (Bulgaria): Analysed X-ray emissions from the lunar surface.
• Near Infrared Spectrometer (Germany): Mapped surface composition.

These payloads provided unprecedented scientific data that transformed global understanding of the Moon’s composition and history.

Discovery of Water on the Moon

The most groundbreaking outcome of Chandrayaan I was the discovery of water molecules on the Moon’s surface. Data from NASA’s Moon Mineralogy Mapper (M³) revealed spectral evidence of hydroxyl (OH) and water (H₂O) molecules in the lunar soil, especially in the polar regions.
This discovery, announced in September 2009, redefined lunar science and confirmed that the Moon is not an entirely dry body as previously believed. The finding also influenced the planning of subsequent lunar missions worldwide, including NASA’s Lunar Reconnaissance Orbiter and India’s own Chandrayaan II and Chandrayaan III missions.

Challenges and Mission Termination

Although initially planned for two years, the mission faced technical difficulties that led to its premature end. On 29 August 2009, communication with the spacecraft was lost, likely due to overheating of onboard electronic components.
Despite the early termination, Chandrayaan I had completed 95% of its primary objectives, including high-resolution mapping and water detection, making it an outstanding success by scientific and operational standards.

International Collaboration and Significance

Chandrayaan I symbolised India’s collaboration with global space agencies, demonstrating how scientific partnerships can yield transformative results. The joint work of ISRO and NASA was particularly notable in achieving the discovery of water.
The mission also established India as a credible spacefaring nation, capable of designing, launching, and managing interplanetary missions using indigenous technology.

Legacy and Impact

Chandrayaan I left a profound legacy in both Indian and international space science:

• It expanded knowledge of lunar geology, identifying diverse minerals such as magnesium, aluminium, and iron-bearing compounds.
• It confirmed the presence of water, reshaping theories about the Moon’s origin and evolution.
• It strengthened India’s technological capabilities, paving the way for advanced missions like Chandrayaan II (2019) and Chandrayaan III (2023).
• It inspired public and academic interest in planetary science and aerospace engineering across India.