Mangalyaan: ISRO's Mars Orbiter Mission

Amber G. · Post by **Amber G.** » 20 Sep 2014 09:19

PRajaram wrote:...

SriKumar seems to have researched and found the same graphic that I was looking at...

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.
.

Sorry did not see this post, yes you are right, as I posted before, the orbits of the 2 missions are almost same (in fact if one draws them on scale on a computer screen, it will be difficult to see the difference)..Remember, 1 million Km is less than 1% the total size of the orbit..

Of course, when it comes to MOI, one is not looking at the big picture, but what happens close to Mars..so there is much more "zooming" and one has to be very accurate...

SSSalvi · Post by **SSSalvi** » 20 Sep 2014 09:42

^^^
It is NOT that MAVEN and MOM TOOK different TMI orbits ... The TMI orbits were DESIGNED to suit their respective goals. There are at least a dozen possibilities in which the craft will go from Earth to Mars .. but each will intersect with Mars orbit in different fashions.

Actually the Trans Martian Orbits of both crafts were chosen to match their final required orbits around Mars.
( In fact the orbit raising after PSLV launch was done with perigee in Pacific ocean south of equator was also a part of final Martian orbit )
The injections are in the SAME planes as their FINAL Martian orbits. There is no ( purposefully introduced ) deviation to place the crafts in their respective orbits.

SSSalvi · Post by **SSSalvi** » 20 Sep 2014 10:22

Chosen a easy way out to show why there is no occulation/eclipse. Used 'NASA Eyes' program to generate this graphic.

MAVEN is always in sunlight and is in visibility with Earth during MOI.( Sun and Earth are behind reader ) whereas MOM is in shadow region during TMI

juvva · Post by **juvva** » 20 Sep 2014 11:16

MOM is ready for MOI ( from MOM's FB page):

dinesha · Post by **dinesha** » 20 Sep 2014 13:43

How challenging would it have been for the MOM team to target the Orbit similar to that of Maven's 150Km-6500KM. Was this limited by the extra fuel requirement, volume of the tanks and the payload fairing weight of the PSLV? Did the fuel consumed during the Orbit raising maneuver around the earth made the difference for the final achievable orbit around Mars?

harbans · Post by **harbans** » 20 Sep 2014 16:48

( In fact the orbit raising after PSLV launch was done with perigee in Pacific ocean south of equator was also a part of final Martian orbit )

Was thinking before if any part of the early escape maneuvers were done with the final orbit insertion calculations in mind..did cross my mind, but never knew it was part of it. Such details and a good step by step documentary should have been up in MSM prime time now really enthusing kids and many about this historic endeavour. But sadly they are more interested in discussing some inconsequential crap. Next few days i will park myself on this topic on BRF for news, updates, analysis (much to learn from the stalwarts here), ISRO and Emilys blog.

csaurabh · Post by **csaurabh** » 20 Sep 2014 18:16

dinesha wrote:How challenging would it have been for the MOM team to target the Orbit similar to that of Maven's 150Km-6500KM. Was this limited by the extra fuel requirement, volume of the tanks and the payload fairing weight of the PSLV? Did the fuel consumed during the Orbit raising maneuver around the earth made the difference for the final achievable orbit around Mars?

It is a matter of thrust and weight related calculations. Maven engine delivers over 1000 N of thrust, MOM is only 440.

girish.r · Post by **girish.r** » 20 Sep 2014 18:28

MOM will fail onlee.

SSSalvi · Post by **SSSalvi** » 20 Sep 2014 20:39

Dilbu wrote:MOM will fail onlee.

girish.r wrote:MOM will fail onlee.

BTW, both using exact expression , 'onlee' reduced 3 cry smilies to 1 , good

.

Fall? Where?

Have dinner with your words friend. You have to eat those.

Unfortunately, .. even if they fail to reduce the speed of MOM, it will NOT fall but will go in hyperbolic orbit.

( let me confess .. when they first announced Mars mission my thoughts were not much different than those I posted in the post at top of this page. But after they released first details of operations plan then skepticism rediced by over 70% )

I am sure they will have plan B .. Firstly .. ( If I was the driver of MOM Taxi ) I would have simply turned my camera to Mars and clicked a few shots. After all my cameras were designed for 80000 kms orbit.

Secondly, .. (and this would have been more sensible ) even in hyperbolic orbit I can have time to retry and achieve some other orbit around Mars ( after all Mars has gravitational field as far as half a million kms )
-----------

This was in lighter mood but if I, as a man on street as far as Mars mission is concerned , can think of these alternatives to overcome the catastrophe I am sure mission planner would have thought of other learned alternatives to this situation and already have algorithms ready for it.

putnanja · Post by **putnanja** » 20 Sep 2014 20:47

SSSalvi, I think you don't understand our BR anti-jinx expert Dilbu! It is an anti-jinx to make sure things go smoothly

. it has worked on cricket matches, recent elections etc, don't underestimate it

Picklu · Post by **Picklu** » 20 Sep 2014 20:49

Arre sirji subh subh bolo

MOM will fail onlyeeeee

Dilbu · Post by **Dilbu** » 20 Sep 2014 20:58

Naheee. Zor se bolo. MOM will fail onlee.

member_20317 · Post by **member_20317** » 20 Sep 2014 21:01

@SSSalvi Saar - These people are only Nazarbattus. To remove Ku-Drishti, Buri-Nazar.

They would not have been required had ISRO cared to put this on the Mangalyaan.

...................................

But more seriously there used to be something said about the usage of lasers to power spacecraft with giant mirrors on them. They were said to have steadily increasing acceleration entirely regardless of the mass of the spacecraft.

