Author Topic: ISRO Mars Orbiter Mission - Nov 2013 launch to September 2014 arrival - UPDATES  (Read 453507 times)

Offline Star One

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It seems ISRO was using the redundant paths introduced in the fuel line for this engine firing.

Quote
it encountered a problem when a specific redundancy test was being conducted and it failed to reach the desired velocity it was to achieve.

http://www.ndtv.com/article/india/india-s-mars-mission-hits-first-hurdle-444424

Thanks for that. I see that article is again talking about it slingshoting out of Earth orbit.

Offline antriksh

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ISRO press release
http://www.isro.gov.in/pressrelease/scripts/pressreleasein.aspx?Nov11_2013
Quote
Supplementary Orbit Raising Manoeuvre Planned for Mars Orbiter Spacecraft
In the fourth orbit-raising operation conducted this morning (Nov 11, 2013), the apogee (farthest point to Earth) of Mars Orbiter Spacecraft was raised from 71,623 km to 78,276 km by imparting an incremental velocity of 35 metres/second (as against 130 metres/second originally planned to raise apogee to about 100,000 [1 lakh] km). The spacecraft is in normal health. A supplementary orbit-raising operation is planned tomorrow (November 12, 2013) at 0500 hrs IST to raise the apogee to nearly 1 lakh km.

During the orbit-raising operations conducted since November 7, 2013, ISRO has been testing and exercising the autonomy functions progressively, that are essential for Trans-Mars Injection (TMI) and Mars Orbit Insertion (MOI).

During the first three orbit-raising operations, the prime and redundant chains of gyros, accelerometers, 22 Newton attitude control thrusters, attitude and orbit control electronics as well as the associated logics for their fault detection isolation, and reconfiguration have been exercised successfully. The prime and redundant star sensors have been functioning satisfactorily. The primary coil of the solenoid flow control valve was used successfully for the first three orbit-raising operations.

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.

While this parallel mode of operating the two coils is not possible for subsequent operations, they could be operated independently in sequence.

So lots of redundancy testing is going on! This wouldn't be possible if they had gone directly for TMI.

Was testing the parallel mode  intentional to trigger thrust augmentation by attitude control thrusters?
« Last Edit: 11/11/2013 11:34 AM by input~2 »
Nasadiya Sukta:
Srishti se pehle sat nahin thaa, asat bhi nahin | Antariksh bhi nahin, aakaash bhi nahin thaa | chhipaa thaa kyaa, kahaan, kisne dhakaa thaa | us pal to agam, atal jal bhi kahaan thaa ||

From: 1st verse of 129th Hymn of the 10th Book of Rig Veda

Offline antriksh

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It seems ISRO was using the redundant paths introduced in the fuel line for this engine firing.

Quote
it encountered a problem when a specific redundancy test was being conducted and it failed to reach the desired velocity it was to achieve.

http://www.ndtv.com/article/india/india-s-mars-mission-hits-first-hurdle-444424

Thanks for that. I see that article is again talking about it slingshoting out of Earth orbit.

Mostly media is using this terminology. Both Maven and MOM are following the same trajectory. Only difference is major part of Maven's delta-v is provided by the launcher, whereas in MOMs case its the spacecfrat itself that needs to generate additional 1555 m/s delta-v by progressively firing at the perigee.

Also because of such trajectory design ISRO is now getting time to test its systems designed for the first time for the Mars mission.
Nasadiya Sukta:
Srishti se pehle sat nahin thaa, asat bhi nahin | Antariksh bhi nahin, aakaash bhi nahin thaa | chhipaa thaa kyaa, kahaan, kisne dhakaa thaa | us pal to agam, atal jal bhi kahaan thaa ||

From: 1st verse of 129th Hymn of the 10th Book of Rig Veda

Offline ss1_3

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Was testing the parallel mode  intentional to trigger thrust augmentation by attitude control thrusters?

