Mangalyaan: ISRO's Mars Orbiter Mission

rahulm · Post by **rahulm** » 12 Nov 2013 13:30

ISRO is constituting a Failure Analysis Committee to investigate the glitch.

ISRO Chairman K. Radhakrishnan said: "All is well and operations completed as planned."

The ISRO chief had said Monday that a failure analysis committee would examine the glitch the spacecraft had hit, but added that crucially, not much fuel was wasted in the failed attempt.

India's Mars mission back on track: space agency

SSSalvi · Post by **SSSalvi** » 12 Nov 2013 15:03

Oh .. I was waiting anxiously to check the improperly raised ( 78300 Kms ) orbit in 4th orbit raising.

But details of that particular orbit are not available. The last update available is for 8th Nov 2013. ( 71620 Kms orbit ).

Today morning 5 AM ISRO raised orbit from 78276km to 118642km.

So now whenever update happens we will see only info pertaining to 118642 Kms orbit.

These figures show how the orbits are placed upto 3rd ORM.

More info ( for a common man, not initiated into space science ) is available here

Singha · Post by **Singha** » 12 Nov 2013 15:48

a bit OT but my wife works in water filter products (RO types and UV types) and though its 1000 times simpler than a space ap, the amt of flaws they uncover in physical proto testing related to valves, flow rates, reliability and durability is amazing...despite the individual comps being certified for XYZ by the vendors or even the full units being claimed to work in other countries.

there is absolutely no way to even build a reliable water RO unit using just sw simulations let alone a kit being sent to mars.

this cost cutting might bite us just as the lack of vacuum test facility did to one gslv test.

member_23694 · Post by **member_23694** » 12 Nov 2013 16:04

^^^^^^^^
another OT
Sir too many things are currently being relied upon based on simulation confidence most notably the H-Bombs .

they even save money from putting cameras in space vehicles ... strange , either others are too rich and fine in showing their
wealth or we try to save too much to the extent of paise
Just for a second imagine a camera in PSLV C-25 while it was in coasting phase , it was worth a try.

prashanth · Post by **prashanth** » 12 Nov 2013 17:44

^
Agreed.These are some lessons for future missions.
IMO, they skipped full scale hardware testing using a mock-up probably because the satellite is based on the proven I1-K bus (and also because of time constraints).The IRNSS and some GSATS are based on this configuration. Simultaneous operation of the main and redundant fuel valves was probably not required in these sats.

Lilo · Post by **Lilo** » 12 Nov 2013 17:48

Reason for firing both together could be..
Greater the thrust and lesser the time the thrusters are on fire as near to perigee - better the efficiency of the orbit raising maneuver(in terms of kilometers elongated) vis a vis propellant usage - is how I understand.

So 2 firing simultaneously == more thrust
With Impulse constant near perigee and corresponding lesser time of firing.

NRao · Post by **NRao** » 12 Nov 2013 18:43

Reason for firing both together could be..

They were testing various aspects of the system - one of which was to use both of them at the same time. (That is failed is also inconsequential.)

too many things are currently being relied upon based on simulation confidence

It has been going on for decades (in umpteen fields - nothing new) and yet we have lived happily with this technique. The flaw is not in the methodology, it is elsewhere - typically problems arise when they do not take the (simulation) numbers seriously or the process is not followed to its natural end.

Victor · Post by **Victor** » 12 Nov 2013 19:40

As the ISRO press release above points out, it is very fortunate we found out the limitation now and not during the critical deceleration to Mars orbit. That would have been fatal.

juvva · Post by **juvva** » 12 Nov 2013 20:20

Maybe this scenario (both solenoids energised) was tested on ground, but not in vaccuum and/or cold conditions.

One possibility is, the power supply is getting derated in space and is unable to supply drive current for simultaneous operation of both solenoids.

However this is all wild speculation until if and when ISRO/FAC releases more information.......

