Lunar Laser Ranging Instrument (LLRI), one of the
11 scientific instruments (payloads) carried by Chandrayaan-1 spacecraft, has
successfully been turned ON today (November 16, 2008). The instrument was
switched ON when the spacecraft was passing over western part of the moons
visible hemisphere. Preliminary assessment of the data from LLRI by ISRO
scientists indicates that the instruments performance is normal. LLRI sends
pulses of infrared laser light towards a strip of lunar surface and detects the
reflected portion of that light. With this, the instrument can very accurately
measure the height of moons surface features. LLRI will be continuously kept
ON and takes 10 measurements per second on both day and night sides of the
moon. It provides topographical details of both polar and equatorial regions of
the moon. Detailed analysis of the data sent by LLRI helps in understanding the
internal structure of the moon as well as the way that celestial body evolved.
It may be recalled that earlier, three other
payloads of Chandrayaan-1 Terrain Mapping Camera (TMC), Radiation Dose
Monitor (RADOM) and Moon Impact Probe (MIP) were successfully turned ON. MIP,
carrying Indian tricolour, was released from the spacecraft on November 14,
2008 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 taking breathtaking 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.