Four-hundred kilometers away from you there is a laboratory whose results no
other lab can replicate. Those results do not fit with our day to day experience,
as in this lab even time itself runs differently,
slower, than anywhere on Earth. That’s because this lab is the International Space Station.
And in this video, we’ll see how even the most mundane of
experiments have surprising results up there.
But how is a laboratory even built in outer space? How does the human body survive there?
And once the station's life is lived, how do you bring such a megastructure down from space safely?
I’m Alex McColgan and you are watching Astrum. Join me today as we celebrate the
ISS: a place where science and exploration transcend borders.
The idea to have an orbiting habitable station in space has concretely been in our imaginations
since 1868, the American author Edward Everett Hale wrote about “The Brick Moon” - a space
station made of, errr, bog standard bricks. The US began taking the idea seriously in the 1950s,
and then in 1984, Reagan gave the presidential order to build in the ISS, which since its
launch has been a marvel of scientific discovery. Over its decades of operation,
the ISS has not only expanded our understanding of the universe but also demonstrated the power
of unity in the pursuit of knowledge. Which is an incredible achievement, given that its
genesis owes much to a time when the Earth was a button press away from nuclear armageddon.
War has led to technological developments that seemed impossible in peace time. Radar,
jet engines, computers, nuclear weapons & marmite were all developed through a desperate war effort.
A nation’s fight to survive is perhaps one of the greatest motivators for technological advancement,
and the Cold War, despite no shots being fired,
was no different because it pulled the trigger on the Space Race.
But what about the times when there is no finish line, when there is no enemy to be conquered?
Well, we wander. Incredible scientific discoveries are also often made when
scientists are left to be curious, left to ask questions that sometimes
seem to have no useful answer, and left to actually collaborate.
That is how the idea for the International Space Station was
born. —
The ISS was conceived after the ambitions of the USA’s Freedom space station and the
Soviet Union’s Mir-2 were shelved, at a time when space spending was no longer justified by
either government now the space race was over. The ISS program today has the involvement of
13 other member states, including Canada, Japan, the UK and other European countries.
The ISS is a huge structure by any measure: spanning 108 by 73 m
it would just about fit inside a football pitch. It weighs a staggering 450 tonnes,
and with an estimated cost to date of $150 Billion dollars it’s worth nearly 5 times
its weight in gold. Clearly, it was never an option to launch all of this in one go,
a move that would have been both impractical and extremely reckless, so the ISS was planned
to have a modular structure, one to be assembled in space, piece by piece.
Each module was designed and built by a member state before being launched into orbit on one of
three vehicles: America’s Space Shuttle system, or Russia’s Soyuz or Proton rockets. Remarkably,
every launch carrying a component of the space station delivered successfully,
numbering 40 to date. There have been delays and mishaps, of course, and some resupply launches
have failed, but if a component made it to the launchpad, it’s now part of the space station.
The orbiting megastructure that we’re familiar with today is comprised of three main sections.
The backbone of the station is called the integrated truss structure (ITS), it
is unpressurised and uninhabitable but it supports much of the functionality,
storage and equipment on the Space Station. The ITS was designed to bear 4 huge pairs
of double-sided solar arrays, capturing light from the sun and rays reflected from the Earth,
which can generate 248 kW at peak. But the ISS can only generate electricity for 45
minutes per orbit, so the station requires batteries to power the systems while the
sun is eclipsed by the Earth. Much of the power usage onboard is ultimately
transformed into heat so the station needs large radiators capable of discharging 70kW
of heat into space in order to safely regulate the temperature on board for its inhabitants.
Below the ITS, the space station is divided into two pressurised and habitable halves,
the Russian Orbital Segment and the United States Orbital Segment. So
how was all this built? Where would you start?!
Let’s watch several key stages of construction to understand how the whole can be built!
The first module put into orbit was the Russian ‘Zarya’ module in November 1998,
this module featured 4 docking ports ready to accept the future modules and solar panels to
provide the station’s first power source. The next mission launched later that year
from the John F. Kennedy Space Centre in December carrying the ‘Unity’ module.
The docking of Unity to Zarya would mark the beginning of a new global space age.
