Author Topic: ISRO Mars Orbiter Mission - Nov 2013 launch to September 2014 arrival - UPDATES  (Read 454234 times)

Offline antriksh

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As the s/c approaches Mars will it focus the camera and other instruments on the planet before MOI burn to (e/i)nsure some science return from the mission ?

I read in media that ISRO is planning to take pictures after MOI maneuver completes.
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 seshagirib

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As the s/c approaches Mars will it focus the camera and other instruments on the planet before MOI burn to (e/i)nsure some science return from the mission ?

I read in media that ISRO is planning to take pictures after MOI maneuver completes.

antariksh: do you have any pointers to the media reports? -Thanks

Offline ss1_3

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Test-fire planned for MOM engine
Quote
"Since the engine has been idle for more than 300 days, we may have to test fire it," Isro chairman K Radhakrishnan told TOI.

There is some uncertainty over a couple of valves and parts malfunctioning because of the corrosive fuel. After firing for the trans—Mars Injection, the primary fuel channel has been disabled to prevent leaks. The planned test—firing will be carried out using a secondary channel which will remain open for the actual firing on September 24 to remain in the Martian orbit. The test is not without handicaps. Since the spacecraft is moving at a speed of more than 22km per second, test—firing for a mere five seconds can take it away from the trajectory by more than 100km. This deviation will have to be factored in while carrying out the final orbit—capture manoeuvre around Mars.

http://timesofindia.indiatimes.com/City/Bangalore/Isro-prepares-to-testfire-orbiter-for-September-24-rendezvous-with-Mars/articleshow/41647855.cms

Offline ss1_3

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 Live telecast for the MOI

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“We are going to have the MOI on the September 24 morning. The engine firing is planned to start at 7.18 a.m. and last 28 minutes,” ISRO Chairman K. Radhakrishnan told The Hindu.

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The ultimate moment, according to Dr. Radhakrishnan, will be “when we get the message at 8.15 that morning that the orbiter has captured the Mars orbit. Theoretically, that fructifies the objective of this mission. But today, our job is to gear up for the orbit insertion.”

The spacecraft enters the Martian range of influence on September 22. ‘The action’ starts two days later when it would be about 700 km from the planet. First, at 6.50 a.m., the spacecraft will be turned or re-oriented.

The most crucial act is to fire the engines on it to slow the spacecraft from a velocity of 22 km a second to 1.5 km a second. ISRO plans to fire all nine ‘guns’ on board: the main ‘LAM’ or liquid engine and eight small thrusters.
http://www.thehindu.com/news/cities/bangalore/isro-gearing-up-for-date-with-mars/article6376971.ece

Offline Steven Pietrobon

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The most crucial act is to fire the engines on it to slow the spacecraft from a velocity of 22 km a second to 1.5 km a second.

That's a delta-V change of 20.5 km/s! Surely there's a mixup somewhere. Mars orbit insertion is more like 2.5 km/s delta-V.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline seshagirib

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Quote
The most crucial act is to fire the engines on it to slow the spacecraft from a velocity of 22 km a second to 1.5 km a second.

That's a delta-V change of 20.5 km/s! Surely there's a mixup somewhere. Mars orbit insertion is more like 2.5 km/s delta-V.

Maybe they meant a delta-V of -1.5 km/s from 22 km/s, would this be enough deceleration for the longish elliptical orbit being planned?
« Last Edit: 09/04/2014 07:42 AM by seshagirib »

Offline tolis

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Quote
The most crucial act is to fire the engines on it to slow the spacecraft from a velocity of 22 km a second to 1.5 km a second.

That's a delta-V change of 20.5 km/s! Surely there's a mixup somewhere. Mars orbit insertion is more like 2.5 km/s delta-V.

The most likely explanation (to me anyway) is that the stated 22 km/s is the speed relative to the Sun, not to Mars.

Tolis.

Offline ss1_3

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LAM test-fire on Sept 22

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On September 22, about 48 hours prior to its crucial orbit insertion, the Mars Orbiter Mission's (MOM) 440N liquid apogee motor (LAM) will be test-fired for five seconds.

 The engine's test-firing will result in the spacecraft deviating from its trajectory, which will be corrected later.

 Isro chairman K Radhakrishnan told TOI on Friday that should there be a problem with the motor, the space agency will resort to its 'Plan B' for the Mars orbit insertion. This backup plan involves firing of the eight 22 Newton thrusters for the insertion.

http://timesofindia.indiatimes.com/home/science/Isro-to-test-fire-MOM-engine-on-September-22/articleshow/41822030.cms?

