Indian Space Programme Discussion

JTull · Post by **JTull** » 15 Dec 2015 20:27

The extra-fuel for re-start that it will be carrying could be used to deploy heavier payloads. Seems like a waste. Unless they intend to force a re-entry to reduce the space debris.

member_29268 · Post by **member_29268** » 15 Dec 2015 21:24

Looking at the time gap between PS4 shut-off and re-start, which is ~46minutes (1/2 of the orbital period for the altitude at which satellites will be injected for this mission) and will bring the PS4 stage at diametrically opposite end (apogee /perigee) of the orbit. Looks as an orbit raising manoeuvre to me. To what end, not sure.
All electric satellites have a tremendous weight advantages (~40%) in terms of conventional ones. GSLV Mk2 class satellites can easily be launched (in reasonable transfer duration) using PSLV if the initial orbit is higher than the Sub-GTO capability of PSLV. But if you can tolerate transfer times of 4-6 months than sub-GTO should be OK.
Extra fuel might not increase the payload capacity significantly.

SSSalvi · Post by **SSSalvi** » 15 Dec 2015 21:51

The Main burn of PS4 is for 2+ minutes.
2nd burn is only for 4 secs .. so fuel weight difference is negligible.
-----
2nd burn is of course on the other side of Earth. But the burn occurs at an altitude of 524 kms and in fact it reduces the speed from 7610 to 7607 meters/sec.

Sat seperation occurs at 550 Kms alt with 7585 meters/sec.

Increase in altitude is the effect of regular Earth orbit of 4th stage.

SSSalvi · Post by **SSSalvi** » 15 Dec 2015 23:03

Latest info about 2nd burn:

A unique feature of this flight is that 46 minutes after all the satellites are launched the 4th stage will Re-start and will remain ignited for 4 seconds.

This may appear to be an insignificant thing but there are technological achievements for ISRO if this happens.

This will provide a capability towards launching satellites in diverse orbits in a single flight.

The critical technological factor is that the engine has to be cooled before the 2nd burn.

( Quoting from my blog )

member_29267 · Post by **member_29267** » 16 Dec 2015 05:45

SSSalvi wrote:Latest info about 2nd burn:

A unique feature of this flight is that 46 minutes after all the satellites are launched the 4th stage will Re-start and will remain ignited for 4 seconds.

This may appear to be an insignificant thing but there are technological achievements for ISRO if this happens.

This will provide a capability towards launching satellites in diverse orbits in a single flight.

The critical technological factor is that the engine has to be cooled before the 2nd burn.
( Quoting from my blog )

Something to look forward to. IIRC PAM-G (for direct GEO injection) to be used on GSLV is based on the 4th stage of PSLV. Looks like testing of this restart ability has something to do with that. We need more info on this.

SSridhar · Post by **SSridhar** » 16 Dec 2015 12:29

Orbital transfers employ a 2-burn technology usually. So, something is being tested for that purpose using the 4th stage.

symontk · Post by **symontk** » 16 Dec 2015 13:11

krishGAgain wrote:Something to look forward to. IIRC PAM-G (for direct GEO injection) to be used on GSLV is based on the 4th stage of PSLV. Looks like testing of this restart ability has something to do with that. We need more info on this.

PAM-G is different from PSLV 4th stage. PAM-G has more fuel. The first use will be Chandrayaan-2. Hopefully it will replace PSLV 4th stage later. It can be incorporated to GSLVMk3 replacing C-25 so that a uniform core can be used for different payload reqs

Neela · Post by **Neela** » 16 Dec 2015 16:29

PSLV-C29 Launch Webcast link
http://www.isro.org/pslv-c29-teleos-1-m ... aunch-live

Vipul · Post by **Vipul** » 16 Dec 2015 16:41

Indian rocket to land on moon in 2017; to launch solar mission.

India's second lunar probe Chandrayaan II will land on moon in 2017 and the country's first solar mission Aditya L1 is likely to be launched in 2019, Lok Sabha was informed today.

