(Image courtesy: Pallava Bagla)

Dr. Carle Pieters, a world famous lunar scientist is currently a professor at the Brown University, Rhode Island, USA and is the team leader for an instrument that NASA is flying on Chandrayaan-1 to map the minerals of the moon.

Pallava Bagla: We have with us Dr. Carle Pieters, somebody who knows the moon like the earth and loves the geology of the moon and also knows a lot and wants to understand more of the origin of the moon, and the earth and moon history together.

Dr. Carle, so you are flying something on Chandrayaan. What are you doing on it?

Carle Pieters: Well, we are flying a instrument called Moon Mineralogy Mapper or M3 for short and as the name implies it is designed to map the mineralogy of the surface by looking at the colour, but not just the colour the way our eye

Pallava Bagla: That was the colour grey
Carle Pieters: That's because our eyes have a limited range of sensitivity but if you expand that range beyond what human eye can see to hundreds of channels, towards the blue, into the ultraviolet and into the near infra red you can see a lot more, and in those wavelengths our minerals have very diagnostic spectral properties and ..

Pallava Bagla: So you are going to be looking for certain minerals on and on this model of the Chandrayaan, roughly where is the M³ or the Moon Mineralogy Mapper?
Carle Pieters: This is what represents the M³ here. This is the electronic package and this is the spectrometer itself. And it will be looking at the moon that way.

Pallava Bagla: So this is what is going to look at the moon and find out what minerals are there?
Carle Pieters: That's right.

Pallava Bagla: And roughly tell you what the origin is? Will it throw light on that?
Carle Pieters: You won't point out and say oh what's the origin. But what you do is by mapping minerals in the geological context and at high resolution coupled to other instruments that Chandrayaan is carrying, it allows you to understand the geology of the moon. And geology is based on both internal processes, external processes and the composition of...

Pallava Bagla: But why look at the geology of the moon? Why don't you study the geology of the earth which is much closer?
Carle Pieters: We do study the geology of the earth but the geology of the moon is different.

Pallava Bagla: Why?
Carle Pieters: Well, let's see - about four and a half billion years ago when the earth was forming

Pallava Bagla: Which is a little after the big bang...
Carle Pieters: Well

Pallava Bagla: A lot of after the big bang .
Carle Pieters: Well, a lot after the big bang, but after the sun formed. The sun formed and then the remaining material formed into planets. It was a pretty violent time. There was lots of small planets were forming and some became bigger, and the bigger you were, the bigger you became and about four and a half, 4.5, five billion years the proto earth, which was pretty good size at that time .

Pallava Bagla: Very early earth...
Carle Pieters: It's the early earth, right, about two thirds the size it is now..

Pallava Bagla: Not the green and blue earth we see today..
Carle Pieters: No, no, none of that yet, but it was that time the solar system was still very violent because it was all these things moving around and hitting each other, but things were getting big and the proto earth and a Mars sized body collided. And that collision affected both and ripped off some of the outer of the earth and probably some of the outer of this other object and formed a ring around the earth and the earth got a little bit bigger and that ring around the earth gradually congealed into the moon. The earth and moon are intimately related right at the very beginning. Now that means they have a lot of the same common elements.

Pallava Bagla: Oh that's why you are interested in the geology?
Carle Pieters: That's right, that's right, but this process made them also different. So they have some common origins, but the earth was bigger, and it had a lot of what we call volatile elements - gases, water, ultimately an atmosphere. Whereas the moon, because it was the debris, it basically lost its volatiles, but it nevertheless became a small planetary body and these now are coupled together. So the earth has wonderful geology - it has atmosphere, it has rain, it has wind, the moon has pure geology.

Pallava Bagla: There is no erosion?
Carle Pieters: No erosion, no erosion from wind, rain. Its good rocks. Its all the things that happened to rocks.

Pallava Bagla: So it is like a history book which you can read? Is that a good way of interpreting it?
Carle Pieters: That's a very good way, because after these two planetary bodies formed, well of course, they continued for the next four and a half billion years and you have impacts, you have solar wind, you have everything else happening in the solar system, and the earth, because it has an atmosphere and erosion and because it is internally very dynamic..

Pallava Bagla: So the earth changed and the moon has remained frozen, is that right?
Carle Pieters: Exactly. That's it in a nutshell. The moon records four and a half billion years of history.

Pallava Bagla: So you are like an archeologist for the solar system. Would that be a good way of..
Carle Pieters: That's an excellent way of seeing it, yes, now

Pallava Bagla: And this archeology you are going to do using this Moon Mineralogy Mapper?
Carle Pieters: Well, the whole suite of packages..

Pallava Bagla: Oh, so all of them you are going to .
Carle Pieters: All of them together, because each provides a little bit, something different. Our M3 provides the mineralogy of the moon in a global context and you can look at a crater, and you can see different parts of a crater, and you can see whether this area has a unique mineralogy, maybe a useful resource, whereas this area is older plains. But then when you couple it with some of the other instruments they give you the topography, the detailed structure, or, the CIXS we were just talking about, gives you the elemental abundances. Getting elemental abundances and mineralogy you have a lot more information than just

Pallava Bagla: How has it been, your experience, working on Chandrayaan?
Carle Pieters: It has been a delight.