Offline sdsds

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I have trouble understanding a fundamental aspect of a Mars Orbit Insertion. Doesn't a spacecraft arriving on a Hohmann transfer ellipse really need a prograde (not retrograde) burn to match the heliocentric velocity of Mars? Isn't it at apohelion, and thus needing a "kick" to circularize its heliocentric trajectory?  :-\
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Online Phillip Clark

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I have trouble understanding a fundamental aspect of a Mars Orbit Insertion. Doesn't a spacecraft arriving on a Hohmann transfer ellipse really need a prograde (not retrograde) burn to match the heliocentric velocity of Mars? Isn't it at apohelion, and thus needing a "kick" to circularize its heliocentric trajectory?  :-\

The gravitational field of Mars accelerates the spacecraft which - relative to Mars - is in a hyperbolic orbit.   Therefore you need a retrograde burn to slow down and get captured as a martian satellite.
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Offline sdsds

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My calculations indicate MOM will have a Vinfinity with respect to Mars of 2.65 km/s. At the altitude of the intended orbit's periapsis, Vescape is 4.78 km/s. So MOM's Mars-relative velocity near periapsis before the burn will be sqrt(Vescape2 + Vinfinity2) or sqrt(4.78^2 + 2.65^2), or 5.47 km/s. The target orbit has a periapsis velocity of 4.67 km/s. MOM would need to slow down (with respect to Mars) by only 5.47 - 4.67 = 0.8 km/s, or 800 m/s.

That seems way too easy! Perhaps I'm misinterpreting https://en.wikipedia.org/wiki/Hyperbolic_trajectory#Velocity ?

(EDIT: Spaceflight 101 reports a "planned change in velocity of 1,100 meters per second" in the August 24 update.
http://www.spaceflight101.com/mars-orbiter-mission-updates.html)
« Last Edit: 09/06/2014 11:21 AM by sdsds »
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Offline Galactic Penguin SST

A good overview of MOM's science instruments from Aviation Week: http://awin.aviationweek.com/portals/awin/Interactives/AWST/mom/mom.html

BTW maybe the thread can have a better title like "Indian Mars Orbiter Mission - Launch and Mission updates"?  ;)
Chinese spaceflight is a cosmic riddle wrapped in a galactic mystery inside an orbital enigma... - (not) Winston Churchill

Offline seshagirib

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A good overview of MOM's science instruments from Aviation Week: http://awin.aviationweek.com/portals/awin/Interactives/AWST/mom/mom.html

BTW maybe the thread can have a better title like "Indian Mars Orbiter Mission - Launch and Mission updates"?  ;)

Interestingly the camera slide says that it will be used to image the sattelites Phobos and Diemos.This is the first time I am seeing any mention of plans to study the sattelites. Hope they also have (revised) oppurtunistic plans for looking at the comet too.
« Last Edit: 09/08/2014 02:50 PM by seshagirib »

Offline vyoma

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http://business-standard.com/article/current-affairs/q-a-with-isro-chairman-114091200426_1.html

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Can you take us through the chain of events scheduled from now to September 24? Also what is going to be the crucial challenge?

On September 14th, we will be uploading the sequence of commands in the spacecraft with time tagging. It will be followed by test firing and then on the crucial day (September 24) at 8.15 a.m we will be able to say the Mission is successful.

The crucial challenge will be restarting the 440N main liquid engine, the single main engine which has been sitting idle for 300 days, since the Trans-Martian Insertion Burn was performed. This is the longest interval between LAM firings ever - the engine is usually employed on Geostationary Satellites that use it over a period of days or weeks to achieve their planned orbit.

On the ground we did testing of a similar liquid engine to see its restart characteristic, this was done well before the MOM launch. It was positive. In the recent days also again we have done ground testing and it was also successful.

Quote
Do you have plan B, if there is a problem in restarting the engine?

Yes. Using the small eight 22 N thrusters for attitude control or orientation, which will not give you this original target though. It will be salvaging of the mission. But what we have tried to ensure before hand is to build in the necessary facilities for ensuring restart and also confirmation.

At the time of MOI if you find it didn't restart, then we will loose that opportunity to operate the contingency, since it has to start early considering they are small thrusters and it takes longer duration.

In Plan A it is 440N plus, with the eight thrusters, to be fired in the given duration. But if the main engine does not fire, then we have to do the entire job by the small thrusters but then you have to fire them for longer duration and if you have to get the correct ellipse around Mars, you have to start firing early. There must also be enough fuel for that purpose.

Offline antriksh

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As the s/c approaches Mars will it focus the camera and other instruments on the planet before MOI burn to (e/i)nsure some science return from the mission ?

