Author Topic: FAILURE: IRNSS-1H, PSLV C39, SLP, August 31, 2017 (13:30 UTC)  (Read 65151 times)

Offline vineethgk

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http://indianexpress.com/article/technology/science/isro-suspects-pyro-elements-failed-to-separate-rockets-heat-shield-4831240/

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The Indian space agency is strongly suspecting the failure of pyro elements for the non-separation of the heat shield of its rocket Polar Satellite Launch Vehicle’s (PSLV) XL variant on Aug 31, said a senior official.
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According to K. Sivan, Director, Vikram Sarabhai Space Centre (VSSC), all the systems during the rocket’s flight worked well while the only suspect place is the pyro elements.
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One fortunate aspect of the failure is that ISRO has all the flight data as the rocket was not lost during its one way journey.
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“Tests are going on to find out the reasons for the failure of heat shield separation. Each test takes around 72 hours,” Sivan told IANS.

Offline worldtimedate

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Last month’s failed mission of PSLV appears to have dried up the influx of usual news reports of the forthcoming satellite launch of ISRO appearing in the Indian Newspapers. I have found the following news report though a bit old by 10 to 11 days, yet it brings to light some issue that could have precipitated the failure of the PSLV mission. M.Y.S. Prasad, the former director of SDSC making some interesting points related to the mission failure as well as quality control responsible for the failure of the GSLV-F02 launch in 2006 and component problems in IRNSS-1A.

Source : Non-separation of PSLV heat shield can be due to process quality issue, and not a design failure, say space technology experts

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"The PSLV rocket has been successful for the past several years. So the question of design failure does not arise. It could be an issue of a failed component or a process quality issue," M.Y.S. Prasad, a former Director of the Satish Dhawan Space Centre, told IANS.

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This is the first time that a satellite launch mission has failed due to this reason, perplexing current and former officials of the Indian Space Research Organization (ISRO). "It is really perplexing that such a thing has happened. Normally, the PSLV rocket has several redundancies built into it," R.V. Perumal, a former ISRO scientist, told IANS.

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Noting all the commands are pre-planned and built into the computers, he said that there cannot be any manual command. "The computers have to give the necessary commands. The commands have to be relayed by the electrical circuits. The pyro circuit has to get initiated which, in turn, has to cut the mechanical elements so that the two parts of the heat shield get separated," he said.

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Prasad maintained that something could have gone wrong in this four-step sequence or in the sub-systems, as redundancies have only been built into some systems. "The computer programmes may have several redundancies to take care of an eventuality. So they can be tested on ground before and also during preparation for the flight. The electrical circuits and some pyro elements will also have redundancies.

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"A rocket has several one-time operation systems. Such systems cannot be pre-tested and cannot have redundancies[/b]. Only sample tests can be made with items manufactured in that batch. And then a system is used in the rocket," he said, terming the one-time operation systems 'the riskiest items; in any rocket.

Ruling out design failure, Prasad said the most probable cause of failure could be the quality of a rocket component or some error in the assembly of systems.

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Offline K210

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Reason for failure has been found. Report will be released shortly. Launches to resume from november.

http://economictimes.indiatimes.com/news/science/india-to-resume-satellite-launches-by-december/articleshow/60702472.cms

Offline Star One

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ISRO to be back with launches in Nov.-Dec.

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The Indian Space Research Organisation expects to resume launch of satellites in a couple of months once its failure analysis committee releases its report. The committee is conducting tests on why the PSLV-C39 mission of August 31 failed to release a back-up navigation satellite into space.

ISRO Chairman A.S. Kiran Kumar on Friday said the committee would release its report "very soon". The launches would be resumed in November or December after necessary steps are taken. He was speaking on the sidelines of an event to mark 25 years of the formation of Antrix Corporation, which markets ISRO’s products and services.

http://www.thehindu.com/todays-paper/tp-national/isro-to-be-back-with-launches-in-nov-dec/article19695173.ece

Offline worldtimedate

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Pyro devices to blame for PSLV failure: ISRO

The Indian Space Research Organisation (ISRO) has come round to the inference that the PSLV C-39 mission on August 31 was doomed by the failure of the pyro devices that actuate the separation of the heat shield encasing the satellite from the rocket.

