Mangalyaan: ISRO's Mars Orbiter Mission

Vayutuvan · Post by **Vayutuvan** » 25 Nov 2013 07:38

Whatever.

sanjaykumar

my stomach is hurting.

Karan M · Post by **Karan M** » 25 Nov 2013 11:46

Today's dose of Q-tiyapa

India's resident village idiot - Bidwai, doing what he does best. Waste bandwidth with his caterwauling. Have fun.

http://www.thedailystar.net/beta2/news/ ... -in-space/

ashish raval · Post by **ashish raval** » 25 Nov 2013 13:18

^^ just hate to say this, but these socialist journalists morons are utter failures having very low IQ being at lower end of the bell curve and barely passing every standard in school. They have deep rooted jealousy for stellar brains, read scientists, engineers, doctors and lawyers right from school,throughout their non-scientific subject study and no recognition by society which naturally owes to non critical thinking subjects and being at the bottom of the pyramid in intelligence. The thing they do I.e. journalism and social science is infact a hobby or a volunteer work, I would not event count them as subjects of human endeavour.

Growing up and in work they want to screw everyone else.

These rats needs to know their mental boundary by tight slap by someone with courage.

Akshay Kapoor · Post by **Akshay Kapoor** » 25 Nov 2013 16:00

SaiK wrote:well i disagree on the under or over paid aspects as you have not weighted on other economic factors - GDP, living standards, needs, etc. of course, OT. we have this dirty habit of comparing salaries immediately and say we are under paid etc without analyzing ground facts.

the fact remains, that desh overheads are way down when compared to NASA. unless we break the cost down to component levels, unit levels, resource levels, there is no sense in comparing or boasting ISRO>>NASA yadi yada. I think we need to focus on the mission objectives more than just shooting our mouth on cost.

the mission is half done now. sope, let us keep quite.

+ 1

Akshay Kapoor · Post by **Akshay Kapoor** » 25 Nov 2013 16:09

ashish raval wrote:^^ just hate to say this, but these socialist journalists morons are utter failures having very low IQ being at lower end of the bell curve and barely passing every standard in school. They have deep rooted jealousy for stellar brains, read scientists, engineers, doctors and lawyers right from school,throughout their non-scientific subject study and no recognition by society which naturally owes to non critical thinking subjects and being at the bottom of the pyramid in intelligence. The thing they do I.e. journalism and social science is infact a hobby or a volunteer work, I would not event count them as subjects of human endeavour.

Growing up and in work they want to screw everyone else.

These rats needs to know their mental boundary by tight slap by someone with courage.

Success creates its own constitunecy. As we are more and more successful (in all spheres) these jokers will get drowned out. Its human nature to jump on bandwagons and success is the best. But these guys need to be challenged (tight slap;-) on their own websites and blogs etc and you can use the BR forum to get info for a strong and credible rebuttal.

gakakkad · Post by **gakakkad** » 25 Nov 2013 16:16

what pro-fool-bid wai et al have to regurgitate through their mouth is well known...I thing it is best we avoid posting the crap in space dhaaga...i suppose it can be posted in the piss-ops dhaga where we can beat them up...

In future when we have a high profile mission ,we should avoid discussing what left buffoons and briturds have to say about it...they are too insignificant to be in our field of vision...we don't care what they say, or what they do...

mangalyan would go down in history books and be taught to kids even 2 centuries from now...but what these retards have to say would be remembered by none...not more worthy than toilet paper...

member_28108 · Post by **member_28108** » 25 Nov 2013 16:32

I don't think prafool Bidwai can see anything positive in India.He tries to put down every effort.I read it to see how much a twisted mind can work.

member_28108 · Post by **member_28108** » 25 Nov 2013 16:36

Image from ISRO FB page

The Six Keplerian Elements

The six orbital elements, also known as Keplerian Elements, are the parameters required to uniquely identify a specific orbit. Keplerian Elements for an orbit around earth are explained below:

1. Semi-major axis of an orbit represents the size of the orbit. Semi-major axis is the distance measured from the centre of the ellipse to either the Periapsis or the Apoapsis.

