Indian Space Program Discussion

Arunkumar · Post by **Arunkumar** » 20 Apr 2011 18:30

Congratulations ISRO.

AJames · Post by **AJames** » 20 Apr 2011 19:42

Luxtor wrote:
AJames wrote:The PSLV reliability contrasts with GSLV failures. I think the problem with the GSLV is some basic design decisions that were taken early on which contribute to poor reliability. The main one is in my opinion the decision to start the cryogenic stage in mid-air. Cryogenic engines are inherently problematic, and particularly at the start up stage. Reliability has to be engineered in at the start, not added as an afterthought. The US space shuttle and Ariane heavy lift vehicles for example start their cryogenic stage on the ground before starting the solid boosters. This way, if the engines don't start properly, then the launch can be aborted and the engines shut down before the solid fuel boosters are fired. By adopting a cryogenic which is started in mid-air, ISRO has made a rod for its own back in my opinion.

All rockets that have cryogenic upper stage need to be started at high altitude (mid-air) at a later time after the initial lift off. Ariane does light its lower main cryogenic on the ground at lift off but the upper cryogenic is lighted during flight at higher altitude.

You are right, and the version of Ariane that uses upper stage cryogenic engines is Ariane 5 ECA which has 8 successful launches, but in the case of the Ariane, the decision was taken to use gas generator cycle cryo engines, which are less efficient and less advanced than the combustion cycle cryo engines used in GSLV's upper stage and the US space shuttle. The reason for this decision is that Ariane space traded off efficiency for reliability - they thought combustion cycle engines would be too risky. That is the main reason for Ariane Space's very low failure rate. The US space shuttle doesn't use a cryo upper stage and starts the main cryo engines at launch. It seems to me that ISRO is trying to do something which is much more difficult technically than its competitors, and it is therefore not surprising that they are hit by more failures.

The question is: are there any combustion cycle upper stage engines used by others, and do these have a good reliability rate? Why wasn't a cryo main stage used in GSLV rather than a cryo upper stage - was this for stage interchangeability with PSLV?

PratikDas · Post by **PratikDas** » 20 Apr 2011 20:03

SSridhar wrote:If 90% of the output of the remote sensing satellites remain unused, then it is the problem of the end-user community, not ISRO.

Agree completely! NRSA isn't a charity. The images cost money but businesses need to think of the tangible and intangible benefits of buying the images. Google has demonstrated its foresight with Google Maps and then Google Earth and that story is still unfolding.

Vipul · Post by **Vipul** » 20 Apr 2011 21:00

Congrats ISRO.

Gagan · Post by **Gagan** » 20 Apr 2011 21:21

There is a problem at the government level also.

GoI won't allow the really high resolution imagery into public domain.
I wonder what kind or resolution is given out to the people who want to do a town planning project.

I am sure that they get better resolution images via google earth than NRSA is allowed to give them.

SSSalvi · Post by **SSSalvi** » 20 Apr 2011 21:27

^^^

Unless you have a timelined database you can't know what was happening sometime back.

E.g. There are many instances where lake encroachments take place and most of the time there are debates whether lake existed and upto what extent. Instead they could simply use the old database to see where was the boundary of lake for several years earlier.

But that clean approach is seldom used because then there will be just one answer : correct or wrong. and always such clean answers are painful.

Inspite of several constraints data bases have been created from the days of magnetic tapes. Remember maintaining magtape even for a year has a lot of problems like sticking etc.

Now of course with digital storage techniques the large volume of data can be stored in very small physical size ... which was not the case earlier.

You simply can't avoid excess storage than the actually used data.

====

@ gagan

Unfortunately your last sentence is true.

But you can't have as much repeatative coverage from any other country than your own database.

KrishG · Post by **KrishG** » 20 Apr 2011 21:59

First of all, Congratulations to ISRO !

There's another important news coming out today about the GSLV-D3 failure.

