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Since November 2, 2000, the International
Space Station has been continuously crewed
meaning humanity has had a permanent presence
in space.
This importance of this station cannot be
overstated—NASA has literally filled a book
with all the ways the ISS has benefited humans
on earth.
It’s helped develop new cancer treatments,
enhanced robotic surgery technology, improved
data processing techniques, its benefits stretch
far and wide.
It is quite possibly the most significant
science experiment humanity has ever undertaken.
It is also quite possibly the most expensive
single item humanity has ever built at an
overall cost, so far, of about $160 billion.
Breaking that down, each day that each astronaut
spends on the ISS costs about $7.5 million.
The ISS is a joint project between Russia’s
Roscosmos agency, Japan’s JAXA, Europe’s
ESA, Canada’s CSA, and the US’ NASA.
Physically, though, it’s split up into the
Russian segment and the US segment with these
two countries more or less taking responsibility
for managing and supplying their side.
At over 350 feet or 110 meters long, the station
is longer than a 747 and has more interior
space than the average six bedroom house.
Space is still at a premium, though, as science
experiments and equipment take up most of
the room so normally there are only a maximum
of six crew members onboard at any given time.
Back on earth, though, there are thousands
of people working to support the activities
of those six.
Now that the international space station is
built and operating, the whole mission is
basically a big logistics problem—it involves
getting people, food, water, supplies, and
experiments up and down from the station in
a consistent, cost-effective, and safe manner.
Food, as an example, is one of the only completely
non-renewable resources onboard the ISS.
Water can be recycled, oxygen can be generated,
supplies can be reused, but food is one and
done.
That means there has to be consistent shipments
from earth to the station.
About half the food is supplied by the Russians
and the other half by the Americans.
There are a few constraints to space food—it
has to be shelf stable as there are no refrigerators
onboard, it has to last about two years as
resupplies only happen a few times a year,
it has to be light as weight is precious on
the resupply rockets, and it has to be easy
to prepare as astronauts’ time is valuable.
Within those parameters, the Russians use
a system of canned food while the Americans
use a system of flexible pouches which have
the advantage of being lighter weight than
the cans.
This NASA food is produced at the Johnson
Space Center in Houston, Texas.
Long before they launch, the astronauts do
a taste test to determine which foods they
like most and they express these preferences.
Based off those, NASA will produce and load
more of the best liked foods.
The astronauts can choose from hundreds of
items—spaghetti and meatballs, barbecue
beef brisket, Caribbean chicken, vegetable
quiche, beef enchiladas, the options go on
and on.
Somewhat surprisingly, the ingredients for
the food are just purchased at a grocery store
like any other meal.
There’s no special sourcing or special ingredients,
although they do inspect the ingredients carefully
after buying to be extra sure that they’re
safe.
As far as we know, no astronaut has yet gotten
food poisoning in space and NASA wants to
keep it that way.
The food is then prepared fairly conventionally
until the last step.
Food is made shelf stable and lightweight
by one of two methods—thermostabilization
or freeze drying.
With thermostabilization, heat is used to
destroy microorganisms and enzymes that would
cause food to spoil.With freeze drying, the
food is frozen and then almost all moisture
is removed.
With this technique, there is nearly no water
left in the food, which is normally the bulk
of its weight, so a full serving of spaghetti,
for example, weighs only one ounce or 28 grams.
The space station has a water recycling system
that recovers about 80% of the water onboard
which means that, while they do occasionally
have to resupply water from earth, it’s
more efficient to ship food up without water
in it since the water onboard can be reused
for multiple meals and that also helps keep
it shelf stable.
Overall, freeze drying reduces the total food
weight they have to take up.
NASA currently pays about $29,000 per pound
for shipment to the Space Station.
Each gallon of water they bring therefore
costs them about a quarter of a million dollars.
That also means each of those one ounce portions
of spaghetti costs them about $1,800.
They’ll also typically include a few pieces
of fresh fruit anytime a rocket goes up as
a treat and, with these shipment costs, each
apple is worth almost $10,000.
This is why so much focus is put on minimizing
weight.
In addition to the food they make, some foods
are just shipped up as is.
For example, if a crew member has a particular
type of granola bar they like, the food preparation
team will go out and buy some of those as
a sample and perform some tests in their lab
to figure out if it’s, as they call it,
“flight compatible.”
In that, they’re basically looking to be
sure that it’s not too crumbly as they don’t
want crumbs floating around into all the nooks
and crannies of the station, as well as being
sure it’s not too liquidy, both for the
purposes of weight and to be sure that it
doesn’t cause free liquid to float around.
Assuming it passes these tests, astronauts
can pretty much bring what they want for snacks.
It will be repackaged into NASA’s pouches,
but there’s a surprising amount of simply
store bought food on the station.
Once all food is produced and packaged, it
is shipped to one of four launch sites—either
the Mid-Atlantic Regional Spaceport in Virginia
where Northrop Grumman Cygnus resupply spacecrafts
are launched from; Cape Canaveral, Florida
where SpaceX Dragon spacecraft are launched
from; Baikonur Cosmodrome in Kazakstan where
Russian Progress resupply and Soyuz crewed
spacecraft are launched from; or Tanegashima
Space Center in Japan where Japanese Kounotori
spacecraft are launched from.
