Mangalyaan: ISRO's Mars Orbiter Mission

Amber G. · Post by **Amber G.** » 17 Sep 2014 02:29

Waiting for - September 22, when the color camera will be turned on (and start sending images back to us).

and of course..9:48 p.m. September 23, My time (U.S. Eastern time) Then about 42 (30+12) nerve-wracking minutes before ISRO tells us something ...10:30 PM US Eastern time.

Some may like this, (May be Mangalyaan2) .. the challenges faced by other space-craft to Mars (in 2012) captured in NASA's famous ..“seven minutes of terror”
http://www.jpl.nasa.gov/video/index.php?id=1090

NRao · Post by **NRao** » 17 Sep 2014 02:43

Dare Mighty Things

Amber G. · Post by **Amber G.** » 17 Sep 2014 02:45

If you have not seen this.. Enjoy... (Hope Mangalyaan can produce something like this).
This is from ESA's Mars mission.
Floodwaters of Mars

partha · Post by **partha** » 17 Sep 2014 03:04

Amber G. wrote:Waiting for - September 22, when the color camera will be turned on (and start sending images back to us).

I thought camera will be turned on after MoI on Sept 25th. On Sept 22nd, it is just test firing of the engine for 4 seconds.

SaiK · Post by **SaiK** » 17 Sep 2014 03:05

^you should have perhaps seen the lander video live! that was awesome that i saw some time back. check it out in jootube.
this one: gZX5GRPnd4U

? forgot

SriKumar · Post by **SriKumar** » 17 Sep 2014 03:33

Amber G. wrote:
SriKumar wrote:
....
Seeing that its orbit (of any satellite) is a function of solely of the gravitational force it experiences + the force from the thrusters, I would have assumed primacy would be given to the on-board accelerometer readings. To use radar, one would have to know a priori (and very accurately) the gravity field around Mars in 3D (how would ISRO know this without sending anything prior) and also, what if the on-board accelerometer shows a gravity reading at variance with what was calculated/assumed to be at that pre-determined spot. Which one would be over-ridden? Thanks.
Actually, as you know for most of MOM's journey - while no rockets are fired - the space craft is in "free fall" - zero gravity. Zero weight means zero acceleration (as measured by internal devices) .. and unless you look out, you can not even tell which direction Mars is. , let alone how strong the gravitational field is)

Martian gravity is very accurately mapped, by all the spacecraft's sent before. Actually Phobos and Deimos have given all the mapping we need to calculate when/where and how much delta-V one would need.

Forgot about the free-fall part....yes, the accelerometers would show zero except for cases where there's a change in velocity/direction. thanks for the details.

member_22733 · Post by **member_22733** » 17 Sep 2014 03:53

^^^^ Aarrgh, any vehicle traveling along a space-time geodesic will be in free-fall. How could I forget that one. My grad school physics courses have to be re-visited.

Amber G. · Post by **Amber G.** » 17 Sep 2014 04:04

partha wrote:
Amber G. wrote:Waiting for - September 22, when the color camera will be turned on (and start sending images back to us).
I thought camera will be turned on after MoI on Sept 25th. On Sept 22nd, it is just test firing of the engine for 4 seconds.

>>prasannasimhaji may add/correct but from sources mentioned before...

On September 22, Mangalyaan’s main engine will be switched on briefly for testing. Then, assuming all goes well, two days later (at 7:18 a.m. India Standard Time on September 24) the spacecraft will orient itself and start a 24-minute engine burn that will neatly place it into a highly elliptical orbit around Mars.

The mission has so far gone more smoothly than expected; a recent scheduled en-route course correction was canceled because it was deemed unnecessary, and everything on board the spacecraft appears to be working normally.

The spacecraft’s color camera will be turned on September 22 to start sending images back to Earth. Later ISRO will turn on the Methane Sensor for Mars, which will address a question of great interest to planetary scientists and astrobiologists.