SaiK · Post by **SaiK** » 12 Nov 2013 20:59

Pratyush wrote: The drawback means the planned simultaneous operation of two coils would not be possible anymore, but if the rest of the operations happen as planned, the spacecraft will reach the Martian orbit on September 24.
Can some one tell this lay man what is the meaning of the portion in bold.

imo, just plain and simple DDM.

Indranil · Post by **Indranil** » 12 Nov 2013 21:29

Lilo wrote:Reason for firing both together could be..
Greater the thrust and lesser the time the thrusters are on fire as near to perigee - better the efficiency of the orbit raising maneuver(in terms of kilometers elongated) vis a vis propellant usage - is how I understand.

So 2 firing simultaneously == more thrust
With Impulse constant near perigee and corresponding lesser time of firing.

Exactly my thoughts.

NRao · Post by **NRao** » 12 Nov 2013 21:49

Seems to me that they had three options: either of the solenoids are individually or both simultaneously are energized. The last one failed (for whatever reason). Under the circumstances it really does not matter that it failed. The first two options are sufficient for the success of the mission.

juvva · Post by **juvva** » 12 Nov 2013 22:12

NRao wrote:Seems to me that they had three options: either of the solenoids are individually or both simultaneously are energized. The last one failed (for whatever reason). Under the circumstances it really does not matter that it failed. The first two options are sufficient for the success of the mission.

But they do need to know the root cause of the failure, so that they can mitigate risks of additional failures down the line.

SaiK · Post by **SaiK** » 12 Nov 2013 22:26

pooch: apogee kick? & what is the farthest distance required to effectively transfer or least gravity pull?

http://my.execpc.com/~culp/space/orbit.html

NRao · Post by **NRao** » 12 Nov 2013 22:41

juvva wrote:
NRao wrote:Seems to me that they had three options: either of the solenoids are individually or both simultaneously are energized. The last one failed (for whatever reason). Under the circumstances it really does not matter that it failed. The first two options are sufficient for the success of the mission.
But they do need to know the root cause of the failure, so that they can mitigate risks of additional failures down the line.

WRT root cause - absolutely.

However, this "failure" - from what we can see today - is not a show stopper, even if the RCA does not turn up anything.

PratikDas · Post by **PratikDas** » 12 Nov 2013 22:48

indranilroy wrote:
Lilo wrote:Reason for firing both together could be..
Greater the thrust and lesser the time the thrusters are on fire as near to perigee - better the efficiency of the orbit raising maneuver(in terms of kilometers elongated) vis a vis propellant usage - is how I understand.

So 2 firing simultaneously == more thrust
With Impulse constant near perigee and corresponding lesser time of firing.
Exactly my thoughts.

If this theory is true then either:
a) Mangalyaan no longer has a 440 N rated LAM but a lesser rating for all intents and purposes, or
b) the 440 N rated LAM can be turbocharged so to speak with extra fuel to get more than 440 N when operating both solenoids

The mission couldn't possibly have relied on option (b) because it is too risky. Either the LAM is rated for 440 N and used at that thrust or it is rated for a higher thrust. One doesn't mess around. At least I hope the engineers aren't this cavalier.

If option (b) is ruled out then let us try to understand option (a). If both the primary and redundant solenoid are required for 440 N, then one has to ask why the primary fuel flow wasn't designed to be sufficient for delivering the maximum 440 N thrust by itself. Also, the 440 N rating was proven through Chandrayaan so I don't see how anything less than 440 N could have been used to plan the trajectory to Mars, which implies that option (a) would set back the Mangalyaan mission significantly, but ISRO says the spacecraft is in Normal condition.

In summary, nothing about this theory of extra thrust makes sense to me.

Indranil · Post by **Indranil** » 13 Nov 2013 00:14

PratikDas wrote: If this theory is true then either:
a) Mangalyaan no longer has a 440 N rated LAM but a lesser rating for all intents and purposes, or
b) the 440 N rated LAM can be turbocharged so to speak with extra fuel to get more than 440 N when operating both solenoids

The mission couldn't possibly have relied on option (b) because it is too risky. Either the LAM is rated for 440 N and used at that thrust or it is rated for a higher thrust. One doesn't mess around. At least I hope the engineers aren't this cavalier.

