Heat Strokes Might Have Killed Chandrayaan-1

September 2009

Chandrayaan-1's mission ended on 28 August 2009 — after 312 days instead of the planned two years — when communication with the spacecraft was abruptly lost. Overheating was a persistent problem throughout the mission and is considered a key factor in its early demise.

Within a month of reaching lunar orbit, the spacecraft's temperature rose to around 50 °C. Mission controllers rotated the craft and operated only one instrument at a time to manage heat. The excess heating was later attributed to a batch of DC–DC converters with poor thermal regulation, compounded by lunar orbital conditions that were hotter than pre-mission estimates.

In May 2009 the orbit was raised from 100 km to 200 km, partly to reduce the thermal load. The heat is also linked to the failure of both star trackers — the sensors used to determine the spacecraft's orientation — which forced controllers to rely on back-up gyroscope and Sun-sensor procedures during the final months.

Despite the shortened mission, Chandrayaan-1 achieved most of its scientific objectives, including the discovery of water on the Moon. The thermal lessons learned directly informed the design of Chandrayaan-2.

Source: Wikipedia — Chandrayaan-1