Bharat Rakshak

Srikumar,

A polar orbit would have entailed the same risk with a larger delta-v component and thus consuming more fuel. To put it in polar orbit around Mars, the space craft has to do a perpendicular trajectory run.

What are the current risks for Mangalyaan

1. LAM may not fire
2. LAM will fire but will not stop (will burn up all the fuel)

Mangalyaan going into occultation and loss of communication is just a process. Not a risk. Anyway, ISRO cannot make any last minute changes.

In case of #1, the risk will remain the same whether it is polar or equatorial.

In case of #2, if all of the fuel is exhausted - instead of orbiting at @500 km peri- Mangalyan may be at @350 km peri-., curtailing its mission life by few days.

Now why a perpendicular change in trajectory? Come back to rumali roti analogy where the ground you are standing is actually Sun and your body is Earth.

Turn the Solar system and view it perpendicularly. Anything you lob higher will either fall back to Earth or if it escapes Earth will fall back to Sun. In this case Mangalyaan is lobbed so high that it starts falling towards Sun intersecting Mars trajectory and at the same time of Mars being there., except it is falling faster towards Sun in-relation-to Mars. Hence all the probe has to do is slow down just enough that it starts falling towards Mars. There is no change in trajectory. Now for a polar orbit around Mars, the probe has to be either ahead or behind Mars, has to slow down enough to start falling towards Mars and then kick back enough to have its perpendicular velocity put it in an orbital slot.

The fuel required for that change might be say additional 25 Kg. But remember, for a probe, that is almost 2x the payload mass!!

One remarkable thing lot of DDM misses is the precise calculation of fuel, payload and most importantly - navigation and precision engineering of measuring devices to aid it.

It all boils down now if the valves in LAM hold up or not.

Tanaji wrote:Another dumb question : Why is the final MOM orbit elliptical and not circular or polar? Am I correct in guessing that these orbits require more fuel for station keeping and to get into that orbit in the first place? Do these orbits provide any advantage over elliptical orbits?

Of course you are correct in guessing that it will require some more fuel to trim the orbit.

The basic question is, what is the advantage you see of a circular orbit over an elliptical one?

For me, elliptical orbit is ideal. Since it will give more time for the spacecraft to communicate to earth. All the clicky's it takes while it is on the occultation on a daily basis can be sent while it is doing a longer journey on the other axis of the ellipse.

Change to medium gain antenna should be complete but no news.

ISRO tweet says
"ISRO ‏@isro 1h
#MarsOrbiter live update: Medium Gain Antenna takes over pic.twitter.com/vg31LeMmDm"

T-3hrs 04:17:32 Change over to Medium gain Antenna

T+12.5 minutes 07:30:02 Confirmation of burn start

T+19.48minutes 07:37.01 eclipse ends

T+24.23minutes 07:41.46 Liquid engine burn ends

T+25.73 to T+47min 07:42.46 to 08:04:32 Reverse Manoeuver starts

T+30.43min 07:47.46 Telemetry resumes

T+35.23 min 07:52.46 Reverse Manoever ends

location update

at 5:58 AM - 24 Sep 2014 · Details

Slightly OT

I have noticed that all press releases and communication done by ISRO through MSM and SM (FB and Twitter) address the mission with the acronym MOM (Mars Orbiter Mission) though there is already an original Samskrit name, Mangalyaan. Strangely enough, the space agency has NOT used the term ‘Mangalyaan’ to date, in any of its releases (MSM and SM). Even its press-release on LAM test-firing omitted the same.

Incidentally, MSM (including NDTV and CNN-IBN, which toe a Left-Lib line) have been naming the mission primarily as Mangalyaan (MOM being mentioned occasionally).

It makes one feel that the person who handles the media-communication at ISRO (I would like to believe that the top honchos are not aware of this issue) has ‘difference anxiety’ (Rajiv Malhotra’s term in his seminal work ‘Being Different’) in using the Samskrit term thus toeing the line of Western Universalism.

It may also turn out that in the ensuing name war (unintentional, though it may seem to be) MOM may prevail over Mangalyaan due to the propensity of the primary user, i.e., ISRO, in sticking to the former name. This would have ramifications in documentation, history-books and public-memory. Future missions may be named with equally amusing acronyms (MOM, after all, is the lingo of Western popular culture)

Personally, I have written to a few officials pointing out the anomaly.