If option (b) is ruled out then let us try to understand option (a). If both the primary and redundant solenoid are required for 440 N, then one has to ask why the primary fuel flow wasn't designed to be sufficient for delivering the maximum 440 N thrust by itself. Also, the 440 N rating was proven through Chandrayaan so I don't see how anything less than 440 N could have been used to plan the trajectory to Mars, which implies that option (a) would set back the Mangalyaan mission significantly, but ISRO says the spacecraft is in Normal condition.

In summary, nothing about this theory of extra thrust makes sense to me.

Oh sorry! I made a mistake in the comprehension of ISRO's press release. I somehow felt that they were trying to fire both the LAM and the attitude correction motors simultaneously. There is logic to that. The closer you are to the perigee while you are imparting incremental velocity, the more efficient you are in raising the orbit. Hence the higher the thrust, the higher is the rate of imparting incremental velocity and more efficient is your orbit raising operation. That is why I concurred with Lilo sir's post. However a question remains in my mind. Why don't they actually fire the LAM motor and the attitude control motors (those which can work the same direction) together for maximum efficiency during the orbit raising operation?

Anyways, I understand ISROs press release completely now. This is obviously a failure of a test point. Both solenoid valves for fuel supply should have worked in parallel, but they did not. It is okay, because they work independently.

Also many in the press (and here) have got the emboldened part wrong. The thrust attitude control thrusters did not lead to the reduction of velocity. The key is the word "incremental".

During the fourth orbit-raising operations held today (November 11, 2013), the redundancies built-in for the propulsion system were exercised, namely, (a) energising the primary and redundant coils of the solenoid flow control valve of 440 Newton Liquid Engine and (b) logic for thrust augmentation by the attitude control thrusters, when needed. However, when both primary and redundant coils were energised together, as one of the planned modes, the flow to the Liquid Engine stopped. The thrust level augmentation logic, as expected, came in and the operation continued using the attitude control thrusters. This sequence resulted in reduction of the incremental velocity.

The attitude control thrusters are much weaker than the LAM and hence the orbit raising would be much less efficient (same logic as I discussed in the beginning of this post). Hence even if they kept them firing for the same units of time as they had planned before, there was a reduction in the incremental velocity imparted.

I like what they are doing through FB. They respond to questions immediately. And people are hooked. Never seen such great following of a space mission. This is good.

ramana · Post by **ramana** » 13 Nov 2013 00:20

Juvva, One probable cause is the battery power not being sufficient to power both the soelnoids. You may be right it could be solar charging related.
Good that they have a FAB convened already.

Kanson · Post by **Kanson** » 13 Nov 2013 00:21

Lilo wrote:Reason for firing both together could be..
Greater the thrust and lesser the time the thrusters are on fire as near to perigee - better the efficiency of the orbit raising maneuver(in terms of kilometers elongated) vis a vis propellant usage - is how I understand.

So 2 firing simultaneously == more thrust
With Impulse constant near perigee and corresponding lesser time of firing.

Sirji, you give the impression that there are two LAM engines of 440 N thrust. But from ISRO, the craft has only one LAM 440 N engine.

Lilo · Post by **Lilo** » 13 Nov 2013 00:29

Kanson wrote:
Lilo wrote:Reason for firing both together could be..
Greater the thrust and lesser the time the thrusters are on fire as near to perigee - better the efficiency of the orbit raising maneuver(in terms of kilometers elongated) vis a vis propellant usage - is how I understand.

So 2 firing simultaneously == more thrust
With Impulse constant near perigee and corresponding lesser time of firing.
Sirji, you give the impression that there are two LAM engines of 440 N thrust. But from ISRO, the craft has only one LAM 440 N engine.

Thanks Kanson ji and pratikdas ji for pointing out that to me, I was under the impression that there was one main and another auxiliary thruster - got it probably from one of the ddm reports.
Indranilroy ji's later post puts it well.

