## Mangalyaan : ISRO's Mars Orbiter Mission

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SSSalvi
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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

I had missed to notice the 1.25 factor . Anyway hats off for your back-of-the-envelope calculation.

My graphical representation of distance traveled is based on my real calculations based on classical theory of Hoemann Txr Orbit done in 'those' days in 2013 calculated by adding the point to point velocity ( Kms/sec ) accumulated daily.

Amber G.
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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

Just to make it clearer - Let me add a few points to my earlier post about the distance travelled by MoM.
(And comment on Varoon Shekhar's figures in more direct way)

To be clear - The calculation is for Hohmann transfer orbit and this is for ideal (minimum) path. IOW the path = 3.9 AU (about 600 Million Km - see my previous post for details). The T (time period) of this orbit, is (1.25)^(3/2) = 1.4 years. So in ideal condition the (minimum) time of flight = 1.4/2 = 0.7 year.

In real life, planets are not exactly aligned in such a way that minimum path will work. For MoM the elapse time is
about 0.8 year (From Nov 30 to Sept 24 Trans-Mars injection to Mars orbit insertion).. so the orbit part is little more than half..

(I may not have made this very clear in my previous post as I assumed that this will be known)

With this the total path is about 690 million Km. (+- a few %) (600*8/7)

Now if we take the two end point as above (trans-Mars injection to Mars orbit insertion) can we get more accurate values.. Few points:
- The position at trans-Mars is not exactly at earth (but rather in orbit may be about 10^5 Km from earth).. so there may be a little correction..for value of "p"
- The apogee is a little further than Mars' orbit .. (value of "q")
- There may be slight correction due to earth (and Mars) when the MoM is near these planets..

My guess is the answer is about 700 Million miles but I can give correct values (can be easily calculated and they should match official values) if one can define the start and end point (Date/Time of the event, as well as position/velocity at those two points, and that value can be fairly precise)... a few points on orbit is all one needs to get precise values.

Hope this helps.

Varoon Shekhar
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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

I am now veering toward accepting the 690 million km figure , particularly after reading your message, and this very credible and well written article from Frontline in Oct-Nov 2013, obviously written before the mission took off.

http://www.frontline.in/cover-story/mis ... 280848.ece

Amber G.
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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

Varoon Shekhar wrote:I am now veering toward accepting the 690 million km figure , particularly after reading your message, and this very credible and well written article from Frontline in Oct-Nov 2013, obviously written before the mission took off.

http://www.frontline.in/cover-story/mis ... 280848.ece

Interesting that 690 million figure appears in that article! My calculation was done very roughly (no calculators or tables)--2 significant figures but, as said, should be within 3-4%. Of course, MUCH more precise number should be available from official source(s). These, orbits, are VERY VERY precisely known.

Nowadays one just let a computer calculate the orbits but when we studied these there were not even calculators for us.. (as I tell my son, we used bamboo slide rules and stuffs like that ). The path where there is only one body to worry about (like when MoM is close to earth, or Mars, or in between but far enough from both planets) -- aka elliptical orbits with "minor" perturbation are easier -- that's what astronomers did using these methods.

One rather interesting tidbit. There is no easy formula to calculate the length (perimeter) of an ellipse. One can use series expansion which is okay for computers but not that convenient when one does by hand. One of my favorite and remarkable formula comes from Ramanujan. He just writes the formula, does not explain it, does not even give a clue how it came to him but is fairly accurate. ( Don't worry for Mangalyaan orbit my approximation is within a few percentage)

The formula is:
perimeter (path) = pi((a+b)+3(a-b)^2/(10(a+b)+sqrt(a^2+b^2+14ab))) + small correction.
(See my previous post, a is AM, and b is GM of perigee and apogee)

Remarkably he gives the "correction" = 3ae^20/ 68719476736

As usual Ramanujan never explained his “empirical” method of obtaining this approximation, neither in his published work, nor in his Notebooks.. and kept many mathematician busy..(I still see papers trying to get insight in this approximation and numbers like 68719476736... How does one get that number ???.) (The formula is a final sentence of Ramanujan’s famous paper Modular Equations and Approximations to π, but he does not write anything else, and people who searched his notebooks did not find any clue what what his thinking!!

****

Anyway .. since no one else noticed it, this was exactly two years ago -- The Launch..