2. Eccentricity of an orbit is a numerical representation of the shape of the orbit. Eccentricity is an indication of the extent of deviation of an orbit with respect to a perfect geometric circle.

3. Inclination for an orbit around Earth is the angle between the orbital plane and the equatorial plane.

4. Right Ascension of Ascending Node (RAAN) is an angle, measured at the center of the earth, from the ‘direction of vernal equinox’ to the ‘ascending node’.

5. Argument of Perigee is an angle, measured at the centre of the earth, between the orbit’s perigee and the ‘ascending node’.

6. True Anomaly is the angle contained at the centre of Earth, between the direction of perigee and the position of the body at a given time.

The nearest and farthest points in the orbital plane of a satellite around Earth, from the center of Earth, are referred to as Perigee and Apogee respectively. Orbital nodes for an orbit around Earth are the two points where the orbit intersects the equatorial plane. The Direction of Sun, as seen from Earth, at Vernal Equinox is called ‘Direction of Vernal Equinox’.

SSridhar · Post by **SSridhar** » 25 Nov 2013 19:20

Vernal Axis is the axis from the Earth’s centre pointing to the First Point of Aries in the sky.

Bade · Post by **Bade** » 25 Nov 2013 21:19

This has been discussed before here, but it summarizes it nicely.
http://www.planetary.org/blogs/emily-la ... ainer.html

member_28108 · Post by **member_28108** » 25 Nov 2013 23:28

From ISRO FB page

The mom of all slingshots !

ISRO's Mars Orbiter Mission spacecraft has been in Earth bound orbits with different apogees since its launch by PSLV.

This Saturday night is the time to slingshot MOM, into its heliocentric orbit towards Mars.

This voyage is achieved by a complex combination of navigation and propulsion technologies, governed by the gravity of Sun and Mars, and assisted by the 440 N Liquid engine. Further fine tuning of the trajectory is achieved using the Attitude and Orbit Control Thrusters during the Trajectory Correction maneuvers planned en route.

This 680 Million km long interplanetary voyage begins with the mother of all slingshots, code-named Trans-Mars Injection scheduled for December 01, 2013 00:49 Hrs.

member_28108 · Post by **member_28108** » 26 Nov 2013 08:02

I asked about the midcourse correction schedule on the ISRO FB page - here is the answer

When are the midcourse corrections planned ? How many are "scheduled"

First one is planned on December 11. There may be one more mid-course correction during the helio-centric phase, and subsequently, a fortnight before the spacecraft’s arrival near Mars, there will be one more mid-course correction. so the total number is 3 or more decided based on the orbit determination in helioc-centric phase.

member_28108 · Post by **member_28108** » 26 Nov 2013 14:27

SSridhar wrote:Vernal Axis is the axis from the Earth’s centre pointing to the First Point of Aries in the sky.

It just happens to point to the first point of Aries (Coincidental) (will change due to earths precession) but is defined in relation to the direction of the vernal equinox

member_28108 · Post by **member_28108** » 27 Nov 2013 10:14

Mars Orbiter Mission crossed its final perigee and (not its last lap around the earth. The Hohman transfer firing will be on Dec 1st around 00.47.

member_23694 · Post by **member_23694** » 27 Nov 2013 19:30

I read somewhere that 1st December orbit manouver will involve 23 min engine firing consuming 190Kg fuel.
Using this as the basis we have
1st - 416 sec
2nd - 570 sec
3rd - 707 sec
4th - ?
4th Suppl - 303 sec
5th - 243 sec

Total 2239 sec ~ 37 min

Assuming for 4th around 400 sec so roughly 44 min which implies fuel consumption till date of around 364 kg
So till departure for Mars total fuel consumption could be around 550 kg
It started with 850 kg, so roughly 300 kg left for any manouver going ahead.