I am saying this because I think I am stuck with some theory. Why should engine size (1000 KN vs. 440 KN) matter? You can always fire a smaller rocket for longer before the MoM is captured in Mars gravity. Mass and thrust probably would matter only after the capture. Though yes the overall mass of the spacecraft that the PSLV can manage vs. the Amerikhan rocket should matter because then the larger Amerikhan rocket can simply put more fuel too besides a more powerful engine in which case it can keep its engines going longer.

csaurabh wrote:
dinesha wrote:How challenging would it have been for the MOM team to target the Orbit similar to that of Maven's 150Km-6500KM. Was this limited by the extra fuel requirement, volume of the tanks and the payload fairing weight of the PSLV? Did the fuel consumed during the Orbit raising maneuver around the earth made the difference for the final achievable orbit around Mars?
It is a matter of thrust and weight related calculations. Maven engine delivers over 1000 N of thrust, MOM is only 440.

.........................

Or am i just squatting on the thread.....

Vashishtha · Post by **Vashishtha** » 20 Sep 2014 21:08

But more seriously there used to be something said about the usage of lasers to power spacecraft with giant mirrors on them. They were said to have steadily increasing acceleration entirely regardless of the mass of the spacecraft.

Those are called Solar Sails.. They use the energy of photons bouncing off their surface to propel the payload farther.. However, one needs very large surface areas to capture just about enough photons.. Also, the acceleration is extremely slow and although it doesn't need "fuel" or rockets, one must allow for enough time (in days) for it to achieve any meaningful velocity. The tech is good for economical interstellar and interplanetary travel travel.
Solar Sails principles

SSSalvi · Post by **SSSalvi** » 20 Sep 2014 21:14

dinesha wrote:How challenging would it have been for the MOM team to target the Orbit similar to that of Maven's 150Km-6500KM. Was this limited by the extra fuel requirement, volume of the tanks and the payload fairing weight of the PSLV? Did the fuel consumed during the Orbit raising maneuver around the earth made the difference for the final achievable orbit around Mars?

The final achievable orbit was defined before the extra fuel consumed during and subsequent correction while raising 6 step orbit maneuver.

Penalty now may be a reduced timeline. ( but do not forget .. we Indians have a habit of always keeping 'little little' margin for ....' just in case.. ' ) .. they might have put thoda jyada fuel than actually required for worst case mission life.

@ Ravi-g

Good suggestion in your photo. Send it to them whose route from Bangalore to SHAR passes through a stop in between before every launch.

girish.r · Post by **girish.r** » 20 Sep 2014 22:02

girish.r wrote:MOM will fail onlee.

BTW, both using exact expression , 'onlee' reduced 3 cry smilies to 1 , good .

For what its worth, you caught my ctrl+c, ctrl+x with 2 backspaces.

But, it will fail onlee

SSSalvi · Post by **SSSalvi** » 20 Sep 2014 22:17

^^^
Amen ( so be it )

My last on this topic with you. Bye Dear, TC

harbans · Post by **harbans** » 20 Sep 2014 23:15

Salvi Ji, can you refer to any resources/blogs/forums that will be covering this historic event, Indian and Foreign. I am/ will be looking at ISRO site, BRF of course, Emilys Planetary blog, NASA spaceflight forum. This week will be gripping excitement at this historical achievement..don't want to miss on any bytes.

SSSalvi · Post by **SSSalvi** » 20 Sep 2014 23:53

^^^
The four that you mentioned are good enough .. for near real time updates ISRO's MOM specific Facebook ( Der aye durust aye .. at last ISRO PR has taken up the task of info flow. ) is good.

If interested in seeing the simulated situations of most of the space based objects then download 'NASA Eyes' simulator. It gives excellent view of things ( one sample is my earlier post showing why there is no eclipse during MAVEN MOI.)

Amber G. · Post by **Amber G.** » 21 Sep 2014 00:24

^^^ Sorry if posted before and people may already know it but Sankaranarayanan site...using the NASA data ... (Since MOM's data is public knowledge etc) Check this out.. (Very nice)
http://sankara.net/mom.html

(The orbital elements were last refreshed some times ago, and hopefully latest upto-date will be loaded soon.. but still the predicted orbits are , of course, very accurate )

(You can set any time..(from past to future-till sept 25.. zoom in and out.. and much more)

Enjoy.

SaiK · Post by **SaiK** » 21 Sep 2014 01:16

^why does the animation show same path for both mom & maven? may be the launch in the animation is launch + x days when both got into the same orbit. ?

Amber G. · Post by **Amber G.** » 21 Sep 2014 01:31

^^^ Zoom to appropriate level and set the time... for example around the launch time, while MOM is still going in elliptical orbits, MAVEN is is own its way to Mars.. You can set the time (now, launch, or MOI etc to get different times, and you can set the frame of reference (sun or earth)). The output (like Nasa Eyes - it is getting the same accurate data) is mathematically quite correct.

(Also remember, for perspective, 1 million Km is less than a 1% in the grand scale..

. MOM is moving more than 1000 Km in a minute.. etc... so scale is very important...If Maven and MOM's orbits are drawn, as I said before, on a piece of 8x10 paper the difference in their shapes will be hardly noticeable)

SaiK · Post by **SaiK** » 21 Sep 2014 01:35

well.. i was expecting the sling shots!

Amber G. · Post by **Amber G.** » 21 Sep 2014 03:03

dinesha wrote:How challenging would it have been for the MOM team to target the Orbit similar to that of Maven's 150Km-6500KM. Was this limited by the extra fuel requirement, volume of the tanks and the payload fairing weight of the PSLV? Did the fuel consumed during the Orbit raising maneuver around the earth made the difference for the final achievable orbit around Mars?

