CHANDRAYAAN-1: India’s first mission to the Moon
“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.Following this, a hiatus of about one and a half-decade followed. 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.
It will be a quantum jump for Indian Space Research Organisation (ISRO) when it launches unmanned Moon orbiter, Chandrayaan-1, India’s first spacecraft mission beyond the earth orbit, on Oct 22.
The tentative launch is fixed for 0621 hrs when the improvised PSLV-C11 will soar into the sky from the Satish Dhavan Space Centre (SHAR), the island in Andhra Pradesh facing Bay of Bengal with the sprawling Pulikad Lake separating it from the land on the one side. It will carry the Chandrayaan-1 spacecraft with 11 payloads, including six from foreign countries. The mood among the ISRO scientists is upbeat and nearly 1000-strong experts have worked day and night for the past one year.
All four stages of the 83 metre tall PSLV-C11 is fully integrated at the second launch pad with the spacecraft undergoing final tests a few kilometre away. At Bylalu village, 40 km from Bangalore, ISRO has set up the Indian Deep Space Network, which includes two massive dish antennae, one with 32-metre diameter and other with 18 meter.
This will be the master control facility for Chandrayaan-1 which would be orbiting 100 km above the Moon after it is put into its slot on November 8.
”This mission is very different for ISRO which is making a big leap from the 40,000 km Earth orbit to nearly four lakh km Moon orbit.
”Our aim is to further expand our knowledge about Earth’s only natural satellite — the Moon,” SHAR Director M Chandra Dathan told the visiting reporters from Bangalore here on Tuesday.
Mr Dathan said a 52-hour count down would begin on October 21 with 32 hours needed to fill liquid propellants and last ten hours to conduct intensive electronic ground station tests. There will be nobody in the six km radius from the launch pad and everything will be remotely controlled. The launch vehicle would be moved to launch pad on October 17.
”We expect the weather to be good. Rains are expected but there is very less chance of a low pressure area forming in the Bay that might affect the launch date,” Dr M S Prasad, Associate Director of the SHAR said.
The PSLV-C11, the updated version of ISRO’s Polar Satellite Launch Vehicle, is the heaviest launch vehicle in its class with a gross weight of 316 tonnes carrying the spacecraft weighing 1,380 kg.
Chandrayaan spacecraft would be mated with the launch vehicle on October 12 or 13 and once it is launched, it would reach the Earth orbit in 1,089 seconds, Mr V K Srivatsav, DGM (Safety), Range operations said.
Many voyages had already taken place with the countries like the US, Russia and China already having scanned the moon’s surface through dozens of manned and unmanned missions.
But ISRO thinks this does not mean every important aspect of the moon is known to humans or fully understood by them. On the contrary, there are many secrets which the moon is yet to ‘reveal.’ Mr Prasad said these concern the origin and evolution of the moon, very detailed understanding of mineralogy of the Moon, abundance of Helium-3, a relatively clean fuel for future nuclear fusion reactors.
”It also appears that there is presence of water ice in the predominately shadow regions of the Moon’s polar areas,” he said.
The primary objectives of the Rs 386-crore Chandrayaan-1 are to expand scientific knowledge about the Moon, to upgrade India’s technological capability and provide challenging opportunities for planetary research to the younger generation of Indian scientists.
ISRO intends to achieve high-resolution remote sensing of Moon in the visible, near infrared, microwave and X-ray regions of the electromagnetic spectrum. A 3-dimensional atlas of the lunar surface with chemical and mineralogical mapping of the entire lunar surface is envisaged. The Indian payload include terrain mapping camera, Hyperspectral imager, Lunar laser ranging instrument, high energy X-ray spectrometer and Moon Impact Probe (MIP). The last would crash land on the Moon’s surface and through this prove ISRO intends to qualify some of the technologies related to future soft landing missions.
MIP helps scientific exploration of the Moon at a close distance.
It was developed by ISRO’s Vikram Sarabhai Space Centre in Thiruvananthapuram.
The foreign payloads include Imaging X-ray spectrometer and Smart near Infrared Spectrometer
, Sub kiloelectronvolt Atom Reflecting Analyzer, all from European Space Agency, Bulgarian Radiation Dose Monitor, Mini Synthetic Aperture radar built by Johns Hopkins University in the US and Moon Mineralogy Mapper. The last two were developed in association with NASA.