Shroud design to blame for GSLV failure ?
Design flaw behind GSLV crash

Sridhar · Post by **Sridhar** » 20 Apr 2011 23:07

First congrats to ISRO and all the people involved. Heartening to see that the PSLV is turning out to be one of the most reliable launchers in service anywhere in the world.

The failure analysis committee report is also timely. Goes to show how a complex system can fail with the most innocuous of components failing.

Somebody was mentioning about GSLV design, the choice of the upper stage cryogenic etc. There are historical reasons for why the GSLV design is what it is. It is an evolution from the PSLV, which has now proven to be a well-considered design. Its first two stages are identical to the PSLV, and the strapons use the same engine as the PSLV/GSLV second stage. Hence, the choice of the design made sense for an organization that had only developed solid engines for the SLV at the time.

The question can be asked for the GSLV MK3 however, which is a new design from the bottom up. For the GSLV itself, this seems to be a sound decision for the time.

Virupaksha · Post by **Virupaksha** » 21 Apr 2011 00:28

Those who are speaking of Ariane's "reliability" should check its initial successes and failure. Every move from preAriane (Europa) --> Ariane1 --> Ariane2 and so on had failures of 3-6 launches at the minimum. Infact Europa, was such a colossal failure that it was shut down without a single successful launch and the technical competancies were transferred to Ariane with all sunk costs removed.

nothing --> PSLV --> GSLV are such significant moves for ISRO. The initial failures of PSLV got ISRO much more of stick than today, when atleast it has PSLV running. Expect GSLV to stabilise around 2013-2015.

Sridhar · Post by **Sridhar** » 21 Apr 2011 04:14

Hidden in this story on Resourcesat-2 is a small nugget about progress on the GSLV-MK2 and the CUS.

http://www.hindu.com/2011/04/21/stories ... 600900.htm

The failure of the turbo-pump in the indigenous cryogenic stage in the GSLV-D3, which led to the mission's failure in April 20, 2010, had been analysed, said S. Ramakrishnan, Director, Liquid Propulsion Systems Centre (LPSC), ISRO. A modified turbo-pump was successfully tested at the LPSC, Mahendragiri, Tamil Nadu, on Tuesday.

Bade · Post by **Bade** » 21 Apr 2011 06:24

prithvi wrote:India has world's largest collection of Remote sensing satellites ...

This is not true. The suite of remote sensing satellites launched from the US alone is quite large and missions are more diverse than what ISRO has so far achieved. We should never propagate such half-truths which will hurt our credibility.

SSridhar · Post by **SSridhar** » 21 Apr 2011 07:13

ISRO to build orbiter for NASA

The National Aeronautics and Space Administration (NASA) has asked the Indian Space Research Organisation (ISRO) to build an orbiter that will provide the communication between the soil samples collected from the far side of the moon and the earth, according to ISRO Chairman K. Radhakrishnan.

This joint venture between the ISRO and the Jet Propulsion Laboratory in Pasadena, California, would be part of the Moonrise missions planned by the NASA.

“This project is in the planning phase, alongside India's lunar mission programme centred on Chandrayaan-2,” he said.

The ISRO would provide an orbiting communicator to the NASA for this mission, scheduled for 2016.

merlin · Post by **merlin** » 21 Apr 2011 10:33

Bade wrote:
prithvi wrote:India has world's largest collection of Remote sensing satellites ...
This is not true. The suite of remote sensing satellites launched from the US alone is quite large and missions are more diverse than what ISRO has so far achieved. We should never propagate such half-truths which will hurt our credibility.

Would this be true if you only consider civilian applications?

Singha · Post by **Singha** » 21 Apr 2011 10:34

I dont think so.

SSSalvi · Post by **SSSalvi** » 21 Apr 2011 11:21

We have a largest fleet of OPERATIONAL "CIVIL" satellites.

juvva · Post by **juvva** » 21 Apr 2011 11:36

Yes. "CIVIL" satellites...pronunciation: "SEE EVIL"

Multatuli · Post by **Multatuli** » 21 Apr 2011 12:26

Ahem... Could someone please explain what "cryogenic stage shroud" is? In laymans terms, a picture of this mysterious device would be appreciated too.

