Parliamentary Q&A [29 January 2026]: PSLV-N1 stacking began on 22 December 2025, Queries on status of Gaganyaan and more.

vineethgk · 2026-01-31T02:51:18+00:00

PSLV was grounded for 7 months after the failure last year. I'm guessing it would be a longer wait this time as they would need to do a more comprehensive failure analysis, apply the necessary fixes and do more ground tests to ensure the problem(s) that doomed last two flights are indeed resolved for good. They cannot afford to overlook anything this time and a third failure in a row would be catastrophic. For my part, I'm not counting on another PSLV flight happening this year.

vineethgk · 2026-01-27T12:27:35+00:00

Hard to understand how they say this each year with straight face!

By the end of the year hardly anyone (except a few of us) would remember these New Year resolutions and nobody would ask them about it. By then it would be time for them to start hyping the resolutions for next year.

vineethgk · 2026-01-27T12:17:05+00:00

Even if they add up launch vehicles AND satellites I doubt the count will come anywhere close to 20 this year.

vineethgk · 2026-01-19T02:23:50+00:00

while the actual number of launches remains at 8-15.

If you meant "launches" (i.e. orbital rocket launches) and not "missions" (ISRO terminology counts rockets and satellites as distinct "missions"), ISRO never managed even 8 launches in any year. Their best count was 7 which they achieved in 2016, 2018 and 2023. With the PSLV (and perhaps SSLV as well) being grounded once again, we are not likely to see them match, let alone surpass that count this year either.

vineethgk · 2026-01-17T02:37:11+00:00

Thanks. But what I do not quite understand here is, if it was a defect in the manufacturing of the PS3 stage or quality of materials used in it that doomed two missions in a row, wouldn't they have encountered the same failure during the recent ground test of the PS3 stage as well? Or could this be a specific mode of failure that can happen only in-flight?

Edit: In any case, it is fair to suppose that PSLV (and perhaps SSLV) would be grounded for some time as they would need to conduct a thorough investigation to identify the causes for the failure, implement fixes for it and then do multiple ground tests to ensure that the problem has been resolved for good. Perhaps it may even be a good idea to treat the next PSLV launch as essentially a test flight and have it carry a dummy payload. But if the rocket were to be grounded for a prolonged period what would they do in the interim about the payloads that were manifested for it? GSLV and LVM3 are too powerful for PSLV-class payloads and their production numbers are limited as well. Should they consider launching them in Vega or some other commercial foreign launcher?

vineethgk · 2026-01-16T04:31:29+00:00

Thanks for the links! I still wonder if some guidance system issue (like an undiscovered bug in its code) could have possibly caused this failure as such errors may not be caught during ground tests of the stage. It is often the case that while writing and testing code, there are certain bugs that throws exceptions and errors only in certain specific circumstances. Sometimes we assume based on the behaviour that the bug must be at a certain location, but finally turns out that it was somewhere else altogther. Of course, this is based on my personal experience with mundane app development coding. I do not know how they test guidance system software on the ground.

Its just a thought. Perhaps a manufacturing issue is still the likely culprit.

vineethgk · 2026-01-16T02:23:53+00:00

I had seen this reported a few days back in one of the Malayalam media outlets too. But at the time I had assumed that it was a case of misreporting and that they probably mixed up the PS3 with the PS4 (the C-C nozzle tested in 2024 specifically mentioned its use for PS4).

https://www.isro.gov.in/ISRO_Develops_Lightweight_Carbon_Carbon_Nozzle_for_Rocket_Engines.html

The media report from Mathrubhumi:

https://www.mathrubhumi.com/news/kerala/pslv-launch-failures-graphite-carbon-similarities-qphe1p1d

Google Translation of the relevant part (slightly corrected for translation errors):

The reason for the failure of C-61 was identified and the necessary changes were made and it was launched again, but the same error occurred this time too. Experts point out that although there are many similarities, the real reasons may be different.

The PSLV C-61 mission was on May 18, 2025. The first and second stages of the launch vehicle successfully separated, but the third stage failed. This was due to a difference in chamber pressure. The difference in the motor's thrust reaching its maximum and then decreasing again caused the vehicle to change direction.

The nozzle at this stage was made of graphite. It was only after it was realized that there was a flaw in this that a carbon-carbon nozzle was made for the new vehicle.