It would help if forum members to do the following-

1) Write to whomsoever you think would bring in the change needed.
2) Call out ISRO’s bias in social media; question the admin of ISRO handle on FB and Twitter.
3) Use #Mangalyaan instead of #MOM while blogging on SM.

P.S.- Also, in keeping with Bharatiya traditions, it would be ideal if India goes on to re-name its organizations on the likes of MiDhaNi (Mishra Dhatu Nigam), BhaVi Ni (Bharatiya Nabhikiya Vidyut Nigam) and the like.

About 1 hour to go. It is probably around 70,000 kms from Mars (at 22 km/sec). Within range of its cameras......they are probably clicking away....if the orientation is right.

Mangayal Yan Mom Live on Utube

https://www.youtube.com/watch?v=VZL_Vwy ... e=youtu.be

DD has gone live .
MOM will fail onlee.

Live telecast is cool. Amazing achievement. Good luck ISRO!! We are all looking forward to superlative success.

Just saw my uncle and prof Yash Pal watching the action ...

Rotation should have started a few minutes ago.

Will know in 12 mins

lol victor you are always 1 step ahead of ISRO,
ISRO @isro · 3m
Forward Rotation must have begun,it is required to align the direction of firing for effective braking. Confirmation reaches after 12.5 mins

brain freeze with the ultra pure hindi on DD, but loving it

sunilUpa wrote:Just saw my uncle and prof Yash Pal watching the action ...

Are you related to Prof Pal? He had been a major inspiration for me when I was a kid.

Mangalyaan is only the nickname, if you search for problems like 'difference anxiety', you will find it everywhere. Chill.

saravana wrote:

sunilUpa wrote:Just saw my uncle and prof Yash Pal watching the action ...

Are you related to Prof Pal? He had been a major inspiration for me when I was a kid.

No Not to Yash Pal, but to the other gentleman sitting with him

So ISRO using YouTube to stream DD . Keep it simple and cheap, and save the money for a launch

Please keep it in English.....

forward rotatopn confirmed!

This has the ISRO webcast without the annoying DD chyrons on the bottom third of the screen


http://spaceflightnow.com/mars/mom/status.html

Forward rotation has started

opps deleted, forward rotation has started, not completed yet

Did the clapping mean the reorientation went fine? Can't follow Hindi
Edit: the voiceover guy should ease up now. Can't hear anything else

Eclipse should have started.

Rotation complete.

Modi JI reaching the site.

During eclipse MOM will remain in line-of-sight of earth.

MOM will not get sunlight during this period. Will switch to Li Battery and will remain on battery even after out of eclipse till major switch ons are done

disha wrote:Mangalyaan going into occultation and loss of communication is just a process. Not a risk. Anyway, ISRO cannot make any last minute changes. .....Now why a perpendicular change in trajectory?

Not a question of last minute changes.....just initial planning. I am not quite sure why there needs to be a perpendicular kick....MAVEN is in a polar orbit, as far as I know and did not need any perpendicular changes.

Check the approach orbits for Maven and MOM plotted by SSSalvi- they are quite similar.
http://forums.bharat-rakshak.com/viewto ... 0#p1720080

I think the difference between a polar orbit and equatorial orbit around Mars for a satellite is merely the approach vector. MAVEN, as I understand it, approached directly over the pole....so, I dont believe there was a need for a perpendicular maneuver (if I understood your explanation correctly).

This animation shows MAVEN captured by Mars (at 20 seconds, you can see the axis of rotation) and the polar approach.
http://www.youtube.com/watch?v=NiVQKyX7YVo

Oh god...why can't these guys stop talking...

Attitude control started.

sunilUpa wrote:Oh god...why can't these guys stop talking...

More noise than signal....classic DD flowery speech. Why focus on Modi now.

Too much background info and not much status update on DD

Engine burn started.

I saw in a monitor I could see some animation of the 8 small thrusters firing. Worried a bit

ISRO

#MarsOrbiter Burn must have started. All engines must have started firing by now. Skip a few heartbeats and stand by for confirmation.

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