Neela · Post by **Neela** » 13 Nov 2013 01:23

Indranilroy wrote:Anyways, I understand ISROs press release completely now. This is obviously a failure of a test point. Both solenoid valves for fuel supply should have worked in parallel, but they did not. It is okay, because they work independently.

Indranilji
Pl have a look at this press release.

Everything is under control, says ISRO

ISRO scientists explained to The Hindu that the 440-Newton engine onboard is equipped with a primary and a redundant electrical coil that enable the fuel and the oxidiser to flow through two valves of the spacecraft.

During the firing on Monday morning, the team was trying to use both the primary and the redundant coils together as part of a trial. However, there was no fuel flow in this mode and the orbiter could not pick up the required velocity or reach the desired higher orbit.

Two valves. One for fuel and one for oxidiser. Flow control is through solenoid valves. The solenoid valves themselves have a primary coil and a secondary coil as back up. Could it be that when both primary and secondary are switched on, the resultant magnetic flux ( possibly working against each other ) is not large enough to open the valve? Possible explanation?

What you wrote now confuses me:

Anyways, I understand ISROs press release completely now. This is obviously a failure of a test point. Both solenoid valves for fuel supply should have worked in parallel, but they did not. It is okay, because they work independently.

can you elaborate what you mean here?

But any which way you look at it, they have tried to operate the motor in a mode that was not tested in the ground.

ramana · Post by **ramana** » 13 Nov 2013 03:12

That is why they have set-up the FAB.
So let them tell us.

Indranil · Post by **Indranil** » 13 Nov 2013 03:27

Neela wrote:
Indranilroy wrote:Anyways, I understand ISROs press release completely now. This is obviously a failure of a test point. Both solenoid valves for fuel supply should have worked in parallel, but they did not. It is okay, because they work independently.
Indranilji
Pl have a look at this press release.

Please don't use 'ji' for me. I feel uncomfortable.

Neela wrote: Everything is under control, says ISRO
ISRO scientists explained to The Hindu that the 440-Newton engine onboard is equipped with a primary and a redundant electrical coil that enable the fuel and the oxidiser to flow through two valves of the spacecraft.

During the firing on Monday morning, the team was trying to use both the primary and the redundant coils together as part of a trial. However, there was no fuel flow in this mode and the orbiter could not pick up the required velocity or reach the desired higher orbit.
Two valves. One for fuel and one for oxidiser. Flow control is through solenoid valves. The solenoid valves themselves have a primary coil and a secondary coil as back up. Could it be that when both primary and secondary are switched on, the resultant magnetic flux ( possibly working against each other ) is not large enough to open the valve? Possible explanation?

Possibly. On one hand, this is too obvious an error to be missed. On the other hand I can't think of any other reason why both work independently but not in unison. Let us wait for them to tell us.

Neela wrote: What you wrote now confuses me:
Anyways, I understand ISROs press release completely now. This is obviously a failure of a test point. Both solenoid valves for fuel supply should have worked in parallel, but they did not. It is okay, because they work independently.
can you elaborate what you mean here?

I thought the redundancy was at the valve level and not just the coil level. Hence the confusion.

PratikDas · Post by **PratikDas** » 13 Nov 2013 05:19

indranilroy wrote: I like what they are doing through FB. They respond to questions immediately. And people are hooked. Never seen such great following of a space mission. This is good.

Absolutely! Great job, ISRO.

SriKumar · Post by **SriKumar** » 13 Nov 2013 05:40

Lilo wrote:Reason for firing both together could be..

The two thrusters (LAM at 440 Newtons, and attitude control, at 22 Newtons) were not fired together. As I understand it, they happened in sequence (though the control logic is set up to fire them together). Initially, the LAM motor was activated to put the craft in a higher orbit. But this did not work and the LAM motor did not come on (since it was done with 2 solenoid coils instead of one). Then, the craft's automatic decision-making came online and automatically activated the attitude control thrusters (much smaller, at 22 Newtons). See bolded below from press release. http://www.isro.gov.in/pressrelease/scr ... Nov11_2013

During the fourth orbit-raising operations held today (November 11, 2013), the redundancies built-in for the propulsion system were exercised, namely, (a) energising the primary and redundant coils of the solenoid flow control valve of 440 Newton Liquid Engine and (b) logic for thrust augmentation by the attitude control thrusters, when needed. However, when both primary and redundant coils were energised together, as one of the planned modes, the flow to the Liquid Engine stopped. The thrust level augmentation logic, as expected, came in and the operation continued using the attitude control thrusters.

