Chandrayaan - India's Mission to the Moon.
Chandrayaan-1, is India's first mission to the moon launched by India's national space agency the Indian Space Research Organisation (ISRO). The unmanned lunar exploration mission includes a lunar orbiter and an impactor. India launched the spacecraft by a modified version of the PSLV C11 on 22 October 2008 from Satish Dhawan Space Centre, Sriharikota, Andhra Pradesh. The vehicle was successfully inserted into lunar orbit on 8 November 2008.
On November 14, 2008, the Moon Impact Probe successfully separated from the moon-orbiting Chandrayaan and descended towards the lunar south pole in a controlled manner. The MIP impacted Shackleton Crater, of the lunar south pole, on 14 November 2008 releasing subsurface debris that could be analyzed for presence of water ice.
The estimated cost for the project is Rs. 386 crore (US$ 80 million). The remote sensing lunar satellite had a mass of 1,380 kilograms (3,042 lb) at launch and 675 kilograms (1,488 lb) in lunar orbit and carries high resolution remote sensing equipment for visible, near infrared, and soft and hard X-ray frequencies. Over a two-year period, it is intended to survey the lunar surface to produce a complete map of its chemical characteristics and 3-dimensional topography. The polar regions are of special interest, as they might contain ice. The lunar mission carries five ISRO payloads and six payloads from other international space agencies including NASA, ESA, and the Bulgarian Aerospace Agency, which were carried free of cost.
Objectives
The stated scientific objectives of the mission are:
• To design, develop, launch and orbit a spacecraft around the Moon using an Indian-made launch vehicle.
Conduct scientific experiments using instruments on-board the spacecraft which will yield the following results:
• Preparation of a three-dimensional atlas (with high spatial and altitude resolution of 5-10 m) of both the near and far side of the moon).
• Chemical and mineralogical mapping of the entire lunar surface at high spatial resolution, mapping particularly the chemical elements Magnesium, Aluminum, Silicon, Calcium, Iron, Titanium, Radon, Uranium, & Thorium.
• The impact of a sub-satellite (Moon Impact Probe — MIP) on the surface on the Moon as a fore-runner to future soft-landing missions.
"THE MOON" with the history of the early solar system etched on it beckons mankind from time immemorial to admire its marvels and discover its secrets. Understanding the moon provides a pathway to unravel the early evolution of the solar system and that of the planet earth. Through the ages, the Moon, our closest celestial body has aroused curiosity in our mind much more than any other objects in the sky. This led to scientific study of the Moon, driven by human desire and quest for knowledge. This is also reflected in the ancient verse.
Exploration of the moon got a boost with the advent of the space age and the decades of sixties and seventies saw a myriad of successful unmanned and manned missions to moon. This was followed by a hiatus of about one and a half-decade. During this period we refined our knowledge about the origin and evolution of the moon and its place as a link to understand the early history of the Solar System and of the earth.
However, new questions about lunar evolution also emerged and new possibilities of using the moon as a platform for further exploration of the solar system and beyond were formulated. Moon again became the prime target for exploration and a new renaissance of rejuvenated interest dawned. All the major space faring nations of the world started planning missions to explore the moon and also to utilize moon as a potential base for space exploration.
The idea of undertaking an Indian scientific mission to Moon was initially mooted in a meeting of the Indian Academy of Sciences in 1999 that was followed up by discussions in the Astronautical Society of India in 2000. Based on the recommendations made by the learned members of these forums, a National Lunar Mission Task Force was constituted by the Indian Space Research Organisation (ISRO). Leading Indian scientists and technologists participated in the deliberations of the Task Force that provided an assessment on the feasibility of an Indian Mission to the Moon as well as dwelt on the focus of such a mission and its possible configuration.
The task force recommended that given the technical expertise of ISRO it will be extreme worthwhile to plan an Indian Mission to the Moon. It also provided specific inputs such as the primary scientific objectives of such a mission, plausible instruments to meet these objectives, launch and spacecraft technologies that need to be developed and suggested the need for setting up of a Deep Space Network (DSN) station in India for communication with the lunar orbiting spacecraft. The team also provided a provisional budgetary estimate.
The Study Report of the Task Team was discussed in April 2003 by a peer group of about 100 eminent Indian scientists representing various fields of planetary & space sciences, earth sciences, physics, chemistry, astronomy, astrophysics and engineering and communication sciences. After detailed discussions, it was unanimously recommended that India should undertake the Mission to Moon, particularly in view of the renowned international interest on moon with several exciting missions planned for the new millennium. In addition, such a mission will provide the needed thrust to basic science and engineering research in the country including new challenges to ISRO to go beyond the Geostationary orbit. Further, such a project will also help bringing in young talents to the arena of fundamental research. The Academia, in particular, the university scientists would also find participation in such a project intellectually rewarding.
Subsequently, Government of India approved ISRO's proposal for the first Indian Moon Mission, called Chandrayaan-1 in November 2003.
Mission Sequence
• Chandrayaan-1 spacecraft was launched from the Satish Dhawan Space Centre, SHAR, Sriharikota by PSLV-XL (PSLV-C11) on 22 October 2008 in an highly elliptical initial orbit (IO) with perigee (nearest point to the Earth) of 255 km and an apogee (farthest point from the Earth) of 22,860 km, inclined at an angle of 17.9 deg to the equator. In this initial orbit, Chandrayaan orbited the Earth once in about six and a half hours.
• Subsequently, the spacecraft's Liquid Apogee Motor (LAM) firing was done on 23 October, when the spacecraft was near perigee, to raise the apogee to 37,900 km while the perigee to 305 km. The spacecraft took eleven hours to go round the Earth once.
• The orbit was further raised to 336 km x 74,715 km on 25 October. In this orbit, spacecraft took about twenty-five and a half hours to orbit the Earth once.
• The LAM was fired again on 26 October to take the Chandrayaan-1 spacecraft to extremely high elliptical orbit with apogee 164,600 km and perigee at 348 km. Chandrayaan-1 took about 73 hours to go round the Earth once.
• On 29 October, orbit raising was carried out to raise the apogee to 267,000 km and perigee to 465 km. Chandrayaan's present orbit extends more than half the way to moon and takes about six days to orbit the Earth.
• On 4 November, Chandrayaan entered the Lunar Transfer Trajectory with an apogee of 380,000 km.
• On 8 November, the spacecraft's Liquid engine was fired to reduce its velocity to insert the spacecraft in the lunar orbit (LOI) and enable lunar gravity to capture it. As a result, the spacecraft was in an elliptical orbit with periselene (nearest point to the moon) of 504 km and aposelene (farthest point from the moon) of 7,502 km.
• The first orbit reduction manoeuvre was carried out successfully on 9 November. Thus the spacecraft was in lunar orbit with 200 km periselene. The aposelene remains unchanged (i.e 7,502 km).
• After careful and detailed observation, a series of three orbit reduction manoeuvres were successfully carried out and the spacecraft's orbit was reduced to its intended operational 100 km circular polar orbit on November 12.
• On 14 November, the Moon Impact Probe (MIP) was ejected from the Chandrayaan-1 spacecraft and hard landed on the lunar surface near the South Polar Region. It placed the Indian tricolour, which was pasted on the sides of MIP on the Moon.
• Currently, the scientific instruments/payloads are being commissioned sequentially and exploration of Moon with the array of onboard instruments has begun.
When the spacecraft entered its initial orbit about 20 minutes after lift-off, jubilation broke out at the mission control room which so far had been extremely tense. There were congratulatory handshakes among the scientists and warm embraces.
By
Mamta Singh
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