((This, of course makes lot of sense, because, while probability of successful MOI is less than 100%, MOM's very close pass (only about a few hundred Km's about 500Km ** see note **)/flyby is virtually certain. We will certainly get at least one chance, so even if we have more chances later, we have to turn on the camera.. and everything else we have ...so as NOT to miss that chance... so even if MOI fails, we will have good pictures... and may be data on Mars's atmosphere.... Rest assured, camera's will be very busy)..

At present, per calculations ..the closest we will come (around 24th) is about 700Km but if testing on 22nd proceed as planned, this closest distance will be reduced to about 500Km. (This is (approx) the minimum MOM will get even if MOI is successful, of course, then we will pass that close every 3 days or so)

partha · Post by **partha** » 17 Sep 2014 04:48

((This, of course makes lot of sense, because, while probability of successful MOI is less than 100%, MOM's very close pass (only about a few hundred Km's about 500Km ** see note **)/flyby is virtually certain. We will certainly get at least one chance, so even if we have more chances later, we have to turn on the camera.. and everything else we have ...so as NOT to miss that chance... so even if MOI fails, we will have good pictures... and may be data on Mars's atmosphere.... Rest assured, camera's will be very busy)..

Makes sense. Thanks.

Victor · Post by **Victor** » 17 Sep 2014 05:19

Wonder if Mangalyaan will use its small thrusters or reaction wheels to reorient itself just before the orbit insertion motor burn? The latter use electric motors and juice generated on board so probably it will be them.

SaiK · Post by **SaiK** » 17 Sep 2014 05:19

here it is, https://www.youtube.com/watch?v=Esj5juUzhpU
I am sure there were edited.. but very nicely done.

member_28108 · Post by **member_28108** » 17 Sep 2014 07:25

In all approaches they would keep the camera on (It is as mentioned that it will be switched on on Sept 22nd).At least we will get some data if Mars orbital insertion does not occur and only a flyby occurs but the camera cannot be put on till a resolution of at least one pixel is achieved ! (I think that distance may already have been achieved but I am not sure)

Dilbu · Post by **Dilbu** » 17 Sep 2014 15:30

MOM will fail onlee.

wasu · Post by **wasu** » 17 Sep 2014 22:31

Looks like modi is planning to follow this live at ISRO Peenya center on 24th morning.

Amber G. · Post by **Amber G.** » 17 Sep 2014 22:35

From News sources ... NaMo/Obama meet background ..

Nasa and Isro are talking about setting up a Joint Mars Working Group...(under the auspices of the State Department's US-India Civil Space Joint Working Group)

"Nasa is in discussions with the Indian Space Research Organization (Isro) regarding potential scientific collaboration with their Mars Orbiter Mission (MOM), due to enter Mars orbit about two days after Maven (Mars Atmosphere and Volatile Evolution (Maven) orbiter, which will arrive at Mars later this month," said James Green Director, Planetary Science Division, Science Mission Directorate, Nasa.

"With multiple data sets being collected, Nasa and Isro scientists will have a wealth of information to help solve mysteries regarding the Mars atmosphere," he said....

member_28108 · Post by **member_28108** » 17 Sep 2014 23:17

I just read somewhere that the method used for "verifying" the uploaded instructions is to generate a particular 'sum" or which runs parallel with the upload so if everything is correctly uploaded and in proper sequence it generates a code or sequence that is transmitted back that indicates that the upload is correct. I am not so computer programming knowledgeable so someone who knows about these things may dilate and expand and explain further on this. Seems like reading off the OMR sequence indicates the correct answer booklet and the total number of correct and wrong answers and final scores.

Amber G. · Post by **Amber G.** » 17 Sep 2014 23:23

LokeshC wrote:^^^^ Aarrgh, any vehicle traveling along a space-time geodesic will be in free-fall. How could I forget that one. My grad school physics courses have to be re-visited.

IMO, excellent resource is CalTech's following online course type site:
(Basics of Space Flight

(It is intended to be used online via browser. Links to external sites provide further depth -as deep you as you want to go - to many topics. (There are interactive quizzes etc.. but no records are kept.. no grades are given and Caltech does not offer academic credit for this training

... There are good Onl's from IIT's and MIT too... but IMO this is quite good)

Highly recommend it, if one is serious about learning/reviewing science part.

