Transcript for Dimitar Sasselov on Astrobiology

Jim Fleming:  William Blake famously advised learning to see the universe in a grain of sand. That can be the motto for astrobiology, which brings together the science of some of the tiniest things on Earth, microbes, with the study of some of the largest structures in the universe, stars.

Astronomer Dimitar Sasselov is one of the pioneers of the field. He is the founder and director of the Harvard Origins of Life Initiative, and author of "The Life of Super-Earths". Anne Strainchamps wondered:

Anne Strainchamps: Do you ever lie in bed at night and try to imagine what it would be like to see one of those planets?

Dimitar Sasselov: I do. I know that it's very difficult for this dream to become reality, to see them the same way we see pictures from Mars or Mercury. I particularly like lying in the backyard in the summer at night and looking at the stars. There, I can almost see them.

Strainchamps: Will they be beautiful?

Sasselov: What might be beautiful is the unexpected .   The beauty that you experience when you first go to, say, the Bryce Canyon or to Yellowstone. And you've seen all those pictures, and you've heard the stories, but when you see them for yourself, you always discover that there is some set of colors or some shadow that you never imagined. I think our exploration of exoplanets is a similar voyage where, despite all our expectations, we end up being surprised. It's hugely exciting.

Strainchamps: So there're kind of two parts: one is the hunt for these exoplanets, or the hunt for other planets that might be habitable; then the other is to look inside test tubes to hunt for new forms, new kinds of life?

Sasselov: Yes. There is a real connection between what we do in our labs, trying to understand life and its basic functions, and discovering those other environments out there which appear to be similar to our Earth-like environments, but in many ways different.

And so the question there, if the environment's different and life emerged there, would it be based on a different chemistry?

Strainchamps: What's happening in the lab?

Sasselov: What is happening in the lab is extremely exciting: it is the ability to synthesize the individual molecules of life, and to succeed in engaging them in performing the chemical networks that we associated with life. So in the sense...

Strainchamps: You mean they grow?

Sasselov: Yes. They grow; they replicate; they use energy in different ways. These are systems which are self-adapting; they're self-sustaining; they're organic; they're... You can call them "soft machines", in a certain sense.

We are now understanding how to build those systems which, essentially, mimic the functions of life. We can literally build one, or try to build one, and understand, first, the nature of our own biochemistry, and second, how we could possibly build another one.

Strainchamps: Has anybody actually done this yet?

Sasselov: What people have done is that they've tried to achieve that. It's called the "artificial minimal cell". The artificial minimal cell could be built in two different ways. One is top-down: that is, you take the simplest, smallest microbe with the simplest genome, and you try to pare it down even further to come to the, really, basics of function, and the smallest possible  -- "minimal" , that's why it's called minimal --  cell. This top-down approach has been attempted now for almost forty years. People have been working very hard on it, and there was a big breakthrough about two, three years ago, by the Venter Institute.

There is the other avenue to create a minimal cell, which is bottom-up. That is to build all the necessary molecules synthetically in the lab, and then put them together.  That was the huge obstacle for the past forty years, because nobody knew how to build synthetically a key component, which is called a ribosome, or the ribosomes, which all cells in all living creatures have.  They're the ones which actually translate what's on the DNA into actual proteins and...

Strainchamps: Can't replicate without it.

Sasselov: ...molecules. And this was achieved by the George Church lab in our bigger team here about a year ago. So that opens up, now, the possibility to bring this bottom-up approach all the way to creating a minimal cell, and that's what I discuss in my book.

Strainchamps: So, I want to ask you the same question I asked you about the planets: where you do find the beauty in it?

Sasselov: I think life, in itself, is a beautiful phenomenon. I look at it from the perspective of being an astronomer, from the perspective of the stars if you will, and then you look at it as a phenomenon, as a planet which is living  -- a living planet. It is so amazing to see the diversity of life here on our own planet Earth.

In just four billion years of opportunity to do so, life has explored all the possibilities on the planet. Even not mentioning technological civilization and homo sapiens, just the diversity in the microbial and plant and animal life is so amazing, that projecting this, then, on the scale of the galaxy and the rest of the universe is probably beyond our imagination at this point. But it's fascinating anyway.

Strainchamps: Yeah, and especially when you look what life has done: how it's proliferated and how many myriad forms it's taken on this planet. And that's just carbon-based life.

Sasselov: That's right.

Strainchamps: So then if you begin to imagine that there could be many other, alternative, chemistries of life... Wow. It's kind of dizzying. Getting a sort of visceral sense of the abundance across is always really hard.  You used this one analogy of grains of sand on a beach.

Sasselov: Yes. This is a beautiful analogy. And I have to give credit here to Jeffrey Bennett, who came up with the back-of-the-envelope calculation, as we say in science; it is surprisingly true, a few estimates, how many grains of sand there are on all the beaches, all the sand beaches here on planet Earth. It matches, roughly, the number of stars out there. And that just tells you how huge the universe is, and how full of opportunities it is as well.

Strainchamps: Yeah. I read that, and I tried to slow down and think, "OK. Imagine I'm on a beach, and I dip my hand into the sand, and, you know, I can feel the grains trickle through my fingers. And then I look across the beach and I see all that sand and think of all those grains, and then I look down the coastline and I see all the beaches, and then I pull way back and imagine all the beaches on Earth and all those grains of sand.  And that's how many stars are in the universe."

But then, the point of the new discoveries we've been talking about is that that's just the stars. There are billions more planets than there are stars, right?

Sasselov: We believe so, yes. The number of planets at least matches the number of stars, at current estimate. It may turn out that it even exceeds it.

Strainchamps: So, what will change for us, do you think, in a felt sense? The day the headline appears that says that we found life on another planet?

Sasselov: Well, I've thought about this a little bit, and it is a historic shift in the frame of reference. But, you know, whenever this occurred in the past, it took people time to absorb it. I think it takes a generation. The new generation which is born into the new frame of reference simply accepts it as the normal way of life, and that's when they look back and say, "Aha, this is the year. This is the time when that watershed moment occurred."

Strainchamps: Do you think it'll be a good change? I mean do you think we'll become, I don't know, kinder, better people as a result?

Sasselov: Yes. I actually am convinced that it will be a good change, partly because we look back in history, and every time we understood something deep about the world around us, eventually it led to things which benefited us  -- both our souls, and our material being.   It reminds me of the Copernican Revolution, which was meant to be a very esoteric mathematical, astronomical change in the frame of reference, but resulted in the Industrial Revolution in technology, and, then, everything that we know today, and which makes our lives better and makes us better, eventually.

Strainchamps: Yeah, I was trying to think how I would feel if I knew there was life elsewhere in the universe, and I just had a quick, kind of, glimpse of it. But it made me feel that the world -- the universe -- is a friendlier place than I thought. It did make me feel less alone. That sounds corny, I guess, but I know that's how I felt.

Sasselov: That's exactly what I meant. This is exactly the kind of feeling that I would get myself, and that's why I think that this will be a positive change for all of us, for Humankind.

Fleming: Dimitar Sasselov teaches Astronomy at Harvard and is the founder and director of the Harvard Origins of Life Initiative. His new book is called, "The Life of Super-Earths." Anne Strainchamps spoke with him.

Comments for this interview