I seriously doubt if this was intentional. I think something didn't work as expected for the 440N engine and as a result the attitude control thrusters fired. Such redundancy tests (at least with the propulsion system) can seriously put the whole mission in jeopardy and they must be aware of this. It's hard to believe that they didn't anticipate how the parallel mode would have behaved, they might have already simulated such tests at LPSC before launch. Not to mention they also lost some fuel (during s/c reorientation, perhaps?) in the process. Surely, something caught them off guard.


Anyway, fingers crossed, hope they will be back on track after tomorrow's manouver.

Online sanman

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So it sounds like they have 2 fuel lines - a main one and an extra one for backup - and the fuel flow through each is regulated by their respective solenoid valve. So as a systems check, they tried to use the main fuel line / flow valve and that worked, then they tried to use the backup fuel line / flow valve and that worked, but when they tried to use both fuel lines  / flow valves at the same time, then that resulted in a stoppage of the fuel flow to the rocket motor and its shutoff.
The automatic thrust augmentation logic then kicked in to restart the motor, however the resulting orbit achieved was only 78K km instead of 100K km.

So what they've learned from this is that they cannot use both valves / fuel lines together at the same time.

I wonder why. Is it a pressure issue? Maybe they can't get the required pressure to push enough fuel through, if both valves are open instead of just either one?

Isn't this something that should have been tested on the ground first? I recall reading that ISRO did not build a duplicate mockup of the spacecraft for testing on the ground, but only tested using software simulations. Maybe this is something which would have turned up had they tested on a physical duplicate of the spacecraft.

Offline antriksh

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So it sounds like they have 2 fuel lines - a main one and an extra one for backup - and the fuel flow through each is regulated by their respective solenoid valve. So as a systems check, they tried to use the main fuel line / flow valve and that worked, then they tried to use the backup fuel line / flow valve and that worked, but when they tried to use both fuel lines  / flow valves at the same time, then that resulted in a stoppage of the fuel flow to the rocket motor and its shutoff.
The automatic thrust augmentation logic then kicked in to restart the motor, however the resulting orbit achieved was only 78K km instead of 100K km.

So what they've learned from this is that they cannot use both valves / fuel lines together at the same time.

I wonder why. Is it a pressure issue? Maybe they can't get the required pressure to push enough fuel through, if both valves are open instead of just either one?

Isn't this something that should have been tested on the ground first? I recall reading that ISRO did not build a duplicate mockup of the spacecraft for testing on the ground, but only tested using software simulations. Maybe this is something which would have turned up had they tested on a physical duplicate of the spacecraft.


They have tested propulsion system at sea level and simulated vacuum conditions. What could be use of a mode with both the valves opened?

BTW, from this, it seems it was intentional to test the augmentation logic. But they could have very well regulated the thrust of the main engine to trigger the same logic.

Quote
“The satellite’s engine doesn’t work when both coils are simultaneously on,” a spokesman for the ISRO told The Wall Street Journal.

“This is not at all a setback, we got our redundancies [backup plans] checked by this process,” said the spokesman, who declined to be named. He said it was not necessary for both coils to be on at the same time during the rest of the flight plan.

Quote
http://blogs.wsj.com/indiarealtime/2013/11/11/first-hiccup-for-indias-mars-mission/

So their are two levels of redundancies for propulsion: 1) first is a redundant fuel line to the main engine that would be used in case the prime fuel line suffers failure and 2) is the use of attitude thrusters for augmentation/provision of thrust.

Now we know that the 2nd and the last option can provide 1/3 rd thrust required.

Hoping for the best!!
« Last Edit: 11/11/2013 12:27 PM by antriksh »
Nasadiya Sukta:
Srishti se pehle sat nahin thaa, asat bhi nahin | Antariksh bhi nahin, aakaash bhi nahin thaa | chhipaa thaa kyaa, kahaan, kisne dhakaa thaa | us pal to agam, atal jal bhi kahaan thaa ||

From: 1st verse of 129th Hymn of the 10th Book of Rig Veda

Offline AJA

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The LAM control software incorporates "Thrust level augmentation logic". So yes, it was intentional that that attitude control thrusters fired, when the S/C sensed that its main engine was not firing.