(Edited; Correct the typo in the link)

Amber G. · Post by **Amber G.** » 17 Sep 2014 23:29

prasannasimha wrote:I just read somewhere that the method used for "verifying" the uploaded instructions is to generate a particular 'sum" or which runs parallel with the upload so if everything is correctly uploaded and in proper sequence it generates a code or sequence that is transmitted back that indicates that the upload is correct. I am not so computer programming knowledgeable so someone who knows about these things may dilate and expand and explain further on this. Seems like reading off the OMR sequence indicates the correct answer booklet and the total number of correct and wrong answers and final scores.

As you may know, this is very basic (and routine).. Just google/wiki for "checksum" for more details.

(Similar techniques are applied, for things like "digital signature" etc in slightly different way but basically these methods are to verify the contents. Even the most primitive computers had "parity bits" which is nothing but "checksum" type methods)

Amber G. · Post by **Amber G.** » 18 Sep 2014 01:29

Some may find this interesting ...

The process of orbit determination is fairly taken for granted today. During the effort to launch America's first artificial Earth satellites, the JPL craft Explorers 1 and 2, a room-sized IBM computer was employed to figure a new satellite's trajectory using Doppler data acquired from Cape Canaveral and a few other tracking sites. The late Caltech physics professor Richard Feynman was asked to come to the Lab and assist with difficulties encountered in processing the data. He accomplished all of the calculations by hand, revealing the fact that Explorer 2 had failed to achieve orbit and had come down in the Atlantic ocean. The IBM mainframe was eventually coaxed to reach the same result, hours after Professor Feynman had departed for the weekend.

from: The Life and Science of Richard Feynman by Gleick.

juvva · Post by **juvva** » 18 Sep 2014 09:13

Mars & Beyond - Eureka with ISRO Chairman K Radhakrishnan

https://www.youtube.com/watch?v=ALPKTEi ... INtosOgE5W

Neela · Post by **Neela** » 18 Sep 2014 13:34

X-post

Amber G mentioned this already.
Here it is from ISRO

member_28108 · Post by **member_28108** » 18 Sep 2014 23:00

that picture is very succinct in its description.

SriKumar · Post by **SriKumar** » 19 Sep 2014 04:07

Question.
Per this ISRO link, slide 10, 'T' is when the main engine starts in order to slow down the MOM orbiter. Forward rotation starts at T-21 minutes. Attitude of the craft is adjusted at T-3 minutes via thrusters.
http://www.isro.gov.in/mars/pdf/press%2 ... %20MOI.pdf

Any idea why this is done just a few minutes before the eclipse/communications black-out? A better approach would have been to do this 2 or 3 hours before the 'T', which gives ISRO ample opportunity to confirm that the forward rotation is correctly executed & the attitude is correct- and more importantly, this would give them time to make corrections if required. (The idea assumes that the MOM craft does not rotate on its own due to Martian gravity, and that it maintains its orientation).

As it stands now, with a 8-minute travel time of the signal to earth, only the forward rotation can be confirmed/verified before the eclipse starts. ~~And the attitude cannot be verified.~~ **

**Added later: I guess 'attitude control with thrusters' at T-3 probably does not refer to actual firing of thrusters. It probably refers only to activation of systems that control the attitude which would be needed when the main engine fires.

disha · Post by **disha** » 19 Sep 2014 05:01

^^ Check the slide again and see that there is a cutover to medium gain antenna.

Cutover from what? It is cutover from high gain antenna to medium gain antenna. That is when the attitude is adjusted, there is no link to high gain antenna. The idea is to hold on to the "widest" communication pipe as long as possible.

SSSalvi · Post by **SSSalvi** » 19 Sep 2014 10:12

Some facts about dynamics involved in MOI of MAVEN and MOM.

http://indiaspaceactivity.blogspot.com/ ... maven.html

Dilbu · Post by **Dilbu** » 19 Sep 2014 14:28

MOM will fail onlee.