Inside the space shuttle the Unity module was equipped with two Pressurised Mating Adapters
(PMAs) that interfaced the American ports to the Russian port and to the Space Shuttle’s
ports. The space shuttle was fitted with a robotic arm called the Canadarm which
could attach to the 12-tonne Unity module and position it above the Space Shuttle’s
docking port. This movement had to be done extremely slowly. Once aligned,
the Shuttle’s thrusters were fired to engage the ports. When Zarya was reached, the Canadarm was
again used to reach out and grab the Russian module and guide it towards the PMA on the
Unity module. When it was in place the thrusters were carefully engaged to make the connection.
After a few checks, the joined space station was released - after two weeks of manoeuvres.
With only these two modules, the station was uninhabitable. But that changed in July in
2000 with the launch of the Zvezda module from Russia, bringing life support and living quarters
for 2 astronauts. Later that year, the ‘Z1 Truss’ module was connected, ready to join the habitable
orbital segments to the ITS. And that November, Russia launched two cosmonauts and an astronaut;
Yuri Gidzenko, Sergei Krikalev and Bill Shepherd to the space station to become its
first inhabitants. Their docking marked the last time that the space station would be uninhabited,
and a crew has been on board every day since. For the first 4 months until the first laboratory
module, named Destiny, was attached to the Space Station, the astronauts were methodically
commissioning the station’s key systems, and assisting with the delivery of further modules.
In April 2001, an incredible tool was delivered by the Space shuttle that could be used to manoeuvre
objects in space without the need to complete a spacewalk, called the Canadarm2. It was the
successor to the robotic arm aboard the Space Shuttle Endeavour. It could be attached by either
end at specific Power Data Grapple Fixtures across the station. This means that the arm
had the incredible ability to ‘walk’ across the station to different locations to assist wherever
there was a PDGF. A future Endeavour mission in 2022 extended the utility of the Canadarm2 by
delivering the Dextre, a ‘tele-manipulator’, essentially giving the Canadarm2 a hand.,
Over the next 10 years, modules were continually added including 5 more laboratory modules from
Russia, Japan, Europe and the US. Research aboard these laboratories is truly multidisciplinary and
the questions studied can span fields including astrobiology, astronomy, physics, chemistry,
space weather and space medicine. By the end of 2009 the last of the main
solar arrays had been installed, meaning that the ISS finally appeared like it does today.
But not all the planned modules made it into space, the Columbia disaster in 2003
led to the cancellation of some projects, including the artificial gravity module,
a module that used centrifugal force to simulate anywhere from 0.01g to
2g for use in experiments. Artificial gravity has been a mainstay of sci-fi
and it would have been extraordinary to see humanity test its own system on the ISS.
Not least because the astronauts and cosmonauts would have appreciated it too! The absence of
gravity on the station is a huge complication for day to day life. Almost nothing behaves as
you would expect, ranging from the mundane to the deadly. Even the simple act of drinking a
coffee made by the station’s barista, the ‘ISSpresso’, could be risky when you’re
surrounded by sensitive scientific equipment, zero gravity and 100 laptop keyboards.
A significant part of the station’s research program has been on understanding the behaviour
of objects, fluids and people in a zero-G environment, and if Trump’s
recently announced manned mission to Mars is to be successful,
a trip that would take upto 10 months each way, it will stand upon the research from the ISS.
Studies on the past crews of the station have shown how in the chronic absence of gravity,
the human body will ruthlessly atrophy any organ or structure that is surplus to its requirements.
Organs are expensive to run! The musculoskeletal system in particular will degrade; bones
weaken and the heart shrinks. Careful exercise regimens must be planned in order for the crew
to maintain bone density and heart function and for their physical health. The ISS is equipped
with a custom gym so the crew can maintain some of their fitness, but despite all that equipment,
it cannot fully simulate the coordinated strength and balance required to walk on Earth,
and the astronauts effectively have to relearn how to walk on their return!
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The lack of gravity affects other organisms too, in space even microbes behave differently.
Aboard the ISS, zero-G has been found to alter the gene expression of certain
Salmonella pathogens that just so happens to have the effect of increasing their virulence,
making them deadlier! Well, I guess it could have gone either way!
More immediate problems also present themselves in zero-G. Fire is of course dangerous in most
situations, but on Earth, we at least have an intuition for how it moves and behaves. In space,
fire can expand in any direction because without gravity, there is no convection,
and so the less dense hot air no longer rises. Flames in space can sit and persist,
or even be invisible for lengths of time because a low burn rate can be sustained by diffusion.
