My Subjective Probabilities on India’s Moon Mission

[Author’s Note December 29 2008: Please see my ‘Chandrayaan adds a little good cheer! Well done ISRO!”  — as a good Bayesian would, I  have had to update my subjective probabilities ex post and gladly so!]

The subjective probability I would place on the odds

of our Moon rocket leaving earth orbit successfully is 20:1 against,
of it reaching the moon’s vicinity about 50:1 against,
of it entering lunar orbit successfully about 100:1 against,
and of it transmitting half the data it is intended to about 200:1 against.

Going to the Moon requires a spacecraft reach an “escape” velocity of some 40,000 km per hour. After some 324,000 km, the craft escapes Earth’s gravity and comes to a “standstill” or “neutral” point, a fictional station on the Earth-Moon axis, still some 32,000 km (about 19 Moon radii) away from the Moon. The Moon’s gravity then gradually takes over, drawing the spacecraft faster and faster towards the Moon, to either land on its surface or go into orbit around it, though to avoid a fatal impact crashing into the Moon, the spacecraft may require retrorockets to slow itself down.

All Indians will be delighted if the Moon-launch  tomorrow is successful. At the same time, all Indians, especially millions of wide-eyed children, will be more than disappointed if ISRO’s plans fail through avoidable error.  It was of the highest national importance to try to ensure beforehand that the Indian mission succeeded if it is going to be tried at all.  That has not taken place.

The numerous sources of possible failure include

(A) launch-failure causing the spacecraft to never reach, let aside exit from, terrestrial space onto a path to the Moon, all through belts of intense heat and radiation;

(B) trajectory-failure causing the spacecraft to move wrongly through cislunar and translunar space, miss the Moon and go into solar orbit like everything else in the solar system;

(C) failing to enter lunar orbit, crashing into the Moon instead;

(D) failing to transmit intended data from lunar orbit.

Only if all these and more are avoided, can ISRO’s Moon mission be considered successful.

Here are some questions the PM and his Government needed to answer before the liftoff but failed to do so:

1. Is there an indigenous rocket powerful enough for a spacecraft to reach 40,000 kmph, the escape-velocity from Earth’s gravity?  If a foreign rocket is being used in whole or in part, what are the terms of collaboration?

2. India’s will be mankind’s 85th mission to the Moon on record and there  was a vast amount of publicly available knowledge already gained in other countries; did ISRO do a survey of all previous Moon missions by other countries, especially the USSR and USA since 1957 to investigate and analyse the numerous errors and failures they made?  If not, why did it not do so ?  If we did absorb all existing lessons available, and there are people at ISRO wholly conversant with what went wrong with every case of launch-failure, trajectory-failure, instrumentation-failure causing spacecraft to fail to reach or leave Earth orbit, or miss the Moon, or fail to communicate etc, what identifiable improvements did this learning cause in our Mission-planning?  The cause of nationalism is not served if we repeat the known mistakes of others;  why were we made to feel so confident we were not headed to be making the same mistakes as had been already made by others?

3. It is a blow to national prestige and self-confidence if there is failure at any stage of this difficult enterprise and it may have been better to do the job in discrete and successful stages or not do it at all than fail at it most spectacularly; was any thought given to breaking down the present aim into several stages – e.g., improving rocketry to aim at a “parking orbit” around Earth permitting ground control to better calculate trajectories to the Moon, then to flyby the Moon, then to attempt to go into lunar orbit? Why are scientific payloads being planned to be carried even before we have gained any experience in successful rocketry through terrestrial, cislunar, translunar and lunar space?

4. Our country has not been a major manufacturer of engines, aircraft bodies, computers or communications and imaging equipment, all vital to this enterprise; did we import the components to be used and if so, which ones?

5. Science is universal, and belongs to all mankind; all mundane international disputes appear petty when seen from selenocentric space which is the one good reason to want to try to reach it; why not release into the public domain for scrutiny by everyone in the country and the world the equations involved in the rocketry, and even whether Newtonian or Einsteinian frames of reference are being used?

Subroto Roy
October 21 2008


19 Responses to “My Subjective Probabilities on India’s Moon Mission”

  1. chandra Says:

    I am proud our India is capable of sending space craft to the moon, this is our prestigious issue, in this mission we proved our technology to the whole world.

  2. drsubrotoroy Says:

    Well, I certainly HOPE I am proved wrong in my assessment of the probabilities and that the previous commentator is right. But we must be realistic (something the Government of India’s bureaucrats and politicians only very rarely show themselves capable of being).

    Subroto Roy

  3. drsubrotoroy Says:

    Well, I hope bad weather is not made an excuse for bad science and a bad bureaucratic mindset and bad governmental wastefulness.