I read this to mean that the control logic is designed to automatically augment a loss in thrust from LAM with attitude control thrusters.

Kanson · Post by **Kanson** » 13 Nov 2013 06:08

PratikDas wrote:If this theory is true then either:
a) Mangalyaan no longer has a 440 N rated LAM but a lesser rating for all intents and purposes, or
b) the 440 N rated LAM can be turbocharged so to speak with extra fuel to get more than 440 N when operating both solenoids

The mission couldn't possibly have relied on option (b) because it is too risky. Either the LAM is rated for 440 N and used at that thrust or it is rated for a higher thrust. One doesn't mess around. At least I hope the engineers aren't this cavalier.

If option (b) is ruled out then let us try to understand option (a). If both the primary and redundant solenoid are required for 440 N, then one has to ask why the primary fuel flow wasn't designed to be sufficient for delivering the maximum 440 N thrust by itself. Also, the 440 N rating was proven through Chandrayaan so I don't see how anything less than 440 N could have been used to plan the trajectory to Mars, which implies that option (a) would set back the Mangalyaan mission significantly, but ISRO says the spacecraft is in Normal condition.

In summary, nothing about this theory of extra thrust makes sense to me.

Anyway ISRO could be answering these Qs, adding my 2 cents for discussion sake...440 N LAM is meant to operate in wide range of conditions as Space adventure demands. It can operate in low pressure/low flow. There are built-in safeguards to mitigate such low pressure eventuality. One such built-in safeguard(firing of two coils together) failed in the testing. No big issue. It doesn't affects its operation - my opinion.

Indranil · Post by **Indranil** » 13 Nov 2013 08:04

For the benefit of all. I asked my question on FB on the Mars Orbiter page.

Greetings ISRO team,

I have a question. Due to Oberth effect, the faster the acceleration during the orbit transfer operation, the more efficient the transfer. Is my understanding correct? Or is there something I am missing here because the acceleration is not constant here.

If my understanding is correct, why not use the LAM and the Attitude correction motors (those which can produce thrust in the same direction as the LAM) in unison during the orbit transfer operations?

And by the way thank you for providing prompt updates and answers to our questions. I think your prompt updates and answers are going a long distance in piquing the interest of Indian youths towards science and engineering.

And they answered

ISRO's Mars Orbiter Mission wrote: Generally, Isp of Attitude Control Thrusters is less as compared to LAM. Comparatively, it will result in more fuel consumption to achieve same delta V. Have a look at this random example: http://www.apfc.com/UK/products_1.php

negi · Post by **negi** » 13 Nov 2013 09:37

^ This wiki page actually answers above.

http://en.wikipedia.org/wiki/Spacecraft_propulsion

Due to the Oberth effect and starting from a nonzero speed, the required potential energy needed from the propellant may be less than the increase in energy in the vehicle and payload. This can be the case when the reaction mass has a lower speed after being expelled than before – rockets are able to liberate some or all of the initial kinetic energy of the propellant.

Also, for a given objective such as moving from one orbit to another, the required \Delta v may depend greatly on the rate at which the engine can produce \Delta v and maneuvers may even be impossible if that rate is too low. For example, a launch to LEO normally requires a \Delta v of ca. 9.5 km/s (mostly for the speed to be acquired), but if the engine could produce \Delta v at a rate of only slightly more than g, it would be a slow launch requiring altogether a very large \Delta v (think of hovering without making any progress in speed or altitude, it would cost a \Delta v of 9.8 m/s each second). If the possible rate is only g or less, the maneuver can not be carried out at all with this engine.

