INDIA’S first moon mission is its boldest and most ambitious scientific endeavour. But is it really that big a deal, considering that such journeys were routinely made by satellites from the United States and the erstwhile Soviet Union almost half a century ago? Is the Indian Space Research Organisation (ISRO) merely trying to reinvent the wheel? After all, there have been more than 65 missions to the moon, many of which made successful landings. Twelve astronauts have already walked on the surface of the earth’s natural satellite.
Mylswamy Annadurai, the mission director of Chandrayaan-I, puts things in perspective. Chandrayaan-I, he says, is not about reinventing the wheel but about working on the wheel to improve it.

There is a great qualitative difference between the lunar missions being undertaken now and the ones that were launched in the ’60s and the ’70s. There have been great leaps in technology in the last three decades and scientists have devised much better equipment to carry out their experiments. The goals of these lunar missions have also changed. The earlier expeditions were driven mainly by the urge to establish the technological supremacy of one superpower over the other, though these also resulted in a wealth of scientific data being collected. That sort of competition has now given way to collaboration. This is exemplified by the fact that six out of the 11 payloads on Chandrayaan-I are from foreign countries. The effort is to maximise the scientific yield from every expedition by sharing knowledge and skills.

Chandrayaan-I comes at a time when there is a renewed global interest in the moon. Despite the numerous visits—the 17-year period from 1959 to 1976 saw as many as 60 lunar missions—there is a great deal about the moon that is still unknown to mankind. There is no final word on the origin and evolution of the moon, or on its composition and mineralogy. The possibility of existence of water has not been conclusively ruled out.

Of late, scientists have been excited over the likely presence of a huge amount of Helium-3 in the moon's atmosphere. Helium-3 can be used as clean fuel in future nuclear fusion reactors and has the potential to solve the desperate energy crisis that the world finds itself in. Additionally, the moon is already being looked at as a possible base camp for carrying out explorations into deeper space. For this purpose, some of the continuing and future lunar expeditions will also explore the possibility of long-term stay for man on the moon.
The sudden spurt in lunar missions since last year is therefore hardly surprising. Both China and Japan sent their moon missions in the latter half of last year; Chandrayaan-I will join them in a few days’ time followed by the Lunar Reconnaissance Orbiter of the US, which is slated for an April 2009 launch. None of them will land on the surface of the moon. They will all orbit around it at different distances and carry out a number of studies with the help of the various equipments mounted on them.

WHAT MAKES CHANDRAYAAN DIFFERENT?
So, just what will Chandrayaan do that has not been done earlier by any of the other lunar missions? Chandrayaan is carrying 11 payloads, which, individually and together, will carry out a range of studies. Some of them have never been attempted before.
*With a Terrain Mapping Camera (TMC), Chandrayaan will attempt to capture the high-resolution three-dimensional topography of the entire moon's surface. Aided by a laser altimeter to determine the altitude of the spacecraft from the moon’s surface, the TMC should be able to prepare an elevation map with an accuracy of about 10m. Such data would enable scientists to understand the moon’s evolution and also single out areas on its surface, which can be of scientific interest in the future.
*An instrument called Hyperspectral Imager will try to determine the mineral composition of the moon’s surface by obtaining spectroscopic data. This will help in augmenting the already available information on the mineralogy of the moon. Chemical and mineralogical data are other indicators in strengthening man’s knowledge about the origins and early evolution of the moon.

A high-energy X-ray spectrometer will carry out the first-ever experiment of its kind to test the hypothesis of the presence of water-ice deposits in the moon’s polar region. It will also attempt to identify the areas with high concentrations of uranium and thorium.
Though Chandrayaan is just an orbiter and not a lander, it will also test its technologies for a future soft landing on the moon’s surface through the Moon Impact Probe (MIP), which will be ejected from the main spacecraft and will hit the lunar surface at a selected location. Besides qualifying technologies for a future landing mission, the MIP will enable an examination of the moon from very close quarters.

CHEAP AND GLOBAL
It is a tribute to the Indian scientific community that it has been able to design and execute a mission that is not only the cheapest-ever lunar expedition but also likely to return maximum ‘science value’ for its cost. The budget for Chandrayaan-I is estimated at Rs 386 crore, which comes to less than $80 million to current exchange rates. In contrast, the Chinese mission Chang’e-1, which flew off last year, cost about $169 million. Japan’s Kaguya, which was also launched last year, and the forthcoming LRO of the United States are even more expensive, at about $260 million and $460 million respectively. NASA’s two ‘low-cost’ missions in the ’90s, Lunar Prospector and Clementine, also cost more than Chandrayaan-I, once their costs are adjusted for inflation.

The 11 instruments that Chandrayaan-I is carrying are probably the maximum that any lunar spacecraft has had on board. Because of this, its ‘science value’, which is a loosely defined term to measure the scientific return from a mission, is also likely to be the highest. ‘Science value’ is based on a rough ratio of the number of instruments on board a spacecraft to the total cost of the mission.
The low cost has been ensured by complete indigenisation, a rigorous schedule and innovation. Chandrayaan has been completed in just about four years with most of its instruments and equipment having been designed and built in India by Indian engineers and companies. Despite the fact that it carries six payloads from foreign countries, scientists associated with the project undertook very few foreign tours, which contributed to saving not just money but also time.

With six foreign payloads on board, Chandrayaan also has a more pronounced international flavour than any other lunar mission. Of the six, three are from the European Space Agency (ESA), two from NASA and one from Bulgaria. These were selected from the 26 proposals received from various international institutions after a careful examination of their merits and compatibility with the Chandrayaan mission both in terms of scientific objectives as well as engineering aspects.
In addition to these, there are a number of non-science drivers for the Chandrayaan project.

THE JOURNEY
Chandrayaan-I will be pushed into space by the Polar Satellite Launch Vehicle (PSLV) C-11, which will be launched from the Satish Dhawan Space Centre at Sriharikota on Wednesday. After ejecting from the launch vehicle, the spacecraft will enter an elliptical orbit around the earth. After one complete revolution around the earth in an orbit of apogee (farthest point from the earth) of 3,87,000 km, the spacecraft will approach the moon at a distance of a few hundred kilometres from its north pole.

Following this, the spacecraft will be slowed down enough to be captured by the moon’s gravity into an elliptical orbit. It will subsequently approach the moon until it reaches a target distance of 100 km from the moon’s surface. Later, the Moon Impact Probe will be ejected from the main spacecraft and hit the lunar surface at a selected spot.
The Chandrayaan mission will last for two years, during which the various instruments on board will take measurements and collect data.

THE FUTURE
Chandrayaan-1 is to be followed by Chandrayaan-2, which will be able to land on moon's surface. Chandrayaan-2 will be a collaboration between India’s ISRO and Russia’s Roskosmos space agency and is slated for a 2011 launch. Like in Chandrayaan-1, ISRO is expecting a keen interest from international institutions in placing their payloads on Chandrayaan-2 as well. The Union Cabinet recently gave its approval to the budget for Chandrayaan-2, which, at Rs 425 crore, is only marginally more than that of Chandrayaan-1.

CHANDRAYAAN-1: VITAL STATS
Launch vehicle: PSLV
Launch site: Sriharikota
Weight of the spacecraft at the time of launch: 1,400 kg
Shape of the spacecraft: Cube of dimensions 1.5 m
No. of payloads: 11
Mission duration: 2 years