Austin · Post by **Austin** » 21 Apr 2011 12:35

AJames wrote:The question is: are there any combustion cycle upper stage engines used by others, and do these have a good reliability rate? Why wasn't a cryo main stage used in GSLV rather than a cryo upper stage - was this for stage interchangeability with PSLV?

What about the Russian cryo they use now on GSLV , is that a gas generator cryo engine or a combustion cycle cryo ?

suryag · Post by **suryag** » 21 Apr 2011 12:36

In addition to shroud, please explain fairing or faring

Gagan · Post by **Gagan** » 21 Apr 2011 13:41

CUS & Shroud

Gagan · Post by **Gagan** » 21 Apr 2011 13:52

Payload Fairing parts on either side of the Satellite.
These are the huge white covers that envelop the payload (satellite) in the initial few minutes of the launch.

Payload Fairing now fully covers the satellite and will sit atop the launcher rocket.

There, right at the top:

suryag · Post by **suryag** » 21 Apr 2011 14:15

Thanks Gaganullah ji

Vipul · Post by **Vipul** » 21 Apr 2011 19:48

ISRO to conduct GSLV test flight in 2012 with Russian cryogenic stage engine.

The Indian Space Research Organisation ( Isro ) will conduct a test flight of Geosynchronous Satellite Launch Vehicle ( GSLV ) with a Russian cryogenic stage engine by the first half of 2012, said its chairman K Radhakrishnan .

The test flight would be conducted only after making necessary improvements based on the analysis of the GSLV F06 that failed on December 25, 2010.

"We modified the booster pump in the liquid propulsion tank and tested it on Tuesday . More tests need to be conducted before it is integrated with the engine . We are also looking at a problem posed by the shroud of the rocket . The shroud failed so the connector could not function ," said S Ramakrishnan , director , Liquid Propulsion Systems Centre of Isro . Of the seven engines procured from Russia , only two are left, said Ramakrishnan .

Two of India's GSLV launches last year had failed - GSLV (D3) on April 15 and GSLV- F06 on December 25. Isro has had a troubled past with GSLV , on which rest India's ambitious space programmes like the manned mission to space . Only two of the seven GSLV launches have been total successes. Though Isro claims that four launches had been successful, independent observers say only two of them were total successes.

AJames · Post by **AJames** » 21 Apr 2011 23:20

Austin wrote:
AJames wrote:The question is: are there any combustion cycle upper stage engines used by others, and do these have a good reliability rate? Why wasn't a cryo main stage used in GSLV rather than a cryo upper stage - was this for stage interchangeability with PSLV?
What about the Russian cryo they use now on GSLV , is that a gas generator cryo engine or a combustion cycle cryo ?

It is combustion cycle like the indigenous Indian version, but I was wondering where else is it used, whether it was used on an upper stage, and what is its failure rate.

Austin · Post by **Austin** » 21 Apr 2011 23:32

AJames wrote:It is combustion cycle like the indigenous Indian version, but I was wondering where else is it used, whether it was used on an upper stage, and what is its failure rate.

In the GSLV test that has happened so far , on how many occasion the russian cryo failed after it fired , thats is one way to find out the failure rate.

AJames · Post by **AJames** » 21 Apr 2011 23:34

ravi_ku wrote:Those who are speaking of Ariane's "reliability" should check its initial successes and failure. Every move from preAriane (Europa) --> Ariane1 --> Ariane2 and so on had failures of 3-6 launches at the minimum. Infact Europa, was such a colossal failure that it was shut down without a single successful launch and the technical competancies were transferred to Ariane with all sunk costs removed.

nothing --> PSLV --> GSLV are such significant moves for ISRO. The initial failures of PSLV got ISRO much more of stick than today, when atleast it has PSLV running. Expect GSLV to stabilise around 2013-2015.