A high-level meeting chaired by ISRO chairman A.S.Kiran Kumar held at the VSSC here on Friday came to the conclusion on the failure of the pyro devices. The meeting was informed that simulation exercises were on to ascertain the reason for the malfunctioning of the pyro devices.

"We have isolated the component responsible for the failure of the mission but it remains to be established why it failed to function," VSSC Director Dr. K.Sivan said. "We are testing various versions and hope to arrive at a consensus in seven to 10 days". The exercises are expected to help the scientists analyse the failure from various angles.

The failure review committee set up by ISRO had zeroed in on the electrically-operated pyro devices as the culprit after it was found that the command for separation had gone through but failed to trigger the mechanical process that pops open the heat shield.

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Offline DatUser14

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Any updates to when this will decay?
Titan IVB was a cool rocket

Offline Steven Pietrobon

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"The committee looking into what led to failure of PSLV-C39 on August 31 has identified the primary reason. "There was a bellow in the system which did not allow pressure to build up and shredded the nose cone," said ISRO chairman AS Kiran Kumar on Monday."

http://bangaloremirror.indiatimes.com/bangalore/others/Poor-pressure-build-up-failed-PSLV-C39/articleshow/61349021.cms
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline worldtimedate

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"The committee looking into what led to failure of PSLV-C39 on August 31 has identified the primary reason. "There was a bellow in the system which did not allow pressure to build up and shredded the nose cone," said ISRO chairman AS Kiran Kumar on Monday."

http://bangaloremirror.indiatimes.com/bangalore/others/Poor-pressure-build-up-failed-PSLV-C39/articleshow/61349021.cms
The PSLV Users Guide says the following about fairing separation.

"The heat shield fairings are joined vertically through a contamination-free, linear piston cylinder separation and jettisoning mechanism (zip cord) running along the full length of the heat shield.  A clamp band joint is employed for attaching the heat shield at its base to the vehicle.

The heat shield fairings are separated by the actuation of the clamp band joint at the base and the zip cord. The gas pressure generated by the mild detonating cord of the zip cord expands a rubber bellow, pushing the piston and cylinder apart after shearing the rivets holding the two halves. The force acting on the half shells pushes them laterally away from each other thus achieving the required jettisoning velocity. The bellow assembly retains the residual gases and prevents contamination of the spacecraft."

Perhaps the bellow did not expand properly?  Maybe it is the part that "shredded" rather than the "nose cone"?

 - Ed Kyle

Quality control will continue to dog ISRO in its space launch mission in the future. This is not the first time that such quality control issue has emerged as the reason for launch failure of ISRO mission. Three GSLV MKII mission failed due to quality control issue. It is now high time for ISRO to sort out the quality contorl issue before assembling the launch vehicle.

I was not rather surprised at all when the PSLV mission failed on August 31, 2017. The writing was on the wall, because of ISRO's sudden rapid sequence of satellite launches with a view to cranking up the higher number of launches, ISRO and many public and private companies that manufactured components for the launch vehicle overlooked meticulous testing at  some important stages of the components that resulted in the whole mission being jeopardized and the flawless launch record of PSLV, ISRO'S workhorse being tarnished.

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Offline input~2

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Decay dates from SatEvo:

C:                              late October 2017
B (PSLV DEB):           around Christmas 2017
A (IRNSS 1H/PSLV):   early July 2018
Revised decay dates from SatEvo with latest TLEs (epoch > Sept 4, 22:48 UTC)

C (PSLV DEB)           early November 2017
B (PSLV DEB)           early November 2017
A (IRNSS 1H/PSLV)  mid-August 2018
Spacetrack has recorded decays for both Object B and C on December 5, 2017
« Last Edit: 12/10/2017 10:05 AM by input~2 »

Offline Cristiano

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Here’s my first attempt to predict the PSLV-C39/IRNSS-1H reentry date with a Monte Carlo simulation:



[http://cristianopi.altervista.org/IRNSS-1H_2018-03-10_MC.png]

The simulation includes the Newtonian and relativistic accelerations of all the planets, Sun and Moon. The Earth is the WGS 84 ellipsoid and for its gravity field I use the GRACE Gravity Model version 3 Combined truncated to the degree and order 25 (to save the running time, while retaining good accuracy when compared to the EGM2008 model). For the air density I use the NRLMSISE-00 model along with a data file for the solar and geomagnetic indices.