Pratyush · Post by **Pratyush** » 19 Sep 2014 14:34

All praise to Dilbu onlee

SSSalvi · Post by **SSSalvi** » 19 Sep 2014 19:32

disha wrote:^^ Check the slide again and see that there is a cutover to medium gain antenna.

Cutover from what? It is cutover from high gain antenna to medium gain antenna. That is when the attitude is adjusted, there is no link to high gain antenna. The idea is to hold on to the "widest" communication pipe as long as possible.

One of the press briefing in April says that they will bring in High gain antenna. But later nowhere there is any reference of actual change to HGA.

Anyway .. the reason for MGA is that it will have a larger beamwidth so even if the craft goes in some unexpected orientation ( or even tumbling ) there is some scope for communication to overcome the situation.

member_28108 · Post by **member_28108** » 19 Sep 2014 21:48

Due to the forward rotation of the craft for firing the high gain antenna will not be in optimum orientation for sending signals and the medium gain antenna takes over. Also at this stage we will be mute spectators to the event of events approve 8-10 light minutes away so nothing can really be done and everything depends on the crafts autonomous functions. It is like watching children take theory JEE exams. Nothing you can do but just watch and hope all the preparations bear fruit

SSSalvi · Post by **SSSalvi** » 19 Sep 2014 22:10

Just for fun.
Quotes from the posts in one of the prestigious spaceflight forum ( around July 2012): ( Italicized quotes apparently from Indy )

" Very unlikely that this will launch in 2013. I'm going to say 2016 at the earliest. "
" I don't know why they're even claiming it would launch in 2013, hell the design isn't even finalized yet. "
" Is 2013 even a launch window to Mars? "

( smiley is mine ) .. answered " 2013 is a launch window. MAVEN is launching next fall. "
" Maybe 2013 is when the next *phase* of the Indian Mars programme is started/launched? "
" Do any of their launch vehicles actually have the throw capacity to put a significant & useful payload into orbit around Mars, ......... "
" ..... but I remain convinced that the haste with which the mission has been approved, in spite of the launch window opening practically tomorrow (in 14 months, which will require a very fast development and testing phase), has something to do with the fact that China will likely launch something to Mars in 2016" replied " I agree that's why I fear that as a result of this undue haste there is far higher likelihood that the mission will end negatively. Something which will not stand any future Mars exploration by the country in good stead.
"
" Actually, the main reason for the haste is because of the fallout of a political corruption scam. .... ( a very longish detail of Telecom scam ) "
" India's politically embattled Prime Minister Manmohan Singh is increasingly trying to associate himself with ISRO, hoping that the national pride it invokes will rub off on him "

rsingh · Post by **rsingh** » 20 Sep 2014 00:04

Such knowledgeable posts here (Amber ji et all), sometime it seems you guys could handle complex interplanetary probes on you own.I bet if SUARCO abduls have slightest idea of fijiks involved in complex calculations done by our spin doctors on this thread.

disha · Post by **disha** » 20 Sep 2014 02:57

All space probes (less likely the really big Massa ones) have to compete with several and severe trade-offs. Like if we put HGA here, where is the space for MGA - oh let us put MGA there - oh where will we fit our solar panels then?., OK done - but then where will the thruster go? over there - okay - now will all this fit the mission profile? Damn!

That is why the space probes incl. MOM have to do several calisthenics. It is truly amazing that we are so far (or so high?) at such a shoe-string of a budget. Even thinking of attempting this requires serious "cojones". I would rather say that our MOM is more like the final high throw of rumali roti - thrown high into Sun's orbit and now we are waiting for our buddy Mars to catch it.

I was listening to Sandy woods from Macdonald observatory and she was talking of India's Mars program and in the background the launch of Mangalyaan was being played. It was good to hear ISRO' scientists countdown with heavy Indian ascent.

I have one suggestion for ISRO, instead of doing countdown in English, they start counting down in various Indian languages. It will be really musical to hear

Okati, Do, Mundru, Nalugu, five (with very heavy Mallu or Oriya ascent that sounds like Bhive), .... SHUNYA

The above is actually my second suggestion. My first suggestion is that every ISRO launch attempt should start with a ceremonial bullock cart. Heck when Indian Gaganaviharins step out into space, their first step should be a bullock cart ride to the launch vehicle!