Here is my perspective.

First the MOM's selected orbit is not necessary because we can not do 150Km-6500Km orbit, but what we wanted to do.. with the resources we have (and keep some of it in reserve etc), and what our mission objectives are, a more elliptical orbit was decided...The orbit was NOT decided merely because it is the best one can achieve.

For a purely a technical exercise, the MOM's rockets, (and remaining fuel) can produce a more closer (as close as MAVEN or even closer) and more circular orbit - that is if my calculations are not grossly inaccurate . Having said that, I would rather be safe and conservative (very conservative) than fool-hardy just to achieve closer orbit. .. May be my CH4 detecting equipment works well at 1000 Km (and does not need to go at 200 Km)...And I will conserve/save fuel for orienting those high-gain antenas or other stuffs. May be I don't want to take a chance, and push my navigational and control system to their limits... What MOM wants to do (as CLEARY stated in its mission statement) is to validate (and learn) all the existing systems for future space flights. ... One certainly does not want to take any unnecessary chance.

But who knows --- may be in a few months from now, if the side thrusters still have fuel, and MOM has achieved all its objectives.. and still can have some fuel in reserve to adjust antenas etc...and powers to be tell the engineers it is ok.. at some point (at perigee) one may decide to fire rockets -- (after all one would need only a few Km/sec delta-V) and go closer to the surface..

( Such things have happened in past in a few other missions)... After all, if we are going to be in the vicinity for a long time, we will have more time to think about such things.

For perspective, if the main rockets fail, the side thrusters are good enough to produce a delta-V to put MOM in mars's orbit, and as current plan, they will be used in this scenario...So if all those nimbu-mirchee work, may be the the main rocket fail

and achieves the required delta-V and those small rockets could be used later, to make MOM fail even more..

(remember, for rough calculation the escape velocity on Mars surface is about 5Km/sec - so you need a small delta-v for orbit maneuvers)

SwamyG · Post by **SwamyG** » 21 Sep 2014 06:46

NASA TV is going to have live coverage of MAVEN tomorrow at about 8:30am CST.

SwamyG · Post by **SwamyG** » 21 Sep 2014 07:06

Good to read an article on ISRO, without people living on less than $2 day stuff.

http://en.ria.ru/analysis/20140917/1930 ... ce-or.html

Dr. Morris Jones, a space science commentator and writer, explained to Radio VR that there was a purely technical reason why both missions are set to arrive at Martian orbit at practically the same time.

“The reason these missions are both arriving at orbit roughly at the same time is because of orbital mechanics,” he said. “They were both launched at roughly the same time when the Earth and Mars were in a very good position for flying quickly between the two planets; that’s why you see more than one mission flying to Mars.”

The cost of the project is surprisingly low: 4.5 billion rupees, or $70 million, not at all pricey compared to America’s space ventures. For comparison, NASA spent $671 million on its MAVEN spacecraft.

Prof. Bell thinks that if India’s Mission is successful, it will demonstrate that lower-cost ways to get there are possible and feasible.

“It opens up space exploration to more countries who can’t afford to spend giant fractions of their gross national product on space exploration but who want to spend the most [they can] to demonstrate that they are technologically advanced, to demonstrate that they have the capability to be space nation,” he said.

“And this is important, this is extremely inspirational to the citizens of a nation. It means the inspiration, motivation and education it provides, especially to the young people in countries that do this. It is just incredibly valuable. It inspires people to go on to understand science and technology, engineering and mathematics, and computers that will lift up the whole country technologically in ways that are very intangible,” he added.

Dr. Jones, however, thinks that we are seeing the makings of a new space race; not between the US and Russia but between the countries of Asia

Dilbu, please do overtime here onlee. Forget other threads.

csaurabh · Post by **csaurabh** » 21 Sep 2014 07:25

SaiK wrote:^why does the animation show same path for both mom & maven? may be the launch in the animation is launch + x days when both got into the same orbit. ?

It is the same path actually. That is determined by orbital mechanics. MoM and Maven use the same launch window ( it is available for a few days once every two years approx ).

ravi_g wrote: I am saying this because I think I am stuck with some theory. Why should engine size (1000 KN vs. 440 KN) matter? You can always fire a smaller rocket for longer before the MoM is captured in Mars gravity. Mass and thrust probably would matter only after the capture. Though yes the overall mass of the spacecraft that the PSLV can manage vs. the Amerikhan rocket should matter because then the larger Amerikhan rocket can simply put more fuel too besides a more powerful engine in which case it can keep its engines going longer.

This is correct. Maven also has a bigger fuel tank. It is all about the delta v produced, which depends on thrust and burn time.
also that is not kN but N. Even jumbo jet engines can't produce 440 kN thrust!

ravar · Post by **ravar** » 21 Sep 2014 09:26

Interesting to note that ISRO chose MOI with MangalyAn in the blind i.e., from T +5 to T+ 30.43 minutes, there is NO telemetry.

Newbie question- is there any option of recording the data by the spacecraft during the blind period and transmitting it back once the telemetry resumes? (ISRO can surely use the data to fine-tune its simulation models in future) TIA.

Amber G. · Post by **Amber G.** » 21 Sep 2014 09:28

csaurabh wrote:
.... Even jumbo jet engines can't produce 440 kN thrust!

Just for perspective, a big jet (say a 777, I took last time) indeed can produce about that much... (largest ones top at around 500 kN )
Space shuttle (each of its three engines) - about 2 million N or 2MN, while its rocket boosters about 20MN.