[Credit - Isro - Isro social media picture]

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

Varoon Shekhar you may be interested: This may give you all the figures you may be interested in: (Credit: Isro #Mangalyaan_Launch_Anniversary_Special)

(Mars Orbiter Mission Profile)):

1. Geo Centric Phase
The spacecraft is injected into an Elliptic Parking Orbit by the launcher. With six main engine burns, the spacecraft is gradually maneuvered into a departure hyperbolic trajectory with which it escapes from the Earth’s Sphere of Influence (SOI) with Earth’s orbital velocity + V boost. The SOI of earth ends at 918347 km from the surface of the earth beyond which the perturbing force on the orbiter is mainly due to the Sun. One primary concern is how to get the spacecraft to Mars, on the least amount of fuel. ISRO uses a method of travel called a Hohmann Transfer Orbit – or a Minimum Energy Transfer Orbit – to send a spacecraft from Earth to Mars with the least amount of fuel possible.
2. Helio Centric Phase
The spacecraft leaves Earth in a direction tangential to Earth’s orbit and encounters Mars tangentially to its orbit. The flight path is roughly one half of an ellipse around sun. Eventually it will intersect the orbit of Mars at the exact moment when Mars is there too. This trajectory becomes possible with certain allowances when the relative position of Earth, Mars and Sun form an angle of approximately 44o. Such an arrangement recur periodically at intervals of about 780 days. Minimum energy opportunities for Earth-Mars occur in November 2013, January 2016, May2018 etc.
3. Martian Phase
The spacecraft arrives at the Mars Sphere of Influence (around 573473 km from the surface of Mars) in a hyperbolic trajectory. At the time the spacecraft reaches the closest approach to Mars (Periapsis), it is captured into planned orbit around mars by imparting ∆V retro which is called the Mars Orbit Insertion (MOI) manoeuvre. The Earth-Mars trajectory is shown in the above figure. ISRO plans to launch the Mars Orbiter Mission during the November 2013 window utilizing minimum energy transfer opportunity.

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

Thanks Amber, that's very good. I have a feeling that ISRO's next Mars Mission won't be using the MET( or Hohmann) orbit, but will go 'straight' up like NASA's Maven spacecraft did. We'll see though.

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

Varoonji - Perhaps you mean orbit raising maneuvers before Helio Centric phase to conserve fuel..

*ALL* space probes right now use essentially the similar orbit(s).... Fuel requirements (or better engines), or position of other planets, put some restrictions (or opportunities) but *all* orbits at present are essentially elliptical... Most of the maneuvering (and firing of the rockets) is done in the beginning and in the end - there are minor adjustments in the way but essentially the probe follows a standard elliptical orbit wrt to the Sun.
(Hence virtually Earth-mars time period will be 0.7 years (minimum)+ few months ).months...Every extra day (above 0.7 Years will add about 2.5 million Km on the path).

This of course applies to the part -- Helio Centric Phase (see my post above - between (2) & (3))..The difficult part, is of course before (1) and after (3) -- to fire the rockets accurately enough that it goes in the right path and be captured in the right orbit after (3)

Both MoM and Maven are similar in this respect. (about the same transit time +- a few weeks). MoM used some creative ways to use less fuel.. raised the orbit around earth, and final thrust was fired when it's orbit was at perigee (wrt to earth) and has higher velocity requiring less delta-v with respect to sun.

****

Before I wrote about the unsung heroes - engineers who made the inertial-guding-system-cum-thurster which put MoM in final Mars orbit. I am still very impressed by the precision and would like to know more about engineering aspects of that unit. (Many years ago, I remember Feynmann showing in a physics class such accelerometers from JPL.. at that time they cost millions and we were very impressed...much more impressive for Indian engineers to achieve the same result with less expensive units)... If anyone has more details about this, I will appriciate them sharing this here...

I talked about this before: worth to see what I said then https://forums.bharat-rakshak.com/viewtopic.php?p=1720428#p1720428... I will like to know more...
Last edited by Amber G. on 06 Nov 2016 08:57, edited 1 time in total.

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

Orbits of MoM vs Maven
..
Hope this is helpful - It has been published many places but summery may help understand the basics..
(Credits - figures has been cut and pasted from isro, Nasa, and main news sources, and previous posts.

MAVEN: launched on an Atlas 5 rocket at 1:28 p.m. EST (1828 GMT) on Monday (Nov. 18) from Florida’s Cape Canaveral Air Force Station. Within one hour of launch, MAVEN entered in a Hohmann Transfer Orbit with periapsis at Earth’s orbit and apoapsis at the distance of the orbit of Mars. MAVEN reached Mars orbit on 22nd September 2014.

