Paul Sanchez

Pendick:

Alright. This is Daniel Pendick, science journalist. It’s November 10, 2015, and I’m at the Division of Planetary Science Meeting in Washington, D.C., talking to Paul Sanchez. Maybe you can pronounce your name, and spell your name out, and say what your current affiliations are. And where are you?

Sanchez:

My name is Paul Sanchez, if I pronounce it in English. In Spanish, it would be [spoken with an accent] Paul Sánchez. I am originally from Ecuador. Right now, I am working at the University of Colorado, Boulder. I am affiliated to the Colorado Center for Astrodynamics Research. I’m working under the supervision of Professor Daniel Scheeres.

Pendick:

Okay. So you are an astrodynamicist.

Sanchez:

No. I am a physicist.

Pendick:

A physicist.

Sanchez:

Yeah. My actual specialization is material sciences.

Pendick:

Oh.

Sanchez:

Then, this goes –

Pendick:

I’ll get to that. So, we just wanted to get a quick sense of your family origins and influences. So in other words, parents and also grandparents, if you think it’s relevant. What they did, where they came from, were they university people, you know?

Sanchez:

Right. Well, no, they weren’t. Actually, my grandmother from my mom’s side went to school just for a week. That was it. She had three children, and my mom was the middle child. My mom didn’t go to university. She just finished high school. That was enough at the time. You didn’t need to go to university to get a job. I think only one of my aunts from my dad’s side has been to university, in that generation.

Pendick:

You were born in Ecuador?

Sanchez:

I was born in Ecuador, yes. My family was born in Ecuador. As far as I know – let me see – up to my grandma’s mother. They were also born in Ecuador, my family were. They were from Ecuador. I’ve been told that my grandma’s aunties were fair-skinned and had green eyes and red hair. But whether or not they had some kind of European blood in them, I am not really sure.

Pendick:

That’s interesting. Family myth.

Sanchez:

Yes. But I’ve seen pictures.

Pendick:

Oh.

Sanchez:

There really are pictures. That’s from my mom’s side. From my dad, my grandfather used to work on the trains. He was a mechanic. My grandma – I don’t really know if she had a profession. I really don’t know. My mom and my dad were both accountants. Again, they were formally high school. They didn’t go to university. That was just good enough back then. They were able to raise my sister and I. That was enough. My sister, she did go to university, too. She’s married now. She was studying biochemistry and pharmacy at the time. She didn’t finish that. She dropped out and became an executive bilingual secretary.

Pendick:

So you were both the first, at least in the generation, to go to college.

Sanchez:

Yeah, except for my dad’s sister. [I have been thinking about this answer for years, this is a mistake; maybe I was just nervous. My dad’s sister went to college and so did one of my dad’s brothers; my mum’s sister did too (she became a teacher). Most of the rest of my cousins in the family have also attended college. I am the only one with a PhD though.] She went to college. She’s a nurse. Right now, she works in one of the public hospitals in Ecuador, but she’s not a nurse anymore. She’s in charge of pretty much all the nursing system in Ecuador.

Pendick:

Right. So you were born in what year?

Sanchez:

1976.

Pendick:

I’m asking because if your grandfather was very technically oriented in science, that would help to explain why you went on that trajectory. It’s always interesting to find out when it happened.

Sanchez:

Now, hard sciences like me, no – the professions have been very technical.

Pendick:

Right. So in early school, did you gravitate toward technical things? Was that an early interest of yours?

Sanchez:

Not really. I was a good student. I wasn’t particularly interested in anything when I was in school. I was not a bad student. I rather believe I was pretty good. Sorry about the lack of modesty, but you can see my grades and you can see that I wasn’t bad. I was just very curious. That was it. I wanted to know. That was the main motivation. It wasn’t about studying hard, it was just about learning things. Many times I have said this to my friends: I make a very clear difference between learning and studying. You study when you have to take a test. When you learn, you just learn it, regardless of whether or not you’re in school or doing something else. You just go read and learn it.

Pendick:

What were you curious about, besides soccer, I mean.

Sanchez:

I don’t actually like it. Nope. I don’t like it. Really, I was curious about anything and everything. I was possibly gravitating a bit more towards math. I would just really read anything. At some point, my mom and dad were tired of me asking “Why?” and they had to occupy me. Not with books, because I was too young. We used to have a series of small booklets called, “Why?” That was the title. They bought me that, and I would just read every single one of them. That was when I was still in school.

Pendick:

Encyclopedias, things like that? Looking things up?

Sanchez:

I would read that too. Again, back then, we didn’t have internet. In Ecuador, it just arrived in the early ’90s, so there was no internet whatsoever. Everything I had to read was in books, and just in Spanish. When I got to high school, I would begin to read books about biology and math, statistics, physics, nothing really too deep, because I couldn’t understand it. Just encyclopedias that we had, I would begin to read them in high school. My high school was very strict, but it was actually very good. I liked it. I was still curious about anything and everything I could get my hands on. One day I was gravitating more into math and physics.

Pendick:

Was it a boys’ school? They segregated –

Sanchez:

Yes.

