By -Gayatri Chandrashekar :India’s maiden moon mission aims to take the unmanned Chandrayaan 1 spacecraft to orbit the moon that is 3,84,000 kilometres away from the earth, at an orbital height of a hundred kilometres from the moon’s surface.
The Rs 386 crore mission beyond the earth’s orbit, will study the earth’s only natural satellite with the aid of its eleven on-board instruments and send vast quantities of data over two years on varied parameters. The quest will inquire into the moon’s origin, evolution, physical and chemical attributes, presence of clean fuel like Helium-3, uranium and thorium, the endowment of minerals such as magnesium and titanium and most compellingly the presence of water ice near the lunar poles. The wealth of information will help design future manned and unmanned missions for space exploration.
In this bold first step, the Indian Space Research Organisation (ISRO) will land a scientific probe, the Moon Impact Probe (MIP) into the moon and gather data for insights into the moon’s gravity, its ultra-thin atmosphere and its physical features.
Almost forty years after man landed on the moon, why is there a spurt of interest into the mysteries of our closest celestial neighbour ? Why are the European Space Agency- ESA, Japan, China, USA and Russia actively embarking on deep space probes and lunar missions with renewed zeal ?
One reason is the technological advances of the last three decades. Computers have shrunk, increased their power and speed many times over and communication technologies bring whispers in the cosmos to man-made ears, the antennae of ground stations with unbelievable clarity. Powerful on-board systems, advanced guidance and navigation and real time feed-back loops give humankind the power to look deep into the eternal questions such as the origins of the universe and the star systems , the elemental particles and the fundamental laws that pervade the universe. Despite many unmanned and manned missions, the moon, the most studied of our celestial neighbours still holds many secrets that remain unravelled.
ISRO holds the Chandrayaan mission as a flagship programme to attract bright young Indians to its fold. India has other compelling reasons too. Increasingly, deep space probes that go beyond a hundred thousand kilometres into space, are collaborative efforts between countries, thanks to the massive funding and multi disciplinary skills needed. India is keen to enter the select group of collaborating countries in planetary explorations and the first step is to prove its own credentials by demonstrable success on its own strength.
In a way Chandrayaan-1 can be seen as an international effort. Of the eleven instruments on board the 1380 kg satellite, five are indigenous and six are from other countries.
The Indian payloads are :
• Terrain Mapping Camera to study the lunar physical features
• Hyper Spectral Imager for a study of the mineral composition
• Lunar Laser Ranging Instrument to create a comprehensive topographical field of the moon and to generate an improved model of the lunar gravity field
• High Energy X – ray spectrometer to identify regions of ice, uranium and thorium and
• Moon Impact Probe that will impact into a desired location on the moon to explore the descent and the thin atmosphere of the moon at close quarters briefly and to qualify technologies for future soft landing missions.
The foreign instruments are:
• Chandrayaan 1 Imaging X – ray Spectrometer from ESA for high quality mapping, using x ray fluorescence techniques. designed specially to look for Magnesium, Aluminium, Silicon, Iron and Titanium on the moon. This has been developed by Rutherford Appleton Lab, U.K. and ISRO satellite centre of Bangalore.
• Smart Near infra red spectrometer from ESA to study the lunar mineral resources, formation of the surface features, the way different layers of the moon’s crust lie over one another and the way substances are altered in space.
• Sub kilo electron volt Atom Reflecting Analyser from ESA to study the lunar surface composition and its reaction to solar wind and to study the moon’s magnetic anomalies. India has contributed actively to the development of this payload also.
• Radiation dose monitor from Bulgaria to study the radiation environment around the moon,
• Mini Synthetic Aperture Radar from USA for detecting water ice in the permanently shadowed regions of the moon’s poles upto a depth of a few metres.
• Moon Mineralogy Mapper from USA for mapping minerals spectroscopically in high spatial and spectral resolutions.
Chandrayaan-1 is of cuboid shape with a solar panel on one side. Many of its sub-systems are miniaturised to enable the safe and efficient functioning of its eleven scientific payloads. The solar panel generates a maximum of 700 W power. A 36 ampere-hour lithium ion battery supplies the satellite with power when the solar panel is not illuminated.
Charting New Pathways:
In Mission Chandrayaan-1, the ISRO will be engaging in many activities it has never carried out before. These are :
• Enabling a spacecraft to escape the earth’s gravitational force, putting it on a lunar trajectory and after reaching the moon’s vicinity gradually lowering the satellite and allow it to be captured by the moon’s gravity. The distance travelled by Chandrayaan-1 will be over 3,87000 kms, and this is more than ten times typically travelled by the Insat satellites;
• Track, control and command the spacecraft through its entire journey from Sriharikota to the moon through highly complex manoeuvres;
• Receive signals from deep space on the health and well being of the satellite during its orbital life as also the complex and voluminous data from the instruments on board over a period of two years and from the MIP when it is intentionally impacted into the moon.
• Control and command Chandrayaan-1 through its two years in orbit;
• Analyse and share the voluminous scientific data from the moon in all its variety with the scientific community.
More powerful launch vehicle PSLV C 11
The PSLV C11 has been rated up for the Chandrayaan mission. The 316 tonne launcher has been fitted with larger strap on motors for the task. Eighteen minutes after the launch, the satellite will be on its own. It will be on a highly elliptical initial orbit. By firing the powerful apogee motor on board from ground control, when the satellite is in the vicinity of the nearest point to the earth repeatedly, the spacecraft will be put on its path to the moon. Through carefully calibrated firing of the apogee motor once again, Chandrayaan-1 will be lowered to a 100 km lunar orbit, once it has been captured by the gravitational force of the moon with the help of firing of the apogee motor.
Deep Space Network Station
How strong would the radio signals from that far in space be ? From about four lakh kilometres, they would no doubt be feeble. In order to receive, boost , analyse and act on the data, a very state of the art, Indian Deep Space Network station has come up in
Byalalu, 35 kms from Bangalore . The station has an 18 metre and a 32 metre antennae to receive deep space signals. The giant 32 metre parabolic dish can support interplanetary missions of the future in addition to moon missions. The Electronics Corporation of India has fabricated and commissioned the facility to international standards. The village of Byalalu itself is ideally situated, free from extraneous radio noise and surrounded by hills on all sides with the ground level somewhat dipping compared to the surrounding areas.
Chandrayaan-1‘s launch from Sriharikota is scheduled on 22 October 2008 at 6.20 am. The spacecraft is expected to be in its lunar orbital home by 8 November, a fortnight later. Chandrayaan-2, a mission with Russian collaboration will place a lander/ rover with instruments on the moon’s surface by 2011-2012.
The first extraordinary steps in reaching out and touching the moon are in place. The thoroughness with which ISRO conducts all its activities is manifest in the Chandrayaan-1 mission too. This generates the confidence that this high profile programme will meet all the mission objectives and will be crowned with success.