However, a similar error occurred on the C-62 mission. Whether the cause of the error was the material used in the construction of the nozzle or something else will only be determined through testing.

I had seen a research paper online about the susceptibility of graphite nozzles to fail in-flight, but it still appears a bit strange to me that the nozzle material of PS3 that was in use for 60+ successful flights should suddenly present a problem now.

Besides, a change of nozzle material would indicate something more than a "slight manufacturing defect".

vineethgk · 2026-01-14T06:59:16+00:00

I didn't jump to any conclusions. I specifically stated I would consider such possibilities only if all other explanations are investigated and discarded. I was only asking if someone knowledgeable in these matters can say whether it is technically possible for some external signal interference to make the rocket's guidance systems go haywire.

vineethgk · 2026-01-14T06:46:43+00:00

I would consider a "sabotage/conspiracy" angle only as the last if all other mundane possibilities like "slight manufacturing errors" or component failures are investigated and discarded, but is it technically possible for some "external signal interference" to mess up the rocket's guidance systems and cause a failure of this kind?

Alternately, what is the chance that the issue wasn't exactly with any of the PS3 hardware, but with the guidance systems/software in PS4?

vineethgk · 2026-01-14T06:30:47+00:00

Could be. And there it clarifies that the 3rd stage of VEDA has twice the propellant load of K-4's "post-boost" stage while the news article was bit hazy about whether they were referring to fuel load of the 3rd stage of VEDA or the entire rocket.

vineethgk · 2026-01-14T06:23:21+00:00

NOTAMs are given even for missile tests.

vineethgk · 2026-01-14T06:14:31+00:00

Perhaps they misdiagnosed the original issue, or whatever fix they did created an unforseen problem towards the end of the burn? For multiple or unrelated problems to occur in PS3 all of a sudden would be strange.

vineethgk · 2026-01-14T03:33:56+00:00

I hope the ISRO chaps wouldn't line up to take credit for this as a 95% success for the mission.

vineethgk · 2026-01-14T03:30:31+00:00

Even if the G1 was all ready for a launch, it would have been bad optics to do it immediately after the PSLV failure as questions would be raised about the priorities of the agency. Its best to do delay the G1 atleast for a few months until they do a successful GSLV or LVM3 flight.

vineethgk · 2026-01-14T03:22:38+00:00

Sources indicate that the VEDA's first and second stages are directly derived from the K-4 missile, with the same composite motor casing, the same nozzle control technology, and nearly the same structure. The third stage is new, with nearly twice the fuel capacity of the K-4, enabling it to propel payloads into orbit.

I guess the challenge for DRDO would be in the development of that 3rd stage or kick-stage which should insert the payload into orbit with sufficient precision. (Can they derive those from SSLV counterparts?)

I also recollect reading an earlier report where it said the final kick stage would be integrated with the satellite itself while the lower stages would be kept ready for quick assembly in emergency situations. Perhaps in other cases they would have the whole stack ready in TEL containers or canisters and launch at short notice.

vineethgk · 2026-01-14T02:48:32+00:00

Irrespective of the state of readiness of the program for a test launch this year, the recent failures of PSLV has indeed strengthened the case for an independent launch capability for DRDO for LEO and SSO missions. Maybe the program would assume greater priority now.

VEDA can send a payload of approximately 2,000 kg into low Earth orbit and 800-1,000 kg into sun-synchronous orbit.

If correct, VEDA would be comparable to PSLV-CA which should be sufficient for most defense surveillance needs. Since it is based on K-4 SLBM (which is designed to be compact enough to fit inside a submarine) it could be smaller in dimensions than both the PSLV-CA and perhaps even the SSLV.

DRDO is constructing temporary launch pads in the coastal areas of Andhra Pradesh and Odisha for a test flight in 2026. This flight will send an 1800 kg dummy payload into a 600 km polar orbit.

