Do Aliens Exist? | Meet an Astrobiologist

I'm Dr. Universe, and if you're anything like me, you've got big questions about our world. I get lots of questions from kids wondering about aliens.

In this episode, we meet Afshin Khan, an astrobiologist who studied signs of life when she was a Ph.D. student at Washington State University. She shares her adventures to uncover the teeny, tiny life that forms framboidal pyrite on Earth -- and what it would mean if we found those structures outside Earth.

As always, submit your burning questions at askdruniverse.wsu.edu.  Who knows where your questions will take us next!

Learn more about astrobiology from scientists like Dr. Khan at Blue Marble Space Institute of Science.

Thanks to the amazing student actors at Regional Theatre of the Palouse.

As always, submit burning questions at askdruniverse.wsu.edu. Who knows where your questions will take us next.

Transcript

Dr. Universe
Welcome back young scientists. I'm Dr. Universe, and if you're anything like me, you've got lots of big questions about our world. I get asked a lot of questions about aliens.

Students
Are there aliens on any planet? Brooks, 11, Georgia.
Is there any proof of the existence of aliens? Harsha Vardhan, 9, India
Are aliens real? Rosie, 10, Mississippi
Are there aliens? Isa, 9, Canada
Do aliens exist? Adrian, 11, New Zealand
Dear Dr. Universe, We are writing as a 5th grade class at Uplift Hampton Primary. We would like to know if aliens are real. If they are real, how far would we have to go to find them?

Dr. Universe
Those are big questions. Right away. I can tell you that so far there's no evidence of green monsters with giant eyes and long fingers creeping around the solar system. But that doesn't mean there isn't life of some kind out there.

I met Afshin Khan when I was answering another question about how life started on Earth. And I knew she would be the perfect scientist to ask about extraterrestrial life because that's what she studied when she was a PhD student at Washington State University. Now Dr. Khan wears two hats. She works in medical research to help solve human diseases. And she's part of the Blue Marble Space Institute of Science.

First, can we talk about what astrobiology is?

Afshin Khan
Astrobiology is really this large, fascinating field of science where all fields of science can converge. So back in the day, people, if they were interested in life sciences, they went on to become a doctor or a life scientist. And if people were interested in studying the star systems, they went into astronomy. But if you were interested in finding out if there was life on all those star systems or the planets around those star systems, then what do you do? That's where astrobiology comes in.

So it's a way of converging all your physics and mathematics and astronomy with biosciences or biology and chemistry, which is the study of life. I have met people with economics background and sociology and lawyers coming to astrobio conferences just because they are interested in the future of humanity in the universe.

We like to think that sometime in the future, we'll be able to spread out on other planets. And then maybe whenever engineering allows us the capabilities to travel outside of our solar system, to other star systems. And so people are very interested in seeing how humanity will evolve on those planets.

Dr. Universe
So do you think there's life outside of Earth?

Afshin Khan
The likelihood is so high, right? If Mars was like Earth -- if it had surface water in the pas -- the chances are that Earth-like life evolved there. And even if it's not there today, there may be something that's thriving in the subsurface -- in the ground or in the caves. There's like so many what-ifs that they're there, and we just haven't looked all over Mars. And we haven't had humans go and explore.

It's a very different scenario when a human goes and explores a particular area than when you send a programmed robot to do it. We still want to send a human explorer because they would know exactly where to go and look for what and run some tests. And then you have an answer to whether there's life for now -- maybe within two days or a week at most.

Dr. Universe
What kind of signatures do you look for?

Afshin Khan
One of the definitions of life is that it needs a source of energy. It metabolizes. And you have these chemical reactions because we need things to keep us alive. So those metabolites that come out of our body, that's a kind of biosignature.

So people who study dinosaurs, they don't just study the bones of these organisms. They also study their metabolic waste that was left behind. That's fossilized. That kind of gave an idea to scientists of what their environment was like or maybe what they were eating at that time.

Dr. Universe
Like dinosaur poop?

Afshin Khan
Yes, dinosaur poop. Say if you go out of your house, and there's dog poop in your garden. So that will tell you that somebody walked their dog outside of your apartment or outside of your house. So even before you see the dog, you'd know that a dog passed by just by looking at that metabolic waste.

So that is the same concept that we try and apply. Before we even find that actual evidence of life, there are going to be trace signatures that that organism must have left behind, and that's what we try and identify and that was one of the things that I did.

