Author Topic: GSAT-7A - GSLV F11 - December 19, 2018 (10:40 UTC)  (Read 20336 times)

Offline worldtimedate

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Re: GSAT-7A - GSLV F11 - December 19, 2018 (10:40 UTC)
« Reply #160 on: 12/22/2018 07:19 am »
The perigee has not increased beyond the increase after the first orbit burn ! If they perform the burns every day, they perigee should have changed by now above the 11,600 Km mark.

What do you mean by your above statement ? The perigee has increased to 11,600 km mark after the first orbit raising operation.

please check the following
https://www.n2yo.com/satellite/?s=43864

Offline isro-watch

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Re: GSAT-7A - GSLV F11 - December 19, 2018 (10:40 UTC)
« Reply #161 on: 12/23/2018 03:17 am »
I meant no update after the first burn. No details of second burn and further increase in perigee.

The perigee has not increased beyond the increase after the first orbit burn ! If they perform the burns every day, they perigee should have changed by now above the 11,600 Km mark.

What do you mean by your above statement ? The perigee has increased to 11,600 km mark after the first orbit raising operation.

please check the following
https://www.n2yo.com/satellite/?s=43864


Offline maint1234

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Re: GSAT-7A - GSLV F11 - December 19, 2018 (10:40 UTC)
« Reply #162 on: 12/23/2018 10:41 am »
Don't worry. Gsat 11 took a week for its final burn.
So this was launched on the 19th and we can expect the 3rd firing around today and final firing by the 25th.
For some reason isro has become quite cautious about its announcements, maybe the couple of satellite issues it had.

Offline maint1234

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Re: GSAT-7A - GSLV F11 - December 19, 2018 (10:40 UTC)
« Reply #163 on: 12/24/2018 09:22 am »
Update -ISRO

"Dec 24, 2018
Latest update on GSAT-7A
After the launch of GSAT-7A on December 19, 2018, four orbit maneuvering operations have been performed successfully on GSAT-7A satellite using onboard Propulsion system. At present, the satellite is placed in an orbit with a perigee (nearest point to earth)  of 35,800 km and Apogee (nearest point to earth) of 36,092 km with 0.2 deg inclination which is very close to the its final orbit."

Offline A.K.

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Re: GSAT-7A - GSLV F11 - December 19, 2018 (10:40 UTC)
« Reply #164 on: 12/24/2018 02:44 pm »
At present, the satellite is placed in an orbit with a perigee (nearest point to earth)  of 35,800 km and Apogee (nearest point to earth) of 36,092 km with 0.2 deg inclination which is very close to the its final orbit."
Farthest point to earth.

Offline worldtimedate

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Re: GSAT-7A - GSLV F11 - December 19, 2018 (10:40 UTC)
« Reply #165 on: 12/26/2018 01:35 am »
Isro's GSAT-7A moves closer to its final orbit

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Scientists in the Indian Space Research Organisation completed the fourth orbit manoeuvring operation on Monday to move GSAT-7A, the communication satellite, to its final orbit. The satellite is now very close to its final geostationary orbit, which is around 35,786km.

At present, the satellite is placed in an orbit with perigee (nearest point to earth) of 35,800km and apogee (farthest point to earth) of 36,092km with 0.2 degree inclination, which is very close to its final orbit.

Offline worldtimedate

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Re: GSAT-7A - GSLV F11 - December 19, 2018 (10:40 UTC)
« Reply #166 on: 12/26/2018 01:49 am »
VSSC Director S. Somnath states that in the future GSLV MK-II missions, GSLV MK-II will be able to place heavier satellits

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ISRO will undertake placing heavier satellites onboard its geosynchronous launch vehicle in future following the successful launch of an advanced communication satellite on Wednesday, Vikram Sarabhai Space Centre Director S Somanath said. "There is always (scope of) further improvements in GSLV and in the coming GSLV-F10s and F12 missions, we are going to make bigger payload compartment to accommodate still bigger spacecrafts and that is another important challenge in front of us," he said.

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He said the scientists were ready for that change and to make sure that the GSLV continues to remain very successful and "rugged" vehicle like ISRO's trusted workhorse, the PSLV (Polar Satellite Launch Vehicle). Earlier, referring to the salient features of the GSLV-F11 launch, Mr Somanath said the vehicle was an improved version where scientists brought changes in the cryogenic stage as well as second stage to improve payload capability.

"This resulted in a lot of engineering changes and new elements. The (GSLV) vehicle itself is 1.5 metres longer than the previous GSLVs and it calls for understanding aerodynamics, hardware design and control systems," he said. "This is sixth consecutive success of the GSLV. It only shows that this vehicle is going to stay longer and to make more missions in the years to come with improved capability," he said.

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He said the second stage propellant loading of the vehicle has been increased from 37.5 tons to 40 tons while cryogenic stage propellant loading from 12 tons to 15 tons along with enhanced thrust value for cryogenic stage, he said. "This has been successfully demonstrated in this mission and we got 2,000 km more than what we expected. This is a great achievement," he said.

Source :

ISRO Says Placing Heavier Satellites Aboard GSLVs Next Challenge

GSLV emerging as new workhorse, on par with PSLV: ISRO

Offline Steven Pietrobon

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Re: GSAT-7A - GSLV F11 - December 19, 2018 (10:40 UTC)
« Reply #167 on: 12/26/2018 04:17 am »
VSSC Director S. Somnath states that in the future GSLV MK-II missions, GSLV MK-II will be able to place heavier satellites

The article didn't say heavier, but "bigger". The new larger payload fairing will allow larger volume satellites, but I'm not sure if that translates to heaver mass satellites.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline tappa

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Re: GSAT-7A - GSLV F11 - December 19, 2018 (10:40 UTC)
« Reply #168 on: 12/26/2018 11:11 am »
VSSC Director S. Somnath states that in the future GSLV MK-II missions, GSLV MK-II will be able to place heavier satellites

The article didn't say heavier, but "bigger". The new larger payload fairing will allow larger volume satellites, but I'm not sure if that translates to heaver mass satellites.

