Even as Indian space scientists are working on the partial restoration of communications satellite INSAT-4B, they are worried because of the recurring failure of their satellites due to power supply glitches.
The reason may be the failure of imported components, according to Indian Space Research Organisation (ISRO) scientists.
ISRO has lost two of its satellites earlier -- Chandrayaan in 2009 and INSAT-2D in 1997 -- and INSAT-4B partially now.
A big setback to the space agency, which is trying to get a foothold in the global communications satellite building market is the failure of the W2M satellite co-built by ISRO and EADS Astrium for Eutelsat Communications in January.
"It seems the culprit is imported components for satellite power systems. The Chandrayaan satellite was lost due to power problems in an imported component. It seems the culprit is the imported components used in supplying power to the satellites," an ISRO official told IANS over phone on condition of anonymity.
The DC to DC converter in the Chandrayaan satellite failed, which in turn heated up other components/equipments and stopped their functioning, ultimately forcing ISRO to junk the mission well ahead of its planned life of two years.
Another ISRO official, on condition of anonymity, said: "The component is imported as its size is small whereas the Indian built one is bigger. In space, every additional gram is important. The problem with INSAT-4B may not be connected to DC to DC converter and it is similar to the problem that afflicted W2M satellite."
The 3.4-tonne W2M, the heaviest built by ISRO, launched by Ariane5 rocket from French Guyana in December 2008, developed a problem in its power supply sub-systems when it was being transferred to its intended orbit from the test orbit and Eutelsat later said the satellite is not available for service.
According to ISRO, the problem with INSAT-4B is a power anomaly in one of the satellite's two solar panels and six Ku-Band and six C-Band transponders were switched off so that there is power for the remaining 12 transponders (six Ku-Band and six C-Band).
ISRO officials said the agency imports the solar cells to make the solar panels that supply power to the satellite.
Queried about ISRO tightening its quality control processes, an official said the agency is now focusing on the component quality.
For ISRO, loss of satellites means loss of revenue opportunities - that is higher than the cost of satellite and the rocket that launched it.
Now eyes are on the successful operation of the to-be launched Hylas communication satellite built by ISRO/EADS Astrium for Britain-based Avanti Communications. Its success is expected to clear any doubts of India's capability in satellite manufacturing.
"We have taken care of the power supply glitches in that," an ISRO official said.