Mangalyaan:

Because PSLV was used ( relatively lower payload capability) MOM spent about four weeks in earth orbit (added complexities like adding radiation shielding to endure the numerous passages through earth’s radiation Belts). MOM has fired its Liquid Motor six times – always when passing perigee to gradually increase the apogee of the orbit to work its way up to departing Earth orbit in a fuel-efficient manner. The sixth (including one correction) firing placed the spacecraft in a 600 by approx 193,000 kilometer orbit around Earth and sets up the proper perigee passage for the final engine burn that puts the vehicle onto its Trans-Martian Trajectory using s standard Hohmann Transfer Orbit on 30th November/ 1st December. MOM reached Mars orbit on 24th September 2014 (2 days after MAVEN).

(Note: The orbits around Earth (1) and Mars (3) of MoM are NOT on scale of the bigger picture - If looked on scale with the bigger picture - they will be essentially points - orbits too small to be seen - right next to Earth and Mars).

As said before, the major portion of both orbits were nearly identically shaped ellipses with sun as focus.

(Disclaimer: I am not with ISRO , and the data taken here is from publicly available sources. I am just a physicist, not an expert on any part of MoM's or Maven's mission - Just know Celestial Mechanics very well)

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

Just checked, lot of this, has already been discussed here so for interested people lot of good stuff is already there..
for example this from about 2 years ago ... (and a few more posts -- just do a search)..
https://forums.bharat-rakshak.com/viewtopic.php?p=1549141#p1549141

Or look at this: about a year ago... did not realize did the same calculation then !!!
https://forums.bharat-rakshak.com/viewtopic.php?p=1719394#p1719394
Amber G. wrote:
vina wrote: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...

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

Okay last message for today .. the anniversary of MoM launch!

Many people asked, then, how long MoM will last. The life was supposed to be only for 6 months.. but some people wondered, after reading that it was left with more fuel then anticipated. They asked can life be extended. I said then that it will last much longer ...

Following I posted more than 2 years ago!

Amber G. wrote:
What is the life of the orbiter? How many years/months?
Supposed to be six months. But probably would be a little longer that mom has more fuel.

Sorry, but would like to add something here... as this topic keeps coming on here..

How long the MOM's life would be?
Depends on what you call 'life'..
..It has much less to do with fuel than people seem to think here.

How long MOM will orbit Mars?

In all probability a very long time decades, may be centuries. The orbit (after all the fuel is gone) may vary a little from the present one, but essentially it will remain orbiting Mars -- a 3 day (give or take a few hours) period...(Unless some future maneuver uses some fuel and crash it into Mars, or MOM has a self destruct button )

Long before that - few things may happen ...

- People may get bored .... money runs out so people may just stop monitoring it..
- Antena stops working (no fuel to direct it to Earth), or some other systems stop working.. so no one will be able to monitor / receive data from it.
- XYZ (substitute your favorite villain - Modi, MMS, IITian/ evil Nasa ) destroys everything.

(You get the idea)

No significant fuel is needed to keep MOM in orbit. (Remember Mars atmosphere is much thinner than Earth, and MOM is remains higher than 500 Km - so orbit it not going to "decay" in any significant way) There will be small tugs (Mars being not a perfect sphere + tugs from Sun, Jupiter, Saturn, Earth etc) which will cause perturbations in elliptical orbit but that is NOT relevant at all for time period of many decades. ... long before that, our systems and equipments will break down.

So may be 73 years from now, mangalyaan73, will capture an old Mangalyaan and tug it to a museum in Bangalaru - who knows...

(Or isro guys, after a year or so, plan a controlled crash on the moon, just to check if they can measure small mars-quakes to improve their earth-quake predicting devices)

In any case, my point is, let us stop relating how much fuel left with the life of MOM.

So after all these years, MoM is still there! They even plan to change the orbit a little in Jan 2017 so that it will avoid a long lasting eclipse. (The batteries can not last for 7-8 hours long duration of the eclipse, if they do not change the orbit a little)...It is going to remain for many more years to come!..Not bad for something which they designed to last in orbit for 6 months or so!

Varoon Shekhar
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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

Yes, the idea is not so much how long MOM/Mangalyaan will 'last', but for how long will it continue to beam data/information about Mars. Some ISRO spokespeople have said a few years.

