SUCCESS stories at the Defence Research and Development Organisation are occasionally interspersed with failure. An experiment on January 20 was one such.
The supersonic cruise missile BrahMos missed the target at the Armys range at Pokhran in Rajasthan because its global positioning system (GPS) blanked out, said DRDO officials. The American satellites that run the GPS had been switched off on the day Barack Obama was sworn in the United States President, they said. The missile, therefore, travelled for 112 seconds instead of the slated 84 seconds and fell 7 km away from the target.
The officials could not say whether the Americans had deliberately switched off the GPS satellites to test whether Indias missile mission would be a success without them. They conceded that it was possible to switch off GPS-linked satellites selectively. The failure of the mission, therefore, has underlined the need for India to have its own GPS-linked satellites instead of depending on American or Russian constellations, said an official.
BrahMos, jointly developed by India and Russia, is essentially an anti-ship missile. It can hit targets 290 km away, and can cruise at a particular altitude at Mach 3 (three times the speed of sound). BrahMos is the only missile in the world, according to the DRDO, that can hit targets both in sea and on land, without any change in its hardware; only the software in the missiles computer has to be changed.
Officials of the DRDO described the January 20 mission as a difficult one because the target was just 50 km away instead of the normal 290 km. The missile, launched in a land-attack mode, had to hit a particular target out of a cluster of targets. The Army insisted that the error in hitting the target, which resembled a chemical weapons factory, could not exceed one metre. Reflectors had been installed to mislead the missile.
The DRDO, therefore, made a new seeker for the missile to meet this challenge. A software was developed with a new algorithm, which was to help the missile reach the target by using the GPS data obtained from the U.S. satellites. The mission demanded that the missiles inertial navigation system (INS), its GPS receiver and its seeker should all work together.
But there were constraints on the mission. A DRDO official said: When the missile is flying very fast, it is difficult to perform manoeuvres. The GPS data did not come in time, so the INS data with its uncorrected error was taken as the reference and we missed the target.
A repeat mission on March 4, with the American GPS-linked satellites turned on, was a success.
T.S. Subramanian
