London, Nov 28: India's first uncrewed lunar probe, Chandrayaan-1, is experiencing the hottest temperatures it has yet faced, which have forced it to take a 'summer break', using its instruments sparingly until mid-January to get through the hot patch.
Chandrayaan is currently over the sunlit side of the moon, a place where spacecraft are expected to heat up because they receive energy directly from the Sun as well as infrared radiation given off by the Moon. According to a report in New Scientist, the spacecraft is currently facing external temperatures of 100 degrees Celsius, and cooling systems aim to maintain the spacecraft's interior at around 40 degrees C. "It is local summer for the satellite," Chandrayaan project director Mylswamy Annadurai told New Scientist.
When the craft passes by the dark side of the Moon external temperatures will fall to as low as -100 degrees C.
Still, the Indian Space Research Organisation (ISRO) is working in unknown territory, on its first mission operating outside the Earth's gravity.
"The thermal environment is very demanding. I think it somewhat surprised ISRO," observed Paul Spudis, scientist at the Houston-based Lunar and Planetary Institute. "They have ways to mitigate the issue, so I do not see this as a big problem," he added.
Annadurai said that the spacecraft systems are designed to withstand different temperature ranges depending on their use and exposure to radiation.
For example, solar panels that supply power to the spacecraft can withstand from minus to plus 120 degrees C. Others, like its infrared detector can only handle up to 50 degrees C.
Nine of the 11 instruments on-board Chandrayaan have now been switched on for calibration and simple health checks.
The spacecraft's temperature is expected to stabilise by the end of December.
Until then, scientists will use one instrument at a time, as required, but will be able to operate all instruments simultaneously by mid-January.