Pallava Bagla: A delight?
Carle Pieters: A delight, yes. Let me say that I am honoured to be a guest on this spacecraft, because it is not only a good basic spacecraft, but it is also very international. It has a suite of instruments which are a wonderful package that works together and will all be coordinating our data as it is required and I really enjoyed meeting and working with the people.

Pallava Bagla: But you are an American.
Carle Pieters: Yes, I am an American.

Pallava Bagla: And Americans put sanctions and denials on India and, that's politics, I understand you are a scientist, but you almost lost that flight because of various export control regimes. Would you have felt bad?
Carle Pieters: Of course I would have felt bad. Definitely. The scientific community, I believe, goes beyond politics. Scientist to scientist are very interested in understanding the nature of our solar system. And that is what drives us. The technology driver is the propulsion, and all those kind of engineering aspects are a different level. But at a scientific level, all scientists have a common bond. And that is what makes us

Pallava Bagla: So have you enjoyed this role reversal where western instruments are flying on an eastern mission?
Carle Pieters: I don't think it's a reversal. I think it is a joint effort.

Pallava Bagla: Is it a natural progression towards more international collaboration?
Carle Pieters: I would hope so, and I think especially in the case of the moon it provides us a wonderful opportunity just for that because as you know, there are two missions already circling the moon
Pallava Bagla: Which is the Japanese Kaguya and the Chinese Change
Carle Pieters: That's right. Chandrayaan-1 would be the third one and it would be followed by a US mission.

Pallava Bagla: Lunar Reconnaissance Orbiter. But that is delayed.
Carle Pieters: That is right. Well, Chandrayaan was delayed a little too.

Pallava Bagla: Yes.
Carle Pieters: But, it doesn't really matter when each of these get launched because what matters most from the scientific point of view is that the data they will accumulate and it is the integration of this state, this wonderful feast of data that ..

Pallava Bagla: But are the Chinese going to give you some data?
Carle Pieters: I don't know. They said they would, eventually. The Japanese have a policy very similar to Chandrayaan, which is release of data one year after the mission and

Pallava Bagla: But here you are sharing the data - the Indians and the Americans and the British and the Swedes are going to share data. Is that right?
Carle Pieters: That is right. But remember it is not one data that understands the universe. It is the entire integration of data. We've been studying the earth for ever since humanity learned how to read and write. I mean we are still not done. The same will be the case with the moon. With this armada of investigations that are going to be around the moon, that combination of information which by its nature is international. I think it is a wonderful step forward for scientific integration of the global community.

Pallava Bagla: Were you scared of putting your instrument on Indian mission? They have never flown as far as the moon. This model is representative of the spirit of India.
Carle Pieters: Well, of course it is scary anytime you fly an instrument on a spacecraft. There have been failures, everyone has had failures. However India as you know has a very strong success record in launches and that typically is one of the most risky part of a mission.

Pallava Bagla: Fifteen continuous successful launches
Carle Pieters: Yes, it is something to be quite proud of. However, once we get past that, then all these instruments have to work. What terrifies me, what excites me is, I know now more than ever that there are so many parts to this. Every single one has to work perfectly and it requires an enormously talented team, and now its an international team, to make everything work perfectly. I certainly hope that is what the case will be and fully expect it, but I need to be realistic in that spacecrafts do fail and I know I have several colleagues who have been on spacecraft that have not returned data.

Pallava Bagla: You think ISRO has done its best in testing and putting it together?
Carle Pieters: I think they have done a wonderful job. There are still tests to be done. The basic spacecraft is ready to be sent to SHAR for the final integration.. there'll be tests to be done there. There'll be tests to be done in orbit so testing will continue. Every engineer and scientist

Pallava Bagla: But you have confidence on them?
Carle Pieters: Oh, there is no reason not to. I don't know the one million items that have to be checked off the list. I do know the people are highly competent. And I know that no one wants this to fail, so I think that's the best .

Pallava Bagla: What has been your experience working with the Indian space agency? Has it been a two way street? Have you learnt something from them?
Carle Pieters: I think it has been a very rewarding experience for everyone. I have worked mostly on the scientist to scientist level, but working with the engineers both at JPL Hoover, the people who have actually built our instrument, and similarly with the ISRO engineers who have put this spacecraft together, so it takes scientists, it takes engineers from all walks of the different parts of the system to have it come together. I can't say .

Pallava Bagla: And the Indian taxpayer to pay for it! Don't forget them...
Carle Pieters: That's right, and the US taxpayers too.

Pallava Bagla: US taxpayers are that part. How much did it cost? How much does the M3 cost?
Carle Pieters: I feel uncomfortable about it .