When the Mars Colour Camera, Methane Sensor, MENCA et all stop providing data about Mars, I suppose that's when we can say that Mangalyaan has stopped functioning, and has fulfilled its operational life. They have continued to beam pictures and data, a year and a half later than their original six month 'life'!

That's interesting about the paths of Maven and MOM- the general media said something about India's 'weaker' PSLV needing a different/longer path to get to Mars, compared to Maven's. The idea being that when the GSLV becomes operational and available, it will take a path just like Maven or any other mission from the US, Russia or Europe. That's all lay readers would probably pick up!

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

Varoon Shekhar wrote:Yes, the idea is not so much how long MOM/Mangalyaan will 'last', but for how long will it continue to beam data/information about Mars. Some ISRO spokespeople have said a few years.

Yes, Yet, if you look at this thread, many (including brfites) were bringing the question of fuel...forgetting that one can remain in orbit for centuries without fuel.. this in spite of *multiple* times that part being pointed out.
The idea being that when the GSLV becomes operational and available, it will take a path just like Maven or any other mission from the US, Russia or Europe. That's all lay readers would probably pick up!

Again, for many (including those who were writing for newspapers) this was sort of not knowing basics of classical mechanics. Fuel is used to put the probe (1) to escape earth's gravitational influence, (2) to put it in the correct orbit to reach Mar's orbit at a time where Mars also happens to be there and (3) get captured by Mar's gravity for an orbit. Apart from some corrections in mid flight, 99% of the orbit is just like any elliptical orbit around sun.

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

Thanks I see. Why was a big deal made, by some, lay and science folk alike, about the lighter vs heavier vehicle, for reaching the Mars orbit? Some mentioned more powerful rockets not having to circle the earth so many times(the slingshot method) while others lamented the lighter payload of the PSLV vs the GSLV

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

I think this is the best tribute to our scientist and ISRO

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

MOM mission was 3 years ago not 2 years ago

https://en.wikipedia.org/wiki/Mars_Orbiter_Mission

Regarding the payload weight of MOM, it would have been slightly better if GSLV was used but not significant. Also the time taken to reach Mars cannot be reduced unless you find an exotic fuel . The trouble is two fold, the weight of the satellite and velocity of the satellite. Both the parameters come to play when satellite does the braking to enter the orbit. But if you are going to a smaller planet like Venus or mercury, this can be avoided. Mercury again will have the Sun's G pull too

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

AmberG wrote:MAVEN: launched on an Atlas 5 rocket at 1:28 p.m. EST (1828 GMT) on Monday (Nov. 18) from Florida’s Cape Canaveral Air Force Station. Within one hour of launch, MAVEN entered in a Hohmann Transfer Orbit with periapsis at Earth’s orbit and apoapsis at the distance of the orbit of Mars. MAVEN reached Mars orbit on 22nd September 2014.

Mangalyaan:

Because PSLV was used ( relatively lower payload capability) MOM spent about four weeks in earth orbit (added complexities like adding radiation shielding to endure the numerous passages through earth’s radiation Belts). MOM has fired its Liquid Motor six times – always when passing perigee to gradually increase the apogee of the orbit to work its way up to departing Earth orbit in a fuel-efficient manner. The sixth (including one correction) firing placed the spacecraft in a 600 by approx 193,000 kilometer orbit around Earth and sets up the proper perigee passage for the final engine burn that puts the vehicle onto its Trans-Martian Trajectory using s standard Hohmann Transfer Orbit on 30th November/ 1st December. MOM reached Mars orbit on 24th September 2014 (2 days after MAVEN).

Oh, absolutely agree with you that both paths will be ellipse (didnt see your post long ago, would have responded back then), and can be largely superimposed. But there are differences and you pointed out the key.. Maven enters transfer orbit within 1 hr of launch , while Mangalyan swings around the earth and for a few times before going off on it's way to Mars.

Yes, the ISRO method is far more efficient (in terms of fuel use), and indeed the most efficient one, in terms of firing at the perigee in earth orbit where the velocity is highest and the best place to add delta V. So the question is why didn't they do it different for Maven . Why didn't NASA do what ISRO did ?

