A significant rise in temperature inside Chandrayaan — as a result of the spacecraft getting nearer to the sun while going around the moon— is preventing India’s first lunar mission from entering into the operational phase.The high temperatures are likely to continue at least till the middle of next month when the spacecraft will move sufficiently away from the sun for the heat to subside. Though this rise in temperature was entirely expected and not a cause for any concern, the scientists at the mission control in Bangalore are playing safe by not switching on all the instruments simultaneously so as to avoid further rise in temperature because of the internal heat generated by the functioning of these instruments.“This rise and fall in temperature inside a satellite is a normal cyclical process. There is nothing unusual about it. But since this is the first cycle being faced by Chandrayaan, we are being extra cautious. We have decided to wait till the temperatures dip to bring the mission into the operational phase,” Mylswamy Annadurai, project director of Chandrayaan-I, told The Indian Express.As of now, all but two of the instruments onboard have been switched on and tested. But at any given point of time, only one instrument has been operational.“Two of the instruments which are still to be switched on are not only more sensitive to heat but also to high voltage. We thought it would be wise to wait for the temperature to go down before testing them,” Annadurai said.Annadurai compared the temperature fluctuations to the seasonal cycle on earth. As the spacecraft moves nearer to the sun, the temperature inside it will go up. Similarly, when it moves away from sun, the temperature will go down. During its two-year lifecycle, Chandrayaan-I will have two ‘summers’ and two ‘winters’. The spacecraft will well-designed to withstand these temperature fluctuations.The extra-cautiousness on the part of mission scientists is only because this is Chandrayaan’s first experience with such phenomenon. “We are well within the upper limit of the spacecraft’s temperature bracket. But we want to remain in this comfort zone as it is our first experience,” Annadurai said.The spacecraft has heater, which is capable up increasing the temperature during the ‘winter’ but there is no such mechanism available to deal with ‘summers’, he said. In case, the temperatures start touching the upper limit, there would be no option but to switch off one or some of the instruments on board to avoid any damage to them.Apart from this small hiccup, Chandrayaan is doing perfectly fine, Annadurai said. The data sent by each of the instruments that have been turned on have been analysed and found to be according to expectation. The operational phase of the mission will begin once all the instruments start operating continuously.