Pallava Bagla: A few thousand dollars, a few hundred thousand, a million..
Carle Pieters: No, no millions, its .

Pallava Bagla: Several millions?
Carle Pieters: What our instrument is, it's what is called a mission of opportunity. There is a program within NASA called Discovery which normally has a competed program to fly space grade. But they will also allow competed programs to fly instruments on another spacecraft and we submitted our proposal to NASA for this peer review and we were selected at the same time that we were selected by ISRO.

Pallava Bagla: So you succeeded in a competition, first at NASA, then at ISRO?
Carle Pieters: No, first ISRO, NASA, then ISRO. So it's both.

Pallava Bagla: So its not simply that the Americans came in and they were given a warm welcome?
Carle Pieters: No, it had to be a peer reviewed.

Pallava Bagla: And you succeeded in that peer review...
Carle Pieters: Yes.

Pallava Bagla: Against many odds probably?
Carle Pieters: Well, see that time there were fifteen proposals submitted. I think we were the only ones selected.

Pallava Bagla: At that point
Carle Pieters: Hmm. So we were very happy.

Pallava Bagla: So ISRO was tough on you, on the other PI's who submitted proposals?
Carle Pieters: Oh this was on the US side.

Pallava Bagla: Oh on the US side there was such a rejection. And what about the rejections.
Carle Pieters: I don't know how many ISRO has received. You have to ask them that.

Pallava Bagla: And what kind of science do you expect to do after the data starts coming out? Its pictures or maps or .what'll it be?
Carle Pieters: Well, okay, this instrument is what we call an imaging spectrometer, which by its name you can see it will have images. It acquires images, but as I mentioned earlier we look at the colours of these images will have, 230 spectral bands to them.

Pallava Bagla: That's a lot of them
Carle Pieters: There are just three colours.

Pallava Bagla: Red, blue and green
Carle Pieters: 230 across the spectrum, so that is why we call it an image cube of data. For every surface element or pixel we call it, across an image will have these 230 spectral channels.

Pallava Bagla: So how will the taxpayer in the US and how will the taxpayer in India benefit by you having sent this instrument to the moon?
Carle Pieters: That depends on, there are many applications, the first of which is to map the mineralogy of course which identifies the surface character, tells where different materials are, and in so doing it identifies what processes had to occur to create those. For example with a pair of binoculars you can see the large craters on the moon. When you have a large crater impacting, it changes the surface properties, and one of the things it does is it digs into the surface and excavates material. So when you look at the inside of that crater then you can look at the minerals that were deeper. So we can look for the depth. At the same time because it is such an energetic event it melts material. So you will see material draped over parts of it that appears to have been melted.

Pallava Bagla: Will it in anyway help when the moon is colonized and humans start living on the moon?
Carle Pieters: Well it will help that you can see things close up.

Pallava Bagla: No but the M3
Carle Pieters: Oh, yes, in that I would expect M3 and some of the other instruments in combination will allow you to identify what areas are optimum. For example you want to build a house, you want to know well what's the formation, is it high, is it low, is it rough, are there different kinds of materials are there on one side or on another side. You want to know something about the geology of where you want to build the house.

Pallava Bagla: Know your landscape
Carle Pieters: That's right. That is what we will be doing. We'll identify where these illiminite rich areas are, where these other minerals, my favorite is olivine. It's a very beautiful mineral. There is a lot of a mineral called plagioclase which is high albido, very bright mineral. And then of course there is this basaltic materials that are very similar to earth salts except they are very low in volatile elements. So we will identify the terrains and the processes that created those terrains and the other instruments will provide the topography and the elemental abundance.

Pallava Bagla: So you will give the cue to where we should colonise...
Carle Pieters: That's right.

Pallava Bagla: Is it a good idea to colonise the moon?
Carle Pieters: Well I don't know how to answer that. The question I would answer is why are we doing this now, why is it interesting to humanity and my answer to that question is that this is a long term investment. We know earth. We don't know it completely, but we know it fairly well. We know earth has problems that needs to be solved. We know that we need to have long term vision, long term resources and the first place that you are going to go is the next step out, which is the moon. So this is

Pallava Bagla: That is our closest neighbour
Carle Pieters: That is our closest neighbour, but it's a long term investment. It's not tomorrow. But if we don't start it now, we don't have tomorrow. And it will take a fifty year, maybe hundred year, I don't know kind of planning, to understand the geology, to understand what areas are most interesting and might have the most useful resources, what areas might be the best place to have a small colony.

Pallava Bagla: So you think ISRO has invested right in the long term?
Carle Pieters: Oh I am completely and I am thrilled that ISRO, the international community on Chandrayaan, and the international community that are also interested in the moon currently are working together in a peaceful manner. And that's what my dream is that this is the beginning of a long term peaceful exploration of another planetary body.

Pallava Bagla: So there you have it. A long term peaceful collaboration towards the exploration of the closest neighbour of earth, and ISRO it seems, according to Dr. Carle, has invested well in this long term vision.