India’s great leap over the moon

 

article by Nirad Mudur appeared in DNA on Monday, October 13, 2008 

 

The country is about to begin its campaign to conquer the moon, setting the tone for its role in a future global effort to colonise earth’s natural satellite.

It’s nine days to countdown. On October 22, the Chandrayaan-1 spacecraft is expected to blast off from Sriharikota and aim for the moon, making India join an elite club of a handful of nations to have tried sojourning at the earth’s natural satellite.

Just days ago, action stations at the Indian Space Research Organisation (Isro) moved
Chandrayaan-1 from the Isro Space Applications Centre (Isac) in Bangalore to the Satish Dhawan Space Centre (SDSC) at Sriharikota, about 80km north of Chennai. The spacecraft will orbit the moon for two years at an altitude of 100km before Isro’s scientists will intentionally crash it into the moon’s surface.

India may be late, but it has an agenda. “Till now, moon missions have been in localised spaces,” says M Annadurai, mission director, Chandrayaan-1. “But we are planning to cover the entire moon, both sides of it — the one which faces the earth and the one which faces away.” (You may recall from your school science class that the moon rotates around its axis and revolves around the earth in roughly the same time: 28 days. Therefore, one side of the moon always faces the earth while the other always remains hidden.)

Isro’s plan is to place Chandrayaan-1 in a polar orbit. That means it will revolve around the moon vertically, from pole to pole, rather than around the equator. “This is something no one has done till now,” says Annadurai. “We are trying to improve on the capabilities that others have so far used.”

This orbit would enable the spacecraft to look closely at both poles apart from other regions to scout for traces of polar ice/water on the moon as well as helium-3, which could be used as an alternative power source on earth. The latter is also on the agenda of the Chinese lunar missions which are to be carried out around the same time as the Indian ones.

To achieve these goals, Chandrayaan-1 will carry a total of 11 scientific payloads, of which six are indigenous.

Isro already has a series of remote-sensing satellites in low-earth orbits, which have given various Indian and foreign agencies crucial data for topography and soil mapping, and for crop, mineral, weather, and climate monitoring. The same skills will be applied in exploring the moon ahead of the launch of Chandrayaan-1’s successor.

 

Why our scientists are excited

Chandrayaan-1 will pick up the threads left by US lunar orbiters in a renewed hunt for water on the moon. This will be done in collaboration with the Applied Physics Laboratory of Johns Hopkins University, which is sending its miniature synthetic aperture radar in the spacecraft to map the polar landscape and deposits of water or ice on the lunar surface. In 1994, the SDI-Nasa Clementine spacecraft orbited the moon and beamed radio signals into shadowed craters near the moon’s South Pole. The reflections, received by antennae on earth, appeared to come from icy material. In 1998 Nasa sent the Lunar Prospector to look for water on the moon using a device called a neutron spectrometer. The Prospector sent vague signals on the presence of hydrogen in the polar craters, which led scientists to believe that water could exist on the moon. When the spacecraft’s primary mission was finished, Nasa decided to crash the Prospector near the moon’s South Pole on July 31, 1999, hoping to liberate a bit of its water layer. Several teams of researchers tried to detect a cloud of water vapour but failed. Experts say Chandrayaan-1 will be a significant step in picking up from where Prospector and Clementine left off. This will be tried at the end of the mission when the spacecraft will be crashed into the lunar surface, at one of the poles.

India’s mission objectives
- To design, develop, and launch a spacecraft in a polar orbit using an Indian launch vehicle. Isro is using PSLV, which has successfully launched a series of low-earth orbit remote-sensing satellites
- To develop expertise for planning and execution of mission and ground systems for sending spacecraft beyond the earth’s orbit for future missions
- To undertake high-resolution imaging and chemical and mineralogical mapping of the lunar surface to understand the evolution of the moon
- To systematically map the moon’s topography
- To establish the capability of planetary data analysis through archiving and data dissemination
- To create expertise in the development of detectors and sensor technology for planetary remote sensing for future planetary exploration programmes
- To enhance India’s image in the world by being part of a select group of nations that have the capability to observe planets directly