Episode 6 | 8m 52s | Video has closed captioning.
To understand the dawn of chemistry, scientists can’t use test tubes and flasks: They need a modified Boeing 747 jet. Caitlin Saks and Arlo Pérez Esquivel learn all about NASA’s unique SOFIA (Stratospheric Observatory for Infrared Astronomy) mission, and how it was used to detect the first type of molecule in the universe: helium hydride.
Aired: 09/16/21
From:
- [Arlo] Today, I am going on a mission to find the 1st molecule in the universe.
- [Caitlin] We want to know: how did chemistry begin in the universe?
And how did it lead to all the molecules we have today?
- [Arlo] And for that, we need NASA and a modified jumbo jet... Oh, this is great.
- [Arlo] packed with one of the most unique telescopes on the planet.
(upbeat music) All right, y'all.
It's 6:00 AM.
And I'm on my way to NASA.
I have a serious bed hair, so I'm gonna have to take care of that at some point.
I'm gonna get to go inside the SOFIA aircraft.
Oh, man, I'm so excited for that.
(upbeat music) I've come to Palmdale, California to meet with the SOFIA mission team.
This is amazing.
They use this modified Boeing 747 to study the universe.
Oh, this is great.
- So this is what makes the SOFIA observatory so special.
It's our 17-ton telescope.
This is actually half of the telescope.
The other half is on the other side of the pressure bulkhead.
- [Arlo] SOFIA, which stands for the stratospheric observatory for infrared astronomy, is designed to observe infrared light.
That is light at a wavelength invisible to the human eye.
By studying it, they have been able to detect things like water on the sunlit surface of the moon, celestial magnetic fields, and even find the first type of molecule in the universe.
- Yeah, it's an exciting project to be on, for sure.
(upbeat music) - While Arlo got to travel to visit the SOFIA mission, I caught up with SOFIA project scientist, Naseem Rangwala.
First of all, I want to start off by saying how extremely excited I am to talk to you.
I'm just a space nut.
(both laugh) When people think NASA, they don't think chemistry.
I mean, like, explain yourself here.
- Right, so for us, space is a laboratory.
But we don't have beakers or test tubes.
What we need is a telescope and an instrument with the capability of detecting unique chemical fingerprints of molecules.
- [Caitlin] But what exactly is the benefit of having this telescope on a plane?
- There is water vapor in the Earth's atmosphere that absorbs this infrared light coming from space and preventing us from studying it on Earth, so you either have to be in space or in the stratosphere, where SOFIA flies.
- [Caitlin] But unlike space telescopes, a plane returns back to Earth after every flight.
And its equipment can be swapped out.
This means that different instruments can be built, modified, and improved in order to tackle specific scientific tasks.
- The instrument that you see inside there detects the magnetic fields around the galaxies or the stars that we can view up in the sky.
- [Caitlin] And one of the key instruments for studying chemistry in space is this: a spectrometer.
- So the light from the telescope goes into this for optics.
When the light comes in, it's almost like it goes through a prism.
It kind of gives you a rainbow color.
- [Caitlin] And by breaking up the light that enters the telescope in this way, the spectrometer can analyze the frequency of light it's seeing, and that can tell scientists what molecules are present.
- Molecules can rotate, vibrate at different kinds of motion, and when they do that, they either emit light, or they can absorb light.
But they emit and absorb at very specific frequencies.
It's unique to each individual molecules.
- That is the craziness of these instruments.
We can not only just look at a picture, but determine what's outside that's millions and billions and billions of miles away.
Just by looking at the light.
- [Caitlin] It was using a spectrometer like this one that in 2019, SOFIA reported the detection of something incredible: the first type of molecule in the universe.
After the Big Bang, the first two types of atoms to form were hydrogen and helium.
A hydrogen ion joined with helium to make helium hydride.
Scientists had speculated for decades that this could be the first molecule in the universe.
Only problem was we had never seen this molecule occurring naturally, and though it can be created in a lab, it is so unstable that it doesn't last long.
- [Arlo] This is why scientists turned their attention to parts of the galaxy that have similar conditions to the early universe.
- Even though we say this is the first molecule to form the universe, we cannot go back that far in the history of the universe to the very beginnings to look for this molecule.
So, what can we do instead?
We can look at an astronomical object that would have the right conditions or similar conditions for us to find this molecule.
- [Caitlin] Scientists decided to point the telescope at a planetary nebula 3000 light years away, called NGC 7027.
- And this planetary nebula, it had exactly those right conditions.
It has a very intense ultraviolet radiation.
It's very hot.
- In order to pick up helium hydride's molecular signature, scientists use the GREAT instrument.
I mean, literally, that's what they call it.
- [Murali] German receiver for astronomy at terahertz frequencies.
- Before being installed on the SOFIA aircraft, the great instrument had been recently upgraded and finely tuned to be able to detect the specific invisible infrared frequency of helium hydride.
- Just like you want to tune your radio to your favorite FM station.
The scientists tuned it to the frequency that they expected this molecule to be, and they saw it.
Decades of search was finally coming to an end.
The fact that it exists in space and that we have clearly detected it in space in this planetary nebula allows us to have confidence in our theory of the early universe.
- [Caitlin] So what happened in the early universe?
How did the first molecule come to be?
And how did it lead to all the molecules we see today?
13.8 billion years ago, the universe began with the Big Bang.
At first, our universe was just a hot soup of plasma.
It was in this hot mess around 100,000 years after the Big Bang that helium and hydrogen could come together to form helium hydride, the dawn of chemistry.
- And subsequently, it started the chemical reactions that were needed to continue to form molecules, and one of them was molecular hydrogen.
- [Caitlin] Once the universe cooled enough for gas clouds to condense, and the first stars ignited, the center of these stars became nuclear furnaces where heavier elements could be forged.
- [Naseem] In stars, it's very hot, and it's very dense, and allows two hydrogen to fuse together to form helium.
- [Caitlin] That's right.
More helium is formed in stars, but it doesn't stop there.
- As the star evolves, heavier elements will form and will go into the chain of making carbon, nitrogen, and oxygen.
- [Caitlin] At the end of their lives, some of these stars exploded in a supernova.
- During that explosion, you get all these heavier elements heavier than iron are made in that last moment of the star.
- [Caitlin] And all these elements can combine in countless ways to make all the molecules that make our world, every other world, and even us.
- Understanding chemistry and space is key to knowing our cosmic origins.
- [Caitlin] And 13.8 billion years after the Big Bang, we now have the tools to not only understand chemistry here on Earth, but to understand where it all began.
- To kind of detect that molecule is like finding a lost fingerprint.
It connects us all the way to almost 13 billion years ago.
And that's insane.
It's what we do science for.
- Rather silly question, but I'm just so curious.
With the acronyms, you guys first come up-- - Oh, I gotta tell you that story, yeah.
All the acronyms, they're actually put into a software to come up with these cool names.
- [Arlo] No way!
- Yes.