With the SGP4 propagator I calculate the initial state of the IRNSS-1H for the TLE epoch, then I propagate it with a specially crafted propagator (based on a DOPRI853 integrator).
Then, for 99 times I add a normally distributed random offset to the initial radius vector (to take into account the TLE uncertainty) and I propagate the new random state.

Since I used 22 TLEs, I obtained 22 reentry dates from the original TLEs (the blue dots) and 2178 reentry dates from the modified initial states (the gray dots).
The confidence interval is just based on the variance of the reentry dates.
The simulation took 40h32m of CPU time.

Since the confidence level is high, the reentry interval is very wide.
For a very long integration time like that (600/700 days), the solar and geomagnetic activity will play a significant role in changing the reentry date, but a reentry before next year seems unlikely.

Offline Cristiano

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The following graph is similar to the one posted by eeergo in reply #133:



[radius vector min, med, max]

it shows the predicted radius vector for the apogee, semi-major axis and perigee.

In the next graph (which shows only the predicted perigee radius vector):



we can see that the perigee radius vector will remain about constant until about 2 days before reentry.

Offline Cristiano

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I post this update for three reasons:
1) starting from the TLE 18109.12967795, the orbital elements became highly correlated (which is good);
2) the measured and predicted geomagnetic index (used for the calculation of the air density) increased and now the predicted reentry is 1 year earlier;
3) the current reentry date falls within the reentry interval calculated with my previous (unpublished) simulation (which I did 10 days ago).
Here’s the result:



[original size]

The graph also shows an additional plot for the most probable reentry interval, which is October 16 ÷ October 26 with 32% of the predicted dates.

The following graph shows the predicted trajectories propagated from the original TLEs (notice the logarithmic vertical scale):



[original size]

Offline Cristiano

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This update comes from an improved simulation:
  - changed the gravity model;
  - the satellite latitude and longitude (used for the calculation of the Earth’s gravitational acceleration and for the calculation of the air density) are now calculated with the NASA’s SPICE library ITRF93 high accuracy reference frame;
  - changed the drag coefficient variation as a function of the altitude.

The first graph shows the predicted trajectories propagated from the latest 10 TLEs (notice the logarithmic vertical scale):



[original size]

This simulation seems to confirm the result obtained from my first Monte Carlo simulation: a reentry before next year seems very unlikely.
The reentry date range is from Feb 21 to 25 and theoretically the uncertainty should be +/- 3 weeks.

The second graph shows the radius vector of the predicted perigee:



[original size]

Offline Cristiano

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I slightly improved my Monte Carlo simulation to better take into account the satellite velocity uncertainty.



[original size]

The green line shows the average of the reentry dates (Feb 6).
The most probable reentry interval (according to this simulation) is from Jan 27 to Feb 12, with 52% of the predicted dates.

If we want to try a more empirical approach, we could consider the current decay rate of the mean radius vector (which is the semi-major axis). With the TLEs and the SGP4 propagator, I calculated the mean radius vector:



[original size]

the current value is about 1808 + 6371 km. The linear regression shows a mean decay rate of about 5.24 km/day.
With the help of the simulation, we find that the reentry altitude will be about 160 km:



[original size]

If we do: 2018-08-10 + (1808 – 160) / 5.24 = 2019-06-23. Since we perfectly know that the decay rate is continuously increasing, that date should be considered as the theoretical upper bound for the reentry date; in other words, if the solar activity does not significantly change, we can say that the reentry surely will happen before that date.

Offline Cristiano

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I will continue to update this thread in my new lean and mean site: http://cristianopi.altervista.org/as/, just graphs and brief explanations. This way, I avoid annoying those of you who are not interested in my graphs.
No banners, no popups, but the site needs javascript enabled just to add some basic functionalities.

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