Please correct me if i am missing something and hope the remaining fuel is sufficient for all the aerobatics

in the way and around Mars

SriKumar · Post by **SriKumar** » 27 Nov 2013 22:07

Been wondering about this a bit.....all these orbits around earth that the mangalyaan is making....I dont believe they would add anything to the overall velocity of craft (via the gravitational slingshot concept)?

The only thing that gives the craft its velocity is the amount of fuel in the PSLV, and on board the mangalyaan. There is no other source of energy. So, theoretically anyway, the craft could have been raised into a solar/martian trajectory in fewer orbits, i.e.by firing the mangalyaan motor for a longer period of time, and still attained the same velocity and orbit. So,why so many orbit raising maneuvers? Probably to get time to test the craft's systems, perhaps.

Sridhar · Post by **Sridhar** » 27 Nov 2013 22:34

Emily Lakdawalla of the Planetary Society has written on this very question - her blog post has been linked by Bade above.

To add to what has already been said, is it also possible that a single long firing of the LAM, which would have given the same velocity delta as the sum total of all these repeated firings, would stress the motor more than the repeated firings (for the same total amount of time, but with rest periods in between)? Could that also be a reason for ISRO's progressive velocity increase strategy?

Bade · Post by **Bade** » 27 Nov 2013 23:20

Srikumar, you are right. There is lot of "wrong assumptions" being made due to incorrect statements used to describe the process in the open media. Fuel burnt is all given to the added velocity there is. There is no gravity assist so to speak in leaving earth orbit.

I guess ISRO wants to extract maximum efficiency by firing the engines as close as possible to the perigee. The longer the burn duration, the kick given is spread over a large distance along the orbit as the satellite is moving always. Also, it has just a 440N thrust, unlike MAVEN which had a bigger booster attached to it for the initial kick once up in space.

SriKumar · Post by **SriKumar** » 27 Nov 2013 23:49

^^^ ...burn duration. Had not thought of that.....I can imagine ISRO would like to limit the burn duration to the max. velocity as much as possible. For it to travel across the Indian ocean i.e. where the perigee occurs ....i.e. off the eastern coast of southern Africa to, say, Malaysia, it might take about 30-40 minutes perhaps (per a quick look at a web-based satellite tracker I once checked, during perigee). This would roughly represent the overall time window, not all of it optimal. Of this time, maybe "peak velocity" window might be for about half or a fourth of that time.

member_28108 · Post by **member_28108** » 28 Nov 2013 09:13

The principle used is the Oberth effect. Firing at the perigee allows a higher kinetic energy to be imparted. It does use gravitational principles and Kepler's laws! The sling shot here used is not a classical gravity assist where the acceleration is achieved by a hyperbolic approach to a very large body but the assist here is acceleration that occurs at perigee. Firing the motor here when kinetic energy is the highest (and potential energy the lowest) imparts a better delta v.

JayS · Post by **JayS** » 28 Nov 2013 11:57

One would want, ideally, to give an instantaneous step input of required deltaV immediately after perigee (to raise the apogee). But this is not possible, not even a short duration impulse due to low thrust engines of MOM. So they take up time to build up deltaV required. You wouldn't want to give it in one go as then you would be adding deltaV away from perigee due to longer burn time. This would be waste of energy. So ISRO must have gone for 6 orbit raising. The other factor being error correction. As this is being done for the first time, total 6 burns would let one give more chances for error corrections.

juvva · Post by **juvva** » 28 Nov 2013 13:25

ISTRAC: Nerve centre of India's Mars Mission
A slide show:

http://economictimes.indiatimes.com/sli ... 515582.cms

member_28108 · Post by **member_28108** » 28 Nov 2013 15:28

http://www.ndtv.com/article/india/isro- ... r-1-451781

Schedule of midcourse corrections

Amber G. · Post by **Amber G.** » 29 Nov 2013 13:26

SriKumar wrote:Been wondering about this a bit.....all these orbits around earth that the mangalyaan is making....I dont believe they would add anything to the overall velocity of craft (via the gravitational slingshot concept)?