Pendick:

Was it religiously affiliated, like a Jesuit high school?

Sanchez:

No. My primary school was religiously affiliated. It was a Catholic school, which is not rare. When I went to high school, there was a military high school, it was ruled by the Air Force in Ecuador. I actually had a rank. I had a rank because I did six years of military instruction.

Pendick:

Military school was in parallel to public schools and private schools?

Sanchez:

Yeah.

Pendick:

I see.

Sanchez:

But this was private.

Pendick:

A private military academy.

Sanchez:

Yeah. Almost an academy, yes. The thing was it wasn’t called an academy because it wasn’t ruled completely by the air force. It was partially by the air force and partially by the direction of civil aviation.

Pendick:

Interesting.

Sanchez:

So we had a military side, but also a civilian side.

Pendick:

Well, I have to ask you your rank now.

Sanchez:

I’m a sergeant.

Pendick:

Okay. Alright. Did you throughout high school, until the end, it was general studies? You weren’t focusing especially on science? Although you said you weren’t just in math.

Sanchez:

The thing was, at the time, it was secondary school, not just high school as you call it here.

Secondary school is six years, right? During the first three, there is no difference. You just study everything. When you finish the third year, you have to choose different specializations. You have to. It’s different now. You had biology and chemistry, physics and math, and then you have social studies. In my secondary school, we had only physics and math. I went for that because that was the one I liked.

Pendick:

I see. Okay. Then the college experience – then what? Did you go right away? If you went to school, there, you’ll have to explain, because I’m not sure how the system works.

Sanchez:

Right. Yes. After I finished secondary school, I went to – where you have college here, in Ecuador we have universities and we have the polytechnic schools, similar to France. We have a big influence from them. I went to I think the biggest polytechnic school in Ecuador, the National Polytechnic School. Then again, you used to have two years of preparation and then four years for your degree. Not really a degree, a title. We didn’t – even now, we don’t have degrees in Ecuador. We just have a title. So I went through that. I went through the first two without choosing any particular career. Then in the third year, I chose physics. Even before finishing second year, I wasn’t really sure. The thing is, in Ecuador, we do not really have a scientific tradition, so careers in physics, math, chemistry – pure chemistry or pure physics – we do not really see them as profitable, because the only thing you can do is go on and teach. Even then, there are not many positions at universities and polytechnic schools, and you have to go teach in high schools. That was not something I wanted to do. I never saw myself as a teacher.

Pendick:

So basic research is not as fully developed as it is, say, in Europe or North America. Okay.

Sanchez:

I needed to make a choice between mechanical engineering and physics. I wasn’t quite sure what to do at the time, until I – to go for mechanical engineering, you have to be good with machines. You need to be able to figure them out, to build them really, to design them. What I realized was that when my dad was fixing the car, I was never close to it. I was never even interested in doing that. I might try to imagine how to do it, but I never got my hands dirty and went to fix it. Then it dawned on me that I wasn’t going to be a mechanical engineer, then my thing was physics.

Pendick:

So it takes how many years?

Sanchez:

Six years.

Pendick:

Six years. Do you come out with the equivalent of a master’s level?

Sanchez:

Yes, it’s a bit of an equivalent to a master’s, but we do not really have the degree. My Ph.D. is my first degree.

Pendick:

They don’t grant degrees in college.

Sanchez:

No.

Pendick:

Interesting.

Sanchez:

You might have degrees for – you might have a bachelor’s degree for teaching, maybe when you become a nurse you have a bachelor’s degree. Lately we have implemented a master’s degree for some things. But it’s not general. In engineering, you become an engineer. That is it. No degree whatsoever.

Pendick:

You get hired for a job.

Sanchez:

Yes. Basically you get a professional title.

Pendick:

How do you get from there to sitting here at the Division of Planetary Sciences?

Sanchez:

It was a long way. The thing is that given that I became a physicist, I knew that I wouldn’t be able to stay in Ecuador. That was a given. So I decided to look for universities to do a Ph.D.

I never actually looked into the U.S. for that. I had the impression that the best place to go was somewhere in Europe, so I applied to about seven universities in the U.K. I got accepted, I think, at three of them. Then I chose to go to the University of Nottingham. The main reason for that was that while they were doing something I liked, they were also the fastest with the paperwork. They did everything really quick.

Pendick:

Had you developed an interest yet in what type of physics?

Sanchez:

Yeah. What I was doing when I was in Ecuador, what I decided to actually research before finishing my career in Ecuador, was computational quantum chemistry. That was what I was doing. And when I applied for this Ph.D. in Nottingham, they were doing things in the theory and experiments of high T_C superconductors. T_C is Curie temperature. So you have a superconductor at room temperature, which is about 300 K.

Pendick:

My ignorance – I would think of that as just physics, solid state physics, you’re calling it quantum chemistry.

Sanchez:

It is. The thing is, it’s a mixture. It’s physics, yes, but then you go deeper and you get into quantum chemistry. Then you can get into the theory of quantum chemistry, and you go into the computational side of that. I was on the computational side.

