Roa lkse iz fpfdrks euh”kkA
Roa jft”B euq usf”k iUFkkeAA
O Moon! We should be able to know you through our intellect,
You enlighten us through the right path.
Rig Veda part – 1/91/1
(About 2000 years B.C.)
India'slunar odyssey has begun with Chandrayaan?1 taking off from Satish Dhawan Space Centre,
SHAR, Sriharikota in Andhra Pradesh at 6:22 am IST on October 22. Chandrayaan?1 is an unmanned orbiter, a lunar satellite. Its sojourn will last for a tentative two years. Why embark on this exorbitant mission? The present chairman of Indian Space Research Organisation (ISRO) quips in ? ?to expand scientific knowledge about the origin and evolution of the moon, upgrade India'stechnological capabilities and provide challenging opportunities to young scientists working in planetary sciences?.
Mission'sscientific objectives
Chandrayaan?1 is vouched to carry out high-resolution remote sensing of the moon in its visible, near infrared (NIR), low energy X-rays and high energy X-ray regions. An extensive chemical and mineralogical mapping of the entire lunar surface for distribution of mineral and chemical elements including high atomic number elements such as uranium, radon and thorium will be conducted with high spatial resolution. The concomitant transmission will ennoble identification of different geological units to infer the primeval evolutionary history of the moon and to fathom out the stratigraphy and nature of the moon'scrust and thereupon ascertain certain aspects of magma ocean hypothesis. This may further unravel the compositions of impactors that bombarded the moon during its early evolution that is inexorably linked with the formation of the earth as well. Another intriguing phenomenon is the radiation environment of the moon produced by solar radiation and galactic cosmic rays. An isotope of radon, that is a product of uranium decay chain forms a thin crust on the lunar crust. Also, the permanent sunlit and night side of the moon with its permanently shadowed cold polar regions crop up several pertinent posers. The tentative expenses for the entire project is pegged at around Rs 400 crore.
The Chandrayaan?1 sojourn
Chandrayaan?1 will reach a highly elliptical Initial Orbit (IO) having its perigee (nearest point from the earth) 250 km while the apogee (farthest point from the earth) will be 23,000 km. Subsequently Chandrayaan?1 anticipates two more elliptical orbits whose apogees lie still higher at 37000 km and 73,000 km respectively before attempting third one attaining a whopping apogee at about 387,000 km. This would happen at an opportune moment by firing the spacecraft'sLiquid Apogee Motor (LAM) when the spacecraft is near perigee. The third ellipse will land the spacecraft within a few hundred kilometer vicinity of moon. Thereafter the spacecraft will be sufficiently slowed down by firing LAM so as to enable the gravity of the moon to capture it into an elliptical orbit going within 100 km circular polar orbit. Finally at some conducive time, the lunar probe will be ejected from Chandrayaan-1 spacecraft to hit the lunar surface in a chosen area and glean upon the lunar surface with its array of instruments including cameras, spectrometers and Synthetic Aperture Radar (SAR).
Structure and functioning
Chandrayaan?1 is cuboid in shape with sides of approx 1.5 each weighing 1380 kg at launch and 675 kg at lunar orbit. It has a solar panel projecting from one of its sides. The spacecraft structure has been mainly built using composites and aluminum honeycomb material. The thermal subsystem consisting of paints, tapes, multiplayer insulation blanket, optical solar reflectors, heat pipes, heaters and temperature controllers ensure the proper functioning of the spacecraft by keeping its temperature within acceptable limits. The moon probe will be put in the lunar orbit at 100 km from the moon surface by India'sindigenously made launch vehicle, Polar Satellite Launch Vehicle-C11 (PSLV-C11), a 44.4?metre, 316-tonne workhorse. PSLV-C11 uses large strap-on motors (PSOM-XL) with a large amount of propellant to achieve higher payload capability. PSLV-C11 has four stages using solid and liquid propulsion systems alternatively. PSLV-C11 has sophisticated telemetry to guide it through the predetermined trajectory and maintain continual tracking.
Chandrayaan-1 has in total 11 science payloads of which five payloads are indigenously developed by Indian scientists. The rest six payloads come from European Space Agency, Bulgarian Academy of Science and also NASA.
The ground station network to enable a smooth passage to Chandrayaan-1 requires the triumvirate?India Deep Space Network (ISDN). Mission Operations Complex (MOX) and Indian Space Science Data Centre (ISSDC), all three nodal agencies constituted by ISRO in Bangalore to provide to and fro conduit of communication. The Payload Operation Centres (POC) is an integral part of the Ground Segment that avail science data to payload scientists.
Chandrayaan-1 has been assiduously built at ISRO Satellite Centre, Bangalore in conjunction with ISRO'sDepartment of Space (DOS) establishments ?Vikram Sarahai Space Centre (VSSC), Liquid Propulsion Systems Centre (LPSC) and ISRO Inertial systems unit (IISU) of Thiruvanthapuram, Space Applications Centre (SAC) and Physical Research Laboratory (PRL) of Ahmedabad and Laboratory for Electro-optic Systems (LEOS) of Bangalore.
India is hogging the limelight of a rare achievement to exult over. Its high time to heap kudos on those eggheads, the scientific camaraderie who were gung ho about the mission and triumphed in surmounting all the vicissitudes of science and cynicism.
Bon Voyage!
(The writer is a freelance journalist with varied interests, reachable at ratnaub@gmail.com)
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