I read in media that ISRO is planning to take pictures after MOI maneuver completes.

antariksh: do you have any pointers to the media reports? -Thanks

Quote
Events to follow

September 24: At 6.57 am, Final phase of operation will start. Reorientation of the spacecraft should commence and it has to stabilise.

At 7.15 am: Liquid engine firing would start and in the nominal operation that should be for about 24 seconds. Then once the desired velocity is achieved, the computer will give the command to cut the firing based on the accelerometer, which is onboard the spacecraft.

Signal will take 12.5 minutes to reach here. That means Isro will know only after 12.5 minutes what is happening at the space.

At 8.15 am, Isro could confirm whether the operation is successful.

Later on the day: Colour camera will also be operated on the same date.

http://www.business-standard.com/article/current-affairs/isro-says-india-s-mars-orbiter-mission-is-on-target-114091200825_1.html
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 vyoma

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http://www.thehindu.com/sci-tech/science/mars-spacecraft-to-be-ordered-into-orbit/article6405731.ece

Quote
K. Radhakrishnan, Chairman, Indian Space Research Organisation (ISRO), said, “Commands will be loaded into the Mars spacecraft on Sunday for its insertion into the Martian orbit.” Since the spacecraft is on its course to Mars, there would be no trajectory correction manoeuvre of the spacecraft, originally scheduled on the same day. “We are doing a re-start of the 440 Newton engine for four seconds at 2 p.m. on September 22. We are doing that re-start to confirm [that the engine will erupt into life on September 24],” he said

Offline AJA

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Does anyone have a link to the pork-chop plots for the MOI burn, and/or the entire mission?

I'm wondering if, instead of a quick test burn (which stops once they've confirmed that everything's flowing cleanly through the pipes):  what if they make a substantial burn now? Such that they knock off a substantial amount of the required delta-v? It might give them more cover later on (in case a restart on the 24th doesn't come through on time for whatever reason), for the final insertion burn... maybe even allowing them to insert with only the attitude thrusters..

Of course, it may not be feasible... if any substantial burn now would lead to them missing Mars entirely... which is why I was asking for the plots.

Also, all this uncertainty regarding restart, and MOI has me thinking: Since the ISRO chairman says

Quote from: Business Standard Q&A piece
This mission is essentially a technology mission. It is to demonstrate our ability to orbit a spacecraft around Mars and the five scientific instruments we have put in are secondary ones.

... why did they include something like a Mars Colour Camera, instead of an experimental ion engine (in addition to the LAM)? The scientific community already has a million images of Mars... taken from much closer than Mangalyaan's nominal peri-areion. They've got full-disk images too - and if AIUI, all this data is already in the public domain. Sure, more images always helps; but the tradeoff is having a system which enhances the chances of mission success, while validating a new indigenous implementation of an alternative propulsion technology.

It'd have to be a really small engine (and fuel tank) to fit within the weight of a couple of the payload instruments on Mangalyaan... but maybe they could've used Xenon as the pressurant for the blow-down tanks of the LAM, and used the same Xenon reservoir as prop for a test ion engine. Smaller size would've been offset by continuous thrusting.
« Last Edit: 09/13/2014 06:42 AM by AJA »

Offline vyoma

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A good overview of MOM's science instruments from Aviation Week: http://awin.aviationweek.com/portals/awin/Interactives/AWST/mom/mom.html

BTW maybe the thread can have a better title like "Indian Mars Orbiter Mission - Launch and Mission updates"?  ;)

Interestingly the camera slide says that it will be used to image the sattelites Phobos and Diemos.This is the first time I am seeing any mention of plans to study the sattelites. Hope they also have (revised) oppurtunistic plans for looking at the comet too.

MCC probing Martian satellites was mentioned in earlier reports as well:
http://www.isro.org/mars/payload.aspx
http://www.thehindu.com/sci-tech/science/isro-not-engaged-in-space-race-with-china/article5278134.ece (Oct 2013)
Quote
The tri-colour MCC gives images and information about the surface features and composition of Martian surface. They are useful to monitor the dynamic events and weather of Mars. MCC will also be used for probing the two satellites of Mars — Phobos and Deimos, ISRO officials said
« Last Edit: 09/13/2014 08:18 AM by vyoma »

Offline vyoma

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Does anyone have a link to the pork-chop plots for the MOI burn, and/or the entire mission?

These links might help:
http://sankara.net/mom.html
http://www.isro.org/mars/mission-profile.aspx

Offline Mader Levap

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... why did they include something like a Mars Colour Camera, instead of an experimental ion engine (in addition to the LAM)?
Tech demonstration mission has to demonstrate they can use, power and operate scientific instruments successfully, get data and process them.
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