[quote name='Raj Malhotra' date='09 March 2010 - 07:11 PM' timestamp='1268141639' post='104995']
I think that GSLV Mark-3 will become fully operational around 2014-15. Any idea what would be the weight of INSAT series by that time, as I understand that the weight of these satellites is also increasing over time
[/quote]
INSAT's are being launched in 2 configurations. The 2K bus is for 2-2.5 tonne weight and is designed taking into account GSLV-1/2 launcher payload limited to 2.5 tonne. OTOH INSATs launched by European Ariane launch vehicle are in 3.3 tonne category using 3K bus.
Larger overall weight allows increased fraction of mass of communication & solar panel payload that earns revenue, compared to non-dead weight of vehicle frame and station keeping hardware and fuel. Thus vehicle mass permitting one tries to push as high a satellite as possible. Increased satellite mass also makes it costly, and any failure there off becomes a insurance nightmare. Thus heavier payloads also carry redundant hardware for station keeping. It is a optimization abttle to extract the maximum performance for a given cost and risk rate.
One could easily argue that both 2K and 3K bus are near optimum for their category and 3K is slightly more cost effective than 2k. That cost effectiveness difference is not big to burn a hole in the pocket.
Bottom line teh GSLV Mk-III with 4 tonne payload will increase INSAT cost effectiveness further and competitive compared to other space launchers. Pls note that ISRO's launcher cost (including organizational overhead) is far lower than Ariane, thus overall cost-value proposition of a 6 tonne satellite launched by Ariane and a 4 tonne satellite launched by GSLV-MkIII, the latter will still be more cost effective. So it is not a payload mass game only.
I think that GSLV Mark-3 will become fully operational around 2014-15. Any idea what would be the weight of INSAT series by that time, as I understand that the weight of these satellites is also increasing over time
[/quote]
INSAT's are being launched in 2 configurations. The 2K bus is for 2-2.5 tonne weight and is designed taking into account GSLV-1/2 launcher payload limited to 2.5 tonne. OTOH INSATs launched by European Ariane launch vehicle are in 3.3 tonne category using 3K bus.
Larger overall weight allows increased fraction of mass of communication & solar panel payload that earns revenue, compared to non-dead weight of vehicle frame and station keeping hardware and fuel. Thus vehicle mass permitting one tries to push as high a satellite as possible. Increased satellite mass also makes it costly, and any failure there off becomes a insurance nightmare. Thus heavier payloads also carry redundant hardware for station keeping. It is a optimization abttle to extract the maximum performance for a given cost and risk rate.
One could easily argue that both 2K and 3K bus are near optimum for their category and 3K is slightly more cost effective than 2k. That cost effectiveness difference is not big to burn a hole in the pocket.
Bottom line teh GSLV Mk-III with 4 tonne payload will increase INSAT cost effectiveness further and competitive compared to other space launchers. Pls note that ISRO's launcher cost (including organizational overhead) is far lower than Ariane, thus overall cost-value proposition of a 6 tonne satellite launched by Ariane and a 4 tonne satellite launched by GSLV-MkIII, the latter will still be more cost effective. So it is not a payload mass game only.