Pendick:

I see, because a superconducting material is a compound, and there’s quantum effects.

Sanchez:

Yes.

Pendick:

So it’s chemistry and quantum physics. Okay. That makes sense. What year was that?

Sanchez:

When I finished my degree in Ecuador?

Pendick:

No, when you started at Nottingham.

Sanchez:

I started in 2001.

Pendick:

Alright. So high temperature superconductors were underway – I’m sorry. The low temperature – they’re called high temperature sometimes. I’m sorry. That’s right. High temperature superconductors. That was well underway.

Sanchez:

Yes, they were doing all those things in different labs around the world. In Nottingham, they were doing that, too. They were doing the experimental side. The thing is, when I got to Nottingham, I settled down and went to talk to my supervisors, I had two, Prof. Peter King and Dr. Michael Swift. Prof. King told me, “We have this other project that has to do with granular matter. If you want to, you can change. The thing is, with superconductivity, we’re already tired. We have no idea what to do with it. We don’t know [how] to keep on doing it. It’s like having a blind man trying to see something through a telescope which is 100 miles away, and we want to change. But you can choose. But if you choose something with grains, then I guarantee you’re going to have a really good thesis. So how about you tell me tomorrow whether or not you want to change.”

Pendick:

Granular matter, or properties of granular matter? Material science.

Sanchez:

Yes. So I went to my apartment and thought about that, and I was thinking, yeah, all these things with quantum chemistry are really interesting, but everything I do is really black box with the program. I had a rough idea how it works, but I hadn’t actually done it myself. Quantum mechanics is quite abstract. You need a really high skill in math, and I am a very visual person. So I went back to him the next day and said fine, I will change. He said, “Okay, these are the books, and these are the papers. Just go read them.” So I did.

Pendick:

What were they working on in granular matter? More theoretical questions?

Sanchez:

At the time, they were working in everything, really. Theory, experimental simulation. So one of the students was already doing the experiments: Nasreen Burtally. She was studying in the U.K. She’s in London. I was supposed to go, then, into simulation and the theory.

At the time, they were doing granular separation of binary mixtures. That’s another way to write the title. You get the separation of binary mixtures. That is it. What happens is that if you have grains, different kinds of grains inside a fluid, and you vibrate it, they separate. This is very important for the pharmaceutical industry and also for the mining industry, because in the pharmaceutical industry, you want to mix things, and you can do it if you remove the fluid. In the mining industry, you need to add a fluid because then you can separate everything with a 95% purity. That is really cheap. That was interesting. Of course, you can have zebras, and you can explain the lines.

Pendick:

Right.

Sanchez:

So my project at the time was to simulate the systems and find out why, why they formed different patterns when they separated, because sometimes get – if you have a binary mixture, you can have one of the materials will be right in the center and it stays there. And sometimes that just goes to the top. We didn’t know exactly the reasons for that, and I found that out.

Pendick:

Right. That would be very useful to know that.

Sanchez:

I did that, and finished at the end of 2004. I graduated in 2005, and I went back home.

Pendick:

Got your Ph.D. in 2005?

Sanchez:

Yeah. The graduation was in July 2005. I defended in January of that year. It took me just over three years to finish my Ph.D. I went back home, and I wanted to stay home, right? I tried to find a job, but as I said, we don’t have a scientific tradition, so it was complicated. We don’t have that many positions. I went to different universities. I went to my own polytechnic school. Things happened. I didn’t get any job. Then I decided that I needed to apply to somewhere else. I couldn’t just stay home and do nothing. So I applied for different postdoctoral positions. I got one in France at the University of Rennes 1. At the beginning of March 2007 [This is 2006, I got the year wrong.] – I stayed one year in Ecuador, just trying to find something – in March 2007 [2006] I went to France.

Pendick:

Let me just back up one step. I’m curious about your family’s reaction to all this, because you go to graduate school, and you invest all these years in studying, then you come home and can’t find a job. What was their attitude toward this, being hard-working accountants and all?

Sanchez:

They were happy to have me home. For Latin Americans, family is very important. We do not move out of our house unless you get married or you get a job. It’s not like here, where you get out in the world when you’re 15. You go to college, and everything in your house is gone, you have nothing you had, you have to find your own place. That’s not the way we do it. Even now, I have all my things back home. I have my room that nobody uses. They were quite worried. They didn’t know whether or not it was best for me to stay home. The thing is – there is something my mom has always said: You have to go where your bread is, meaning, you need to go where you can get a job and feed yourself. I found a job in France, so I went to France.

Pendick:

A job doing what, exactly?

Sanchez:

It was with the University of Rennes 1, the Université de Rennes 1. I was working at the time with Patrick Richard and Renaud Delannay.

Pendick:

We should probably spell that out for the poor transcriber – the French university.

Sanchez:

Ah. It’s the University of Rennes. “Rennes” is spelled R-E-N-N-E-S-1, because there are two universities, number 1 and number 2. So this is number 1, which has to do with all the hard sciences. Number 2 has to do with all the arts and music and philosophy and all that.

