Irvin Hirshfield
Taylor Tate: Hi, my name is Taylor Tate. I’m a junior at St. John’s University and today we’ll be talking to Irvin Hirschfield, a microbiologist.
IH: My name is Dr. Hirschfield, Irvin Hirshfield, I am a microbiologist and I’m an associate Professor of Biological Sciences at St. John’s University.
TT: So, we’re going to be talking about life beyond Earth. Do life forms exist beyond Earth?
IH: Ok, well this is a question that’s, as I’m sure you know, has been asked over and over again. And one thing I think is that this idea that life can exist in other planets has permeated our culture. We see this in Sci-Fi movies all the time. Often these are creatures that would do us harm, but, if we look at the numbers… So, for example I was looking at studies with the Hubble telescope, which is circling the Earth outside of our atmosphere. Through this telescope, it’s estimated that there are 10 to the 20 third stars in the Universe and that might even be an underestimation. But let’s suppose that only on .1 percent of these, there is one habitable planet circling this star, that’s 10 to the 20th planets that could potentially have life on them. So, yes, there’s a huge number of planets that possibly could be inhabited. So, we think that there’s a good chance that there is life out there.
TT: Do you think that the scientific community backs your claim that life form exists on other planets?
IH: Well, it’s not my claim. I’m just reading what other people think and it seems logical to think that we’re not the only planet in the Universe, with which there are trillions and trillions of planets, that life would exist on. In fact, some people think, as perhaps we’ll discuss later, that maybe life could exist on certain moons of large planets, like Jupiter. One that’s touted is a planted called Europa and it’s encased in ice. At the equator I think the temperature is something like -200 degrees Celsius. But it’s thought to have enormous oceans that are warmed by tidal friction from Jupiter. Just like we have tides here, Jupiter pulls on the waters of this planet and can heat them up. So, it’s thought that that’s a possibility. And, one of the things I noticed through the NASA site, I believe, is that in about 10 years NASA is planning to send a robotic probe, a solar powered probe, that will circle Europa and gather information about it. So, I guess NASA is putting some stock in the possibility that there could be life on Europa.
TT: So, where she we be looking to find these microbes?
IH: Well, look, ok, so let’s suppose I had my fantasy voyage, space voyage, if this were possible –which it’s not right now- but if I had my fantasy space voyage, I would look to go to an exo-planet, that is one that is far away, and what astronomers have been doing, you could say astrobiologists is what I’m trying to say, but astronomers, they’ve been looking at, they’ve developed a technique to try to detect planets flying around other suns. Now what they look for is something that they call in the Goldilocks Zone, alright, in other words, this is a planet that’s like Earth, it’s not too far from their sun, because then it gets very cold, or it’s not too close because then it gets too hot. So, you know, like “Goldilocks,” this is just right. Right. So, yeah, if I could get there, then I would expect that we could detect whether it has an atmosphere like ours, etc. I would expect to find life there. Ok, now this might be more advanced life. We don’t know. Maybe it would only be microbes. We don’t know. But, if we want to look for something that’s realistically within our grasp, I would say the two best places to look would be Mars, I mean this is what we think. Mars, and I mentioned some of these moons – Europa is one of them, Titan has been mentioned. But I want to focus on our solar system, because I think if we have any chance, it would be in our solar system, at least in the relatively near future. So, I’m calling the relatively near future – I would call this, say, 100 years from now. I’ll be conservative. What I would say is this…when Mars…Alright so let’s look at Earth’s models, ok, because science uses models and we use models that we understand and try to see if these models can extend to other studies. Alright, this applies to microbiology, molecular biology, any type of biology. You have models that you work with. So, on Earth, we find microbes in a huge number of ecological niches and, you know, one of the, on Earth we study whether microbial life exists within a variety of places. No matter where we look within limits, of course, we seem to find microbial life. So let me be a little more specific, I’m being very general here. So, for example, we have bacteria that are called extremophiles because they seem to live, by our standards, in extreme conditions, in harsh conditions. So for example we have hypotherophiles these can grow even at 110 Celsius which you make recognize as above the boiling point of water. We have bacteria that live, and I’ll get to this later, below the surface of the Earth. So actually there’s a large biomass below the surface of the Earth that’s estimated to go maybe, I’m going to say down about a mile. These bacteria don’t photosynthesize but they can get their energy from chemicals, they can use the minerals from rocks to gain nutrients – it sounds weird, but they’re not like us. So, call these bacteria chemolithoautotroph, which means “chemo” they get their energy from chemicals, “litho” they get what we call reducing power from inorganic substances, and “autotroph” they get carbon from carbon dioxide. Ok, so they can survive under these conditions and, in fact the temperature can get up to even 60 degrees it’s been estimated in some of these niches.
TT: So basically, you would say that bacteria that strive under extreme conditions would be there beyond Earth?
IH: Right, so if I were going to Mars, I mean I’m not the only one who thinks this, I’ve said this for a long time, where would I look for life on Mars? So, I assume that Mars is about the same age as the Earth, which is about 4.5 to 4.6 billion years; we think that it took about a billion years before life forms showed up on Earth. It sounds like it’s easy to throw this number out but it’s an unimaginably long period of time. I think it’s beyond our capability of truly understanding what a billion years is. But if I were to go to Mars, the surface of the planet seems very hostile to life, but although from what I’ve read, at the equator, in what they call Martian summer, the temperature can get up to about 70 degrees Fahrenheit, which I didn’t realize. But nevertheless, I would look underground. I think that’s what a lot of people would say. We would look underground because maybe water might exist there. So, using our Earth models, what do we look for for life. We’d want to look, they would have to have some sort of carbon, they have to have a way of making energy, and as far as we know, at the present time, life is associated with water. So, water, energy, carbon, these are the things that these, say bacteria if they exist there, would have to have access to. Now in the past it, let me just say, it is thought that there are bodies of water on Mars, but these have disappeared. But there is evidence for water underground.
TT: What are Human’s responsibility after we find life beyond Earth?
IH: I think that we have to tread carefully as to try not to disturb their ecosystem. I mean, people will be curious, the scientific community will be curious, if an experiment is done, it will be this; first, does this microbe have DNA or does it not. If it does, then maybe they’re like our microbes. If it doesn’t hen this would suggest that there are alternate pathways to biology in the universe. So this would be of great interest. Now, the other thing I would say is we carry a lot of microbes, we have a micro biome, we are essentially, radical to say, but many microbiologists would say this, we are a human microbe hybrid. We have to make sure we don’t contaminate them, as well.
TT: Why?
IH: Because we don’t know if our microbes would be an alien species there.
TT: What does that mean?
IH: An alien species is one which is out of its normal ecological environment. We have tremendous problems on earth with this already, with plants and animals. So we have to be careful not to contaminate them. We have to be careful that they wouldn’t contaminate us. But I think we can do this robotically, at least on Mars. So, we could eliminate some of this, the danger. And maybe that’s what will be tried first.
TT: Thank you for your time here today. And, thank you for watching this video, as part of the NASA astrobiology debates.