Mr Dathan said when the spacecraft is launched from the SHAR it would first move to highly elliptical transfer orbit around the Earth.
After circling the Earth in its transfer orbit for a while, Chandrayaan-1 will be taken into more elliptical orbits by repeatedly firing its liquid apogee motor and the space craft will be ultimately maneuvered to the Moon following a path called Lunar Transfer Trajectory which lines 3.87 lakh km from the Earth.
Countdown for the launch of Chandrayaan-I begins
Sriharikota: As the countdown for the Wednesday launch of lunar mission Chandrayaan-I on board the polar satellite launch vehicle (PSLV-C11) started early Monday, this spaceport off the Bay of Bengal coast was bustling with activity, excitement and a bit of anxiety.
With the countdown starting at 5.22 am, about 1,000 top scientists and technologists are working round-the-clock to send India’s first spacecraft mission beyond earth orbit from the picturesque spaceport, located on an island about 80 km from Chennai.
Housing the Satish Dhawan Space Centre of the state-run Indian Space Research Organisation (ISRO), the spaceport is popularly known as SHAR (Sriharikota Range). The rocket-launch station was built in 1971 over an area of 43,360 acres (175 sq km) along a 50-km coastline between Pulicat lake and the blue lagoon.
“Sriharikota was chosen as India’s spaceport because of its strategic location, topography, good launch azimuth corridor for space missions, advantages of earth rotation for eastward launches, nearer to the equator and an uninhabited area for safety,” SHAR spokesman N Ravindranath said.
With the state-of-the-art technology for producing solid propellant, processing heavier class solid rocket boosters, the facilities are equipped for testing their flight worthiness.
The first launch pad and the second launch pad are equipped with propellant storage and servicing, integration and launch facilities to meet the requirements of PSLV and GSLV (geo-synchronous satellite launch vehicle). A host of facilities for tracking and real-time flight data processing include range instrumentation.
“The spaceport has best-in-class infrastructure for launching satellites into low earth orbit, polar orbit and geo-stationary transfer orbit. The complex provides complete support for vehicle assembly, fuelling, checkout and launch operations,” Ravindranath said.
The various stages of PSLV and GSLV, their sub-systems and the spacecraft are prepared and tested in separate facilities before they are moved to the launch pad for integration. A 76-metre tall mobile service tower (MST) facilitates the vertical integration.
The foldable working platforms of MST provide access to the vehicle for elevations. A massive launch pedestal, made up of steel plates, acts as the base on which the vehicle is integrated. The umbilical tower houses the feed lines for liquid propellants and high-pressure gases, checkout cables and chilled air duct for supplying cool air to the satellite and equipment bay.
“A few hours before the launch of any mission to polar or geo-synchronous orbit, the MST is withdrawn and the vehicle remains on the launch pedestal. The 3,200-tonne MST moves at snail’s pace to its parking slot on 32 wheels, eight in each corner, on a twin rail track,” Ravindranath explained.
The second launch pad provides redundant facilities for launching operational PSLVs and GSLVs and to have quick turnaround time for more launches. It is being augmented for future launch vehicle configurations such as GSLV-MkIII.
“The launch vehicle is assembled and checked out on a mobile pedestal in the vehicle assembly building and then moved in vertical position to the launch pad on a rail track. The second launch pad is being used for the Chandrayaan-I mission to reduce pad occupancy and move the vehicle back to the VHB for protection in the event of cyclone warning,” Ravindranath pointed out.
Besides launch pads, the spaceport boasts of a high-tech range instrumentation facility comprising tracking, telemetry and tele-command systems. High precision radars track the launch vehicle.
“The tele-command system is used to transmit command to the vehicle. If the vehicle malfunctions and deviates from the trajectory beyond the acceptable limits, the range safety officer terminates the flight using the telecommand,” the official affirmed.
As the heart of the spaceport, the mission control centre (MCC), situated about six km from the launch complex, coordinates and conducts the launch operations during the countdown phase and till the injection of the satellite into its designated orbit.
The MCC is linked to all the ground stations through communication links for voice and data transmission. The launch preparations on the vehicle are monitored from the MCC using a multi-channel closed-circuit television system,” Ravindranath noted.
Of the 2,600-plus people employed to operate the spaceport, about 700 are scientists and technologists. A township has been built on the island, surrounded by the sea on the east and backwaters on the other three sides.