PSLV-XL C50 - CMS-01 (ex GSAT-12R) - SLP - December 17, 2020 (10:11 UTC)

[Steven Pietrobon]

ISRO Chairman announcing mission success. Saying this is a continuation of GSAT 12 mission!

[Steven Pietrobon]

Next mission is PSLV C51 with three satellites. Carrying private Earth observation mission called Anand? from Excel India?. Other satellites are from Spacefix India? called Saditsat? and the University Consortium Unitysat.

Solar panels have deployed.

Wishing everyone Merry Christmas and a Happy New Year.

[Steven Pietrobon]

End of webcast.

Congratulations to ISRO for the successful launch!

[K210]

Congratulations to ISRO for the successful launch!

[K210]

Liftoff shots

Full Gallery: https://www.isro.gov.in/pslv-c50-cms-01/gallery

[K210]

Liftoff/Onboard camera video:

[TheVarun]

 Good launch!   Still no mention of the exact weight of the CMS-01 anywhere that is readable/audible . And no reasonably precise date for the SSLV-D1, which is very long awaited!  It was originally scheduled for the end of 2019.

[Danderman]

Good launch!   Still no mention of the exact weight of the CMS-01 anywhere that is readable/audible . And no reasonably precise date for the SSLV-D1, which is very long awaited!  It was originally scheduled for the end of 2019.

The story here on the front page gives the mass of CMS-01.

I still have not seen the orbital parameters of the GTO interim orbit. The launch azimuth was 102.9 degrees, which implies something around 12 degrees orbital inclination.

[input~2]

2 objects have been cataloged:
2020-099A/47256 in 275 x 20881 km x 17.79° (Arg. of perigee: 178.73°)
2020-099B/47257 in 257 x 20656 km x 17.86°

[SMS]

https://twitter.com/TSKelso/status/1339697661415280642

[zubenelgenubi]

What will be the delta-V from initial sub-GTO to GEO?

[Steven Pietrobon]

What will be the delta-V from initial sub-GTO to GEO?

1980 m/s.

http://www.sworld.com.au/steven/space/orbit.zip

Delta-V calculator by Steven S. Pietrobon. 22 Jun 2019.
Enter negative perigee height to exit program.
Enter negative height for geosynchronous altitude.

Enter initial perigee height (km): 275
Enter initial apogee height (km): 20881
Enter required inclination change (deg): 17.79
Enter required perigee height (km): -1
Geosynchronous perigee = 35786.0 km
Enter required apogee height (km): -1
Geosynchronous apogee = 35786.0 km

Burn at   275.0 km: theta1 =  0.00 deg, dv1 =  359.1 m/s
Burn at 35786.0 km: theta2 = 17.79 deg, dv2 = 1622.1 m/s
dv = 1981.2 m/s

Burn at   275.0 km: theta1 =  0.19 deg, dv1 =  360.6 m/s
Burn at 35786.0 km: theta2 = 17.60 deg, dv2 = 1619.0 m/s
dv = 1979.7 m/s

[Danderman]

So PSLV flew at an azimuth of 102.9 degrees from the launch site, resulting in a 17 degree inclination orbit, since the launch site is at 13 degrees.

Why didn’t PSLV fly due East at 90 degrees to enter into a 13 degree orbit? That would have allowed more payload.

[Steven Pietrobon]

So PSLV flew at an azimuth of 102.9 degrees from the launch site, resulting in a 17 degree inclination orbit, since the launch site is at 13 degrees.

Why didn’t PSLV fly due East at 90 degrees to enter into a 13 degree orbit? That would have allowed more payload.

I believe its to avoid flying over populated areas that are directly east of the launch site. Could also be due to ground station access along the flight path.

https://spaceflight101.com/gslv-gsat-6a/flight-profile/

[Danderman]

So PSLV flew at an azimuth of 102.9 degrees from the launch site, resulting in a 17 degree inclination orbit, since the launch site is at 13 degrees.

Why didn’t PSLV fly due East at 90 degrees to enter into a 13 degree orbit? That would have allowed more payload.

I believe its to avoid flying over populated areas that are directly east of the launch site. Could also be due to ground station access along the flight path.

https://spaceflight101.com/gslv-gsat-6a/flight-profile/

[GWR64]

So PSLV flew at an azimuth of 102.9 degrees from the launch site, resulting in a 17 degree inclination orbit, since the launch site is at 13 degrees.

Why didn’t PSLV fly due East at 90 degrees to enter into a 13 degree orbit? That would have allowed more payload.

My theory:
If the PSLV started to the east, the upper stage would have to ignite twice.
One ignition to achieve a LEO, then a ballistic phase and then a second ignition over the equator.
For a proper GTO perigee/apogee must be above the equator. (incorrect at Ariane VA241)
The second ignition would then be out of sight of the Indian ground stations.
The launch to the southeast shortens the way to the equator.

[A.K.]

https://twitter.com/isro/status/1341036782494707714?s=19