The EVA thrusters (the kind you saw in the movie Gravity) could produce about 4N..
(to lift the meat of a quarter pounder at local McD is about a N - that's why some people call it a "newton-burger"). 440N is the force require to lift a young adult (of about 44 Kg).

Amber G. · Post by **Amber G.** » 21 Sep 2014 09:36

ravar wrote:Interesting to note that ISRO chose MOI with MangalyAn in the blind i.e., from T +5 to T+ 30.43 minutes, there is NO telemetry.

Newbie question- is there any option of recording the data by the spacecraft during the blind period and transmitting it back once the telemetry resumes? (ISRO can surely use the data to fine-tune its simulation models in future) TIA.

Indeed one of the primary mission objective is to record that data and send it to earth and analyze it for future. (Rest assured, many routine things, eg good photographs of known objects with the background of stars - to pinpoint position, etc will be sent too)

BTW, "blind or not blind" makes no difference here. MOM must be able to act and depend on it's own computer as the radio delay time is about 12 MINUTES. .. (It will take about 24 minutes for roundtrip of radio signal !)

bharats · Post by **bharats** » 21 Sep 2014 11:23

ISRO’s priorities not right…!

“My personal opinion is: this (Mars mission) is not a big priority project for us. We should have concentrated more on qualifying the cryogenic engine (for GSLV-Geosynchronous Satellite Launch Vehicle) and make our manned mission initiative move forward,”
-former ISRO chief G Madhavan Nair
Read full at: http://tech.firstpost.com/news-analysis ... 11076.html

An old article published in firstpost in 2012 but has not lost relevance in todays’ context.

Interplanetary probes Chandrayaan and Mangalyaan - at what cost to INDIA?
Many of us realize the interplanetary probes development cost as the total cost of the project. In reality, there are secondary costs associate with these projects. There are costs which include the number of hours our best program managers and engineers minds spend on these projects. The alarming factor is while doing so; the best minds are deprived for critical and vital projects which augment the very existence of ISRO. ISRO should rather focus its energy on qualifying the indigenous cryogenic engine and stage for GSLV (rocket) as also for GSLV-Mk III, which is being developed to carry four-tonne class of satellites.
Skewed mission- Every interplanetary mission has two objectives. One of them is an engineering objective and another scientific. ISRO is not very determinative on what scientific objective it could achieve with limited payload capability to Martian orbit. Indian scientific community merit more and ISRO could have done real science with higher payload capabilities to orbit. This could have achieved only through better rocket, and ISRO could not live with PSLV forever as this is not a silver bullet for all INDIA needs. ISRO rocket engineers knew these and are tight-lipped as the leadership focus in on now shifted to road shows rather real scientific research.

What happens next?
ISRO critical core competency projects are delayed to the extent as our program managers and engineers are being utilized for inter-planetary engagements. Because of these ISRO has limited time for developmental projects that would have saved millions thru foreign exchange and ISRO could have saved in indigenization projects and the cost required for foreign launchers. This observation is corroborated as ISRO could not get GSLV Mark 3 lift off on time. ISRO is not required to show the world that it could do, until they achieve the core competencies. In real world it’s more like painting a wall before plastering.

What ISRO need now?
ISRO need a refocus of its leadership. ISRO has a leadership vacuum and is in dire need a visionary leader as Prof. Satish Dawan known for his great leadership. Prof. Satish Dawan was focused on the core competency development and his efforts were pivotal for ISRO for its solid propulsion technology as we seen today. Though he is often criticized of of detrimental to cryogenic technology development projects, once would understand that the limited resources ISRO had in 70 and 80s, he aligned all resources to achieve the sole mission of solid propulsion capability, which was the need of the hour. ISRO needs a leader who focuses on core capabilities building rather than public stunts.

Do ISRO ever need interplanetary probes?
Answer is yes, but time is not right. ISRO need more to do at house rather than showing on the roads. ISRO should venture in to interplanetary traveling after building core competency at house. There is no rush, as losing priorities would cost precious to ISRO in the long run with the limited gains ISRO achieve today. And more alarmed that ISRO has more similar projects like interplanetary probe to Sun, and engaging similar would forever deprive or delay the great minds from ongoing core competency projects.
INDIA being a developing country, ISRO priorities are skewed and need a path correction. In a nutshell, ISRO need priority focus on core competency development on rocket propulsion, capacity building in communication and remote sensing satellites rather invest in inter-planetary travels.

Yagnasri · Post by **Yagnasri** » 21 Sep 2014 12:14

Why not the nation has some desire to have project its soft power. If all goes well India is the 3rd nation to this kind of mission along with Russia and Khan. China failed. May that is also a worth while things to do.

rsingh · Post by **rsingh** » 21 Sep 2014 12:35

Amber G. wrote:
ravar wrote:Interesting to note that ISRO chose MOI with MangalyAn in the blind i.e., from T +5 to T+ 30.43 minutes, there is NO telemetry.

Newbie question- is there any option of recording the data by the spacecraft during the blind period and transmitting it back once the telemetry resumes? (ISRO can surely use the data to fine-tune its simulation models in future) TIA.
Indeed one of the primary mission objective is to record that data and send it to earth and analyze it for future. (Rest assured, many routine things, eg good photographs of known objects with the background of stars - to pinpoint position, etc will be sent too)

BTW, "blind or not blind" makes no difference here. MOM must be able to act and depend on it's own computer as the radio delay time is about 12 MINUTES. .. (It will take about 24 minutes for roundtrip of radio signal !)

Pardon ? Is there any pic of known objects with background of stars? I missed that. I used to think that brightness contrast is so much that if you take pic of mars horizon or moon ………..you do not get stars in the same frame.

bharats · Post by **bharats** » 21 Sep 2014 13:00

Narayana Rao wrote:Why not the nation has some desire to have project its soft power. If all goes well India is the 3rd nation to this kind of mission along with Russia and Khan. China failed. May that is also a worth while things to do.