The only thing that gives the craft its velocity is the amount of fuel in the PSLV, and on board the mangalyaan. There is no other source of energy. So, theoretically anyway, the craft could have been raised into a solar/martian trajectory in fewer orbits, i.e.by firing the mangalyaan motor for a longer period of time, and still attained the same velocity and orbit. So,why so many orbit raising maneuvers? Probably to get time to test the craft's systems, perhaps.

Hello SriKumar,
First, to be clear without math (needed to do orbits in central gravitational force) it is difficult to really explain but I will try. Best is any standard text book or lecture on classical mechanics (at my time we used old Goldstein's book - which I found interesting that it is/was still being used in MIT 30 years later

... Hope this ocw from MIT is helpful ..

http://ocw.mit.edu/courses/aeronautics- ... _Lec17.pdf

... If I understand you correctly I'll make a few comments..

...I dont believe they would add anything to the overall velocity of craft (via the gravitational slingshot concept)..

One simple way to explain the whole idea of swinging by earth (or any planet - gravity assist or "slingshot" effect) without too much math is to say that this gravity assist "adds" the planet's velocity (actually approx. twice the planet's velocity) - with respect to sun - even if you burn very little fuel - remember earth is moving at the speed of 30Km/sec - so if you plan it right and burn the fuel at right point - (giving it right direction) and do it more times - you can get better delta-V... (This is why we have launch window's, timing etc.. so that things are as good as possible)

IOW, for simplicity assume a rocket is travelling with velocity +v, at certain point, (with respect to sun) approaching earth. If earth was not moving (with respect to sun) then after "rounding" the earth, (where it will become a little faster at perigee but will slow down again around the original point) it will return with same velocity .. -v. If earth is moving with speed U (again for simplicity, assume it is in the same direction) then the return velocity of the rocket will be (v+2U). (It is sort of elastic cricket ball hitting a bat, only if bat also moves then the rebound will be faster).

Interestingly if you do all the calculations, final result does come out as if you consider it as an elastic collision !)

Of course, you are not not dealing with scalar quantities, but have to deal with vector calculus, as different directions are involved.. but in short it DOES matter how many times and when you burn the fuel.

As to "energy"... all this interaction changes NOT only the space craft's speed but also earth/mars speed (Not to mention all other bodies speed

. Of course, earth's delta-V is very very very small (but earth is very massive so energy is not negligible)..so thinking in terms of energy only is not helpful to calculate how much fuel is required. In fact the whole calculation is quite complex and sometimes counter intuitive for common folks.

Another good reference is from caltech:
http://www2.jpl.nasa.gov/basics/bsf4-1.php
(Sorry if these references were already given)
Hope something is useful ..

vina · Post by **vina** » 29 Nov 2013 14:16

AmberG wrote:As to "energy"... all this interaction changes NOT only the space craft's speed but also earth/mars speed (Not to mention all other bodies speed . Of course, earth's delta-V is very very very small (but earth is very massive so energy is not negligible)..so thinking in terms of energy only is not helpful to calculate how much fuel is required. In fact the whole calculation is quite complex and sometimes counter intuitive for common folks.

Indeed. All the diagrams I have seen until now is of a "two body" problem, ie, earth and mars and the transit from earth to mars via a Hohmann transfer . All this just ignores the "Heliocentric coast" phase, that we see in all the ISRO brochures. So really, it is a 3 body problem, the earth, sun and mars. So shouldn't be like this ? Ideally, the velocity should be such that it just about escapes the earth's influence , gets into an orbit under the influence of the sun such that the point at which that orbit meets Mars is the lowest velocity point of a large elliptical orbit around the sun, and then the Mangalyaan's thrusters fire and decreases and decreases that low velocity even lower so that the spacecraft is captured by Mars and doesn't continue in it's elliptical orbit around the sun.

