ISRO feels the heat as Chandrayaan 1's temperature rises

Chandrayaan 1, the country's first unmanned lunar craft, has reportedly recorded an increase in temperature, of almost 10 degrees, with the temperature inside the craft going up to over 50 degrees C.

Such a rise in the heat is capable of damaging some of the more sensitive payloads within the moon craft, Madhavan Nair, chairman of Indian Space Research Organisation, said.

Scientists said Chandrayaan 1 has been functioning normally despite a rise in the moon's surface temperature, S Satish, director of the Indian Space Research Organisation (ISRO) said.

The high atmospheric temperature over the moon has caused temperature inside the satellite to go up to over 50 degrees C, prompting scientists to look for measures to cool off the sophisticated instruments.

The ISRO director said the craft's nine payloads, which have been switched on, are working fine and sending back data so far.

The Chandryaan 1 mission has so far deployed nine payloads, including Lunar Laser Ranging Instrument (LLRI) which can very accurately measure the height of moon's surface features by sending pulses of infrared laser light towards a strip of lunar surface and detecting the reflected portion of that light.

Chandrayaan-1 – Terrain Mapping Camera (TMC), Radiation Dose Monitor (RADOM) and Moon Impact Probe (MIP) – were successfully turned on earlier. MIP, carrying Indian tricolour, was released from the spacecraft on 14 November and 25 minutes later, successfully impacted the lunar surface as intended. TMC took pictures of the Earth and moon when the spacecraft was on its way to moon. After reaching lunar orbit, TMC has been sending pictures of the lunar panorama. RADOM was also switched on in the Earth orbit itself.

The pictures and other scientific data sent by Chandrayaan-1 spacecraft from lunar orbit have been received by antennas of Indian Deep Space Network (IDSN) at Byalalu. The spacecraft operations are being carried out from the Satellite Control Centre (SCC) of ISRO Telemetry, Tracking and Command Network (ISTRAC) at Bangalore.

While the Chandrayan project has so far been successful, the ISRO is yet to activate the high energy X-ray Spectrometer (HEX) and the Sub keV Atom Reflecting Analyser (SARA).

HEX will examine the moon's polar region for the presence of water, uranium and thorium, whereas SARA will analyse the surface composition of moon's body.

As of now, data is being received from the 9 scientific instruments on board which are giving all the data, including the 3-dimensional images of the lunar surface.

But the two instruments are crucial to the mission and the success of the mission will also depend on the data received from these two payloads.

The problem, ISRO officials say, is a normal impact of the fluctuations in temperature during the lunar orbit.
 
''It is a usual phenomena because it is summer on the moon. There is nothing to worry. It will be normal by December,'' said Satish.

The satellite is getting extra heat as it is in a straight line with the sun and the moon, said moon mission chief M Annadurai.

"The moon, our satellite and the sun are in same line and this means our craft is receiving 1,200 watts of heat from the moon and 1,300 watts from the sun per meter square," said Annadurai.

He said ISRO will keep some of the more heat-sensitive payloads idle to ensure they are not affected by the heat and start some payloads that are more heat-resistant.

''Two of the high voltage payloads SARA and Hex will be switched on shortly. These payloads are sensitive equipment and need more voltage,'' he said, adding that by the first week of December, the moon's atmosphere will cool down.

Scientists expect to use the satellite's thermal blanket to keep the temperature inside low but that could affect normal operations of the equipment.

The moon craft is receiving 1,200 watts of heat from the moon and 1,300 watts from the sun per meter square, BBC quoted project director Annadurai as saying.

Annadurai said it was possible that the location of the satellite can be the reason for the very hot temperatures and it is likely that the satellite is relocated to save it from extreme heat.