You are absolutely right Steven.

However, considering the optimization of the GSLV as ISRO gains comfort with GSLV, I suspect there should be scope for increasing in the payload mass. Is this realistic? If yes, how much increase is possible with incremental improvements?

Offline worldtimedate

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Re: GSAT-7A - GSLV F11 - December 19, 2018 (10:40 UTC)
« Reply #169 on: 12/26/2018 10:58 pm »
VSSC Director S. Somnath states that in the future GSLV MK-II missions, GSLV MK-II will be able to place heavier satellites

The article didn't say heavier, but "bigger". The new larger payload fairing will allow larger volume satellites, but I'm not sure if that translates to heaver mass satellites.

Well, the article used both words "heavier" and "bigger" to confound many of us in reference to bigger payload compartment, bigger spacecraft and heavier satellites. Didn't the article in the beginning say "ISRO will undertake placing heavier satellites onboard its geosynchronous launch vehicle in future" ?. Wouldn't a bigger spacecraft result in its payload being heavier as well ? Anyway, you can take a look at the two following news report. It can be evident upon reading them that GSLV MK-II's payload capacity will not remain stuck at 2.25 ton. With the incremental upgrade, it will be capable of lifting a satellite weighing between 2.6 ton to 2.8 ton. Actually before the Chandrayaan 2's payload grew from 3.2 to 3.8 ton, GSLV MK-II was supposed to be the launch vehicle to launch it into a sub GTO type earth parking orbit of 170 X 20,000 km.

Because of the delay in uprating the GSLV MK-II, ISRO has finally decided to launch the Chandrayaan 2 with GSLV MK-III. The plan for launching the GSAT-31 and GSAT-30 communication satellites weighing 2.6 ton that has been shelved as well owing to this reason will now be launched by Ariane 5.

The following two articles - which include the interview between the reporter T. S. Subramanian - whose articles, news reports for the Indian Space Program are treated with great credibility - and K. Sivan, ISRO Chairman and Umamaheshwaran, the former Mission Director for GSLV MK-II - clearly states that ultimately GSLV MK-II will reach a heavier payload capacity of 2.7 to 2.8 ton.

Quote
GSLV-MkII is capable of putting a 2.8-tonne satellite into orbit. The original Chandrayaan-2 composite module weighed 3.2 tonnes and you were talking about building an enhanced GSLV-MkII.

You are right.

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Umamaheswaran R., now Associate Scientific Secretary, ISRO, told me in October 2016 that GSLV-MkII can put 3.2 tonnes into an initial orbit of 180 km by 20,000 km.

Yes. We enhanced the GSLV-MkII with high thrust engines and so on. With the enhancement, the number is 2.7 tonnes into GTO [geostationary transfer orbit]. Now, 3.2 tonnes has become 3.8 tonnes. And 22,000 km has become 37,000 km. This combination cannot be launched by GSLV-MkII.

Source : ISRO developing vehicle to launch small satellites

Quote
"The indigenous cryogenic engine in this mission performed very well," said Mission Director Umamaheswaran R. "For the sub-assemblies also, it was a satisfying mission. Our effort will be to improve the capability of the GSLV-Mk II to put into orbit satellites weighing between 2,600 kg and 2,800 kg," he added.

Source : Cryogenic gains for GSLV

Offline GWR64

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Re: GSAT-7A - GSLV F11 - December 19, 2018 (10:40 UTC)
« Reply #170 on: 12/27/2018 12:00 pm »
strange NORAD TLE from 12/26/2018 for GSAT-7A / 2018-105A

Quote
GSAT-7A                 
1 43864U 18105A   18360.78644925 -.00000130  00000-0  00000+0 0  9997
2 43864   0.1594 229.2014 0714209 107.6187 270.0610  0.90457660   125

35558 km x 42009 km
inclination:    0.16 deg
argument of perigee:    107.6 deg

 ???

Offline GWR64

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Re: GSAT-7A - GSLV F11 - December 19, 2018 (10:40 UTC)
« Reply #171 on: 12/27/2018 10:24 pm »
new TLEs, source celestrak

Quote
GSAT-7A                 
1 43864U 18105A   18361.52866843 -.00000153  00000-0  00000+0 0  9990
2 43864   0.1585 229.2383 0714231 107.5869 151.7669  0.90458916   129

Orbit unchanged, apogee still at 42009 km

What's going on?

Offline PonRam

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Re: GSAT-7A - GSLV F11 - December 19, 2018 (10:40 UTC)
« Reply #172 on: 12/28/2018 06:17 am »
It has settled down now, info from n2yo.

NORAD ID: 43864
Int'l Code: 2018-104R
Perigee: 35,800.1 km
Apogee: 35,953.1 km
Inclination: 0.2
Period: 1,440.3 minutes
Semi major axis: 42247

Offline GWR64

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Re: GSAT-7A - GSLV F11 - December 19, 2018 (10:40 UTC)
« Reply #173 on: 12/28/2018 07:19 am »
Yes, the new TLEs seems to fit.
Probably the object was confused.
Many launches with many satellites in the last few weeks and
Santa's sleigh had to be tracked as well.   ;D

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