Ariane 1 and 2 are completely different vehicles form Ariane 5. For a cryo, the Ariane 5 has a fantastic success rate - 2 failures and a partial failure out of 56 launches.
http://en.wikipedia.org/wiki/Ariane_5
What is more the failures are limited to the first flight and the first flight of the ECA variant. The partial failure was the second flight. I believe this is due to a design decision by Ariane Space to design for reliability from the ground up, choosing the less advanced and less efficient gas cycle generator cycle engines for reliability reasons.

AJames · Post by **AJames** » 21 Apr 2011 23:43

Gagan wrote:CUS & Shroud

I am not an aerodynamicist, but looking at the image, surely the cylindrical lip at the bottom will catch the supersonic air flowing over it and cause severe air turbulence inside. Shouldn't the lattice be right at the bottom of any shroud provided?

Sridhar · Post by **Sridhar** » 21 Apr 2011 23:48

The GSLV-MK2's cryogenic engine uses a staged combustion cycle, while that for the GSLV-MK3 uses a gas generator cycle. Does anybody know the rationale behind these two decisions? It seems counterintuitive at first glance that ISRO adopted the route of first developing a more complicated engine, and then chose a less complicated design (and a less efficient one) for the MK3's engine. Clearly, the first glance is not very informative, so does anybody know the constraints and/or considerations that went into these decisions?

Varoon Shekhar · Post by **Varoon Shekhar** » 21 Apr 2011 23:55

The GSLV-MK2's cryogenic engine uses a staged combustion cycle, while that for the GSLV-MK3 uses a gas..

A couple of very layman like questions: For the GSLV, are the MK2 and MK3 project teams totally separate and different, or is there major interaction between them?

Also, did ISRO solve that software issue that prevented them from launching polar sun-synchronous satellites in the most efficient manner? Something about a less direct trajectory that they were forced to take; with another software, they are able to launch more directly and efficiently. They were working on this 3 years ago, and when they launched the Israeli satellite Techstar/Polaris, they mentioned the problem.

Sridhar · Post by **Sridhar** » 22 Apr 2011 00:10

It is not a software issue. For polar sun-synchronous orbits, launching from Sriharikota involves a dog-leg maneuver to avoid flying over Sri Lanka. In the first flight of the PSLV, which was a failure, there was a software error that led to the failure (every sub-system worked perfectly). This error was fixed in the subsequent flight and the PSLV has not had a failure ever since. The dog-leg maneuver cannot be avoided unless ISRO builds a new launch site, from where a flight due south would not involve flying over land. There was a mention of using Balasore or some site near there for polar launches (the site is not ideal for geosynchronous launches as it is farther away from the equator than Sriharikota). But there has been no concrete plan for that. The loss of payload capacity due to the dog-leg maneuver is considered small relative to the cost of replicating an entire launch complex. At least as of now.

Bade · Post by **Bade** » 22 Apr 2011 01:17

SSSalvi wrote:We have a largest fleet of OPERATIONAL "CIVIL" satellites.

Is this for only IRS series land remote sensing and its equivalent elsewhere ?

Most of NASA and NOAA missions are in the civil domain too. The broad classifications are ocean, land and atmosphere remote sensing. In each of these categories there are quite a few launches both "operational" and in "experimental" mode. Frequency of launches are much higher than ISRO's too.

The LandSat series is the apples to apples comparison with IRS class from ISRO. For Oceans, there is in civilian domain, Aqua, Terra, SeaWiFS (till recently) and altimetry missions vs ISRO's Oceansat-2. There are many science missions from NRL etc which is not used operationally as such but data is available.

Then there are the NOAA operational polar and geostationary missions with global coverage for both. That is the equivalent of METSAT(Kalpana) from ISRO.

The communications satellites are all in civilian domain, under private entities. Then there are specialist science mission payload. Some satellites have so many payloads for different operational missions that counting them all as one, since on same satellite bus does not do justice to the breadth of the activities.