Pendick:

Okay.

Sanchez:

So I went to France for a year. I couldn’t speak a word of French. The thing is, I could understand about 70% of it, because I speak Spanish. I just couldn’t say anything, which was at times very frustrating, but that’s how it goes. Someone who is meant to read this—they need to learn some of the language before they go to a different country. It’s essential. The project they had there was something called “super stable heaps.” They were trying to form a pile of grains with really high angles in the slope, because usually you have an angle of about 30 to 40 degrees, and I mean, if you have just gravel, you make a pile, and the angle that the slope gets, the angle in the slope is about 35 degrees. They were getting angles of about 70, but that happens only when you have a flow. My job had to do with trying to explain how that happens and how the container is influencing the behavior of this pile.

Pendick:

You call it a job, but was this a postdoc research position?

Sanchez:

It was a postdoc. Yes.

Pendick:

I see. Alright. Well, they were forming piles of what?

Sanchez:

Usually in experiments, we use glass beads. They were about 1 millimeter each, and they were contained between two glass sheets. So we have the two glass sheets, and then you have a container with the grains, and then you let the grains flow, right? As you increase the flow rate, then the angle of the pile begins to go up. The reason for that is the walls. You have friction with the walls, and that is helping everything to stay stable.

Pendick:

It sounds like an industrial process. So, French pharmaceutical companies, are they supporting this? Is that where the money came from?

Sanchez:

I really don’t know. As far as I knew, it was the CNRS, The National Center for Scientific Research, that was doing all this.

Pendick:

Right. Basic research. Alright. Yeah, they have the national – CMAS?

Sanchez:

CNRS. Centre national de la recherche scientifique.

Pendick:

Right. They fund – they’re like the National Science Foundation.

Sanchez:

Yes, something like that.

Pendick:

So how did that go?

Sanchez:

It went alright for me. I learned French.

Pendick:

Good thing to know.

Sanchez:

How to put this? The group itself, I think, is quite hardworking. Maybe they just have a habit of [unintelligible] results. They work really hard. They’re really good researchers. They’re not doing things only on granular matter. They also have people working on – I think it’s called mousses [This is French for foams], Foams.

Pendick:

Foams.

Sanchez:

Foams. That’s something I also do. Is a small group, probably not as big as you have in the US, but they do quite good things. I learned some things from them. I guess I had to – the code that I had started to write when I was in Nottingham, I would still use when I went to France, and implement several things that I am using even now.

Pendick:

I see. You coded something to simulate granular matter.

Sanchez:

Yes.

Pendick:

What is it written in? What code do you use?

Sanchez:

Oh, the language? It’s C. The method I’m using is called soft-sphere discrete element method. That method is the one I am still using. Basically the code I’m using right now to build the research that is carried out in Colorado is an evolution of the code that I started writing when I was in Nottingham, that I used in France, then I used it here.

Pendick:

So when did that come to an end?

Sanchez:

This traveling?

Pendick:

That work, in France.

Sanchez:

That was just for one year. I stayed there until 2008 [This is 2007, I got the year wrong]. I again went back home, trying to go home and get a job, and establish myself. But again, that didn’t happen. I think in a way that was fortunate, because even though I couldn’t get a job in academia, I could get a job with the government. I started to work in the National Secretariat of Science and Technology. I was in one of the departments that was in charge of international scholarships and scientific projects. I started under the director of that section, and then after a month, I became the director. It was good for me, because it was different. The thing is, usually in academia, you work on your own. You go to your office, you do your thing, then you publish your results. You probably have some collaborators, but they live a thousand miles away, so you don’t have to be dealing with them every day. When you work in an office with other people in a department, and then you need to tell them what to do, you do not just give them an order. You need to know how to handle them. You need to talk to them. You need to deal with the governments, and you need to know about the laws and what the president is doing, how much money you have, how many people are going to different countries because of the scholarships. You need to know about the laws and regulations, and if you are going to sign something, you need to call your lawyer, because you don’t want to get sued.

Pendick:

Yeah. Okay.

Sanchez:

So all that side was really good for me.

Pendick:

We call it “professional development.”

Sanchez:

Yes.

Pendick:

Management, planning, communication.

Sanchez:

Exactly. All these things that you do not really learn when you become a scientist.

Pendick:

And they’re important, right?

Sanchez:

Yes, they are really important, because if at some point you have students, you have to know how to talk to them without insulting them.

Pendick:

Well, that’s true. Expectations have changed in that area.

Sanchez:

Yeah. Even though I did learn a lot from it, it wasn’t my thing. I had been trained to be a researcher because I liked being a researcher. It was good to go to that job and learn everything I could, but once you do that – and it’s not that I became an expert in it – then it’s only administration. That wasn’t what I was looking for. It was then when I again started to apply to different jobs. I actually got three offers: one from the Netherlands, one from Spain, and this one in Colorado.

Pendick:

How long were you at that department?

Sanchez:

I wasn’t there for too long, maybe just four or five months.

Pendick:

Really?

