The Hindu : Front Page : First manoeuvre to raise satellite’s orbit

Online edition of India's National Newspaper
Tuesday, Sep 04, 2007
ePaper

Front Page

Front Page

First manoeuvre to raise satellite’s orbit

T.S. Subramanian

“Apogee achieved is lower than target”

It will take over a month for INSAT-4CR
to be fully operational
It is expected to have a lifespan of 10 years

CHENNAI: The first manoeuvre to raise the orbit of INSAT-4C R was performed on Monday by firing the liquid apogee motor (LAM) on board the satellite for 27 minutes from 8.17 a.m. The command for firing the LAM was given from the Indian Space Research Organisation’s (ISRO) Master Control Facility (MCF) at Hassan in Karnataka.

With this operation, the perigee (the nearest point to the earth) of the satellite has been raised to 2,983 km and the apogee (the farthest point from the earth) to 31,702 km.

On Sunday evening, Geosynchronous Satellite Launch Vehicle GSLV-F04 lifted off from the spaceport at Sriharikota in Andhra Pradesh at 6.20 p.m. and placed the satellite in an elliptical, geosynchronous transfer orbit with a perigee of 168 km and an apogee of more than 30,000 km. This was lower than the targeted geosynchronous transfer orbit with a perigee of 170 km and an apogee of about 36,000 km.

Informed ISRO officials said the apogee achieved was lower than the targeted one. This could be due to the underperformance of the third, uppermost cryogenic stage of the GSLV-F04. “There is a reduction in the apogee achieved. It will be corrected. It is nothing to worry,” said a top ISRO rocket engineer.

Another official said “it is not a major problem” but added that more fuel on board the satellite would be spent to manoeuvre it into its final geosynchronous circular orbit of 36,000 km. This would be achieved by firing the LAM several times in the coming days.

The official said it would take more than a month before the satellite became fully operational. It was expected to have a lifespan of 10 years. If a lot of fuel was spent on raising its apogee to 36,000 km, it might have a lesser lifespan. The satellite was in good health.

After INSAT-4CR is made operational, its transponders will be used for providing direct-to-home television service, video picture transmission and news gathering. This is the fifth flight of the GSLV. Its first flight was in 2001.

Printer friendly page
Send this article to Friends by E-Mail

Front Page