The bolded part kind of explains it in layman's language.

Indranil · Post by **Indranil** » 13 Nov 2013 10:06

Negi sahab,

I think you did not understand my question. I am speaking exactly what the wiki page linked by you says. I said get the highest possible rate of \deltaV for maximum efficiency during orbit raising maneuvers. And how do you do it? Use the LAM and all usable Attitude correction motors (ACM) in unison during orbit raising maneuver.

So I asked ISRO about why this is not done. They simply said because the specific impulse (efficiency) of the ATMs is much lower. Hence, though you would save some fuel due to Oberth's effect, but you will lose more due to the relative inefficiency of the ACMs vis-a-vis LAM.

negi · Post by **negi** » 13 Nov 2013 11:01

^ I was specifically talking about the original question i.e. how is high thrust applied over a shorter duration different from low thrust over a much longer duration.

negi · Post by **negi** » 13 Nov 2013 11:04

On use of LAM and ACM in unison I am not sure if the thrust actually adds up as such , it could be that firing of ACM during the orbit change is more to do with keeping the LAM's thruster pointed in correct direction rather than to just add to it's thrust ? LAM does not have a flex nozzle or does it ?

juvva · Post by **juvva** » 13 Nov 2013 13:53

^negi: For orientation one would expect selective and pulsed firing of the attitude control thrusters.
In this case it looks like the avionics fired the thrusters continuosly to either augument the LAM, or as a redundant thrust source because the LAM failed to fire.

Lalmohan · Post by **Lalmohan** » 13 Nov 2013 13:56

negi wrote:^ I was specifically talking about the original question i.e. how is high thrust applied over a shorter duration different from low thrust over a much longer duration.

sorry if i misunderstood, but i am assuming that high thrust/short time == higher acceleration, which i assume from the other link you posted is required to change the orbit

Indranil · Post by **Indranil** » 13 Nov 2013 16:27

juvva wrote:^negi: For orientation one would expect selective and pulsed firing of the attitude control thrusters.
In this case it looks like the avionics fired the thrusters continuosly to either augument the LAM, or as a redundant thrust source because the LAM failed to fire.

I agree with you on the LAM part. I don't think it is steerable (but this is an educated guess). When every kg is important, why add additional weight when the Attitude control motors can orient the craft in all degrees of freedom.

Regarding the usage of Attitude control motors to augment the LAM, ISRO clearly states that it is counterproductive. So they use it only as a redundant thrust source when the LAM is supposed to work and it doesn't.

SaiK · Post by **SaiK** » 13 Nov 2013 21:50

current 11:45est data from nasa isat.

not to scale

PratikDas · Post by **PratikDas** » 14 Nov 2013 19:05

From the ISRO's Mars Orbiter Mission Facebook page,

Second coil is not to give additional velocity boost. Rather, it is a redundancy feature. Hence there is no question of engine doing double work. Note that, both the coils are perfectly functional.

SaiK · Post by **SaiK** » 14 Nov 2013 21:29

Perhaps it was a mission critical redundancy operational check. The ops guys will not have details of such mission visions, but only the top echelon of ISRO would.

PratikDas · Post by **PratikDas** » 15 Nov 2013 06:25

I think we should learn to respect the folks making these statements from within ISRO. They're not DDM. The word redundant was used very early on but almost no one paid any attention to it.

SaiK · Post by **SaiK** » 15 Nov 2013 08:31

dunno if we can clearly validate DDM like that. even the best intended quotes are misquoted or misinterpreted. sometimes, it could be the way they (origin information source) say it..and ddm types it different..

but anyways, we definitely have not disrespected anyone here in this thread.

SBajwa · Post by **SBajwa** » 15 Nov 2013 21:35

MOM’s Midnight Manoeuver.

Tonight is going to be the culmination of the various baby steps MOM has been taking by gradually soaring to higher apogees around Mother Earth. This manoeuver, scheduled at 01:27 hrs IST, will take the spacecraft to - almost half the way to moon - about two lakh kilometers.

Catch the action live !