Sanchez:

Yes, it was very short. The thing with the other two – the one in Spain was that it was very short. It was just one year, and they couldn’t offer me any kind of extension. So I was thinking, well, just for one year I’m not going to leave everything behind if there’s no chance whatsoever that I would get any kind of extension. The one in Netherlands, they called me up and they said that they needed some references from my previous jobs. So I gave them all the information. For some reason, they just never came back to me. What can you do? Then I got the offer from Colorado. It was very interesting. Actually, when I applied for the job, I really thought I was not going to get it, because I knew nothing about asteroids. I knew nothing about all this planetary science thing. But I thought, you know, the worst thing that is going to happen is that they’re going to say “No.”

Pendick:

What is the organization at the University of Colorado that you’re in? University, or one of the institutions?

Sanchez:

One of the institutes. The thing is, the CCAR, the Colorado Center for Astrodynamics Research, is a center within the Aerospace Engineering department.

Pendick:

I see. Okay.

Sanchez:

So that’s where I work. I got contacted by Daniel Scheeres, my present PI, my boss.

Pendick:

Who is that?

Sanchez:

Daniel Scheeres.

Pendick:

Scheeres. S-H-E-E – ?

Sanchez:

S-C-H-E-E-R-E-S.

Pendick:

R-E-S. Okay. Scheeres.

Sanchez:

Yes. I think Dutch descent. He’s actually really good.

Pendick:

What year is this now?

Sanchez:

That was 2008.

Pendick:

2008. Okay. Off you go.

Sanchez:

He sat and explained to me what I was supposed to do, what the problems were that they were trying to solve, and I thought, “Yeah, I can do that. I can do that. These are the ways I can solve these problems.” I didn’t know almost anything about asteroids really, apart from the fact that I could apply what I knew. The thing is, I knew how to solve the problems, because granular matter is granular matter wherever you are.

Pendick:

Same physics.

Sanchez:

Exactly. The same physics.

Pendick:

What were the problems, basically?

Sanchez:

Basically that they didn’t know how they evolved when they rotated. They didn’t know the strength of these asteroids. They didn’t know how to form binaries or asteroid pairs. They needed somebody who could apply all these things from granular mechanics to asteroids. The thing is, granular dynamics or granular mechanics is actually a very new field. Right now, physicists have been doing this for about 25 years, 25-30 years, which is not that much. It’s not that much. I mean, civil engineers have been handling granular matter for centuries. Even the Egyptians, they were doing things with brick, because that was the one thing you had around. You have sand. Actually there was a paper explaining how they could have transported all the big blocks on sand. There’s a paper on that. It seems that what they did – and there’s a depiction of it in some of the pyramids – what they did is they put the big blocks in a sled, and they poured water in front of it, and that reduces the coefficient of friction, because sand doesn’t pile up in front of it. Usually it has a coefficient of friction to about 0.3. Then you can actually transport them.

Pendick:

On the sand.

Sanchez:

On the sand, yes. So those were the problems they were trying to solve at the time. And I was like, yeah, I can apply these other methods. I know these other people have been doing experiments, so yes, I can help.

Pendick:

So is it a matter of – they have observations of asteroids, some of which are just modeled from radar, I understand – and then they are trying to explain the physics of how this could happen.

Sanchez:

Yes. We also have pictures: pictures of Eros, pictures of Ceres, pictures of Itokawa. When you see the pictures, it’s just a bunch of pebbles, rocks, and dust put together, that is what you have. And if that’s what you have, this is a granular media, and it should be treated as such.

Pendick:

Well, you’re talking about something else now, the formation of them, as opposed to how they group up and form binaries.

Sanchez:

That goes into the formation of asteroids, but also into the evolution. The thing is, one of the – a very influential paper was written by Kevin Walsh, who is working right now at SWRI, the Southwest Research Institute. In that paper, they described how you could form a binary system. You have an almost spherical aggregate, and then there’s something called the YORP effect, which is – do you not know that?

Pendick:

I do just happen to know that. I do.

Sanchez:

So should I explain it?

Pendick:

Sure.

Sanchez:

So the YORP thing is really simple. You have solar radiation pressure. The body is not a perfect sphere. It’s not a perfect anything, so it’s going to – the photons are going to impact on it, and be reflected in a non-radial direction.

That’s going to give the asteroid in a torque, which over the millennia, is going to accelerate it. The thing is you begin to accelerate something which is not a solid rock, at some point, it’s going to be able to disintegrate. So they modeled this with a program called PKDgrav. What they found was that the particles from the poles would start to slide down to the equator. They would form by this method the equatorial ridge. But these particles would also begin to fly out. As they fly out, they would begin to accumulate and form a secondary body that would begin to orbit around it. The thing is that it all seems okay until you begin to look into the physics of the method. They know this, I have criticized this many times, I have told them, that the method they were using is something called hard-sphere discrete element method. Hard-sphere DEM. This method should not ever be used for grains in continuous contact. You have a bunch of pebbles in your hands. They are going to be in contact all the time. This method precludes continuous contact. It is not supposed to happen, because it is supposed to be used for something called granular gases, where you have only binary contact. They go, collide, and separate. If you have to force them to stay together, what they do is this [makes motion with hands]. It’s a constant vibration. Therefore, you are imposing a gaseous state, or at best, a liquid state for this aggregate. They should not have done that. Unfortunately, this is the method that the community, worldwide, had been using for the last – at the time – 10 years.