  4. G Harindra Kumar Says:

    Space exploration is a risky business, and even the developed countries have experienced catastrophic failures in the past. Japan is a prime example as it took them close to a decade to get their H-IIA on course. The N-1 was Japan’s first launch vehicle and its maiden flight was in 1975. The N-I was, however imported; the structure of the vehicle was based on Thor-Delta launch vehicle of McDonnell Douglas. ISRO understands the risk of conducting such a mission and to move forward one should always take risks. China is a prime example of taking up chancy projects to enhance national prestige however wasteful and unyielding they may be, the Olympics, manned mission, the Maglev rail project in Shanghai, their own Change mission to the moon are moot examples of steadfastness and daring. Since the PSLV-C11 has successfully launched Chandrayaan in a earth transfer orbit it would take major mess up on the part of ISRO to botch the mission at this stage. In my opinion, what we need to do now is to be totally optimistic on ISRO, if there even a single Public Sector enterprise that deserves kudos, it is ISRO.

  5. drsubrotoroy Says:

    I completely agree with the previous commentator that trying to fly to the moon has been a very risky business. He gives recent examples of Japan and China. I shall publish my survey (done more than a year ago) of all 84 attempts at the Moon by mankind to date (ours is number 85). The greatest number of attempts and the greatest number of failures were by the USSR and USA — who started FIFTY years ago! What I demanded to see from ISRO is some technical understanding of the history of the failures and successes of the USA and USSR attempts since that time. Have they done such a survey? Of course not. I have given my subjective probability estimates of the outcomes: feel free to give yours.

  6. Charan Puneet Singh Says:

    This is too pessimistic, as if the moon mission is a branding exercise for India (and a rant about India’s prestige) rather than a project which is part of the overall scientific development in the country, which it is. Every major project has risks, so does this project. Even if it fails, I will be proud of ISRO for having tried. I do not care if the rocket or the technology was imported. To be able to use an available technology is just being smart.

  7. drsubrotoroy Says:

    Please see my Letter to the ISRO Chairman published elsewhere here. I have nothing against foreign collaboration in this; to the contrary, I advocated (in “India’s Moon Mission” in August 2006) that all the scientific equations being used be made public. Science belongs to everyone. My main concern has been that ISRO seems not to have made any thorough technical survey of all the 80+ missions to the Moon (mostly by the USSR and USA) to learn from the mistakes made. Repeating the scientific errors known and made by others over the last fifty years does not advance the cause of Indian nationalism or of Indian science, only Indian bureaucracy.

  8. ajay Says:

    This set of Dr Roy’s articles has raised some very interesting questions.

    Re the question: “Our country has not been a major manufacturer of engines, aircraft bodies, computers or communications and imaging equipment, all vital to this enterprise; did we import the components to be used and if so, which ones?”,

    I have this to say: India has been manufacturing aircraft bodies, engines etc long ago but under license, which means transfer of technology.
    ISRO has fully exploited the fact that many Govt PSUs and some private companies do have expertise to manufacture hi-tech aerospace components. ISRO’s was banned from trading Hi-tech goods with US, and painfully took the path of developing every computer, electronic component, rocket, motors, materials, fuel etc or made other Indian companies do the job.

    What if Chandrayaan fails? It’s simple, we will build another Chandrayaan and send it again. The first Space Launch vehicle SLV failed in its very first attempt. ASLV failed 3 out of 4 times. PSLV failed only one time even after so many launches. GSLV failed once. So failures are part and parcel of Space exploration. But you can see the success of PSLV to put satellites successfully in many missions. This is called experience and reliability. ISRO is not a superman to have 100% Success rate. if Chandrayaan fails, then ISRO will be even more careful while building another, So chance of Success is even more. Russians and US too had many failures but today they are building space stations, sending human crews, unmanned missions to mars, saturn and even outside solar system. Again experience and reliability were gained with those failures.

  9. drsubrotoroy Says:

    I am sure the previous commentator is right that there has been a lot of import-substitution and indigenous manufacture going into ISRO’s enterprises. But I have heard no argument from anyone yet that it has been rational behaviour on ISRO’s part to repeat the publicly known mistakes of other countries committed over the last fifty years. Of course the USSR and USA failed numerous times — that was back in the 1950s and 1960s. If Chandrayaan-1 fails (despite all the irresponsibly premature self-congratulation and celebration by ISRO’s bureaucrats), ISRO would obviously have a learning experience — but we need to be frank that it would place us at about 1961 perhaps on the world’s technology time-scale. (Please see my “Complete History of Mankind’s Moon Missions”). Also, why talk so much about the scientific payloads sending back data over two years and planting an Indian flag on the Moon when we have first needed to prove to ourselves we can leave Earth orbit? Enough PR-gimmickry please! Other branches of the Government of India are full of it — we expect better from people who would like to be hard-core scientists.

