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One of the perks of being an astronomer
is getting to use amazing technology in even more amazing places.
Some of the world’s most important observatories
are located on remote islands, high deserts, and even Antarctica.
And there’s one telescope whose “WOW” factor might just overshadow the rest.
The Stratospheric Observatory for Infrared Astronomy,
or SOFIA, features a telescope larger than Hubble
mounted inside a Boeing 747SP aircraft. It’s a telescope that flies.
But after twelve years of science, its mission has come to an end.
So let’s look back to see why something like this ever existed,
what it contributed to our understanding of the cosmos,
and what finally did it in.
As an infrared telescope, SOFIA
observed the universe through a super handy part of the electromagnetic spectrum.
For example, it’s used to study things that are a lot cooler than stars,
like planets and asteroids.
They aren’t hot enough to radiate much of their own visible light,
but they do shine in invisible infrared wavelengths.
And infrared light can do what visible light can’t.
It can pass through the huge clouds of dust that litter the galaxy,
enabling astronomers to see what’s hiding behind them.
But infrared astronomy does have one giant drawback:
most of its wavelengths, and especially the longest ones,
get absorbed by molecules in Earth’s atmosphere.
Like water vapor and carbon dioxide.
So while there are some ground-based telescopes
that study the universe in infrared, astronomers usually want to get these telescopes
as far above the atmosphere as possible.
The obvious place to go is into space,
but it’s hard to overstate just how expensive space telescopes
are to build, launch, and operate.
But what if there’s a way to split the difference?
What if you mount your telescope inside a plane?
It’s such a clever idea that SOFIA wasn’t even the first attempt.
Its predecessor, the Kuiper Airborne Observatory,
operated from 1975 to 1995.
But when SOFIA started its preliminary science mission
in 2010, it took the concept to the next level.
Developed by NASA and the German Aerospace Center,
SOFIA could cruise up to an altitude of 13.7 kilometers,
above more than 99% of the atmosphere’s water vapor.
And from that height, SOFIA was able to make some groundbreaking discoveries.
It made the first observation of helium hydride,
which scientists believe may have been the first molecule to form after the Big Bang.
And it helped uncover how even more complex molecules may have emerged…
like the building blocks of life.
Stellar nurseries like the Iris Nebula are home to baby stars in a sea of gas, dust,
and complex organic molecules.
And as they form, those stars emit a lot of ultraviolet radiation.
So the question astronomers had was whether all that UV light
was in the process of breaking these organic molecules down, or helping to build them up.
By using infrared light to track where different organic compounds
were located in the Iris Nebula, SOFIA showed that it was actually a little bit of both.
The closer these compounds are to a star, where the UV radiation is more intense,
the bigger they tend to be.
So while some smaller organic molecules are probably getting destroyed,
this result suggests the ultraviolet light from these baby stars
is also helping them combine into larger compounds.
And one day, those could go on to jumpstart the evolution of life.
SOFIA also helped reveal the lives of galaxies, too.
It turns out, magnetic fields can play an important role in feeding or starving
the supermassive black hole at the center of a galaxy.
When SOFIA studied the core of a galaxy dubbed Cygnus A,
it found powerful magnetic fields trapping matter near its central supermassive black hole.
That allowed the black hole’s gravity to continuously draw
that matter into its proverbial mouth, resulting in an active galactic nucleus.
As all that available matter spirals downward,
it heats up so much the resulting light can outshine all the stars in the galaxy.
But when SOFIA set its sights on the black hole in the center of our own galaxy,
it observed the opposite effect. Instead of providing a never-ending feast,
the magnetic field appears to be directing material away from our supermassive black hole,
putting it just out of reach in a stable orbit.
But not all of SOFIA’s discoveries are so cosmic.
The observatory has made some big contributions closer to home, too.
Like in 2020, SOFIA confirmed that the Moon’s surface contains water…
outside the craters where sunlight can’t reach.
There were a few other studies that hinted this was true.
Basically,
there was one particular wavelength of infrared light that looked like it was being absorbed,
which would happen if there were water molecules there to do the absorbing.
But that light could also be absorbed by compounds with hydroxide in them.
That’s O-H. Not H2O. So the results were inconclusive.
SOFIA was able to draw that conclusion because it had access to longer infrared wavelengths,
allowing it to look for a signal that water molecules emit, but hydroxide compounds don't.
So, with all of those discoveries,
why is SOFIA being retired well before the end of its initial 20-year mission?
Every ten years, the astronomical community convenes to write a report for NASA
that lays out a roadmap for the next decade of exploration.
And the 2020 version of that report claimed that SOFIA’s unique abilities
did not align with the research questions they wanted to focus on answering.
In addition, SOFIA supposedly hadn’t
produced enough scientific papers given what it cost to operate.
Which is a huge bummer, because now there are no telescopes in operation
that can study the universe in the far infrared.
Not even the mighty James Webb Space Telescope can do that.
Despite the outcome, SOFIA is a monument to scientific ingenuity.
If you’ve ever tried to take a good photo out the window of an airplane,
you understand the challenges the project faced.
It might not have worked out as well as scientists had hoped,
but it was a heck of a cool idea.
So thanks to SOFIA for all of the discoveries.
Thanks to all the engineers, scientists, and flight crew that kept SOFIA running
over all these years. And thanks to all of our patrons, who help keep this channel running.
If you’d like to learn how you can support SciShow Space,
head on over to patreon.com/scishowspace.
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