Pendick:

So the physics is wrong.

Sanchez:

Yes. I said that. [Not intelligible, but sounds like saying don’t mean to give offense]. They are really nice. I talked to Derek and Kevin, and they know this. I come to the community from a completely different background: from chemistry, granular matter. When you code, this is the way you do it. At the time, we told them if you repeat all your experiments, I mean all the simulations you have done with this other method, chances are you are going to get different results, so at least you should check it, because we need to know. The system you are describing should be independent of the method you use to study it. So if everything is correct, you should get the same results. But my suspicion is that you will not. Now they are proving me correct. Just now, I just saw one of the posters, and they are using Soft-spheres, because it happens. Two or three weeks ago, I saw another poster, and they compared the previous results to the new results, and there are differences. So, I told you so! [laughs] But anyway.

Pendick:

How different are they? They completely don’t work, don’t form the binaries, then?

Sanchez:

It’s not just the binaries, in a way, I think, they haven’t done anything else with the binaries. They have focused on all simulations they had done at the time, and they find differences. Not that everything is absolutely different. It doesn’t happen – but there are significant differences in the results when it comes to the shapes they get, or how things form.

Pendick:

Right. And that would affect how it matches, how well it matches to the observations.

Sanchez:

I came in 2008, and the first thing to do for me was to update the code. Again, the same code I had been using for the last eight years, I needed to implement self-gravity. The thing is, the usual method is to use a tree code, which basically is the best possible method to calculate longer-range attractions. The problem with that is that it is really complicated, and I couldn’t figure it out. So I decided to make an algorithm of my own. I thought about how to do it for about four months.

I didn’t actually write anything. I just kept on thinking about how to do it. Once I have it in my head, I can code it. It took about four months. Dan and I wrote a proposal for NASA. We got the grant to write this code and then to use it. In the proposal, we said that we would take about, I think, a year and a half just to develop the thing, implement it, then test it. The thing is, at some point, Dan told me, “We really need and should begin to implement the code, because we need it for the research.” I said, alright, I can do that. It took me about four months to think about it, and not write a single line of code. Then, I know this is going to sound presumptuous, but this is how it happened. It took me a week to implement it, and then another week to correlate gravity with the calculation of the stress tensor within the asteroid.

Pendick:

Stress tensor?

Sanchez:

Yes. It just basically is pressure, pressure and shear. That’s it. When I went to see him that week, they said, “Are you sure?” Done. [laughs] And I was really happy. He was really happy, too. Then as soon as I started to use this code to really simulate binary formation, to simulate the formation of asteroid pairs, to really see how things change when you change the material parameters. When you use a Hard-sphere code -- this is one of the reasons why I did this. When you use a Hard-Sphere code, you have a granular gas, a basic liquid. That means you have an angle of friction of about zero. You have water here, you drop it, and it expands as much as it can, and that’s an angular friction of zero. If you have some glass beads, and you pour them out, then you have a slope and you can pour them in a pile, and they don’t spread out that much. So you have a pile with a slope of about 24 degrees.

If you have gravel, and you do the same experiment, then you have a slope of about 35 degrees. That’s different. And that was what I was trying to get across. If you use one code, they cannot – that is not made to simulate something with this angle of friction, you’re going to get a result which doesn’t resemble nature. I tried to prove that. I think I’ve done it. People are now beginning to believe my results.

Then the thing they were trying to also address was the inference of cohesive forces, because there is one result that tells you that there is something called the rubble pile spin limit, that tells you that small asteroids, or any asteroid, really, cannot rotate with a period of less than 2.3 or 2.4 hours. You go to a rotation period which is smaller than that, and the asteroid begins to disaggregate; it begins to deform, because if gravity is the only force that has some impact on it, it begins to deform and then it slows down. It deforms, slows down and at some point it just breaks. This is a known result. I just saw a poster that shatters that. But then when you go to small asteroids, about less than a kilometer, then they can rotate faster. The question is why. How is that possible, if the only one thing is gravity? The idea we proposed – I mean, there were some other papers, especially written by Keith Holsapple at University of Washington, in which he explained that these asteroids must have some kind of cohesion, some tensile strength, and otherwise it’s just impossible. The question was, “How do you get this strength, if gravity isn’t the only thing, how can you get this strength?” The answer we were trying to get across was that these tiny forces of cohesion Van der Waals forces between particles might give you the needed strength.

We have been working for the last four years to prove that. It seems to be true. There are some other studies and observations that seem to support this idea, so starting with that, we have been able to develop some models of how binaries can form, how asteroid pairs can form, how you can get the right shapes, what the real influence of cohesion and angle friction is in these bodies, and that’s what gives me these right now [I think I was trying to say that the idea we had about the origin of cohesion is what produced all these different results about asteroids].