Projection of soft power is good thing to do, not a must at the cost of capacity building in terms of core competency build-up. The worthiness of any projects has to be attributed to the Return on Investments (ROI); in terms of what research ability it brings back to Indian scientific community and benefit as a whole to taxpayers. IMHO, it is not worth to invest extravagant interplanetary travel at the cost of developmental projects.

partha · Post by **partha** » 21 Sep 2014 13:00

With due respects to Shri Madhavan Nair, while reading his criticisms about ISRO, do keep in mind that he is not in good terms with current ISRO chief.

rsingh · Post by **rsingh** » 21 Sep 2014 13:26

bharats wrote:
Narayana Rao wrote:Why not the nation has some desire to have project its soft power. If all goes well India is the 3rd nation to this kind of mission along with Russia and Khan. China failed. May that is also a worth while things to do.
Projection of soft power is good thing to do, not a must at the cost of capacity building in terms of core competency build-up. The worthiness of any projects has to be attributed to the Return on Investments (ROI); in terms of what research ability it brings back to Indian scientific community and benefit as a whole to taxpayers. IMHO, it is not worth to invest extravagant interplanetary travel at the cost of developmental projects.

ISRO is profitable. It is far better then AI sinkhole. India has cheapest communication network in the world that rally works…….;because we have our own satellites. It provides vital secure communication for our force. You have no idea how big players are our remote sensing satellites are.These are everywhere from crop output estimation to damage estimation of crops. What is this strange logic that if there are poor people in country then we have to spend more money to buy modern technology from other countries to help our poors? Please do not criticise just because it is going trend to criticise everything Indian to be taken seriously. Get you facts right. Read Indian press and not necessarily English one.

ravar · Post by **ravar** » 21 Sep 2014 13:46

Amber G. wrote:
ravar wrote:Interesting to note that ISRO chose MOI with MangalyAn in the blind i.e., from T +5 to T+ 30.43 minutes, there is NO telemetry.

Newbie question- is there any option of recording the data by the spacecraft during the blind period and transmitting it back once the telemetry resumes? (ISRO can surely use the data to fine-tune its simulation models in future) TIA.
Indeed one of the primary mission objective is to record that data and send it to earth and analyze it for future. (Rest assured, many routine things, eg good photographs of known objects with the background of stars - to pinpoint position, etc will be sent too)

BTW, "blind or not blind" makes no difference here. MOM must be able to act and depend on it's own computer as the radio delay time is about 12 MINUTES. .. (It will take about 24 minutes for roundtrip of radio signal !)

Amber ji, thanks for the reply.

But I believe there is a crucial difference. In the event of MAVEN not making its MOI properly (i.e., crashing onto Mars), NASA will be able to get all the data until the last moment that telemetry is possible of what went wrong since they are not in the blind. They will have a good learning curve even if their MOI is a failure.

Obviously, this luxury is not available to ISRO since they are in the blind during MOI. If something wrong happens, they will not have access to the crucial data to fine-tune another MOI for MangalyAn-2.

IOW, we will have MOI data only if MOI is successful. Am I right?

member_28108 · Post by **member_28108** » 21 Sep 2014 14:24

Actually barring a crash we will still get data after the occult even if it is a flyby.
As far as the criticism of Mangalyaan it is practically a nonsensical argument. The amount learnt and information gained so far itself is hugely instructive. It is myopic to think that this hasn't been of benefit. While people argue of social uses dare I say socialistic uses let us not forget that these interplanetary missions have enthused and spiked recruitment to ISRO. Money is not the only attractant to a job and if ISRO's pay is less than private there must be something else to attract talent. Also don't forget the stupendous amount of learning in ranging, communication and autonomy that has already been acquired. Saying India is not ready for it is a specious argument. Those who dream and dare reap benefits. Talking of India's poor isn't ISRO generating income and to be rewarded rather than other sink holes in society. We waste millions to elect a$$ holes and crib when scientist struggle.
We spend millions and don't crib about cricket matches and film budgets but don't want to give pride and be proud of our scientists.

bharats · Post by **bharats** » 21 Sep 2014 14:50

prasannasimha wrote:Actually barring a crash we will still get data after the occult even if it is a flyby.
As far as the criticism of Mangalyaan it is practically a nonsensical argument. The amount learnt and information gained so far itself is hugely instructive. It is myopic to think that this hasn't been of benefit. While people argue of social uses dare I say socialistic uses let us not forget that these interplanetary missions have enthused and spiked recruitment to ISRO. Money is not the only attractant to a job and if ISRO's pay is less than private there must be something else to attract talent. Also don't forget the stupendous amount of learning in ranging, communication and autonomy that has already been acquired. Saying India is not ready for it is a specious argument. Those who dream and dare reap benefits. Talking of India's poor isn't ISRO generating income and to be rewarded rather than other sink holes in society. We waste millions to elect a$$ holes and crib when scientist struggle.
We spend millions and don't crib about cricket matches and film budgets but don't want to give pride and be proud of our scientists.

The review above is not a re- posting from firstpost, It is my critical evaluation of ISRO, its past and current activities and benefits. As an ardent fan of ISRO, I aspire to bring a perspective on what ISRO shall be doing and not to be doing.

My view, ISRO do not need to disguise Mangalyaan interplanetary probe as a science mission, where the knowledge potential its current payload might bring is by now existing in the international scientific community. At the same time I would not deny the fact that Martian interplanetary mission would bring challenges and learning to our engineers. And it is an un-denying fact that the scientific community in ISRO and external agrees that ISRO could have done better service to scientific community with better payloads had been our GSLV in service.

