Chandrayaan-1 spacecraft will send detailed information about its health

During the various phases of its flight, Chandrayaan-1 spacecraft will send detailed information about its health to the earth through its transmitter, according to Indian Space Research Organisation.At the same time, the spacecraft will be ready to receive radio commands sent from Chandrayaan-1 spacecraft control centre instructing it to perform various tasks.
Besides, the spacecraft receives, modifies and retransmits radio waves sent by ground antennas in a precise way. This plays a crucial role in knowing its position and orbit at a particular instant of time. All these happen at 'S-band' frequencies in the microwave region of the electromagnetic spectrum.
Additionally, as it orbits the Moon, the spacecraft sends valuable imagery and other scientific information to earth through X-band (at a higher frequency compared to S-band), which also lies in the microwave region.
But, such information is transmitted through radio at a very low power of a few Watts. Thus, radio signals carrying that precious information become extremely feeble by the time they travel 400,000 km from the moon and reach the earth.
The ground segment of Chandrayaan-1 performs the crucial task of receiving the radio signals sent by the spacecraft. It also transmits the radio commands to be sent to the spacecraft during different phases of its mission. Besides, it processes and safe keeps the scientific information sent by the spacecraft