Using the dated specifications for a LAM that uses MMH/MON (as opposed to MMH/N2O4 - which is what Mangalyaan uses)- these 22N thrusters are designed for a cumulative operational lifetime of 70k sec, and for maximum continuous steady state firing of 10,000 sec (2h 45 min). So there shouldn't be issues there.


Warning: Speculation follows.


I worked on the image of the solenoid valve for the LAM from the same paper with GIMP, colour coding it to show the propellant flow path (as I understand it - caveat lector: The text description in the paper was obstruse, so I ignored it :P ), and I've attached two images. This is obviously very simplistic. Dark yellow is unfiltered prop/oxidiser, light yellow is the filtered stuff. Green denotes the filters, and red as well as blue denote the inner and outer solenoid windings respectively (single redundancy). The alternating blue-teal stripes (second image) show the helical spring that keep a flange of, and hence the whole of the pink plunger pressed flush against the grey walls. The pink plunger is made of a ferro(?)magnetic metal, and is the only bit that moves. If it's not clear from the diagram, the plunger's hollow and the prop flows through the plunger. The exit from the plunger is sealed flush against the grey walls when closed. The wires at the top are the power lines for the solenoids (and maybe other electronics  - sensor lines etc.)


Now, the interesting bit with respect to the 4th burn - is the arrangement of the coils. ISRO are saying that they can operate the valve on either chain - primary or the redundant secondary - but not both at once. One possible modality that reproduces the problem is if both solenoids have different polarities (in terms of their power connections). A passive metal doesn't care about the polarity of a magnet - it's still attracted to it. So in this case, the valve would remain operable on either chain. But if both are energised, then their fields cancel out, and the resulting magnetic force isn't strong enough to overcome the spring force.


Now given that this is a power connection, as well as ISRO permanently ruling out the possibility of concurrent operation of the valve through both chains, makes me think that this isn't an issue that cropped up post launch, and someone did indeed, get the polarities mixed up - during hard-wiring. (THAT Proton launch comes to mind). Then again, the polarities for the coil may be set by a solid state electronics, and may be software defined; but probably not rewritable. Or even if it's rewritable, it may've suffered a Single Event Latchup or a multi-bit error, that can't be detected/rectified by a software update, or power cycling.


As they say, this shouldn't really affect anything. Each coil should be more than powerful enough to operate the valve on its own. But that extra strength from simultaneous operation might've helped overcome some extra friction - due to corrosion/deposits/fuel freezing (in case the heaters gave out).




PS: Just read sanman and antriksh's posts immediately preceding this one. The paper, and the ISRO release say nothing about a backup fuel line and a second solenoid valve. I don't know for sure, but I'm assuming that the LAM only has two solenoid valves - one for the MMH, and one for the N2O4.
« Last Edit: 11/11/2013 12:38 PM by AJA »

Online sanman

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They have tested propulsion system at sea level and simulated vacuum conditions. What could be use of a mode with both the valves opened?

Well, if you're going to try something during the actual spaceflight, you'd better be aware ahead of time of what it's going to result in.

Quote
BTW, from this, it seems it was intentional to test the augmentation logic. But they could have very well regulated the thrust of the main engine to trigger the same logic.

I'm not sure that testing the thrust augmentation logic was intentional - it sounds like it fortunately kicked in on its own, although by then it was only able to achieve 78K km instead of the planned 100K km. Why would you intentionally perform a test that causes your orbit-raising to fall short?

In that case, it might have been better to do it earlier on, instead of during a longer orbit whose period might infringe on your Trans-Mars Injection window (Dec 1).

Quote
Quote
“The satellite’s engine doesn’t work when both coils are simultaneously on,” a spokesman for the ISRO told The Wall Street Journal.