So really from the time it leaves earth orbit on Dec 1 to the time it reaches Mars in Sep 2004, the speed of Mangalyaan will be dropping wouldn't it as it travels to the farthest point in it's elliptical orbit around the sun (and gets captured by mars because of the thruster firing at the correct instant?).

member_23832 · Post by **member_23832** » 29 Nov 2013 18:40

MOM has edge over MAVEN, say Isro scientists

http://www.dnaindia.com/india/report-mo ... ts-1926574

Comparisons between the Indian and American spacecrafts which have embarked on a mission to explore planet Mars is inevitable, and over the next 300 days, there will several of the.

Although Nasa’s Mars Atmosphere and Volatile EvolutioN (MAVEN) was launched 13 days before Isro’s Mars Orbiter Misison (MOM), it is expected to reach Mars’ orbit on Septmber 21, 2014 three days before the MOM.

Besides, unlike the MOM the US spacecraft will not be made to undergo the trans-mars injection opeartion, which Isro plans to carry out on December 1. This is because Nasa’s powerful launch vehicle has been able to directly put MAVEN on to the Red Planet. However, scientists associated with the MOM are confident that the orbit insertion maneuver process chosen is more reliable, when compared to the procedure followed by Nasa.

“MAVEN upon reaching the designated Mars orbit will have only one chance to enter the the orbit, and if it does not do so, that will be the end. But we have an additional opportunity. In case we reach on September 24, 2014 and we are not able to perform the orbit insertion maneuver, we will have another opportunity after three days of orbiting Mars,” said MoM project director, M Annadurai.

According to Isro, when a spacecraft reaches the nearest point of Mars (peri-apsis), it is maneuvered into an elliptical orbit around Mars by firing the liquid engine. The spacecraft will then move around Mars in an orbit with a peri-apsis of 366 km and apo-apsis of about 80,000 km.

Annadurai said MAVEN will not have this opportunity, and is a huge advantage that MOM does, considering that a majority of earlier launched Mars missions failed during this stage. Russia, for instance, failed on its first 10 attempts, USA six times, while China is yet to enjoy success.

Gagan · Post by **Gagan** » 29 Nov 2013 20:59

The Desi media is being unfair here.
MAVEN is a very high tech mission.
MOM is India's first mars mission, and India wants to make maximum use of this opportunity.
But for the media to start doing comparisons, and denigrating one over the other is unfair to the hard work, mission planning that both space agencies have done. NASA has many missions in orbit and on the surface right now, and so their goals for MAVEN are different. ISRO's MOM / Mangalyaan mission objectives are different.

Why unnecessarily compare and indulge in one-upsmanship hain ji?

NRao · Post by **NRao** » 29 Nov 2013 21:03

It is a fair comparison. They are only talking of risks involved with each options. Let us see what happens.

Amber G. · Post by **Amber G.** » 29 Nov 2013 21:44

avinodhin wrote: Although Nasa’s Mars Atmosphere and Volatile EvolutioN (MAVEN) was launched 13 days before Isro’s Mars Orbiter Misison (MOM), it is expected to reach Mars’ orbit on Septmber 21, 2014 three days before the MOM.

Just a small comment, the total time (path) calculation can be tricky.. For example, famous Voyager 1 was launched about 2 weeks AFTER voyager 2, yet it reached Jupiter almost 4 months before Voyager 2 (and it reached Saturn about 10 months before).

