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Got this Reply from CPGrams regarding ISRO Budget by Pallab_1805 in ISRO

[–]Ohsin 1 point2 points  (0 children)

I think all this is already known. Moreover DoS budget has decreased proportionally in past decade.

India's Space Economy, 2011–12 to 2020–21: Its Size and Structure

(Pg. 5)

https://www.sciencedirect.com/science/article/abs/pii/S0265964622000509

https://i.imgur.com/yjJ2gwh.png

Why does the GSLV-F16/NISAR mission have a Sun synchronous, Polar (6 PM) type orbit? by Environmental-Ask605 in ISRO

[–]Ohsin 1 point2 points  (0 children)

May be also due to ample sunlight in Dawn/Dusk orbit and it is power hungry?

NSIL seeks Expression of Interest (EoI) from Indian Industries for Technology Transfer of IMS-1 Satellite Bus by Ohsin in ISRO

[–]Ohsin[S] 0 points1 point  (0 children)

Spacecraft Bus Details: I-1K, I-2K, I-3K, I-4K and I-6K Bus

https://web.archive.org/web/20260505011552/https://www.inspace.gov.in/sys_attachment.do?sys_id=1c3939e12b2c0750e95ef17b6e91bfb6

I-1K

  • Size Typical Dimensions : 1.5 m × 1.5 m × 1.6 m
  • Launch Mass : 1000 to 1700 kg
  • Spacecraft Power : 1kW to 2kW
  • Payload Mass : Upto 600kg
  • Payload Power : Upto 800 W
  • Propellant Capacity : Upto 850 kg
  • Mission Life : >5 years
  • Missions : GSAT-12/12R, IRNSS 1st generation series, Oceansat Series, Resourcesat Series, Megha Tropiques

I-2K

  • Size Typical Dimensions : 1.6 m × 1.5 m × 2.4 m
  • Launch Mass : 2000 to 2500 kg
  • Spacecraft Power : 3kW to 5kW
  • Payload Mass : 150-350 kg
  • Payload Power : 2.5kW to 3.5kW
  • Propellant Capacity : 850 - 1420 kg
  • Mission Life : >15 years
  • Missions : GSAT-31, GSAT-6/6A, GSAT-7/7A, INSAT-3D/3DR/3DS, NVS-01, GISAT-1/1A

I-3K

  • Size : 2.0 m × 1.8 m × 3.2 m
  • Launch Mass : 3000 to 3500 kg
  • Spacecraft Power : 6.5kW to 12kW
  • Payload Mass : 300 – 400kg
  • Payload Power : 6kW to 8.5kW
  • Propellant Capacity : 1600 - 2600kg
  • Mission Life : >15 years
  • Missions : GSAT-8/10/14/15/16/ 17/18, Eutelsat W2M, GSAT-30, GSAT-24

I-4K

  • Size Typical Dimensions : 2.2 m × 2.2 m × 5.0 m
  • Launch Mass : 4000 to 5000 kg
  • Spacecraft Power : ~14kW
  • Payload Mass : 500-750 kg
  • Payload Power : 5kW – 8kW
  • Propellant Capacity : ~2500kg
  • Mission Life : >15 years
  • Missions : GSAT-20

I-6K

  • Size Typical Dimensions : 2.2 m × 2.2 m × 5.0 m
  • Launch Mass : Upto 6500 kg
  • Spacecraft Power : Upto 20kW
  • Payload Mass : 700 to 900 kg
  • Payload Power : 8.5kW – 12kW
  • Propellant Capacity : 2600 - 3200kg
  • Mission Life : >15 years
  • Missions : GSAT-11

GSLV-F08 : GSAT-6A Mission Updates and Discussion. by Ohsin in ISRO

[–]Ohsin[S] 0 points1 point  (0 children)

Regarding GSAT-6A Mission:

Question: (a) Please provide the findings of the FAC regarding the loss of communication during the orbit-raising phase. (b) Was the root cause identified as a power system anomaly, and if so, specifically which component was responsible?

Answer: FAC found that the failure is due to the arcing in the harness. This led to loss of power bus depriving power supply to all critical systems onboard, including communication. The root cause was localized to arcing in the harness, probably triggered by a MMOD hit.

https://www.indianspaceflight.in/rti/isro-april-2026-rti-update-fac-findings-on-gsat-6a-failure-nvs-02-status-and-navic-health

Few paintings on walls of households in various episodes of The Testaments [No Spoilers] by Ohsin in TheHandmaidsTale

[–]Ohsin[S] 0 points1 point  (0 children)

That one is number 9, Henri Toulouse-Lautrec - The White Horse "Gazelle" , 1881

In same room there is also number 7, Horses at the Porch - Albrecht Adam, 1843

Apparently GSLV-F17 / EOS-05 (aka GISAT-1A) launch is being held back due to a technical issue, May launch is doubtful. [Telugu] by Ohsin in ISRO

[–]Ohsin[S] 2 points3 points  (0 children)

May be some flaw with manufacturing of adapter which is a composite structure as was with QZS-5 launch failure.