Pendick:

That’s interesting. What you describe is what’s supposed to happen when you have interdisciplinary research. You know, somebody from a different field comes in and is supposed to inform what you’re doing, so maybe was this a case of the asteroid people choosing maybe the wrong physics because that’s just not their expertise, and they found the best thing that seemed to make sense was –

Sanchez:

Yes. That was the best possible tool they had, and they did the best they could have done at the time. That’s completely understandable. At some point, even the method I have is going to be seen as obsolete. I’m okay with that. It’s the best thing we can do right now.

Pendick:

I’m just curious whether you have made any contact with the extrasolar disc people, because granular physics is how planetary systems form initially, I would think.

Sanchez:

I think that, I just talked to somebody, and they told me that they read my papers, but I myself haven’t done anything on it. I’m quite busy as it is.

Pendick:

Well, if you need another job – because I know some people at NASA who wrote code, and this is what they do. They say, “Here’s this disk we see, and how do we explain it? How do they form planets?” And there’s some controversy about the physics. There’s two big models for how planets are supposed to form, gas giants versus solid planets. It’s very interesting.

Sanchez:

That’s how –

Pendick:

Let me ask you one more thing, then. It’s come up a few times with people is marketing, right? So you do not hide off in a lab and do research, and everybody just thinks you’re brilliant and offers you money, right? You can go out – you especially, now, you’re an outsider. You’re coming in and telling people, “No, no, I think it works this way.” So how much of this do you have to do, in terms of traveling, going to meetings, doing talks – how big a part of your job right now is that?

Sanchez:

Not as big as my boss. He travels a lot. More than me. This year has been particularly filled with trips and going to conferences. The thing is, I think the community has seen that the things we are doing now – it’s good times. We are presenting a model that has been validating a different field, which is much more strict about how you code. They have seen also there’s a basis of support for things we are saying. I think that even if it has not been 100% accepted, they respect the things we do. As far as conferences go, I have to go to conferences in two different fields, because yes, I want to transmit everything I know from grains to the planetary science meetings, but I also need to take everything I know from the planetary sciences to the granular field, because they knew nothing about asteroids. About three years ago, I went to one of the Gordon conferences, and I told them, you know, this is what I’m doing. These are pictures of actual asteroids, and they look like a rocky beach. It’s all grains and dust. And the community, as such, has done nothing to address this. So if you want to work with me or to collaborate with me, or even compete with me, just let me know, because you are going to be the only other researcher which is going to be doing this.

I think I may have had a bit of an impact, because the next meeting I went to, there were a couple of professors doing things in low gravity. Then last March, I went to Germany to another conference that was called, “Granular Matter in Low Gravity.” They were beginning to bring people doing asteroids, people from industry, people from the granular field doing things in suborbital flights – it’s really basic science. You go up in a plane and you have a box full of grains or rods or something, and you try to track them. Then you try to see the physics of that: if it’s a granular gas, if it’s forming a cluster, how the collisions work, where do they go. This is really basic physics, basic granular physics, that we are not doing in the planetary sciences side, because we don’t see it as useful, because it’s not an asteroid. It’s not a meteorite. It’s not a big tide, because it’s not rings. But they are beginning to do it, because they do have the expertise. There are things I have seen that is like, “Yeah, I have no idea how to do that,” but I have seen students doing great projects. They are beginning to see these – I mean, all the things they have seen in 1-G, if they repeat them in micro-G, you get a completely different result. Something just as simple as having powder in a box – when you remove gravity, or when you let it fall – in the drop towers they have in Germany, then you see that the air, which is trapped, bubbles up. You can see a bubble coming up, because the grains cannot sustain it anymore. You can see that, which is something new. We cannot see that in 1-G, because that just doesn’t happen. It’s not our experience. So I think you call it “marketing it” and call it “going to meetings I like to go.”

Pendick:

Well, you’re selling something, in a way: a new perspective on some old work. Sometimes that’s where progress comes from. You just take a look at it from a different angle, and it looks new.

Sanchez:

Yeah. As far as coming to this community and trying to get all the grants and money to do all the research I want to do, I think the thing is that NASA is a big agency. They have these multi-million-dollar projects, and given that the research you are doing is good science, then they see the value in that.

Pendick:

There’s an application, though. I don’t know – this space asteroid hazard area has just struggled along over the years, but it’s been pointed out that if an asteroid is a pile of rubble and it’s heading toward you, and you have 5 or 10 years to come up with a way to make it go in a different direction, then the structural properties of an asteroid are very important, and you have to know before you put a force on it to maybe divert it or shine a light on it, or whatever you’re going to do, you need to know the physics. I wonder how much of that is driving the support for the physics of asteroids.

Sanchez:

The recent mission called the AIDA mission, which is a collaboration between ESA and NASA. One of their objectives is to see how an asteroid is going to react to a kinetic impactor. They’re basically just going to drop a big ball or something with all the instruments, and they’re going to drop it and see what happens. That is the science part of the mission, because that’s one of the methods to deviate an asteroid from a collision with us.