SriKumar · Post by **SriKumar** » 20 Sep 2014 03:21

disha wrote:^^ Check the slide again and see that there is a cutover to medium gain antenna.

Cutover from what? It is cutover from high gain antenna to medium gain antenna. That is when the attitude is adjusted, there is no link to high gain antenna. The idea is to hold on to the "widest" communication pipe as long as possible.

Well, in that case, the forward maneuver can be done while the high gain antenna is still in place (T-3 hours), which gives then a chance to confirm (and correct, if needed) the forward rotation. That said, it seems like the craft is probably continuing to communicate using the mid-gain antenna from T- 3 hours onwards. The slide says 'Telemetry off' at T+ 5 minutes (due to occult perhaps, which starts at T+4.3 min). Telemetry resumes at T+30 min (occult ends at T+27).

SriKumar · Post by **SriKumar** » 20 Sep 2014 03:32

SSSalvi wrote:Some facts about dynamics involved in MOI of MAVEN and MOM.

http://indiaspaceactivity.blogspot.com/ ... maven.html

Good picture. I suppose Mars is not to scale? The closest point at firing between MOM and Martian surface is 723 km (periapsis is listed somewhere at 400-odd km). Mars probably would look a lot bigger than what is in the picture.

It is interesting that Maven is not in an eclipse when its retro-rocket fires. It has a line of sight to earth and sun (whereas MOM is on the dark side of Mars eclipsed from sun and earth when pulling its critical maneuvers).

SSSalvi · Post by **SSSalvi** » 20 Sep 2014 06:05

^^^
1. True .. it is added later only as a position indicator. However the position is highly accurate to scale.
All drawings are computed 3D graphics .. accurate to few meters.
Time , however may not be correct because the data is based on status pertaining to early Jan 2014 ( which was available in public domain. )

2. MAVEN is entering Mars orbit from North so it may be in fully sunlit position and in Earth's view whereas MOM is approaching along equator so it has to face Shadow of Mars and since Earth and Sun are almost in the same direction, solar eclipse may also be happening.

Will try to create position diagram and post it 2mro ( i.e. today evening in India ) .. ( am in US with daughter right now

)

vina · Post by **vina** » 20 Sep 2014 06:24

It is interesting that Maven is not in an eclipse when its retro-rocket fires. It has a line of sight to earth and sun (whereas MOM is on the dark side of Mars eclipsed from sun and earth when pulling its critical maneuvers).

I suppose that is due largely to the different trajectories/orbital mechanics used by Mangalyan and Maven. Maven started 2 weeks later and ends up a few days earlier at Mars, largely as a result of taking a straight line path (largely) between earth and the spot Mars would arrive at, while Mangalyan uses a very energy efficient transfer. That is largely due to the fact that the US used a big , heavy and costly launch vehicle (with the Russian RD-180 booster if I can add, so by our Indigenous Fetish masters, who question if the Indian mission was 100% indigenous, the US Maven mission is NOT 100% Indigenous

), that had enough power to throw it in such a trajectory.

However, as in everything , life is a compromise. If NASA had adopted what ISRO did, they could have carried a much heavier payload to Mars!

SriKumar · Post by **SriKumar** » 20 Sep 2014 07:28

Maven's path to Mars (could not find a graphic that shows both MOM and MAVEN trajectories to Mars).

Indeed Maven was launched several days after MOM, but many of those days were spent by ISRO orbiting MOM around earth and gradually increasing its orbit. The general shapes of the two orbits after leaving earth's orbit are somewhat similar (both have to take a solar-type orbit to get to Mars). And yes, because of the huge rocket US used, they did not need to orbit MAVEN like MOM did. But now the GLSV is working, then it was PSLV only.