The reason for that is engineering and not really the "payload capability" (okay it is in an indirect way) . See, Maven got the delta V imparted not by it's liquid motor (which has earth storable propellants) , but rather by the cryogenic stage of the Atlas V. Sure the Atlas V upper stage is restartable (I think 6 times restart) and can theoretically can do what ISRO did. Trouble is , the life of a cryogenic stage is measured in hours, before the tanks lose pressurisation and the propellants boil off. They can't do what ISRO did over nearly 2 weeks (I think). That is the reason why Maven reached mars with it's propellant tanks nearly full, while Mangalyan reached with tanks close to empty. Maven got to Mars with on the back of a high thrust cryogenic engine providing it the delta V (in not the most efficient way), while ISRO got there with a pretty low thrust earth storable engine , firing in the most efficient way. So in many ways, the engineering constraints decided the mission planning and the best way to get there for each case.

Caveat.. If you see the ULV's plans to replace the Atlas V with the Vulcan, the new cryogenic stage will use automobile based engine to keep the tanks pressurised and prevent propellant boil off and keep it live for literally weeks. In that case, expect NASA to use ISRO like mission planning to get to Mars in the most efficient way.

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

Also the time taken to reach Mars cannot be reduced unless you find an exotic fuel .

You can't reach faster by using a betterfuelled rocket .. unless you continuously drive using on board driving power.

If you use Solar orbit ( Hoemann Txr ) then by choosing different options one can gain a day or 2 or may be a week .. not more than that.

It is sad to hear comments that one rocket is better than the other for Mars missions. Comparison ends beyond the Earth's Gravitational field.

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

Vina wrote:Oh, absolutely agree with you that both paths will be ellipse...

Vinaji -
Yes, yet from many *including* you, and that too *several times*, in brf itself, there are very *ODD* remarks. /sigh/

For example here <click for your message> and (many messages before and after that, even the MOST BASIC concept of orbits generated one of the strangest of replies. For example your answer involved Simple Harmonic Motion and what not..(quite wrong btw) /sigh/
(
This looks suspiciously like the F = -Kx kind of Simple Harmonic Motion stuff with the center at a distance R from the earth. So I will stick my neck out and venture that in this case, the body in orbit @ radial distance R, but with a Simple Harmonic motion centered on R superimposed on the orbit.

(The path, as that of any body orbiting earth (or sun) is SIMPLE ellipse....No need to introduce 'mumbo-jumbo' which sounds scientific but anything but )

(What I noted then - but did not comment because the whole thing was hard to make any sense - when *after* lecturing others not to use "fictitious' forces like "centrifugal" you used rotating system in your calculation using centrifugal force (that too not accurately, as far as I can guess) but ignored coriolis force - hence the strange wrong answer. Interestingly none of that was needed to deduct that the orbit will be an ellipse and calculation was quite elementary )

I would suggest, if you have not done that, read mine and other posts/explanations following above link. I hope you read my posts there, as the math is same as understanding paths of MoM. The post where I summarize the physics/math is at:
https://forums.bharat-rakshak.com/viewtopic.php?p=2037787#p2037787

The situation is exactly like case B in my problem there. (except that the orbit is around sun instead of earth).... The delta-V is introduced at a point near perigee (wrt to MoM's orbit around earth) to achieve enough velocity to go in hyperbolic orbit around earth but an elliptical orbit around sun, sort of leave earth's sphere of influence, and has the required delta-V (above 30Km/sec of earth's orbit around sun) for MoM's orbit around sun, so that at far end it will reach the orbit of mars when mars happens to be there too.

****
Yes, the ISRO method is far more efficient (in terms of fuel use), and indeed the most efficient one, in terms of firing at the perigee in earth orbit where the velocity is highest and the best place to add delta V. So the question is why didn't they do it different for Maven . Why didn't NASA do what ISRO did ?

***
IMO, critical component/reason of *why* NASA (or ISRO) did (or did not) do to send a probe to mars is the position of planets and timing so that given the restrictions we have to achieve the required delta-V etc.. can we calculate a path of success. Basically can we give a thrust such that when the probe reaches mars orbit it -
A - Finds Mars physically close by.
B- Has enough fuel that it can slow down enough that it is captured by Mars, and achieves an orbit around Mars.
C-Has enough intelligence, and navigational accuracy to fire right amount of thrust at the right time.

Basic understanding of classical mechanics is essential to understand other aspects.
***
Hope this helps.

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

http://www.space.com/23203-india-mars-o ... hotos.html

India's First Mars Mission in Pictures (Gallery)

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

^^^ Thanks.