The food will be carefully packed alongside
everything else making the trip ensuring proper
spacecraft balance.
Thanks to all these weight-saving techniques,
supplies for crew, including food, only represent
a small portion of the overall weight of each
launch.
For example, on one SpaceX launch, crew supplies
only represented 530 pounds or 240 kilograms
of the 6,000 pounds or 2,700 kilograms of
cargo.
The rest of the launch capacity is dedicated
to equipment and experiments.
Now, part of the difficulty of this supply
chain is that launch dates change a lot.
For example, the last SpaceX resupply, CRS-16,
was initially scheduled for August 2018, then
it was pushed back till the 29 of November,
then till December 4th, then again to December
5th when it finally launched.
These delays can come from quite mundane issues.
The December 4th to December 5th delay, for
example, came because it was found that the
food loaded for lab mice who were making the
trip was moldy and had to be replaced.
Even just getting a launch or landing date
in the first place is difficult enough.
Each site has its own set of constraints potentially
preventing use.
For example, Tanegashima Space Center in Japan
can only be used for launch at certain times
of year since, during fishing season, there
are large numbers of ships offshore from the
launch site which could be hit and damaged
if a rocket exploded.
Elsewhere, a Soyuz landing in Kazakstan had
to be rescheduled as there was a G8 summit
nearby which, for security reasons, imposed
airspace restrictions that prevented spacecraft
search and rescue aircraft from flying.
Even the angle of the sun relative to the
ISS constrains when a spacecraft can dock.
The other factor that can affect the supply
chain is that rockets are imperfect.
5 of the 117 resupply missions to date to
the International Space Station did not make
it for one reason or another meaning there’s
a failure rate of 4.3%.
There was even a nine month stretch from 2014
to 2015 when three resupply missions failed.
In times like these, it’s quite important
that the ISS has plenty of backup food, water,
and supplies.
While the astronauts would never starve, running
out of food or water could mean that they
would have to return to earth early potentially
leaving the ISS un-crewed and therefore wasting
many millions or billions of dollars.
When that third mission failed on June 28th,
2015, the station had enough food to last
them for about another fifty days.
In this case, even with three failed missions,
they had plenty of food to last them especially
considering the next resupply mission, a Russian
Progress spacecraft, was scheduled just a
week after the failure and it was successful.
There have been close calls, though.
After the Space Shuttle Columbia disaster
in 2003, astronauts had to cut their daily
caloric intake and supplies got as low as
7 to 14 days of food.
They were one resupply failure away from having
to evacuate.
Sometimes, in order to stretch the food supply,
NASA will have to extend the certified shelf
life of food onboard.
For this purpose, they keep a sample of each
batch of food they make on earth, packaged
and stored in the exact same conditions as
on the ISS, so they can test if food is still
fit for consumption and safe.
Assuming a rocket doesn’t have any issues,
it will typically make it to the ISS in about
two to three days.
Once the spacecraft is near the ISS, the crew
will spend almost a whole working day dealing
with the docking process.
Once that’s completed, either the same day
or the next morning, they’ll open the hatch.
Typically right at the hatch is the crew care
package.
This will include those fresh fruit and vegetables
as well as some items sent up by the crew’s
families.
One time, the crew care package even included
real ice cream.
While there isn’t normally a freezer onboard,
in this instance a portable freezer was sent
up in order to transport samples from an experiment
back to earth but, since it was empty on the
trip up, the crew got this treat.
Over the next few months, astronauts will
go through their food one container at a time
scanning a barcode each time they open one
to let mission control know what their inventory
level is like.
That way, if the food is going quicker or
more slowly than expected NASA can adjust
future shipments.
Onboard, dehydrated food is heated up and
hydrated using a food re-hydrator while other
food can be heated up using another heater.
The point of putting so much effort into food
on the ISS is for the psychological well-being
of the astronauts.
With working long hours bottled up in a small
space for up to a year, the mental stress
of the job is enormous so any effort that
can help reduce that is effort worth doing.
As part of this, NASA puts a good amount of
work into movie night.
They have a large projector screen and, in
addition to their onboard digital library
of about 500 movies, the crew can download
new movies.
The ISS does have an internet connection and
they’ve been known to get some movies, such
as Star Wars: The Last Jedi, while they’re
still in theaters.
That same internet connection lets astronauts
browse the web quite freely, even if it’s
not quick.
While the station does have 300 megabits per
second of downlink capacity, the vast majority
of it is dedicated to experiment and other
data, but astronauts are able to regularly
video call their families using it.
The unloading process of resupply vessels
is quite a slow process, partially just because
there isn’t much storage space onboard.
Once a resupply vessel is unloaded, though,
the crew will start loading it again with
trash.
The Northrop Grumman Cygnus, Russian Progress,
and Japanese Kounotori spacecraft cannot return
to earth so they just burn up in the atmosphere
along with all the trash.
The SpaceX Dragon and crewed Russian Soyuz
spacecrafts do return to earth so they can
bring back samples and experiments.
Once ready, the spacecraft will undock and
slowly drift away from the ISS until it disappears
from view and at that point, the ISS is ready
for another delivery of humans or cargo—one
of the most unique regular deliveries in our
universe.
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