“This is not at all a setback, we got our redundancies [backup plans] checked by this process,” said the spokesman, who declined to be named. He said it was not necessary for both coils to be on at the same time during the rest of the flight plan.

http://blogs.wsj.com/indiarealtime/2013/11/11/first-hiccup-for-indias-mars-mission/

So their are two levels of redundancies for propulsion: 1) first is a redundant fuel line to the main engine that would be used in case the prime fuel line suffers failure and 2) is the use of attitude thrusters for augmentation/provision of thrust.

Now we know that the 2nd and the last option can provide 1/3 rd thrust required.

Hoping for the best!!

Damn chemicals and fluids - so unreliable. Maybe future missions should look at electric propulsion.

Online sanman

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http://www.bbc.co.uk/news/science-environment-24900271

Quote
Mr Bagla told BBC News that the attempt on Monday morning used up about 2kg of the craft's 852kg fuel load.

But Mr Bagla added that the spacecraft's insertion into Earth orbit after launch on 5 November had been so precise, 6kg of liquid fuel had been saved. Even with Monday's glitch, the mission still had a fuel surplus of 4kg.

Okay, so they're still ahead of the game

Offline LouScheffer

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http://www.bbc.co.uk/news/science-environment-24900271

Quote
Mr Bagla told BBC News that the attempt on Monday morning used up about 2kg of the craft's 852kg fuel load.

But Mr Bagla added that the spacecraft's insertion into Earth orbit after launch on 5 November had been so precise, 6kg of liquid fuel had been saved. Even with Monday's glitch, the mission still had a fuel surplus of 4kg.

Okay, so they're still ahead of the game
It seems to me it was really good to find this problem in Earth orbit.  Typically, planetary injection firings use all possible redundancy, since they are mission critical and can't be fixed from the ground, due to delays.  So I suspect the normal Mars-insertion mode would have been both coils/valves energized.  If so, and if the same problem re-occurred, it would be fatal to the mission.

So at least now they can re-program the burn to be try A, then if that does not work, try B.   MUCH better to find this now, rather than when you try to insert around Mars!

Offline antriksh

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http://www.bbc.co.uk/news/science-environment-24900271

Quote
Mr Bagla told BBC News that the attempt on Monday morning used up about 2kg of the craft's 852kg fuel load.

But Mr Bagla added that the spacecraft's insertion into Earth orbit after launch on 5 November had been so precise, 6kg of liquid fuel had been saved. Even with Monday's glitch, the mission still had a fuel surplus of 4kg.

Okay, so they're still ahead of the game
It seems to me it was really good to find this problem in Earth orbit.  Typically, planetary injection firings use all possible redundancy, since they are mission critical and can't be fixed from the ground, due to delays.  So I suspect the normal Mars-insertion mode would have been both coils/valves energized.  If so, and if the same problem re-occurred, it would be fatal to the mission.

So at least now they can re-program the burn to be try A, then if that does not work, try B.   MUCH better to find this now, rather than when you try to insert around Mars!

Ahhh...Right! all redundancies should be used for critical operations like MOI. Now they will have to try if else. This should not be a big problem and a sw patch can easily take care of that if not already handled by fault tolerance and reconfiguration system.
Nasadiya Sukta:
Srishti se pehle sat nahin thaa, asat bhi nahin | Antariksh bhi nahin, aakaash bhi nahin thaa | chhipaa thaa kyaa, kahaan, kisne dhakaa thaa | us pal to agam, atal jal bhi kahaan thaa ||

From: 1st verse of 129th Hymn of the 10th Book of Rig Veda

Online sanman

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Hopefully their software patch can be ready before Dec 1.

Still, it will be interesting to hear from their post-incident review on what caused the problem with using both fuel lines together.

Offline Nomadd

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 You tend to open yourself up to unintended oscillations and shockwaves in some systems when you run multiple paths. But, I can see opening both paths when timing is critical, otherwise redundancy wouldn't do you any good. Depends on how smart the controller is. If it could almost instantaneously switch paths if one didn't respond as expected.