Chandrayaan II will land on the surface of moon in 2017 and this second lunar mission will help explore the possibilities of signs of extra-terrestrial life, Minister of State in Prime Minister's Office Jitendra Singh said during Question Hour responding to supplementaries.

The Aditya L1 mission "is aimed at studying the sun from an orbit around the sun-earth lagrangian point (L-1) which is about 1.5 million km from earth. It will carry seven payloads including a coronagraph to observe the outermost layers of the sun, the corona. Aditya L1 will be launched during 2019-20 timeframe," he said in his written response.

The "approved cost" of the solar mission is 378.53 crore.

Responding to another question, Singh said India has entered the era of "space marketing" and the launch of six Singapore satellites today will earn India 26 million euros.

So far, India has earned 15 million USD and 80 million euros by launching satellites of other countries, he said, adding that $5 million and 65 million euros are in the "pipeline", while apparently referring to the launches proposed in the future.

The minister said a budget of Rs 1420 crore has been approved by the government for realisation of Indian Regional Navigation Satellite (IRNSS) programme, including satellites and associated ground segment.

member_28108 · Post by **member_28108** » 16 Dec 2015 16:49

The Hindi commentator thinks everyone has a PhD in Hindi !!

Nitesh · Post by **Nitesh** » 16 Dec 2015 17:03

Rocket liftoff? Can't find any updates

JTull · Post by **JTull** » 16 Dec 2015 17:03

Everything is naarmal so far. PS2 stage separated, PS3 ignited. Heat shield discarded.

JTull · Post by **JTull** » 16 Dec 2015 17:06

Stage 3 burnout. Coasting now
+7 mins

Nitesh · Post by **Nitesh** » 16 Dec 2015 17:07

Naarmal congratulations to all involved. Thanks JTull

member_29267 · Post by **member_29267** » 16 Dec 2015 17:07

symontk wrote: PAM-G is different from PSLV 4th stage. PAM-G has more fuel. The first use will be Chandrayaan-2. Hopefully it will replace PSLV 4th stage later. It can be incorporated to GSLVMk3 replacing C-25 so that a uniform core can be used for different payload reqs

But, PAM/G was developed based on the PSLV 4th stage using the same engine and many other components. And reeplacing C-25 with PAM-G would be step backward. I believe for LVM3 its the C-25 that provides the majority of deltaV for the payload.

JTull · Post by **JTull** » 16 Dec 2015 17:09

Commentator is saying that Stage 3 still has small residual thrust as it is a solid stage, so there is coasting done before separation so there's no risk of stage 3 catching up with stage 4 during coasting phase.

JTull · Post by **JTull** » 16 Dec 2015 17:10

Stage 3 separated at 581 secs.

Now 660 secs

Still coasting

JTull · Post by **JTull** » 16 Dec 2015 17:14

Stage 4 ignition done at about 904 secs

JTull · Post by **JTull** » 16 Dec 2015 17:15

Stage 4 performance naarmal at 985 secs

JTull · Post by **JTull** » 16 Dec 2015 17:17

Stage 4 shutoff at 7.1 km/s at 1042 secs

JTull · Post by **JTull** » 16 Dec 2015 17:17

Primary payload separated TELEOS-1

JTull · Post by **JTull** » 16 Dec 2015 17:18

KENT RIDGE and VELEOX C1 separated

JTull · Post by **JTull** » 16 Dec 2015 17:18

VELEOX-II separated

JTull · Post by **JTull** » 16 Dec 2015 17:19

GALASSIA also separated

JTull · Post by **JTull** » 16 Dec 2015 17:21

ATHENOXAT deployed. Commercial mission objectives met.

JTull · Post by **JTull** » 16 Dec 2015 17:35

Post launch speeches - everyone congratulating everyone. Preparing for monthly launches of C31 to C34

One person mentioned looking forward to the restart of stage 4. No other news on that.

