Author Topic: ISRO Mars Orbiter Mission - Nov 2013 launch to September 2014 arrival - UPDATES  (Read 454472 times)

Offline pospa

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Attaching the details about apogee and perigee of MOM as on Nov 9th. Apogee has been raised from 40,016 km to 71,159 km.
ISRO is reporting a bit different numbers: ... The observed change in Apogee is from 40186km to 71636km.
http://www.isro.org/mars/updates.aspx
Why norad and isro has not the same numbers and who's numbers are more accurate?
Thx
« Last Edit: 11/09/2013 08:55 AM by pospa »

Offline cave_dweller

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I get the impression that these maneuvers are initiated from ground control when the satellite is at it perigee.
Can these maneuvers be automated and executed using a closed loop control methodology?

The craft should be able to figure out its proximity based on signal latency or a star map or even something as basic as a radar ..

What aspect of navigating the craft requires the maneuver to be initiated from ground control? (Other than the need to maintain control of sequential flow of events)

Thanks in advance for your insights!

Offline jcm

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Attaching the details about apogee and perigee of MOM as on Nov 9th. Apogee has been raised from 40,016 km to 71,159 km.
ISRO is reporting a bit different numbers: ... The observed change in Apogee is from 40186km to 71636km.
http://www.isro.org/mars/updates.aspx
Why norad and isro has not the same numbers and who's numbers are more accurate?
Thx

Probably different definitions - for example osculating versus mean elements. Also possibly both are inaccurate,
but I would use the SpaceTrack TLE values for software that expects TLE data; my guess is that the ISRO values
may reflect the actual heights on that orbit, but I haven't done any calculations to analyse it.
-----------------------------

Jonathan McDowell
http://planet4589.org

Offline baldusi

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I get the impression that these maneuvers are initiated from ground control when the satellite is at it perigee.
Can these maneuvers be automated and executed using a closed loop control methodology?

The craft should be able to figure out its proximity based on signal latency or a star map or even something as basic as a radar ..

What aspect of navigating the craft requires the maneuver to be initiated from ground control? (Other than the need to maintain control of sequential flow of events)

Thanks in advance for your insights!
Given the low perturbation orbit, they can predict with great precision where it is. They might have to update the necessary orbital parameters after each firing. At least that's how I would do it. I would require the ground to give it a "go for execute". Of course that's not actually sending the firing command. But rather uploading orbital parameters, getting a full check of status, and a time of firing. And when everything checks out a go ahead (like "fire in 5h, with xyz attitude to achieve a delta-v of Xm/s"). The delta-v is data that it gets from the inertial system. So it is sort of closed loop.
But GNC is the most sensitive technology, so i don't think they'll release much data.

Online hop

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I get the impression that these maneuvers are initiated from ground control when the satellite is at it perigee.
I would assume they use command sequences uplinked in advance, which are executed by the spacecraft at specific times. All deep space and Mars orbit maneuvers will have to be done that way anyway, so it would be surprising if they did something different for the small part of the mission that is in earth orbit.

Offline vyoma

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Update from ISRO MOM Facebook page:
Quote
The fourth Earth bound Manoeuver slated for 02:06 Hrs IST will hurl ISRO’s Mars Orbiter Mission Spacecraft to an apogee of about one lakh km [100,000 km].
« Last Edit: 11/10/2013 02:41 PM by vyoma »

Online sanman

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ISRO MOM Facebook page says:

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

Quote
During this firing an incremental velocity of 35 m/s has been imparted to the spacecraft. We will come back to you after Orbit determination.

I presume the 4th maneuver is complete, but that it'll take some time to verify whether it was successful.

Offline cave_dweller

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ISRO MOM Facebook page says:

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

Quote
During this firing an incremental velocity of 35 m/s has been imparted to the spacecraft. We will come back to you after Orbit determination.

I presume the 4th maneuver is complete, but that it'll take some time to verify whether it was successful.

I've been observing it for the past hour. It seems to be gaining altitude while losing velocity. I've observed the velocity degrade from 11,400 KM/h to 9,999 KM/h See link:

http://www.satview.org/?sat_id=39370U

I believe its still decelerating.

Velocity of 35 m/s = (35 * 3600/1000) KM/hr = 126 KM/hr -- sounds like a course correction maneuver to me.

Is the loss in velocity due to attempt to gain Apogee? Or ..?

Offline sdsds

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Are you asking about the mechanics of an elliptical Earth orbit? At perigee the velocity will be very fast; at apogee very slow. See for example the attached calculations for one of the prior MOM orbits.
-- sdsds --

Offline cave_dweller

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Are you asking about the mechanics of an elliptical Earth orbit? At perigee the velocity will be very fast; at apogee very slow. See for example the attached calculations for one of the prior MOM orbits.

Hi sdsds, thanks for the info. Conceptually it makes sense to me. Satellite orbiting then may be considered as the "art of falling".

Would I be inaccurate in characterizing an orbit path as a path of controlled fall at a certain altitude with rate of acceleration being the controlling variable?