Online sanman

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Update from ISRO's MOM Facebook page:

https://www.facebook.com/pages/ISROs-Mars-Orbiter-Mission/1384015488503058?directed_target_id=0

Quote
ISRO's Mars Orbiter Mission
6 minutes ago
MOM’s Midnight Manoeuvers !

The supplementary orbit raising manoeuver of ISRO's Mars Orbiter Mission spacecraft, to raise the apogee height to about 1 lakh km completed successfully.

Phew!

Just a reminder on Indian units:  1 lakh = 10^5        1 crore = 10^7
« Last Edit: 11/11/2013 10:56 PM by sanman »

Offline rickl

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Great news!  I was pretty worried yesterday.


It's interesting that the Indian language has short, simple words for such large numbers ("one hundred thousand" and "ten million" in English).
Nominal now means "Yeehah!!"

Online sanman

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I think the origin of India's numbering has to do with what's convenient to represent with the hand.
Base 10 numbering resulted from the 10 fingers we have.
The figure of 1 lakh as 10^5 perhaps because of the 5 digits of the hand.
And then 1 crore as 100 lakhs, because that was a convenient increment up.
« Last Edit: 11/12/2013 03:01 AM by Chris Bergin »

Offline vyoma

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Posts in last few pages are amazing; they're very informative! By the way, here's an update from http://isro.org/mars/updates.aspx:
Quote
Fourth supplementary orbit raising manoeuvre of Mars Orbiter Spacecraft, starting at 05:03:50 hrs(IST) on Nov 12, 2013, with a burn Time of 303.8 seconds has been successfully completed.The observed change in Apogee is from 78276km to 118642km.

And, I found this in one of their FB post's comments:
Quote
Question: Could you please check with ISRO whether energizing primary and redundant coils TOGETHER is a mandatory requirement for successful MOI? Now that this mode is ruled out, is ISRO confident of achieving MOI by energizing ONLY ONE COIL AT A TIME (either the primary, or redundant)? Thanks.

ISRO's Mars Orbiter Mission: energizing primary and redundant coils together is not a mandatory requirement for MOI or any other phase.
« Last Edit: 11/12/2013 03:11 AM by vyoma »

Offline sdsds

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here's an update from http://isro.org/mars/updates.aspx:
Quote
Fourth supplementary orbit raising manoeuvre of Mars Orbiter Spacecraft, starting at 05:03:50 hrs(IST) on Nov 12, 2013, with a burn Time of 303.8 seconds has been successfully completed.The observed change in Apogee is from 78276km to 118642km.

Excellent news! The next opportunity for a burn near perigee (one orbit later than this) appears to be around 46h45m later. That's almost two days, so ~02:45 IST on Nov 14, if my spreadsheet calculations are correct. It would be great to get a confirmation of that timing from ISRO, though!
-- sdsds --

Offline antriksh

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here's an update from http://isro.org/mars/updates.aspx:
Quote
Fourth supplementary orbit raising manoeuvre of Mars Orbiter Spacecraft, starting at 05:03:50 hrs(IST) on Nov 12, 2013, with a burn Time of 303.8 seconds has been successfully completed.The observed change in Apogee is from 78276km to 118642km.

Excellent news! The next opportunity for a burn near perigee (one orbit later than this) appears to be around 46h45m later. That's almost two days, so ~02:45 IST on Nov 14, if my spreadsheet calculations are correct. It would be great to get a confirmation of that timing from ISRO, though!

Next burn early morning 16th. Now waiting for colored Earth shots!!
Nasadiya Sukta:
Srishti se pehle sat nahin thaa, asat bhi nahin | Antariksh bhi nahin, aakaash bhi nahin thaa | chhipaa thaa kyaa, kahaan, kisne dhakaa thaa | us pal to agam, atal jal bhi kahaan thaa ||

From: 1st verse of 129th Hymn of the 10th Book of Rig Veda

Offline ss1_3

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Next burn early morning 16th. Now waiting for colored Earth shots!!

I thought payload testing was scheduled for 11th. Has there been a change in plan- after next burn?

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