I was trying to get at the bocce ball-shaped framboidal pyrite. So pyrite is a mineral, but the bocce ball-shaped nature or the structure of this pyrite is something that forms as a result of bacterial colonies living in a certain kind of environment and metabolizing this pyrite and forming this structure of pyrite.

Dr. Universe
Can you describe for me what the bocce ball looks like?

Afshin Khan
Think of a raspberry, which is kind of empty in the center. It has that hollow in the center. And then you have these tiny single parts of raspberry that form the entire raspberry. Or you can try and imagine a really, really tiny golf ball, which is hollow in the center. That's what framboidal pyrite looks like.

I started looking into what were the conditions that framboidal pyrite forms in and then what bacteria is involved in forming them. Some of the more wide observations made by astrobiologists in different environments -- they had certain different candidates of bacteria, which they think form these, one of which happened to be nanobacteria.

That fascinated me because I knew that this lake has many kinds of bacteria. Any one of those could be forming these framboidal pyrite. But nanobacteria is one of the more controversial life forms. Or at least it was when I was dipping my toes into this. They're smaller than viruses. So they can be anywhere between 50 nanometers to 200 nanometers.

Dr. Universe
A nanometer is exquisitely tiny. One single strand of spider silk is about 5,000 nanometers thick. So we're talking about things way too small to see with a regular microscope.

Afshin Khan
They are extremely tiny. They are visible under an electron microscope.

We were using an organic solvent, which is a chemical. It will leave behind whatever it cannot dissolve. So we knew we would kill most of the bacteria in there. But then some of the hardest ones will probably survive that. And we were right. We were able to image a few of those, and nanobacteria happened to be one of them.

Because the environment is a mix of a lot of geology, biology and everything else in between, it's very hard to tell what you're looking at when you're looking at something under the microscope, you know? If you're looking at tiny circles that are 50 nanometers, it could be anything. How do you know it's bacteria? I mean, you cannot really see anything inside the circle. It's really hard to make out the specific organelles that you will see. And even if you can, it's hard to tell: Is that life? Is it non-life? How do you make sense of that?

So Jill Banfield, in UC Berkeley, published a paper in Nature a while back where they had sequenced these nano structures. And that was the trick! I was like, 'This is how you prove something is alive or not. I will just have to get it sequenced.'

So I went to the Genomics Center at WSU. One of the directors there -- he's amazing -- agreed to go on this major expedition of exploration with me. We had a few hits and misses, but eventually, we were able to pinpoint and get sequences that were very similar to the published sequences by Jill Banfield's lab. So that's when we knew that we were looking at similar structures, and in all likelihood, the framboidal pyrite was coming from these bacteria.

Dr. Universe
Finding framboidal pyrite outside Earth would be evidence of life.

Afshin Khan
If we have a rock being returned from Mars, and when they look at it under an electron microscope, they find these framboidal pyrite-like structures in there, it will tell us that, 'Hey, we find these structures in Earth environments wherever there is bacterial activity. So that means that, if this is coming from Mars, there is likely bacterial activity that must have happened in the past. Or maybe it's happening today.' That's just one clue that tells you okay, there's a trace of this biosignature being present in the rocks of Mars.

Dr. Universe
Do you think that there is anywhere life like us?

Afshin Khan
That's the biggest question. And the universe is vast. The lack of evidence, of course, it doesn't mean that the thing doesn't exist. It just tells us that we have to keep exploring. That's what keeps us going. That's what keeps that question open-ended.
I just find it difficult to think that we're the only intelligent life that evolved in the universe. Now, either way, it's fascinating. If we're the only ones, it's amazing how far we've come. If we are not alone, that's amazing, too. That there's other intelligent life out there, which is very like us or way more advanced on us or maybe not as advanced yet as us because they formed at a later time.

Dr. Universe
That's all for this episode, friends. We hope you loved learning about astrobiology and imagining the kinds of life that might exist outside Earth. Big thanks to Afshin Khan for giving us a window into this incredible field. And to Blue Marble Space Institute of Science who are bringing astrobiology to people of all ages and empowering the next generation of scientists. 

Huge thanks to the amazing theater kids from Regional Theater of the Palouse. RTOP is a proud sponsor of STEAM learning. Discover the art of science, technology, engineering, and mathematics. STEM makes life possible, and art makes it worth living. Support your local arts and humanities programs. Together STEM is gaining steam. 

As always, if you've got a science question tickling your brain, you can submit it at askdruniverse.wsu.edu. That's a-s-k d-r u-n-i-v-e-r-s-e dot w-s-u dot e-d-u.  Who knows where your questions will take us next.