The Terrain Mapping camera (TMC) on board Chandrayaan-1 spacecraft was successfully operated on October 29, 2008 through a series of commands issued from the Spacecraft Control Centre of ISRO Telemetry, Tracking and Command Network (ISTRAC) at Bangalore.
Analysis of the first imagery received by the Indian Deep Space Network (IDSN) at Byalalu and later processed by Indian Space Science Data Centre (ISSDC) confirms excellent performance of the camera.The first imagery (image 1) taken at 8:00 am IST from a height of 9,000 km shows the Northern coast of Australia while the other (image 2) taken at 12:30 pm from a height of 70,000 km shows Australia’s Southern Coast.
TMC is one of the eleven scientific instruments (payloads) of Chandrayaan-1. The camera can take black and white pictures of an object by recording the visible light reflected from it. The instrument has a resolution of about 5 metres. TMC
Payload Configuration Details:
The TMC will image in the panchromatic spectral region of 0.5 to 0.85 µm, with a spatial/ ground resolution of 5 m and swath coverage of 20 km.
The camera is configured for imaging in the pushbroom mode, with three linear 4k element detectors in the image plane for fore, nadir and aft views, along the ground track of the satellite. The fore and aft view angles are ±25º respectively w.r.t. Nadir. TMC will measure the solar radiation reflected / scattered from the Moon’s surface. The dynamic range of the reflected signal is quite large, represented by the two extreme targets – fresh crust rocks and mature mare soil.
TMC uses Linear Active Pixel Sensor (APS) detector with in-built digitizer. Single refractive optics will cover the total field of view for the three detectors. The output of the detector will be in digitized form. The optics is designed as a single unit catering to the wide field of view (FOV) requirement in the direction along the ground track. The incident beams from the fore (+25°) and aft (-25°) directions are directed on to the focusing optics, using mirrors. Modular camera electronics for each detector is custom designed for the system requirements using FPGA. The expected data rate is of the order of 50 Mbps. The dimension of TMC payload is 370 mm x 220 mm x 414 mm and mass is 6.3 kg.
TMC payload is developed by ISRO. Besides TMC, the other four Indian payloads of Chandrayaan-1 are the Hyper spectral Imager (HySI), Lunar Laser Ranging Instrument (LLRI), High Energy X-ray Spectrometer (HEX) and the Moon Impact Probe (MIP). The other six payloads of Chandrayaan-1 are from abroad.