Chandrayaan-1

Chandrayaan-1 was developed and operated by ISRO as India's first mission to the Moon. It launched on 22 October 2008 aboard a PSLV-C11 rocket from Satish Dhawan Space Centre at Sriharikota. After a series of orbit-raising manoeuvres, it entered lunar orbit in November 2008 and operated in a low orbit around the Moon. The mission was designed for remote sensing, including chemical, mineralogical and photographic mapping. Its scientific payload comprised instruments built in India and contributed by partners in the United States, the United Kingdom, Germany, Sweden and Bulgaria.

The orbiter carried 11 scientific instruments, including cameras and spectrometers for studying the Moon's surface and composition. NASA's Moon Mineralogy Mapper (M3) was an imaging spectrometer designed to map lunar minerals, while NASA's Mini-SAR radar observed the polar regions. Chandrayaan-1 also carried a Moon Impact Probe, which separated from the orbiter in November 2008 and deliberately struck the lunar surface near the south pole. Its descent instruments returned measurements, and the event demonstrated an impact-probe capability as part of the wider mission.

Chandrayaan-1 made a major contribution to evidence for water on the Moon. Data from M3 revealed infrared absorption features associated with hydroxyl and water-bearing molecules across lunar surfaces, including polar areas. The findings indicated that water-related material was not confined to a few isolated locations, although its form and abundance vary with local conditions. Data from the Mini-SAR radar also identified polar craters whose radar properties were consistent with water ice deposits. These results helped direct later lunar research; individual instruments provided different kinds of evidence, and interpretations depend on the measurement method.

ISRO reported that Chandrayaan-1 completed its major mission objectives; the spacecraft made more than 3,400 lunar orbits. Communication with the orbiter was lost on 29 August 2009, ending the mission far earlier than its planned two-year lifetime. NASA's mission account describes technical challenges, including high spacecraft temperatures and failures in the star-sensor system before contact was lost. Despite its shorter operational period, the mission returned important observations and demonstrated India's capacity to conduct planetary science and deep-space operations.

Chandrayaan-1 established a foundation for subsequent Indian lunar missions and contributed to international knowledge of lunar water and mineralogy. Its scientific programme combined Indian instruments with instruments provided by foreign partners, enabling complementary observations from one spacecraft. The mission is distinct from Chandrayaan-2 and Chandrayaan-3: it was an orbiter-led remote-sensing mission with an impact probe, whereas later missions had different spacecraft and objectives. Its discoveries continue to inform questions about the Moon's history and the distribution of resources relevant to future exploration.