So, If ISRO need to sustain, a change in focus is the need of the hour. ISRO need to re-prioritize and bring back our rocket propulsion engineering to pace, and also reduce the communication transponders deficit in INDIA. There are other priorities as well which shall come before any interplanetary or sun or asteroid missions. Successful GSLV missions not only has a commercial gain and save foreign exchange in INSAT series satellite launch cost abroad but also more inland launches would give more trust and credibility to our space program partners from availing launch services from ISRO. I believe the soft achievements like Chandaryaan and Mangalyaan could never replace the above, as GEO capability simply would not exist for commercial purpose today. Also ISRO need more research to go on Unified Launch Vehicle (ULV) and semi-cryogenics and simply cannot lock best engineering minds on missions which give lesser Return on Investments (ROI) to society.

And profitability is only a matter of fact or point in time. For a skewed goal, the profitability would be lost in no time. What ISRO reaps today including our communication satellites and constellation of remote sensing satellites are outcome of meticulous planning and remarkable work done by great visionaries and leaders ISRO had in the past. All my point is now ISRO is losing or lost its focus; as deficit on transponder and launch capabilities are no longer appears to be on ISRO priority list, and is a cause of concern. Even ISRO state they are, it simply cannot; and we should also know that ISRO is a Centre of Excellence (COE), but that doesn’t mean that ISRO has access to have unlimited engineering minds. There is a deficit and we need to prioritize to sustain and lead.

Also I have never implied that ‘poor people in country then we have to spend more money to buy modern technology from other countries to help our poors’, What my point is if we wanted to give more back to poor we should invest more of critical and vital technologies rather on extravagant interplanetary probes. As in the current configuration Mangalyaan is going to give limited justice to Indian scientific community as well to the tax payers. Also I cannot completely agree that interplanetary probes would enlighten the youth and some might prefer to work for ISRO, as this could well be equally said for rocket launch capabilities and other innovation in space science as well.

And focus of my write-up was not to support Shri Madhavan Nair, though could not repudiate the fact that ISRO had good progress in rocket propulsion in his tenure. At the same time we cannot ignore the need a leader like Prof. Saish Dawan to bring glory and splendour back to ISRO.

Ashokk · Post by **Ashokk** » 21 Sep 2014 15:43

Lots of interesting nuggets so quoting in full...
Mars Orbiter Mission is on stable trajectory: ISRO chief

With the upcoming crucial manoeuvre of Mars Orbit Insertion (MOI) of ISRO’s Mars Orbiter Mission (MOM) in the early hours of September 24, R. Ramachandran caught up with the ISRO chairman Dr. K. Radhakrishnan in New Delhi and had a one-on-one talk on the preparedness for the D-Day.

Excerpts from the interview:

What is the current state of preparation for Mars Orbit Insertion (MOI) manoeuvre on September 24?

On September 14th and 15th we uploaded the commands for the MOI. During the uploading process we verified them and after uploading everything we again went through the reading of all those commands. These are the commands for Plan A of the MOI manoeuvre. The idea is that all the commands are sitting in the spacecraft’s command processor and any major problem in the ground to satellite link will not affect the firing. The commands are time-tagged.

Plan A involves the main thruster engine, the 440 Newton Liquid Apogee Motor (LAM), and eight small thrusters (22 N) working together for nearly 24 min. That is the nominal plan. We have also uploaded a possible Plan B if it has to be exercised.

What would Plan B be?

Plan B would be the firing of small thrusters alone for a longer duration. But that would be decided after September 22 if it is essential. On September 22 we are going to have a test firing of the main LAM for nearly 4 sec. LAM was used for the initial six orbit raising (around the earth) operations as well as the Trans-Mars Injection (TMI) manoeuvre on December 1, 2013. After that it has not been used for nearly 10 months. The two Mars Transfer Trajectory (MTT) mid-course corrections that were done on December 11, 2013, and June 11, 2014, were done only with the small thrusters. Small thrusters are working; there is no issue. What we are now looking at is the working of the main engine. [See Fig. 1 for the Mars Orbiter Mission Trajectory so far.]

So what steps have been taken to ensure that?

If you look at the fluid circuit all the flow lines coming from the fuel and oxidizer tanks to the main engine have two sets; each flow line has a second parallel path as well. Normally we have only one circuit. What is involved in the process here is, [after the initial operations] the first set was closed. Now the second set has to be energized. What we have to establish is that without any interruption fluid will pass through the second set of flow lines and reach the main engine. For the thrusters, however, fuel and oxidizer are tapped from a different point in the circuit and these flow lines were never closed and were always working as the thrusters were required for MTT corrections. Since we know from the corrections done that these Attitude and Orbit Correction (AOC) thrusters are working, these will always be available.

As for Plan A two things have to happen for the firing to take place. The solenoid coil igniter (there is a redundant second coil as well) above the main engine has to work and the flow lines have to be clear for the fuel and oxidizer to reach the engine simultaneously. Otherwise everything will be stuck.

Now there is some pressure in both the fuel and oxidizer tanks. We have seen on the ground that with this amount of pressure the entire operation works. Before the launch of the orbiter itself in 2013 we had the live test of an identical LAM engine. This LAM engine is the same as that we have been using for our Geostationary Orbit missions and this was also used in the Chandrayaan-1 mission after a gap. Now also we have seen that on the ground the engine operates after a long gap. Hardware identical to what is in the orbiter has been tested after a year-long gap. So, on the ground we have live tested for the restart of the engine after a long gap. This was actually completed last month.