Fluid dynamics is a crucial focus of space research, because without convection even
attempting to boil a kettle is going to land you in a pot of hot water. The Nucleate Pool
Boiling eXperiment (NPBX) was designed to study this exact problem, because without convection,
how do you achieve efficient heat transfer in space? A kettle in space would be hampered by
the formation of a large bubble at the heated base. Not that you would
particularly want a hot cup of tea because, in this convectionless environment, where the
body cools less effectively. So the atmosphere in the habitable areas needs to be well circulated.
Other fluids need to be actively moved around in space by fans and propellors too, and as is the
theme, even these behave differently in zero-G. Fast-moving propellors can cause cavitation in a
fluid, where a cavity is ripped open in the fluid and then explosively collapsed by the surrounding
pressure. That collapse releases shockwaves that carry large amounts of energy and can cause
significant damage. Meaning, that propagation needs to be understood so that our equipment can
go the distance on any space mission. Incredibly, research into cavitation in microgravity on Earth
provided insight into the most explosive acts in our universe - supernovae. A previously
unexplained supernova form has been linked to the collapse of bubbles in a fluid in zero g,
under a process called eccentric core collapse. These experiments so far are all critical for the
success of any future long-duration space travel. But the ISS runs powerful physics experiments too.
In addition to the six pressurised laboratories, the ITS carries an experiment called the Alpha
Magnetic Spectrometer (AMS), one that NASA considers as important as Hubble, and one that
requires so much power and so much bandwidth that almost no other vehicle in space could run it. But
what does it do? It’s a detector, the business end of a particle accelerator. Space has cosmic voids
with hidden objects that can generate particles with energies equivalent to a pitched baseball.
Think about that: 240 exa–electron volts, millions of times more powerful than what
our biggest accelerators can produce. Its stated aim is to research Dark Matter, specifically to
search for evidence of a hypothetical particle predicted by supersymmetry called a neutralino.
Moving on from the hottest particles in the universe to the coldest:
NASAs Cold Atom Lab was designed to explore the quantum properties of matter and can
reach temperatures of 1 ten-billionth of a Kelvin. It was the first to produce the 5th
state of matter — a Bose-Einstein condensate — in zero-G. On Earth, these condensates eventually
collapse due to gravity, but in space, they float and persist: the crew has even been
able to synthesise atomic bubbles onboard the ISS, a form of macroscopic quantum behaviour.
Long-lived BECs in orbit is a significant step and they have uses:
atom interferometers can be made that can be used to measure gravitational waves in
a way that complements LIGO's capability. Atom Interferometry using BECs would be
able to capture the middle band frequencies of gravitational waves that LIGO cannot detect,
allowing us to detect different objects and probe quantum gravity more precisely.
The AMS isn’t the only external experiment on the ISS. The Japanese laboratory module,
called Kibō has a facility known as ‘The Terrace’. In the vacuum of space, Kibō
has been crucial in gathering climate data with sensors to perform atmospheric gas monitoring,
ecosystem thermal imaging, and experiments with laser communications. It also featured
a hyperspectral camera to take images of the ocean around complex coastal areas. Typical
cameras record in three bands, R, G, and B, but a hyperspectral camera records wavelength
information across the entire visible spectrum, which along with the other
data recorded provides a rich dataset to understand the effects of climate change.
Not only is the space station helping us to soar from the Earth,
it is - perhaps more importantly - helping us to continue to walk upon it.
The International Space Station is more than a scientific laboratory though;
it is a symbol of what humanity can achieve when we cooperate and reach for the stars.
As we look to the future, the ISS reminds us that the boundaries of exploration are
limited only by our imagination and our willingness to work together.
In the 2030s, the ISS will complete its final mission. In a carefully orchestrated process,
the station will be deorbited, with its remains safely scattering across
the Pacific Ocean. While its physical presence will be gone, the knowledge and
inspiration it has provided will continue to shape the future of space exploration.
The end of the ISS will mark the beginning of a new era in space exploration. Private companies
like SpaceX and Blue Origin are poised to take on a greater role, while international partners are
already planning next-generation space stations like the Orbital Reef and Lunar Gateway. The
lessons learned from the ISS will guide these efforts, ensuring that its legacy endures.
The International Space Station is an absurdly ambitious project that has stretched across
decades and we only skimmed its contributions to science in this video. If you would like
us to dive into an ISS topic you would like to learn more on, let us know in the comments below!
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