SSridhar · Post by **SSridhar** » 16 Dec 2015 17:39

The 6'o clock launch allowed me to see the PSLV streaking across the sky from my rooftop at Chennai. I could clearly see the PS1 separation, PS1 falling off, Ps2 igniting. It was brilliant. The sky was clear except for one or two low hanging clouds which didn't hinder the view. Itt was a majestic show.

deejay · Post by **deejay** » 16 Dec 2015 17:45

Good one ISRO. Congratulations all at ISRO.

kvraghavaiah · Post by **kvraghavaiah** » 16 Dec 2015 18:02

SSridhar wrote:The 6'o clock launch allowed me to see the PSLV streaking across the sky from my rooftop at Chennai. I could clearly see the PS1 separation, PS1 falling off, Ps2 igniting. It was brilliant. The sky was clear except for one or two low hanging clouds which didn't hinder the view. Itt was a majestic show.

About an year ago, I saw a PSLV launch smoke from Bengaluru; also from roof top. I looked for signature some 15 minutes after launch. So no idea if i could see the live flight, had i seen a few minutes earlier.

member_28108 · Post by **member_28108** » 16 Dec 2015 18:12

^ How can one see a launch from Bangalore ? The flight path never crosses the Deccan plateau.

kvraghavaiah · Post by **kvraghavaiah** » 16 Dec 2015 18:21

prasannasimha wrote:^ How can one see a launch from Bangalore ? The flight path never crosses the Deccan plateau.

Because rocket is not a cruise missile and so does not hug to the terrain. The smoke rises to a height of almost 50 KM, so the clear smoke line can be seen up to almost 500 km from SHAR.

Did anyone else here see from far away like me?

Please rescue my respect.

akashganga · Post by **akashganga** » 16 Dec 2015 18:53

Congratulations ISRO for another successful launch. It is exciting to see 100% commercial launches from isro. Cheers.

member_28108 · Post by **member_28108** » 16 Dec 2015 19:02

Taking the curvature of the earth and the direction and angle of launch I am not sure that is possible. Remember that by the time the rocket has reached 50 Kms it has already moved easterly Practically the horizon is around 5 Kms away for a 6 foot person.At the top of Everest it is 230 Kms With an easterly launch you would not be able to see the plume even if 50 Kms height.Remember that by the time PSLV reaches a height of 47 Kms it has already moved easterly at a rate of 1.8 Kms/sec at approx 90 seconds ie at least 160 kms away. Also do you really think the launch plume is wide enough however dispersed to allow one to see it from 230+100 approx 360 Kms away. I am sure our visual acuity is not that good as the plume may be at the most a couple of hundred meters wide . What you may have seen may have been a jet trail.
I may be corrected but it seems difficult to see this launch or its plume from Bangalore.
If anyone can give evidence to the contrary I may stand corrected.

geeth · Post by **geeth** » 16 Dec 2015 19:09

Did anyone else here see from far away like me? Please rescue my respect

.

Yes, way back, I have seen the blast while lift off from my balcony in chennai , which is quite far off from sriharikotta. Funny part is, on earlier occasion I drove down to marina beach but did not reach in time. It was by chance and was quite surprised to see it from my balcony.

shiv · Post by **shiv** » 16 Dec 2015 19:25

What? Was a PSLV launched today? Missed it I guess

shravanp · Post by **shravanp** » 16 Dec 2015 19:28

Congratulations to ISRO team!

btw, noticed that at every stage separation, there was simply a customary clapping with 'whatever' type of facial expression. It's all too naarmal naarmal.

vanand · Post by **vanand** » 16 Dec 2015 19:33

I saw the smoke trail, and captured it outside my office Chennai. Congrats ISRO

uddu · Post by **uddu** » 16 Dec 2015 19:55

Neela · Post by **Neela** » 16 Dec 2015 19:59

We need Dilbu here for all future PSLV launches.

Gagan · Post by **Gagan** » 16 Dec 2015 20:20

Congratulations ISRO !

What a wonderful speech by P. Kunhi Krishnan - Director SDSC/SHAR. Very impressive choice of words. 52:40 onwards
(Only mess up is the use of Magnanimous instead of Magnificent)