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

For those who are interested, here are some basic numbers...

Ignoring the effect of Earth and mars, and considering sun only .. (true when the probe is far away from earth/mars)
- For a circular orbit around sun at a distance 1AU (eg earth) the orbital velocity is about 30 km/sec. (1AU =(about) 150,000,000 Km)
- At the distance of Mars (1.5AU), for circular orbit, the value is about 24 Km/sec.
- For a transfer orbit, (ellipse whose closest approach is 1AU and furthest is 1.5 AU)
you need a delta-v from circular orbit so that velocity needed is about 33 Km (3km more than 30 km)
- When it reaches Mars the velocity is about 22 Km/sec (delta-V needed will be about 2km/sec to put in a circular orbit around sun -- just like mars.

But one has to 'escape' from earth's gravity, and start it journey to solar orbit.

For this, again rough numbers..

Escape velocity at earth (at surface or LEO) about 11Km/sec -- At higher orbits it is obviously less. .. eg at the height of geosynchronous orbit it is about 4.3 Km/sec..

Similarly escape velocity for Mars (near surface) is about 5km/sec..so if you don't do anything you will zip pass Mars (with about 5km/sec relative to Mars).. you have to slow down (by a km/sec or so) so you start orbiting Mars instead of return back towards earth's orbit.

(The escape velocity is sqrt(2) times the circular orbital speed - eg , if LEO speed is about 8km/sec, the escape velocity at that point is about 8*sqrt(2)=11Km/sec)

Just to give some rough idea's ... Hope that helps.

Manish_P
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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

OT

Is the image legit. I haven't seen the note yet but images are floating on whatsapp pointing to a printing error

The hindi text (in the vertical rectangle) mentions 'Don Hazaar Rupaya' instead of 'Do Hazaar Rupaya'

'Don' is marathi for 2 (and the marathi text below is correct).

In hindi shouldn't it be 'Do' ?

Kakarat wrote:I think this is the best tribute to our scientist and ISRO

SSSalvi
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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

^^^
Hindi is on left .. text direction vertical. So Hindi may not be there in the box where it is written other Indian languages. ( English also is not there in the box ).

Marathi "Don Hazar Rupaye" is also written correctly.

The other devnagari script Don Hazar Rupaya may be Konkani which too is a scheduled language.

pankajs
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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

Apologies for the OT

Interesting that the official name of the Mars probe was MOM (expanded) and Mangalyaan was it unofficial name. It is the unofficial name that has made it to the currency. Not that I am unhappy. I was surprised at that time that it wasn't officially named Mangalyaan following Chandrayaan, the most logical choice.

Sickularism can do strange things. Perhaps having a sanskritized name was offensive to some.

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

The name for the craft -- "Mangalyaan" ("मंगलयान") was always used routinely by newspapers, websites and most sources. The name for the whole mission was, as it was known then and now, MoM or Mars Orbiter Mission ("मंगल कक्षित्र मिशन")..
A typical story for example from space dot com .. here says:
India's Mars Orbiter Mission is the country's first mission ever to explore the Red Planet. See photos of the mission in this Space.com gallery....India's Mangalyaan spacecraf captured this amazing view of Mars on Sept. 28, 2014. It shows active dust storms in the Red Planet's northern hemisphere and is the first full view of Mars from the probe. ...

The picture on the 2000 Rs bill is of the space-craft and it is quite apt to use "mangalyaan".

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

Officially ISRO never called it Mangalyaan ( except for the initial few internal review meetings ).

In later stages ( even in the press briefing brochures and Official Brochure they call the satellite Mars Orbiter or Mars Orbiter Satellite.

Amber G.
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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

^^^ Interesting.
But common name, even then was used quite routinely in newspapers etc.. eg this head line from WSJ/journals/NYtimes/ Indian papers etc.. India Satellite Mangalyaan Reaches Mars Orbit on First Try

http://physicsworld.com/cws/article/news/2014/sep/24/indias-mangalyaan-satellite-successfully-in-orbit-around-mars
(I have used this name routinely)

SSSalvi
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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

True. Colloquially we do refer it a Mangalyaan but in ISRO even named its official Mangalyaan facebook page : ISRO's Mars Orbiter Mission.

Of course MOM is much easier to pronounce and write than Mangalyaan.