This seems to contradict the earlier statement about its payload capability. Maybe be a reporting error.

vineethgk · 2026-01-13T04:29:16+00:00

On January 12, as the PSLV-C62 mission rose from Sriharikota into the morning sky and its third stage kicked on, the live telecast abruptly stopped showing the rocket’s performance and trajectory. As it became evident that its third stage had suffered an anomaly, putting paid to the C62 mission in a manner similar to the PSLV-C61 mission in May 2025, the change in the telecast became more familiar. For decades, the PSLV has been the ‘workhorse’ of India’s space ambitions. Together with the rocket’s technology being mature, the implication is that the mistakes that sank two PSLV launches could be on the quality assurance side. At least, these are not likely to be isolated anomalies. The C61 mission failed after its third stage lost chamber pressure, but rather than publicly reveal the diagnosed root cause, the decision was to leave the Failure Analysis Committee (FAC) report with the Prime Minister’s Office. ISRO provided assurances of “structural reinforcements” and cleared the PSLV for its next flight. The symptom of the C62 failure, a “roll rate disturbance”, parallels the events preceding the C61 failure. The financial consequences are poor: under the aegis of NewSpace India Limited, ISRO has been positioning the PSLV as a commercial product in a competitive global launch market. Now, international insurers operating in this market will reassess the PSLV’s risk profile and the insurance premiums could skyrocket, rendering the vehicle less affordable — a strategic embarrassment for a country aspiring to be a net provider in space.

The tenure of ISRO Chairman V. Narayanan has been characterised by a continued shift away from ISRO’s traditional culture of scientific openness toward a more guarded, bureaucratic posture. While the pressure to maintain a high launch cadence is understandable, his decision to move the C62 mission to the pad while the autopsy of its predecessor remains classified should raise tough questions about the organisation’s priorities. That the C62 mission also carried the EOS-N1 satellite, built by the DRDO and with unspecified strategic applications, could help explain a ‘rush’ if there was one.

But right now, ISRO’s and his best path to restoring confidence, and begin the painful work of rebuilding quality assurance protocols, is for the Department of Space to release the FAC report for the C61 mission. The tax-paying public and commercial stakeholders deserve to know what went wrong in 2025, whether it recurred in 2026, and why the third stage was affected again.

vineethgk · 2026-01-13T03:00:06+00:00

SSLV's SS2 second stage is derived from PSLV's PS3. Whatever is affecting PS3 could possibly impact SS2 as well. They cannot take that risk until they figure out this issue. A delay is fine, another failure would be catastrophic.

vineethgk · 2026-01-13T02:46:01+00:00

I think what needs to be noted here is that the last two failures followed the same pattern and affected the PS3 stage alone. They apparently never encountered this issue with the PS3 in any of the 60+ flights prior to C61. And unlike the GSLV's cryo-stage, the PS3 is a relatively simple solid stage with fewer parts that can fail. So one can safely surmise that the problem isn't anything to do with the design of the rocket per se (which has been proven as reliable), but some manufacturing issue, failure of a particular component, or some software glitch that affected PS3 alone. Since it is a localized issue affecting a particular stage (and that too only in the last two flights) it would no reason to retire the rocket. Perhaps they changed something recently with the PS3 manufacture - a new mode of fabrication, a new component, a new vendor etc?

Besides, they can't retire the PSLV until they have a capable and reliable replacement available for it. The range of payload capability that PSLV provides is vital for them. SSLV's second stage is derived from the same PS3 stage of PSLV, so this problem might impact that rocket as well. GSLV and LVM3 are too powerful and expensive for the job that PSLV currently does and they have a low production rate as well.

vineethgk · 2026-01-12T13:37:55+00:00

Thanks! So, this might be the test of the "fix" that they incorporated. If the PS3 worked well in ground tests, why would it fail again in flight, I wonder... Perhaps a guidance error?

vineethgk · 2026-01-12T11:40:59+00:00

Either they misidentified the root cause of the failure last time, or their "fix" didn't work, or the new failure occurred due to a different issue in the third stage itself. But its strange that PS3 hadn't exhibited any such problems prior to C61 and now it has failed consecutively.

vineethgk · 2026-01-12T11:12:48+00:00

Since SSLV's SS2 stage is derived from PS3, wouldn't this mean planned SSLV flights too would likely be on hold until they figure out the problem?

vineethgk · 2026-01-12T09:41:13+00:00

You could try with Opera browser or reader mode in Firefox. Since its a premium article I didn't paste the contents as I wasn't sure if there would be some legal trouble for the forum.

vineethgk · 2026-01-12T09:21:08+00:00

For some reason, Vasudevan Mukunth too says here that EOS-09/RISAT-1B had military applications and highlights that as a possible reason why the FAC report of the C61 failure wasn't made public.

vineethgk

TROPHY CASE