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.
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.
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.
“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.
"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.
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.
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.
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.
"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.
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.
Quote from: Steven Pietrobon on 11/02/2017 03:15 am"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.cmsThe 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
"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
Quote from: input~2 on 09/02/2017 07:31 pmDecay dates from SatEvo:C: late October 2017B (PSLV DEB): around Christmas 2017A (IRNSS 1H/PSLV): early July 2018Revised decay dates from SatEvo with latest TLEs (epoch > Sept 4, 22:48 UTC)C (PSLV DEB) early November 2017B (PSLV DEB) early November 2017A (IRNSS 1H/PSLV) mid-August 2018
Decay dates from SatEvo:C: late October 2017B (PSLV DEB): around Christmas 2017A (IRNSS 1H/PSLV): early July 2018
IRNSS-1H + rocket stage is reentered March 2.