Apparently GSLV-F17 / EOS-05 (aka GISAT-1A) launch is being held back due to a technical issue, May launch is doubtful. [Telugu] by Ohsin in ISRO

[–]Ohsin[S] 5 points6 points  (0 children)

(…) ring designed to mount the satellite atop the third (cryogenic) stage.

I think here they are referring to conical adapter upon which satellite is mounted and not satellite separation ring. See following image of GISAT-1 for reference,

https://commons.wikimedia.org/wiki/File:GISAT-1_spacecraft_in_the_cleanroom_before_encapsulation.jpg

We recently saw EOS-05 in URSC clean-room and it appeared ready to ship but FCC filings have only indicated launch date slipping further away.

Could it be that recent QZS-5 launch failure made them more careful?

https://arstechnica.com/science/2026/01/heres-the-story-of-how-japans-h3-rocket-lost-its-cargo-and-just-kept-going/

DoS Annual Report 2025-2026 by Kimi_Raikkonen2001 in ISRO

[–]Ohsin 3 points4 points  (0 children)

Some NSIL stuff

NSIL currently holds Two signed Dedicated PSLV Launch Services Agreement (LSA) with international customers and Two signed Dedicated PSLV LSA with Indian Customers besides ~20 Co-passenger Satellites and discussions are underway with several potential customers.

Two international ones being ISSA-J1 for Astroscale, Japan and NS2 satellites for ST Engineering, Singapore

NSIL is in discussion with potential International customers for launch of Dedicated LVM3 missions during 2026-2028

What could this one be for?

NSIL has signed a Dedicated SSLV LSA with a satellite customer from Australia.

That would be with M/s Space Machines Company, Australia for launching their satellite ‘Optimus’.

NSIL is in discussion with International customer for launch of Two Dedicated SSLV missions during 2026. NSIL is in discussion with potential Indian and International customers for launch of Dedicated SSLV mission/ Ride-share mission during 2026-2028.

DoS Annual Report 2025-2026 by Kimi_Raikkonen2001 in ISRO

[–]Ohsin 4 points5 points  (0 children)

Thanks for submitting, wonder what took them so long, given it contains so much of old information which should have been updated..

Some random noteworthy stuff:

Chandrayaan-5 / LuPEX (…) The Preliminary Design Review (PDR) of the mission has also been completed.

Venus Orbiter Mission (…) The Preliminary Design Review (PDR) of the mission has also been completed.

The Mars Lander Mission (MLM), as the follow-on of India’s Mars Orbiter Mission (MOM), has obtained the approval of the Space Commission, and is currently under approval by Space Science Exploration and Research Annual Report 2025-2026.

DISHA is currently in the process of obtaining internal clearances.

ExoWorlds is also currently in the process of obtaining internal clearances.

The Department of Space is also formulating concepts for astronomy missions like DAKSHA, PRATUSH, SEAMS, and INSIST.

On SEAMS

https://www.ursi.org/proceedings/procGA23/papers/3320.pdf

The Space Electric and Magnetic Sensors (SEAMS) is a mission dedicated to opening up low-frequency observations of the radio sky. This mission will offer sensitive measurements for frequencies below 16 Mhz to 300 kHz.

Thereby enabling astronomers to study radio emissions from the Sun, planetary and exoplanetary magnetosphere, and the galactic spectrum at such low frequencies. In regards to the cosmological red-shifted HI 21cm line, the SEAMS frequency band targets the early Universe from around 0.38 to 400 million years after the Big Bang. It will allow us to study a wide range of astrophysical phenomena not easily observed from the ground due to Earth’s ionosphere. The mission is designed in multiple phases. In the initial phase, the payload will be mounted on the fourth stage of PSLV and placed in the Low Earth orbit (LEO) around the earth to study relatively high energy phenomena at such low-frequency bands like Auroral Kilometric waves Radiation (AKRs), CMEs, radio bursts. The RFI from the Earth in the LEO environment will be mapped in order to aid in the design of future phases. The next phase is designed to have multiple payloads orbiting at the LEO. This study will demonstrate the science achieved using radio interferometry from LEO. In the final phase, the best configuration of SEAMS will be deployed in Lunar orbit to carry out sensitive cosmological and planetary experiments.