The link in the above post (which I did not see earlier, SSSalvi's blog) seems to have a clue about MAVEN's position relative to Mars at MOI.....MAVEN will be made to orbit Mars from pole-to-pole (roughly), whereas MOM orbit is planned for more of an equatorial (solar?) plane. Perhaps that's why the approach trajectories looks the way they do, in the previous image.

member_28332 · Post by **member_28332** » 20 Sep 2014 08:09

vina,

SriKumar seems to have researched and found the same graphic that I was looking at. While you are right that MAVEN could have been heavier if NASA had orbited the Earth to build up velocity, one can also argue that a lot of the additional payload would have been the fuel to keep kicking the orbiter into increasingly higher orbits.

I came to the same conclusion that the shapes of the orbits of the 2 missions are roughly the same and that one wasn't more of a straight line than the other. It is just that the MAVEN was able to get on its interplanetary cruise within an hour of its launch while MOM took about a month to begin that cruise.

As to the occult in the case of MOM, it could be the difference between the orbital planes chosen by the 2 probes.

Amber G. · Post by **Amber G.** » 20 Sep 2014 08:16

vina wrote:
It is interesting that Maven is not in an eclipse when its retro-rocket fires. It has a line of sight to earth and sun (whereas MOM is on the dark side of Mars eclipsed from sun and earth when pulling its critical maneuvers).
I suppose that is due largely to the different trajectories/orbital mechanics used by Mangalyan and Maven. Maven started 2 weeks later and ends up a few days earlier at Mars, largely as a result of taking a straight line path (largely) between earth and the spot Mars would arrive at, while Mangalyan uses a very energy efficient transfer. That is largely due to the fact that the US used a big , heavy and costly launch vehicle (with the Russian RD-180 booster if I can add, so by our Indigenous Fetish masters, who question if the Indian mission was 100% indigenous, the US Maven mission is NOT 100% Indigenous ), that had enough power to throw it in such a trajectory.

However, as in everything , life is a compromise. If NASA had adopted what ISRO did, they could have carried a much heavier payload to Mars!

Vinaji - Some clarification. Hope this is useful.

The paths (trajectory) of Mangalyaan, and MAVEN are virtually the SAME in a general sense. When one does not burn fuel in the middle, then within a few percent or so, total time taken (about 10 months), total path travelled (about 700 Km), and shape of the trajectory (when it leaves earth's SOI (vicinity) and enters Mars's) is very similar. When drawn on scale,.. One trajectory will fit nicely on to other.

There is NO "straight line path" (or anything close to that) here. The orbit is, a segment of an ellipse (only a (generally half) part of an ellipse - the ending is being captured by Mars), One end is 1AU (earth-sun distance) and other is 1.5AU from sun..)

(Only difference between MOM and MAVEN's trajectory could be that the two values (1AU and 1.5AU could be a little different as earth's and Mars orbits themselves are elliptical and the end points may differ a little - and location of end points be a little closer/farther than Earth/Mars).

(One can have different trajectories if rockets are used in the path, or the other point of ellipse is much further than Mars's orbit. Thus the time of various Mars probes have been different.. in some cases, as little as 5-6 month - but path is NOT a straight line..)

(Something Newton could have calculated in advance

- Actually if some one gave me the position of MOM (or MAVEN) at a few points just after Dec 1.., I could calculate (on the back of an envelope - may be with a help of a calculator) virtually all timings/positions fairly accurately.. within 1%.. (as long as the craft is not very close to the planet)..(Of course, one needs MUCH more accuracy to control the firing of rockets..

)

MOM, saved fuel (compared to MAVEN) with innovative "earth raising orbits" and timing the fuel burn at most suitable time, and of course, having a highly elliptical and a little distant orbit around Mars...

Amber G. · Post by **Amber G.** » 20 Sep 2014 09:07

BTW, Nasa will broadcast live (as stream it on internet) the MOI of MAVEN. ( MOI: 9:37 PM to 10:23 PM EDT)..

For perspective, Maven's orbit is 150Km- 6300 Km orbital period 35 hours, which within a few weeks will put it in "scientific orbit"- a circular orbit or period about 4.5 Hours..It is going to provide radio relay service.