Pendick:

To hit it is the easiest thing. Send a spacecraft and just hit it.

Sanchez:

Yeah, there are other things. That’s one of the propositions. A gravity tractor you just have the asteroid traveling at the side of the spacecraft and gravity is supposed to pull it if you have enough time. Otherwise, you can just paint it. Paint the asteroid, and the photons from the Sun are supposed to move it. Another one is that you send a bomb, but then, we need to know, if you do that, you’re going to have instead of just one asteroid, a hundred, which may be more dangerous. Another one is – yeah, I heard about this at some point. You have a laser, and you shoot at one side and as you sublimate the material, the material will be pluming in one direction, and the asteroid is going to be pushed in the other way.

Pendick:

Or you could attach a solar sail to it. Well, as far as shooting nuclear missiles at asteroids, first you have to talk somebody into letting you launch a nuclear missile on a rocket, which is not generally a safe thing. Okay, well, that’s very interesting. I think I don’t have – I think we’ve covered our questions here. Is there anything else you want to add to it? Maybe some advice.

Sanchez:

For the younger generation?

Pendick:

You’re a special case. You’re an international scientist. You had to find a home. You came from a country, like you say, that doesn’t have a research tradition or a big research enterprise that could have supported you. Is this something – what do people need to be ready for? Is it worth it?

Sanchez:

I think it’s worth it, depending on what it is you want to get. I think you need to be willing to change and adapt. You need to be willing to learn, not just about science, you need to learn about many things. You need to be humble. You need to know that not everything you do is correct or appropriate, and you need to be humble enough to accept that and to change. I think that you, many times, may hear especially that you have to follow your heart and do what your heart is telling you to do. I don’t think that’s correct. I think you need to listen to your heart, but you need to think before you make any choice. The Bible says the heart is treacherous, and I believe that. Like I said, you should listen to it, but you shouldn’t do what it says. You think about it. You ponder on it. One of my teachers used to say, “You shouldn’t really worry about the future. You make good choices now, and the future will take care of itself.” So if I were to give any advice, it’s “Think before you make your choices.” To not just follow your heart. That’s foolish.

Pendick:

A lot of people have told us, toward the end of their career, “Just find something you really love to do, and do that.” But you might say, “Well, think about the job prospects, too.”

Sanchez:

I love what I do. I really like it. Have you heard the expression, “Find something you like to do, and you never have to work again in your life”?

Pendick:

Yes.

Sanchez:

That’s true. I like what I’m doing. At some point, when I went back to Ecuador, when I was talking to some high school students – the students in my high school – I told them I’d been paid to play on a computer for four years, because basically that’s what I was doing. I liked it that much, that it was like a game. I just needed to solve a problem. It was great. Even now, it’s the same. There’s a problem, and I want to solve it. I want to see how it works out.

Pendick:

Yeah. Puzzles.

Sanchez:

So yes. Find something you like, and then you will be good in it. But again, you cannot just trust your heart.

You have to think about the choice you are going to make, because your heart might change with time. You need to listen to it, ponder on it, but then you have to really think.

Pendick:

What you did, though – you had an interest in physics. But you didn’t have a burning desire to do physics of granular materials. It came along, and you tried it, and found it interesting.

Sanchez:

Yes. That was why I said you need to be willing to be change and adapt, even with language. When I went to the U.K., I could speak English already. But then I kind of needed to change my accent, because even though I could understand them, they could not understand me, so I needed to change my accent. I needed to change the way I ate. When I went to France, same thing. I couldn’t speak any French. I needed to take classes. I needed to learn how to say “hello.” Because when you go to France, if you do not know the person, many times you are going to kiss them four times. If you know them, you might kiss them just once. I didn’t know that. In Ecuador, when we say “hello,” we do kiss women on the cheek. Not the men, except my dad and my grandfather. To all the others, we just shake hands. Sometimes the shaking of hands is something you don’t even do here. That’s pretty common in Ecuador. We shake hands. We make friends and do it.

Pendick:

And often, these are the things that are just in the culture, right? Depending on class and education, we wait for a woman to offer her hand to shake, or you just don’t – you don’t grab the hand. So when you were away, you would adopt local customs, even if it were uncomfortable or exotic or strange?

Sanchez:

If they were really strange, I would say, eh, I am Ecuadorian. I don’t do that. For example, in France again, you give a kiss to your male friends. Yeah, it’s men and women, you kiss them on the cheek. I would do that with my female friends, but not with my male friends, because was like, “Agh,” because that’s way too much, and they knew it. They respected that. In the U.S., I refrained from that. That’s a no-go. But I’m used to that when I go home. What I have seen is that when people from this country go to Ecuador, they sometimes allow others to give them the kiss on the cheek, but many times they don’t, they say “hmmm…. no, I don’t do that.” So I think there is a healthy balance. There’s so much you can do that doesn’t make you too uncomfortable, but if it’s not uncomfortable at all, there is no reason to make your hosts feel uncomfortable.

Pendick:

Alright, good enough. We’ll leave it there.

Sanchez:

Thank you.