Secondly we have also simulated the D-day firing with the propulsion parameters on that day – the tank ullage volume, the pressure, the temperature etc. – for nearly 2000 sec, which is more than the 1500 sec or so required for actual firing, and we have seen how it works. So that guarantee is also there. This was also done last month.

If there is a problem even then, these thrusters will be fired for a longer duration of 90 min. But the middle point of the firing arc will remain the same; only that we have to start early. But we will not get the same performance with Plan B. It will not be the same planned orbit.

The basic issue is you have to see that the pressure in the tanks is sufficient for the entire operation; it should not fall below a critical value of 11-12 bar. [1 bar is about one atmosphere pressure.] If it goes below this level you will not get the required performance. Right now the pressurization system above the propellant tanks – the pressurant tank (with very high pressure) and the two pressure regulators – have been isolated which normally come into the pictures only if the pressure falls below 11 bar. It was a conscious thought out decision to shut the system out and we find that there is no need for them as the pressure now in the tanks is being is at the optimum level of 16.5 bar. And we have tested on the ground the fuel-oxidizer flow performance in the ‘blow down’ mode [where the pressure is allowed to drop gradually from 16 bar] and we have seen that the pressure does not fall below the critical level even after the full firing of about 2000 sec as against 1500 sec during the actual firing. So if the flow takes place there is no issue. But if required at any point the pressurization system can be activated.

There was a planned trajectory correction on September 14. But this doesn’t seem to have been done. Why?

Now when the spacecraft will arrive in the vicinity of Mars, we have been talking about a distance of 500 km plus or minus something like 60 km. If we see the way it is going now the distance will be about 720 km. Our daily calculations also indicate that the trajectory is stable…

How did this gap of 200-odd kilometers arise? I though you were maintaining the error margin of 50 km all through and that is why the planned April correction could wait to be carried out instead in June.

At TMI we took one route that should take us to about 500 km from Mars. To achieve this only we make those minor trajectory corrections. In the original plan we had provided for four corrections. The first was December 11, 2013; the second one was scheduled for April, the third in August and the fourth in September. We did not do the correction in April because it was felt that the spacecraft trajectory was steady and did not need any correction then. We then did the second correction on June 11. The question then was whether we required one in August. We found that there was no need for it because, without the August correction, the trajectory was going to be about only 700 km away from Mars.

[An altitude of] 700 km is a good number because as long as you don't come too close to about 200 km or it goes farther to about 1100 km so that it escapes Mars altogether, we are safe actually. So we didn't want to tinker unless it was essential and in any case September 14 option was available. And if we had done that we would have fired the small thrusters and that correction would have already brought the orbiter to about 500 km. But we did not do the September correction and instead what we have decided to do is to restart the LAM on September 22 when the orbiter will enter the sphere of influence of Mars. This firing, which will last only for about 4 sec, will impart some correction to the trajectory enough to bring the trajectory approximately to 500 km. So instead of firing small thrusters for a longer duration, and earlier, we will be doing it with the main engine on the 22nd for 4 sec.

Why four seconds? There are two considerations. There is a minimum time of firing necessary and four seconds are good enough to get at least 3 or 4 good points to know that the fluid flow is proper and also to measure the acceleration imparted correctly. So we will measure once in 520 milliseconds. The velocity change imparted will be about 2.14 m/s.

The second aspect is the correction from 720 km to about 550 km. The question is when you can do this. If you do it too early, it will give you a different number. And if you do it too close – you can do the previous day too – the problem is your ability or the time required to get into Plan B would be touch and go. That is why we have chosen to do this [test firing] 41 hrs before the actual MOI [that is, at 1430 hrs on the 22nd].

How have you determined the timing of this test firing?

In that time frame [of 41 hrs] we are fully within the IDSN [Indian Deep Space Network] visibility. Actually it will be in the IDSN visibility range for about seven hours from then and so there is sufficient window to do the operation on that day. There is no issue there. As I mentioned, when we fire the LAM, there are two coils in the solenoid [igniter]. First we will try firing the solenoid Coil 1. If Coil 1 works and we get a good indication of the acceleration, then we are through. If it does not work we will fire Coil 2 after a gap of 1 hr. All these operations will be tested on the 22nd. If both the coils do not work, then we don't depend on LAM.

As I said before, the centre point of the firing arc is important for the orbit. If we are going to use Plan B we have fire for more time and so we have to start the process early but the mid point will remain the same. If everything goes well as per Plan A, the nominal orbit [Fig. 2] will have an apoapsis of 80,000 km, a periapsis of 423 km and an orbital period of about 3.2 Earth days [or 76.8 hrs]. If Plan B has to be used, the apoapsis will come to about 0.27 million km. But we have to ensure that the periapsis does not come closer and so we will have to make some small corrections to the orbit.

The braking velocity required during MOI is stated to be about 1.1 km/s. What is the present velocity of the spacecraft which basically determines the burn time of the LAM?

When we speak of velocity of the spacecraft it has to be with respect one of the three celestial objects involved in the mission: the Earth, the Sun and Mars. We don’t talk about the Earth any more. With respect to the Sun, it is 22.57 km/s [81,252 km/hr]. With respect to Mars, when the burn starts the orbiter is speeding at 5.127 km/s at an altitude of 1847 km from Mars. When the burn ends after 24 min, its velocity will be 4.316 km/s and the altitude will be 973 km. During the burn the lowest altitude that the spacecraft will reach is 462 km. This reduction will not be the same as the negative velocity of 1.1 km/s that is imparted because as it moves the velocity increases because of Mars’s influence and the geometry of the trajectory.

What are the key steps involved in the MOI manoeuvre?