Amber G.
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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

^^^ Thanks... I was curious and it becomes interesting. For those who want to look it in more details, here is what I found:
It seems that
- First "official" announcement I can see about India heading to Mars was in 2012 when Prime Minister Manmohan Singh in his Independence Day speech delivered in Hindi in New Delhi where he named/called it "Mangalyaan". He said "Mangalyaan will be a big step in science technology". (Link: https://www.youtube.com/watch?v=rJiJbwjQUHo
- Curiously the "official" English translation of the speech (released by GOI) did not have the word 'Mangalyaan' anywhere in it. And it seems (and has been even noted by a few around that time) in its wisdom ISRO continued to argue that the spacecraft was never christened 'Mangalyaan'.

- Even then, some magazines/newspapers, did use "Mangalyaan" as the name, never even giving a hint that the name is unofficial.
aboard the craft—known as Mangalyaan or "auspicious vehicle to Mars"—are a multispectral camera, sophisticated spectrometers, and a highly sensitive methane sensor...

Funny part is, in that article many isro people are interviewed , and ddm(s) talk about "controversy" not about the name but silly things like:
Mangalyaan would be "a national waste," says G. Madhavan Nair, the former chair of the Indian Space Research Organisation (ISRO

Anyway - Just recently Modi, puts the name controversy to rest..
His government has literally decided to give a Mangalyaan in every person's hand by engraving a motif of the famous satellite on the new currency note. The same way as India's maiden mission to mars gladdened the hearts of Indians filling them with nationalistic pride, the move to demonetise high value notes is instilling a hope in lay people that the economy may now be lifted into a new orbit.

Sources confirms that from among several choices, Modi hand- picked the placement of Mangalyaan on the new currency note. NaMo is a great fan of ISRO and he thinks that Mangalyaan truly represents the 'Make in India' spirit.!!

Nice!

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

^^^
I can find this from 2012 Sept in planetary org
Mangalyaan, India's 2013 Mars mission, is now under construction

ISRO
Mangalyaan
Artist's concept of ISRO's Mangalyaan Mars orbiter.

>>>
(Above must have come from those initial few internal review meetings but, as SSS said ISRO did not have official page)

There does not seem to be an official website for the mission, much less any online press releases from ISRO, so details are sketchy and available mostly only through newspaper articles, which I am hesitant to rely upon. Reports are appearing this week in Asian media ... that the Bangalore-based Hindustan Aeronautics Limited (HAL) has now delivered the structure of the spacecraft to ISRO. Thanks to Pradeep Mohandas for a link to the HAL press release [sept 2012] , which I reproduce in full here: Hindustan Aeronautics Limited delivers Mangalyaan-1 basic structure to ISRO [ press release does mention that it is a Mars Orbiter Mission but not too much details]

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

A possibility : They might have reserved the Mangalyaan title for the Mars LANDER. The first was an ORBITER .. so MOM.

Amber G.
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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

A photo of the Red Planet taken by the simple, low cost camera of Mangalyaan is on the cover of the National Georgaphic magazine.

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

Mangalyaan means "Mars craft" - and could be interpreted as Mars orbiter. Mangal is Mars whether ISRO calls it that or not

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

Manish_P wrote:OT

Is the image legit. I haven't seen the note yet but images are floating on whatsapp pointing to a printing error

The hindi text (in the vertical rectangle) mentions 'Don Hazaar Rupaya' instead of 'Do Hazaar Rupaya'

'Don' is marathi for 2 (and the marathi text below is correct).

In hindi shouldn't it be 'Do' ?

Kakarat wrote:I think this is the best tribute to our scientist and ISRO

The list of languages is clearly mentioned on the RBI website:
https://www.rbi.org.in/currency/Languag ... Notes.html

The website lists 15 languages in the panel.

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

The konkani around the coast of karnataka (udupi-mangalore) has the sound as 'Rupayi' or 'Rupayee' or 'Ruphay'. The 'Rupaya' sounds incorrect...or is it perhaps goan konkani ?

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

MOM has completed a revolution around Mars, ISRO scientist says
by TNN November 26, 2016

Aurangabad: Stating that country's Mars Orbiter Mission (MOM), also called Mangalyaan, has completed one revolution around the Red Planet, Ritu Karidhal, deputy operation director of Bengaluru-based MOM ISRO Satellite Centre said studies based on analysis of data being sent by the orbiter would soon answer different queries related to life on the planet.