Why even ISRO/IMD/NIO acquire foreign mission (primarily from US and ESA) data routinely for operational use.

ISRO activities are largely confined to Indian needs as of now, it has limited global reach despite its polar satellite missions for the breadth of mission types needed to match all that is in civilian domain just in the US itself.

Just one arm of NOAA
http://www.nesdis.noaa.gov/SatInformation.html

Current NASA ones
http://www.nasa.gov/missions/current/index.html

There are planetary ones too, but even the earth specific ones from here are large and diverse. There are also overlapping roles for NASA,NOAA and USGS in earth missions as seen in the list from the last link.

Sridhar · Post by **Sridhar** » 22 Apr 2011 02:13

I don't think the claim from ISRO has ever been that it has the largest constellation of civilian satellites. It has been that it has the largest constellation of civilian earth-observation & imaging satellites of any organization in the world (to be more specific, satellites in polar orbit with cameras to take images of the earth). Maybe the claim is inaccurate, but comm sats, weather sats in geostationary orbit, planetary probes etc. are irrelevant to this comparison.

SaiK · Post by **SaiK** » 22 Apr 2011 02:50

have we signed any treaty for not weaponizing space? I am thinking about satellite based laser beam weapons.

Bade · Post by **Bade** » 22 Apr 2011 05:30

But that is a strange way of defining satellites for "civilian" purposes in the context of earth observation which is a very broad field of activity and is not limited land imaging. If ISRO is restricting itself to just imaging satellites of the Landsat type, then it is better to drop this claim, even if true for imaging only since the world has moved on to doing larger inter related earth observation missions from space for operational use in weather and climate studies.

Dropping this claim does not take anything away from ISRO's current goals and achievements, but it is hard to take the claim seriously. Civilian operational use of remote sensing has a broader meaning to many the world over.

Austin · Post by **Austin** » 22 Apr 2011 09:05

ISRO has one of the largest constellation of civilian satellites for sure , it may not be the largest in the world and it really does not matter , this is not a dick measuring contest.

arunsrinivasan · Post by **arunsrinivasan** » 22 Apr 2011 09:13

Austin wrote:... this is not a dick measuring contest.

Sorry OT, but couldn't resist, isn't all (well almost all) human behavior driven by "my .... is bigger than yours ..."

manoba · Post by **manoba** » 22 Apr 2011 14:04

arunsrinivasan wrote:
Austin wrote:... this is not a dick measuring contest.
Sorry OT, but couldn't resist, isn't all (well almost all) human behavior driven by "my .... is bigger than yours ..."

There is a proverb in Tamil, which is "Murthy sirusu aanaalum kirthi perusu". Meaning, it may be a Murthy of road side temple and a very small, tiny Murthy, but the kirthi could be immense since he satisfies all devotees cherished secret wishes.

Moral: Don't look into the size, but the kirthi. Hasten not and don't dirty your mind, I'm indeed talking about the size of satellite constellation and it's kirthy.

KrishG · Post by **KrishG** » 22 Apr 2011 14:22

Sridhar wrote:The GSLV-MK2's cryogenic engine uses a staged combustion cycle, while that for the GSLV-MK3 uses a gas generator cycle. Does anybody know the rationale behind these two decisions? It seems counterintuitive at first glance that ISRO adopted the route of first developing a more complicated engine, and then chose a less complicated design (and a less efficient one) for the MK3's engine. Clearly, the first glance is not very informative, so does anybody know the constraints and/or considerations that went into these decisions?

It depends on the requirements. GSLV Mk-III needed a high thrust (200 kN) upper stage engine. Engines using staged combustion cycle are known to be more efficient for very high thrust ratings and at lower altitudes (earth-ignited stages). GG engines are simpler and should weigh lesser than SC engines operating at similar chamber pressure and other certain conditions although their ISP will take a hit. So they should have better T/W ratio than SC engines at the operating specifications of Mk-III upper stage.

sanjeevji · Post by **sanjeevji** » 22 Apr 2011 14:46

Weak Russian component downed Indian rocket: Ex-ISRO chief

Chennai, April 22 (IANS) The destruction of India's Geosynchronous Satellite Launch Vehicle (GSLV) in mid air in 2010 was due to an inherent weakness in a component in the Russian supplied cryogenic engine.