Both spacecrafts and their paths were planned by the same group of scientists. .. (BTW the location of other planets were such that the gravity assist was able to reduce the amount of fuel bu a huge margin.. such optimum combination of planetary location might not happen for hundreds of year again so the timing and launch windows for those space-crafts were very crucial)

Lalmohan · Post by **Lalmohan** » 29 Nov 2013 22:21

voyager missions were done specifically to take advantage of the chance in a lifetime slingshot opportunity due to planet alignment

member_23832 · Post by **member_23832** » 29 Nov 2013 23:04

Mars Orbiter Mission successfully passes lethal radiation belts

HYDERABAD: Lethal radiation belts in the earth's inner magnestosphere are no cause for concern for Isro scientists as the Mars Orbiter Mission (MOM) has sufficient safeguards.

Isro scientists explained that the two doughnut shaped blankets that shroud the earth with highly charged plasma particles comprising of electrons, protons and nuclei are called Van Allen Radiation belts.

"MOM has successfully sustained several passes of these lethal radiation belts speculated to have been formed by furious solar winds and harmful cosmic rays," Isro scientists said. These belts are a part of earth's inner magnetosphere and stretch from an altitude of 1000 km to 60,000 km above the earth.

"Prolonged exposure to these belts poses a significant threat to various sensitive components of a spacecraft. MOM spacecraft is designed with sufficient safeguards against such fatal particles," Isro said.

http://timesofindia.indiatimes.com/home ... 590458.cms

Victor · Post by **Victor** » 30 Nov 2013 00:30

NRao wrote:It is a fair comparison...

Well in that case MAVEN loses on a couple of important points--it is using twice the fuel as MOM but has only one chance to get into Mars orbit while MOM has two. Sprinting off to Mars instead of walking there is a commendable goal if one is in a hurry, otherwise it is a waste of taxpayer money. Finally, if ISRO shot 8 MOMs for each MAVEN ($80mm vs $670mm), it is almost certain that ROI and success rate would be far higher than MAVEN's. I'm sure NASA and others are learning a thing or two from this.

Victor · Post by **Victor** » 30 Nov 2013 00:37

Mars orbiter spacecraft to leave Earth's orbit after midnight tomorrow

Indian Space Research Organisation is readying for a 'critical' Trans-Mars Injection (TMI) with firing of the 440 Newton liquid apogee motor (LAM) on board the Mars Orbiter Mission (MOM) spacecraft, launched on November 5, for 23 minutes beginning from 00.49 hours on Sunday (December 1).

Amber G. · Post by **Amber G.** » 30 Nov 2013 00:42

I think there is lot of sloppy analysis (or "explanations" regarding how/why about various trajectories .. and sloppy use of fancy words .. etc) in media (and even here in BRF)..

Hope some fundamental physics is helpful. (Please skip this post if you are not interested

)

First, Hohmann transfer "points" orbit etc, in purely simple terms is not three (or more) body problem ... not even two body problem but math is simple one-body problem. Basically if you want to change the orbit of an object, say from a smaller circular orbit to a larger circular orbit when a satellite is initially put in earths orbit at a lower altitude and the orbit is raised - you give delta-V to make the orbit elliptical (and then give another delta-V to make the orbit circular again)

In case of sending a probe to Mars, the focus of the orbit is NOT around earth, but around sun. You want to give a delta-V so that a probe which is going around Sun along the same orbit as earth, is to be "raised" so that it's orbit changes from circular to elliptical, such that it can go far and reach the orbit of Mars. (the relative velocity of Mangalyaan wrt to earth - a about 8-10 Km/sec (max) is still quite small compared to 30 Km/sec wrt to Sun - so for now, just think of it as an object which is in the same orbit as earth around sun)

So for about 99% of its journey, MOM is just like any other planet going around sun, in an elliptical orbit whose perigee lies near earth's orbit, and apogee lies near Mar's orbit. Also when at apogee, Mars will be at right position to "capture" (with the help of retro-rockets, if necessary) MOM and then it will move around Sun in near circular orbit keeping very close to Mars (actually orbiting it).