Before we start operations on September 24th, the orientation of the spacecraft has to be changed so that its thrust vector is in the appropriate direction to bring down its velocity. This condition has to be achieved for starting the LAM firing. The time given for the reorienting the spacecraft (rotating and changing the direction) and convergence is 21 min. So the reorientation begins at T-21 min. [Fig. 3]

When we get into this changed orientation, two things happen: one, there is an eclipse (of the Sun) [This occurs at T-5 min 13 sec; See MOI timeline]. Because of the eclipse there will be no power generation and so the batteries should have sufficient power to keep the operations going. Second, there will be an occultation taking place between the Earth and the spacecraft during the firing period [This occurs post-firing at T+4.3 min]. So there is no communication after about 4 mins of the start of LAM firing; there will be no signal coming to us in real time for about 20 mins. The thruster firing is only 1 or 0. So you will know whether firing has taken place or not and the required acceleration has to follow. Only that you will not be getting the signal. Once the braking velocity of 1098 m/s is achieved the accelerometer automatically terminates the firing. Then it is just physics and the orbiter should be in the correct orbit.

At the end also, we will start receiving the signal after the firing has just completed because the spacecraft has to be reoriented back. The reverse rotation takes about 10 min as compared to 21 mins for forward rotation. Once this happens we will begin to get the signal and power generation will also be okay. After that we have to get some 5-6 good points to measure the periapsis and the apoapsis so that we get the exact orbit achieved.

The TCM-2 [Trajectory Correction Manoeuvre] that we did in June was virtually a similar operation for our purpose. There was a telemetry cut off when the spacecraft was reoriented.

If the spacecraft misses being captured altogether, it will be lost forever…

Now if you are not able to achieve the velocity reduction at that time it will follow the escape trajectory [Fig. 3] and will be lost. You cannot do anything about it.

The most crucial firing for ISRO’s orbiter in my opinion was the TMI. Because that trajectory, that arc, decides the direction in which we are going. If we had taken a longer duration also it would have been a difficult situation. That we managed successfully. Here now the system has to work. That is the basic issue. And our projections of distance etc. show that they are steady. That is a good indication and we have done the necessary simulations and whatever commands that we have uploaded have also been tested on the ground with similar systems.

What is the situation with regard to the availability of on-board propellant for the operations involved?

For Plan A there is no issue. For Plan B we will be just on the brink because it has to work for a longer duration. The effective amount of fuel available now is about 285 kg and out of that we will be using about 250 kg for Plan A. But if Plan B has to be used we will come to about 281 kg. After that we only require for periapsis corrections. And at least 3 kg of effective will be left, which is sufficient for periapsis corrections. Otherwise what can happen is that after one orbit it may come very close to the Mars surface and it can get lost. So we need that amount for orbit corrections.

What about the health status of the instrumentation in the payloads? Do you have any idea about it?

We have tested it. When the spacecraft was in the earth orbit, all the instruments were tested and some measurements were also made to see how they perform. And sometime in April-May-June, we went through all the instruments once again. Instruments are in good health.

Any issue with regard to power?

As far as power is concerned, since power has to be provided by the battery, we have ensured that power is sufficient. So systems that are not required to be used at that time will not be powered. But thermal control systems have to be on power. Second aspect of the operation would be to test all those systems beforehand which are called upon during the MOI. There should not be any surprise. This is a basic principle which we have been following. All the autonomy provisions except the failsafe mode in case of major failure have been exercised and we have actually authorized the satellite for the autonomous operation of this process. So it will select systems like the appropriate processor, the appropriate gyro etc. The other thing is there should not be any man-made error during the entire operation.

How important is the thermal control in the Martian orbit?

Actually thermal control is not a very big issue like in the case of Chandrayaan-1 [orbital period of about 11 hrs]. But we still require thermal control for all the instruments. There are actually about 120 parameters in all to be tested and what we have seen from the analysis is that the predicted values and actual measurements match well. See we had 300 days for all this. That is the advantage.

NASA’s MAVEN will do its MOI two days before ISRO…

MAVEN has not used any of its on-board fuel so far…

Why? Didn’t they have trajectory corrections to do?

They have basically gone for a very different route. They have not gone straight as ISRO’s Mars Orbiter has done. They have gone up and coming back because their aim is to hit 150 km periapsis. There is a circuitous way of achieving that actually. They reached there anyway using their launch vehicle. Their apoapsis is around 6250 km and periapsis is nearly 150 km. Because of this low periapsis of 150 km they are going very cautiously. Trajectory corrections do not require much fuel anyway, only a few grams or so.

Have there been any cause for concern or hiccups in the mission so far?

As of now I should say in the entire mission from November 5 to date we have had only a couple of small issues. One was during the orbit-raising operations. One we had to abort. The second issue was related to about half an hour telemetry loss during the entire mission. This happened we were switching over from one telemetry system to another. We have three antennas -- low-gain antenna, high-gain antenna and medium-gain antenna – and this happened at the time of switching over from one to another. Otherwise we did not have any issue as far as the entire system is concerned.

What is your current reading with regard to the lifetime of the spacecraft?

If Plan A works we feel that a lifetime of six months should be possible. Because what we require are minor corrections to the orbit. A periapsis of 423 km gives us enough margin. We should only not hit something like 150 km or so. Otherwise it is okay. If it is Plan B we have to see how much less it would be. Only when corrections are required we have to be careful. Even if we have only one propellant, either the oxidizer or the fuel, it may not result in combustion but that itself will produce minor thrust. A gas outage also has an impact. So we can use it. These are all the bonuses that we have.

But there should be enough pressure to achieve that…

Yes, but that is a different story.