"The span of two years on Earth nearly equals to one year on Mars. The Mangalyaan, which entered into the orbit of Mars around two years ago, has completed one revolution. The data being sent by it over a period of last two years is being studied by ISRO for analysing atmospheric configuration," said Karidhal.

Delivering fourth keynote address as a part of Yeshwant Inspirational Talk Series here on Saturday, she said the analysis of the data sent by MOM could reveal presence of carbon content, if any, in atmosphere of Mars.

"The question still exists that whether life existed on Mars and can it be possible in future. The atmospheric studies of Mars using data sent by MOM would help in knowing whether the remote planet has methane or any form of carbon in its atmosphere. If such traces are found, the planet can have life like it is hoped to have had in the past," Karidhal said.

The ISRO scientist said the MOM could last in the space further for at least 5 to 10 years.

"The Mangalyaan does not have any fuel system to support its existence while orbiting Mars but is being purely driven by its different components. The life of these components would decide the future life of MOM," Karidhal said.

Listing down some of the many firsts associated with MOM at the international level, including the mission that was successful in the first attempt, she said the greatest achievement of Mangalyaan was to infuse confidence among countrymen that India was second to none.

"India's Mars Mission has basically empowered 1.2 billion countrymen. The Mission has not only inspired citizens but also instilled confidence that they are second to none," she said.

Later, while answering a student query in the interactive session, the ISRO scientist said studies also need to be done to ascertain whether any correlation exists between astrology and astronomy. "There may be some linking between both these fields, but scientific studies need to be done focussing on cosmic energy," Karidhal said.

To another query, asking why Venus was not considered by ISRO for space mission instead of Mars, she said the second planet from the Sun has relatively harsher atmosphere. Also there are no indications so far that any form of life existed on Venus, which is not the case with Mars, she added.

Started in the memory of late Yeshwant L Garde, one of the founder members of Chamber of Marathwada Industries and Agriculture and former head of Aurangabad Co-operative Industrial Estate, Yeshwant Inspirational Talk Series has been initiated since the past four years with the focus on sharing knowledge among youth.

Website: http://timesofindia.indiatimes.com/city ... 641825.cms

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

The layman's question again- so it took 2 years to make a revolution around Mars? Why would it take so long, is it the peculiar orbit of Mangalyaan? I do know that Mars' moons take much less time to make a revolution around the planet

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

Mangalyaan (Mars too, of course) takes 687 days (about 1.9 Years) to orbit around sun. (The synodic period of Mars is about 2.1 years - as earth takes 1 year to go around the sun)

For Mangalyaan to orbit around Mars it takes about 72 hours 51 minutes 51 seconds (give or take few fractions of a second) - The orbit is ellipse (perigee = 422Km, apogee = 77000 Km).

Varoon Shekhar
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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

Ah, so it was a major DDM error, then, to refer to a revolution around Mars. What they really meant( and the ISRO spokesperson would have known this) was a revolution around the Sun, by Mangalyaan/MOM. Okay, that now makes perfect sense. A lay reader looking at that article, could easily get misinformed. Lay people( though I am not that bad mix up terms like solar system and galaxy. One of my relatives the other day said earth is the only planet in the galaxy. What he meant was solar system, the Milky Way is a galaxy with billions of Suns and solar systems.

So you can imagine how many millions of potential/actual readers would be misinformed by that terrible editing!

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### Re: Mangalyaan : ISRO's Mars Orbiter Mission

http://www.space.com/34943-india-mars-o ... lanet.html

India's Mars Orbiter Mission Has a Methane Problem

The problem has to do with how the instrument collects and processes detections of methane in the atmosphere, a technique known as spectroscopy.

"Imagine that you hold your hand in front of you and extend your four fingers … Suppose that each (finger) represents a methane line. What they have is a spectrometer that can be shifted to … sample each one of the four fingers and then they have a second one that samples the region between the fingers.

"The trouble is they don't actually send back the spectra. What they send back is the two numbers — the sum of the fingers measured by the first channel and the sum of gaps measured by the second channel — and then they take a difference of those two numbers and they think that that's going to be the methane signal," Mumma said.

"The problem, of course, is that when you have other spectral lines … like carbon dioxide lines which vary widely with temperature in terms of their intensity, then those two numbers … don't represent methane alone. The net effect is that there is no way that one can back out those two signals in order to retrieve a methane signal," he said.

Too bad we have to learn this from space.com. Really.