There are calculations which provides optimum timing. (or Minimum delta-V to get the desired result - Not necessary the shortest time span but the most fuel efficient etc)

For the most part of the journey of MOM one can almost neglect earth, Mars etd.. .. most of the calculation is based on Sun and if you calculate delta-V, time etc, you will not be far wrong from more sophisticated calculations. Of course, when MOM is relatively near to Earth (or later near to Mars), we have to take them into account, but for the most part of the journey, dominating force is force due to Sun. (Remember Sun's mass is about 0.3 million times earth - so once MOM is more than a few hundred thousand Kms from Earth - the dominating force is Sun's gravity)

With this, and simple calculation, one can show that time for this journey can be about 150 to 300 days, depending how much fuel (reasonably) you want to burn. Gravity assist can make a BIG difference on fuel. (IIRC first probe to Mars took about 160 days.. and average is about 250 days or so)

Gravity assist can make a very big difference. I already mentioned Voyager, but just to give an example, consider Cassini probe (please check it out for details ). It got gravity assist from Venus twice, then it got another assist from Earth, and then Jupiter on the way to Saturn. Extra delta-V needed was about 1/8 (about 2Km/sec vs 16m/sec - if my calculations are correct) of what would have needed from vanilla Hohmann transfer - it took a little longer going back to Venus and all that, but it was worth it as at time no rocket could have provided the needed deltta-V.

There are many references and good material for Hohmann transfer orbits but one of the good place to look to learn more about gravity assist is a very good article:
http://www2.esm.vt.edu/~sdross/papers/A ... st2006.pdf

SriKumar · Post by **SriKumar** » 30 Nov 2013 02:15

Amber G. wrote: http://ocw.mit.edu/courses/aeronautics- ... _Lec17.pdf One simple way to explain the whole idea of swinging by earth (or any planet - gravity assist or "slingshot" effect) without too much math is to say that this gravity assist "adds" the planet's velocity (actually approx. twice the planet's velocity) - with respect to sun - even if you burn very little fuel - remember earth is moving at the speed of 30Km/sec - so if you plan it right and burn the fuel at right point - (giving it right direction) and do it more times - you can get better delta-V... (This is why we have launch window's, timing etc.. so that things are as good as possible)

IOW, for simplicity assume a rocket is travelling with velocity +v, at certain point, (with respect to sun) approaching earth. If earth was not moving (with respect to sun) then after "rounding" the earth, (where it will become a little faster at perigee but will slow down again around the original point) it will return with same velocity .. -v. If earth is moving with speed U (again for simplicity, assume it is in the same direction) then the return velocity of the rocket will be (v+2U). (It is sort of elastic cricket ball hitting a bat, only if bat also moves then the rebound will be faster).

Of course, you are not not dealing with scalar quantities, but have to deal with vector calculus, as different directions are involved.. but in short it DOES matter how many times and when you burn the fuel.

As to "energy"... all this interaction changes NOT only the space craft's speed but also earth/mars speed (Not to mention all other bodies speed . Of course, earth's delta-V is very very very small (but earth is very massive so energy is not negligible)..so thinking in terms of energy only is not helpful to calculate how much fuel is required. In fact the whole calculation is quite complex and sometimes counter intuitive for common folks.
http://www2.jpl.nasa.gov/basics/bsf4-1.php Hope something is useful ..

Hi Amber G. Thanks for the links and explanations. The, 30 km/s forward movement of earth seems like it would would provide an additional assist each time it is used. Your analogy of elastic collision does help. But, it is not clear to my why this would provide a boost in the overall velocity since mangalyaan (and the PSLV) started on the earth and therefore would have the same initial velocity as earth's revolution ( i.e. 30 km/sec).

