Thanks to NordVPN for sponsoring today’s video.
Back in April, NASA announced that they would cease operations of the infrared telescope
known as SOFIA.
If you have never heard of this telescope, you’re in for a surprise.
Sofia is a fascinating example of NASA trying something quite different, and although it
did not prove to be as effective as they might have wanted, the incredible engineering that
went into it and the things it discovered make this telescope an important part of space
history.
But what is Sofia?
Well, it’s not a ground-based telescope.
Neither is it a satellite-based one.
Sofia is a telescope that sticks out of the side of an aeroplane.
I’m Alex McColgan, and you’re watching Astrum.
Today, as we near the end of Sofia’s operation, it seemed appropriate to look back on the
history of this quirky telescope, and learn about the design choices that went into it
and what discoveries it made.
And ultimately ask, was it worth it?
I don’t know about you, but when I first saw Sofia, or the Stratospheric Observatory
For Infrared Astronomy, my mind was immediately buzzing with questions.
Most pressingly, why an aeroplane?
Why not a satellite like Hubble, or James Webb, or maybe something ground-based?
You might guess that the modified Boeing 747 that houses the telescope is possibly cheaper
than launching a satellite into orbit, and you’d be partially right, but not as right
as you might think.
Sofia was expensive to build, and expensive to operate.
To make a few comparisons, while it cost NASA $1.5 billion to build and launch the Hubble
telescope, Sofia still cost $1 billion, in an 80:20 collaboration with German scientists.
Not that far off.
And the $85 million a year required to keep it going isn’t that much less than Hubble’s
ongoing maintenance costs.
In fact, the high cost of Sofia was cited by NASA as the main reason for discontinuing
it.
You might wonder whether it’s more fuel efficient than a rocket.
Rockets certainly are fuel-guzzlers.
The SpaceX rocket Falcon 9 uses over 75,000 gallons of propellant, a mixture of liquid
oxygen and kerosene.
This fuel-top-up for the reusable rockets costs $200K-$300K.
But Sofia’s Boeing 747 is actually comparable.
Its tank fits around 60,000 gallons of a different type of kerosene, which also costs around
$200,000 to fill up.
And given the fact that it flies 3 times a week for 10 hours at a time, burning through
about half a tank in one run, all in all, that’s a LOT of expensive fuel used.
But it does have some advantages.
The main benefit of space satellites is that they get above the Earth’s atmosphere.
Air molecules refract light, which means that if you can get above the atmosphere you can
get much clearer, crisper images.
Sofia is able to fly above 80-90% of the atmosphere, so it shares this advantage with a space satellite.
But unlike a satellite orbiting the planet, at the end of a flight Sofia can come down
again.
This makes it much easier to maintain, and also to swap out its scientific equipment,
giving Sofia much greater flexibility in the sorts of things it can detect.
This has proved invaluable in Sofia’s 8 years of life, as we’ll see later.
Still, I don’t think this is the true reason Sofia is an aeroplane-based satellite.
To understand the real reason, it’s important to know a little bit about the history of
flying satellites.
For Sofia was not the first.
Flying observatories actually date back to 1957, with the balloon Stratoscope 1.
The idea was simple – put a telescope on a balloon, send it 25km into the air, and
have it take photographs of the sun.
However, plane-based telescopes wouldn’t come along until the solar eclipse of 1965.
Phenomena like solar eclipses are very location-based.
Depending on where you are in the world, you will get a better or worse view of a solar
eclipse.
As the Moon travels between the Earth and the Sun, its shadow travels across the continents,
meaning some get to see the full eclipse, while others only see a partial eclipse, or
none at all.
So, NASA decided to put a telescope on a plane to chase the solar eclipse across the globe,
thus giving it the best view of this phenomenon.
This was something that only a telescope on an aeroplane could do – neither a fixed-in-place,
ground-based telescope nor a locked-in-orbit space telescope could be exactly where it
needed to be.
The first telescope was put on a Convair 990, and was named Galileo, after the famous astronomer.
Galileo’s eclipse-chasing mission was a success, and did so well that NASA asked itself
the age-old question: “What if we do a bigger one?”
This led to the Kuiper Airborne Observatory in 1974, and then Sofia being proposed as
an even larger iteration again in 1996.
Sofia is a technological marvel.
Getting a telescope to work on a moving aircraft is about as difficult as spinning a plate
on a stick while standing on the roof of a moving car.
Don’t try this, by the way.
Sofia would need to take images of objects millions to billions of light-years away.
To do this, it would need to remain perfectly still even as the plane around it rocks with
the wobble of turbulence, the vibrations of its engines, and the rush of the wind ripping
into the telescope’s open cabin.
If the telescope vibrated even slightly from any of this, it would be impossible to track
the stars and planets it was trying to see.
It would repeatedly be super-cooled by the low temperatures of high altitude, then warmed
again at ground-level, potentially leading to cracks and damage to the 8-nanometre-precise
mirror.
An incredible task NASA and German scientists had set for themselves.
They solved these problems ingeniously.
Sofia’s telescope itself is set on a series of gyroscopes, magnetic torque motors and
high-speed cameras that allow it to remain perfectly still as the plane around it moves.