I guess I am re-acquainting myself with all that forgotten newtonian mechanics!!






Offline vyoma

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Do you guys think apogee determination would take long time as new apogee is largish (100k km)?

Offline eeergo

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I think it's safe to say the burn fell quite a bit shorter than planned. With no change in perigee, whose effect will be small anyway:

Inital orbit: 345.1x71636 km --> ~10.4542 km/s velocity at perigee.

Target orbit: 345.1(assumed)x100000 km --> ~10.5665 km/s velocity at perigee.

Therefore, the delta_v should be ~0.1123 km/s, or 112.3 m/s. If they are reporting only 35, clearly they're missing two thirds of the change in velocity (assuming just a premature cutoff, not pointing errors)

With a totally posigrade delta_v, the new apogee should be slightly under 79000 km.
« Last Edit: 11/11/2013 12:52 AM by eeergo »
-DaviD-

Offline Galactic Penguin SST

Unfortunately NORAD isn't helpful since their last TLE on the spacecraft is 2.5 days ago......

Let's hope it's the ISRO PAO being late on updates and not something going wrong......  ::)
Chinese spaceflight is a cosmic riddle wrapped in a galactic mystery inside an orbital enigma... - (not) Winston Churchill

Offline sdsds

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This analysis is speculative, based on the Facebook page indicating a delta-v of 35 m/s and no further information yet forthcoming from ISRO.

* The relative silence is understandable. ISRO uses India Standard Time which is UTC+5:30. It is thus now ~9:45 a.m. there. It may yet take some time for them to put together a news release.
* As indicated above, 35 m/s if accurate would leave MOM in an orbit with a considerably lower apogee than anticipated. (My spreadsheet shows a maximum of 78,250 km.)
* The good news is that they apparently have the 35 m/s value at all. That seems to imply they received from the spacecraft telemetry directly or indirectly providing this value. That seems to imply the spacecraft data management and communication capabilities were not adversely effected by an anomaly, if in fact an anomaly has occurred.
* It is unclear if they also know the duration of the burn, or the reason why the burn provided less delta-v than anticipated.
* It has not been clear (to me) for what percentage of the orbit they have telemetry coverage using ISRO assets. It is also unclear (as it was with the Russians with F-G) if their mission objectives would allow them to use e.g. NASA or ESA telemetry assets.

Breaking news:
A hiccup in the orbital maneuvers for Mars Orbiter Mission
Posted by Emily Lakdawalla
2013/11/10 10:06 CST

http://www.planetary.org/blogs/emily-lakdawalla/2013/11102001-a-hiccup-for-mars-orbiter-mission.html

In her blog Lakdawalla writes: I realize this post doesn't contain much information, but I wanted to have something in the blog before I went to bed. I will keep you informed of further developments as I find them out!

Thank-you very much for the update!
« Last Edit: 11/11/2013 03:30 AM by sdsds »
-- sdsds --

Offline cave_dweller

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The 440N LAM engine is a relatively mature engine.

http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1999ESASP.430..579S&defaultprint=YES&filetype=.pdf

It'll be interesting to understand what happened during the maneuver.

If I am not mistaken, ISRO has experience with these maneuvers having that similarly technical orbital maneuvers were undertaken for Chandrayaan-I mission.


Online hop

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* It has not been clear (to me) for what percentage of the orbit they have telemetry coverage using ISRO assets. It is also unclear (as it was with the Russians with F-G) if their mission objectives would allow them to use e.g. NASA or ESA telemetry assets.
In addition to their own tracking assets, they are getting a lot of DSN time, see http://www.cdscc.nasa.gov/Pages/trackingtoday.html and I would expect they have arrangements to ramp this up if there is an anomaly.

The current orbit is a lot better than what F-G had, it should be visible to a single station for many hours.

Unless there was an irrecoverable hardware failure like Akatsuki, it seems like they are in a pretty good position to recover.

Offline AJA

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Quote
The health of ISRO's Mars Orbiter Mission Spacecraft is normal.

In the fourth orbit raising operation conducted this morning (02:06 Hrs IST) the apogee of MOM spacecraft was raised to 78,276 km against the targeted apogee of about one lakh km.

This is because the incremental velocity imparted to the spacecraft was 35 m/s against the targeted 130 m/s.


A supplementary orbit raising operation is planned at 05:00 hrs IST on November 12 to raise the apogee to nearly one lakh km.


A detailed press note is appearing shortly on ISRO website.


https://www.facebook.com/permalink.php?story_fbid=1395620500675890&id=1384015488503058


EDIT:  The forum's new WYSIWYG editor, and I have a duel coming.
« Last Edit: 11/11/2013 06:07 AM by AJA »

Offline input~2

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« Last Edit: 11/11/2013 07:27 AM by input~2 »

Offline vyoma

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Had been up most of the night scrounging around for updates. Thanks for updates and analysis.  Let's see how will it go.

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
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