"We did several simulation tests to find out why the connectors - the wires that carry command signals from the onboard computers at the top to the rocket's engines down below - snapped," former ISRO chief Madhavan Nair told IANS.

Nair, who headed the Failure Analysis Committee, said the 12-member panel submitted its report to ISRO two weeks back.

According to ISRO, the failed component, called shroud, was made of composites and is part of the Russian cryogenic engine. It got deformed due to the flight load.

ISRO's 418-tonne GSLV rocket (cost Rs.175 crore) carrying advanced communication satellite GSAT-5P (weight 2,310 kg, cost Rs.150 crore) veered off its flight path and began disintegrating within a minute after lift-off from Sriharikota in Andhra Pradesh last Christmas day.

As the weakness was inherent in the shroud, Nair said ISRO should have a dialogue with the Russians to see how the component could be strengthened.

Informed sources told IANS that even in the GSLV-F04 rocket launched in 2007, one of the connectors got snapped due to weak shroud.

"The fault was there from the first GSLV that flew with the Russian cryogenic engine in 2001. The weakness in the shroud caught ISRO on December 25 last year," a source told IANS.

Experts told IANS that the first 15 km of a rocket's flight was very crucial as it is subjected to heavy atmospheric loads. It is more so when the rocket is escaping the earth's gravitational pull at 330 metres per second.

The flow of air along the rocket will be turbulent at the transonic speed - when the rocket crosses the speed of sound. At that point the air will attach to the rocket at some places and detach at some spots in a haphazard manner.

Out of the seven cryogenic engines supplied by Russia, India has used six. One remains to be used.

According to Nair, it is Russia's responsibility to set right the shroud in the remaining cryogenic engine as it is their engine and technology.

"The matter has been discussed with them. But the question of compensation from Russia for the loss does not arise," he said.

The Russians had earlier pointed their fingers at the rocket's bigger heat shield (4 metre) as the proximate cause for high atmospheric load on the rocket that broke it.

The 2010 GSLV's heat shield measured 4 metres in diameter as against 3.4 metre in most earlier GSLV rockets.

At 2,310 kg, the GSAT-5P communication satellite was the heaviest payload ever lifted by a GSLV.

It was 180 kg heavier than the INSAT-4CR launched in 2007, 360-kg heavier than Edusat launched in 2003 and about 780 kg heavier than GSAT-1 launched in 2001.

All GSLV's that flew with Russian cryogenic engine have encountered problems carrying a payload of over 2,000 kg.

In 2006, a GSLV rocket carrying INSAT-4C satellite weighing around 2,168 kg was blown mid air after the rocket became unstable.

In 2007, one of the connecters of the GSLV rocket got snapped and the rocket's performance was considered as below par. The rocket had carried 2,130 kg INSAT-4CR satellite.

Refuting that GSLV is facing a 2,000 kg jinx, R.V. Perumal, a retired ISRO rocket scientist, told IANS: "The increase in the weight of the satellite is only a fraction of the rocket's total weight (418 tonne). It is well within the scatter mass of the rocket. Hence the satellite weight is not the reason for the rocket's instability."

Sridhar · Post by **Sridhar** » 22 Apr 2011 18:54

Bade,

Weather is a totally different application than earth observation for studying natural resources, cartographic applications and such, for which imaging satellite are meant. I don't see the overlap - the former requires frequent observation (at least every couple of hours) whereas the latter works well with infrequent observations. The orbits, the instruments used and indeed how the data are used are very different. I don't understand why you are insisting on mixing the two.

ISRO's claim is a pretty legitimate one and has played at least some role in marketing the organization. Every space agency touts its achievements - why shouldn't ISRO?