I can see how a different planet (or mass) can provide an acceleration to a satellite, because a new celestial body imposes a _new_ force on the satellite (i.e. a force that did not act on the satellite at the beginning) and this new force would provide a means to accelerate. I am treating earth and mangalyaan as a single, closed system, which is in equilibrium-both, before launch and during orbit. When the craft is launched from earth, it is already under the influence of earth-bound forces and has an initial velocity equal to earth's revolution speed (i.e. 30km/sec, though the vectorial direction is a little different each time the craft does an orbit and hits perigee). So, I am not sure what new force acts on it each time it 'rounds' the earth (in order to give it an extra delta v each time). I am focussing on 'new' source of force over and above pre-existing forces in a closed system- if this is incorrect, please let me know. As far as I can see, the rocket fuel (on PSLV or MOM) is the only source of new forces. (Using a spring-mass system as an analogy for gravitational forces; if I put in energy to stretch a spring, the resulting simple harmonic motion of the ~~spring-~~ mass ~~system~~will have the same max. velocity no matter how many times it oscillates) Am missing something here obviously…… Am looking through the links. THanks for that.

NRao · Post by **NRao** » 30 Nov 2013 02:30

I'm sure NASA and others are learning a thing or two from this

Apples and oranges.

I am not too sure, but, I do not think there is anything new in what either of them is doing as far as interstellar working go - the equations should be the same and known to both.

However, India has opted to re-use older systems and the US (and others) design new systems - which is one of the bigger reasons of the cost differences.

As far as why the US (and others) opted to use a riskier means to transit between the two bodies, I am not sure. But for sure it has contributed to more failures on their part and we have to wait to see what happens to the Indian sat. Since MOM has more than one chance to inject I would expect it to succeed - at least have a better chance.

BTW, ISRO used the same method for the moon shot too and it did very well.

NRao · Post by **NRao** » 30 Nov 2013 02:45

B TW, I had seen a graphic (since I was viewing it on my iPod I was unable to post it here and have since lost the URL), which showed that if the MOM was not captured by Mars, then MOM would return to the very position where it left earth. Once it leave the earth's orbit it goes into orbit around the Sun.

ArmenT · Post by **ArmenT** » 30 Nov 2013 03:53

avinodhin wrote:MOM has edge over MAVEN, say Isro scientists

http://www.dnaindia.com/india/report-mo ... ts-1926574

Comparisons between the Indian and American spacecrafts which have embarked on a mission to explore planet Mars is inevitable, and over the next 300 days, there will several of the.

Although Nasa’s Mars Atmosphere and Volatile EvolutioN (MAVEN) was launched 13 days before Isro’s Mars Orbiter Misison (MOM), it is expected to reach Mars’ orbit on Septmber 21, 2014 three days before the MOM.

There's a slight bit of DDMitis here. MAVEN was launched 13 days AFTER the MOM, not before.

Amber G. · Post by **Amber G.** » 30 Nov 2013 06:38

NRao wrote:B TW, I had seen a graphic (since I was viewing it on my iPod I was unable to post it here and have since lost the URL), which showed that if the MOM was not captured by Mars, then MOM would return to the very position where it left earth.

Yes, it will return to the same (almost) position where it last got the boost from the rocket (Dec 1 ?).. ( assuming there is no further rocket burn (mid course correction - or retro-firing near Mars) and it is not disturbed by other planets ..there will be small perturbation due to Jupiter, Mars (when the probe is close - you may get bigger effect), Earth and Venus but the perturbation will indeed be small)

Once it leave the earth's orbit it goes into orbit around the Sun.

It is/was always into orbit around the Sun! - even when it was sitting at the launch pad - just like earth.. Even while "orbiting" the earth, any one looking out from outside (wrt to sun) the motion is more or less orbit around the Sun.

( Remember few km/sec - speed relative to earth - is quite smaller than 30Km/sec - and few hundred thousand km is small wrt to earth-sun distance..)

SaiK · Post by **SaiK** » 30 Nov 2013 06:45

i hope we are getting ready tuning our deep space communication setup at byalalu, ka. .. also i read, nasa going to help us in this regard.. the only thing i am not clear is to what level nasa is going to play role in deep space comms. i was totally excited about our own deep space comm network, till i read that info (i posted few pages back).

anyone?