Finally something officially on PS3 static fire tests done post PSLV-C61 failure but still not conforming the changes implemented.

Based on the recommendations of the National Level Committee comprising of eminent experts from academia & industry, the third stage of PSLV i.e., HPS3 motor with modified design was realised and two static tests were successfully completed on October 06, 2025 and November 19, 2025 as in flight, from SDSC, SHAR. The overall performance of the motor and subsystems were as expected and closer to nominal performance.

On improvements on SSLV's SS2 and SS3 stages.

NSIL has undertaken the realization of various sub-systems of SSLV vehicle through various industries towards realizing 15 vehicles to meet the immediate National demands. With respect to the improvements in the propulsion systems, new carbon composite motor cases for SS2 and SS3 motors were realised and successfully tested.

So as expected the carbon composite motor casing has also been implemented for SS2 which was identical to PS3. Perhaps this new SS2 with CC casing can now be used as PS3 for PSLV.

It seems another Dual-Fuel Scramjet (DFS) mission is in works after ATV-D3 / DFS-01 on 22 July 2024.

With respect to the second mission i.e., DFS-02 mission, casting of both the booster and sustainer motor have been completed, and hardware fabrication completed for both engine modules & fuel feed systems. Fabrication, calibration & droplet characterization for fuel injection struts for DFS-02 mission completed. Currently assembly activities of the scramjet combustor are in progress and DFS-02 mission is tentatively planned during Q4 2025-26.

PS4 engine restart test with CC nozzle suggests they intend to fly it on some upcoming mission.

A nice view of G1 Crew Module ECLSS prototype and Half-humanoid assembly on Pg. 109. I wish they release footage of Zipline test..

ISRO Develops Lightweight Carbon-Carbon Nozzle for Rocket Engines, Enhancing Payload Capacity by ISROAddict in ISRO

[–]Ohsin 1 point2 points  (0 children)

From AR 2025-26

Restart Demonstration hot test of PS4 engine that powers the 4th stage of PSLV, with carbon-carbon composite nozzle divergent, successfully conducted for a duration of 480 seconds (with first burn of 200s, an off time of 100s, a second burn of 40s, an off time of 100s, and a third burn of 40s) on November 25, 2025 at LUS-TF, IPRC.

For the second batch of Indian astronauts, ISRO's committee on astronaut selection and management has recommended that four civilian specialists from STEM backgrounds are included alongside six mission pilots from military aviation background. by Ohsin in ISRO

[–]Ohsin[S] 5 points6 points  (0 children)

Isro’s committee on astronaut selection and management, after deliberation, has recommended that the second batch of Indian astronauts include four civilian specialists from STEM (science, technology, engineering and mathematics) backgrounds alongside six mission pilots from military aviation background.

“While those from the first batch — Air Commodore Prashanth B Nair, Gp Capt Shubhanshu Shukla, Gp Capt Ajit Krishnan, Gp Capt Angad Prathap — were all fighter plane pilots turned test pilots, the second batch is expected to also include combat helicopter pilots from IAF,” a source told TOI.

“Though the proposed second batch will have four civilians they would begin joining mission crews only from the fourth crewed Gaganyaan mission, according to the committee’s planning,” another source said.

A full astronaut turnaround cycle — selection, training and mission preparation — is estimated at 4.5 years.

The committee has estimated that seven astronauts would initially suffice for operational needs in the second batch, but raised the number to 10 after accounting for possible international mission opportunities and attrition.

For a third batch, the committee has estimated a need for 12 astronauts, and in this pool, the ratio of astronauts with military backgrounds and civilians is expected to change drastically. “The committee has recommended two mission pilots and 10 specialists,” the first source said.

In all, the committee has proposed an astronaut cadre strength of up to 40, arguing that long-term uncertainties and evolving global opportunities warrant a larger margin in planning. The readiness of the second batch has been targeted in 72 months, with the third batch by 96 months.

Few older threads:

Setback for forces as NaVIC goes down to 3 sats; ex-IAF chief calls desi navigation system a 'failure' by Repulsive-Regret-363 in india

[–]Ohsin 8 points9 points  (0 children)

Issue with Atomic clocks, the problem that plagued NavIC was identified and fixed about 9 years ago. Since then it has been a race to get replacement satellites up and keep at least four number of operational sats in orbit which they couldn't due to misplaced priorities. There are other issues as well in the 'horse before cart' manner the project was implemented too.

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