  10. Shibu Says:

    I do not see why Dr Roy is believing other countries’ missions were success. Why should we blindly believe without much acceptable proof? And we never want to repeat what others did as it may be a mistake or bluff. Its not a discovery certainly but most of the technology should be different with the same scientific fact and reports. One can never bring out anything new without the reference of an other unless it is a mere luck. The pay load is important as it is necessary to decide what can be loaded in future missions, apart from knowing whether the payload declared by the previous missions by other countries is really possible. I believe we Indians should believe and should be confident that our scientists are also learned and they know what is happening around them. They have the facility and right to explore for the success. And at least now Dr Roy has to accept as they have proved it.

  11. drsubrotoroy Says:

    The previous commentator may be unfamiliar with the space programmes of the USA and USSR mainly since the 1960s. There was an element of propaganda to those too but there is no doubt as to the achievements and failures recorded. I will share everyone’s cheer if Chandrayaan succeeds in doing what ISRO has said. Yet even if it succeeds, it will place India at a technology-level of perhaps 1968.

  12. Shibu Says:

    Yes I accept there are records and am even aware that USA once declared there is nothing left to explore in moon as they have explored everything and their men have even played golf on it. But there is always some thing to be explored more in science. This is the first time India has put some thing which is just 500 hundred km away from moon.

  13. drsubrotoroy Says:

    Well, Chandrayaan was launched successfully and seems to be moving fine in Earth orbit so far. That is good news about the guidance and control systems employed thus far. It is not yet in Lunar orbit. If it achieves that, it will definitely be a credit. I shall be happy to literally eat my words: say a print-out of my subjective probabilities, chopped up fine and placed in some curry. But I will need some very hard objective evidence of Lunar orbit having been achieved.

  14. Vaidhyan Says:

    Hi Dr.Roy, So finally Chandrayaan did enter the moon’s orbit, contrary to what you predicted though you were right about this being one of the key events for success in this mission to be defined. Let’s all now congratulate the great indian scientists present, past and the great future ahead!

  15. drsubrotoroy Says:

    Well, as I have said twice before now, I shall be delighted in due course to congratulate ISRO and literally eat my words (by taking a print-out of them, chopping them up fine and putting them into my curry) but I will need some really hard objective and verifiable evidence about the precise progress of the spacecraft. Could anyone please post links to sites providing such evidence in real-time?

  16. bjwam Says:
    ISRO has announced C-1 has achieved it’s desired science orbit of 100 km. Is this the whole truth?

  17. drsubrotoroy Says:

    Apropos the previous comment, I posted this on November 9 under the title: “Neglecting technological progress was the basis of my pessimism about Chandrayaan”:

    “I have been very pessimistic about Chandrayaan-I’s prospects and I am delighted to hear ISRO say it has been successful in placing the spacecraft in lunar orbit. I have had to wonder where, precisely, my pessimism was mistaken. The answer is that I had completely left out in my thinking the vast technological progress that has taken place in telecommunications and telemetry in the last 40 years. I had surveyed the history of similar attempts by the USSR and USA in the 1960s and that was a history littered by failures of many sorts. Let aside rocket-launch failures, the other main sources of failure were in trajectories and in communications. I have been deeply concerned that India was simply going to fall in the same pitfalls along the way. But what I neglected was that our attempt was being made forty years later and the world has seen enormous technological progress during that time, especially in telecom. The Soviet and American missions took place in the early 1960s when, for example, colour television hardly existed. Today, in 2008, ISRO seems to have managed control and guidance systems that have been up to the (very complex) task of placing the spacecraft in lunar orbit. Hats off to ISRO if it turns out they have succeeded, and cheers if they actually manage to get the scientific data they have wished to receive.

    The same mistake that I made here in a field not my own is what I have myself pointed out being made in a different context regarding the current world financial crisis. Viz., I said in my September 18 2008 Business Standard article “October 1929? Not!” that the world since the 1929 stock market crash had witnessed so much technological progress that the current crisis could not be compared to the one back then.”

    I know of no reason at present to doubt what ISRO is saying. The proof of the pudding will be the scientific results that are hoped for from the payloads.

  18. Rick Says:

    The success of Chandrayaan, its achievement of its target and especially its low cost should be celebrated and has become a matter of discussion everywhere. I believe India is going to increase its capabilities tremendously in the field of science and technology because of US cooperation.

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