The door that opens on the side of the aeroplane comes equipped with an intricately sculpted
ramp on one side, tested in wind tunnels to reduce the 850km/h winds the Boeing flies
at to just 80 km/h.
And the Mirror itself is built using a ceramic-glass composite called Zerodur that has almost no
expansion or contraction under temperature changes.
Its equipment is unique in almost all the world.
Sofia is primarily an Infrared telescope, but thanks to some additions that were made
to its HAWC equipment early on, Sofia is one of the few telescopes capable of seeing the
polarisation of dust clouds.
This gives Sofia the incredible ability to see magnetic fields across galaxies.
However, with its greater size and sophistication than its smaller forerunner Galileo, Sofia’s
costs grew too great for its scientific contributions.
Sofia began its 5 year mission in 2014, and was then given a further 3-year extension.
But while in its first 6 years the Hubble telescope was cited in more than 900 scientific
papers, Sofia featured in only 178.
This led the National Academies Decadal Survey on Astronomy and Astrophysics in 2020 to conclude
that Sofia did not contribute enough scientific discoveries to justify its high running costs.
NASA took their recommendations on board and concluded there was no room for Sofia in the
future of Astronomy, seeing as there are likely bigger and more exciting infrared telescopes
on the horizon that could better use the funding.
So, was Sofia a quirky idea that went too far?
Some in the infrared telescope community would say no.
Its productivity was ramping up towards the end of its life even as NASA decided to cancel
it.
But ultimately, the value of its existence can only be weighed by its discoveries.
Let’s examine a few of the biggest, so you can decide for yourself.
Being an infrared telescope, Sofia is able to see through thick banks of dust that visible-light
telescopes would struggle to penetrate.
As such, it has been able to capture moments like this one in the Orion Nebula.
Here a young star creates a bubble of space around it by blowing the dust away with its
stellar winds, in a process known as feedback.
It was previously believed that only Supernova could do this, so discovering that regular
stars did the same has been a key discovery in understanding the formation of stars in
the early universe.
The stellar winds prevent new stars from forming too close to the current one, while also compressing
the dust further out, increasing the chances of stars being created further away.
And what about this planetary nebula, NGC 7027?
By analysing its light signature, scientists were able to discover Helium Hydride in space
for the first time.
This molecule had long been thought to act as a key building block for more complex chemistry
back when the universe was only 100,000 years old.
But up until Sofia spotted it here, scientists had had no proof it actually could be found
in space, having only created it in lab conditions.
One of many examples of theory outpacing observation.
Sofia’s ability to see infrared gives it insights into the temperature of the universe.
For instance, by noticing that the infrared brightness of debris in double star system
BD +20 307 was 10% brighter than it had been a decade ago, scientists were able to deduce
that two large exoplanets had likely violently collided into each other in the system, heating
up the matter and dust around them.
This cataclysmic collision would otherwise have been very difficult to detect.
But my personal favourites for some of the most mesmerising images are these.
The strange lines that you see weaving through the images of stars here are magnetic fields
that channel mass in ways scientists had only dimly perceived up until Sofia.
These fields can allow mass to escape from galaxies, can keep it away from black holes
like the one in the centre of our own Milky Way, keeping it peaceful and quiet, or can
funnel mass towards black holes, ensuring they are constantly consuming mass.
If you want to know why the universe works the way it does, understanding the role of
magnetic attraction is as vital as understanding gravity.
And that’s something Sofia gives us like no other telescope.
From nebula to planets, from the formation of stars to the fundamental building blocks
of the universe, Sofia has peeled back the curtain to reveal fascinating secrets, and
has done so in a way that is truly unique.
Men and women have ridden along with it, performing science in real-time as it swept its gaze
out across the universe.
Perhaps it was a relic of a bygone time, and planes are not the true future of space exploration.
But without trying things out and innovating, we would never really know.
So, what do you think?
Was it good that we had Sofia, even if only to say that it didn’t achieve as much as
we hoped?
Or would the money have been better spent elsewhere?
What is the price we can put on experience and knowledge?
Either way, for better or worse, for nearly a decade NASA and German scientists really
did try to stick a telescope out the side of an aeroplane.
And that is a fact that has expanded my understanding of what is possible.
Want me to take an episode diving deeper into the discoveries of Sofia?
Let me know by liking this video or in the comments below.
Now, Sofia can see what most other instruments can’t thanks to the upgrade it received.
Did you know, there’s lots of stuff going on behind the scenes on your internet device
that you may not be able to see?
One of the creepiest - I think - is malware ads.
Some malicious ads disguise themselves as simple advertisements, and once you click
and load them - your computer sends your device info to a bad party like your IP address,
browser, OS and more.
Some don’t even need you to click.
With that info, the bad party can send back automatically picked malware suited to your
device.
The solution?
Keeping your system up-to-date helps, but mostly you need a way to block these ads,
and NordVPN’s Threat Protection feature does exactly that, plus a host more.
Get an exclusive NordVPN deal including Nord’s Threat Protection at nordvpn.com/astrum to
get a 2-year plan plus 4 months for free.
I highly recommend checking it out.
Thanks for watching.
If you enjoyed this video, feel free to check out my other telescope videos here.
Thanks to my patrons and members for supporting the channel too.
If you find value in these videos and want to help the channel make more, check the links
in the description below.
All the best, and see you next time.