What do the changes in
locations of ocean life
and astronaut underwear have in common?
Well,
it has to do
with thermal energy transfer.
Stick around to learn more.
Hi.
I'm NASA astronaut, Loral O'Hara, and I'm
living and working
aboard the International Space Station.
Today, we're talking about thermal energy
or heat.
All living things,
whether living in the oceans or in orbit
need to be within
a special thermal balance
within their environment to live.
We call this balance homeostasis.
Too hot or too cold, we won't survive.
Luckily, there are three different ways
that thermal energy
can be transferred from place to place
to help maintain homeostasis:
convection, convection and radiation.
Conduction is how thermal energy
is transferred from one object
to another through direct contact.
When you swim in the cool ocean
thermal energy from your body
is connected directly to the water.
That loss of
thermal energy is felt
as a cold sensation.
Ocean life maintains
homeostasis by living in water
that is the correct temperature
they need to survive.
Astronauts aboard the space station
can even track this by making direct
observations of large ocean
life such as coral reefs
and blooms of algae.
To stay in homeostasis
during spacewalks, astronauts
wear special garments
under their spacesuits,
called a liquid cooling
and ventilation garment or LCVG.
This full body garment with small
tubing sewn into the fabric
is worn close to our skin.
Cool water is packed through the garment,
which helps to conduct heat
away from the astronaut
as we perform spacewalks
in the harsh environment of space.
Similar technology is being increasingly
used on earth
when open air cooling is difficult,
such as for firefighters,
steel mill workers and surgeons
during long procedures.
The next method of
thermal energy transfer,
convection, only applies to fluids
like air and water.
When the temperature of a fluid changes,
its density changes as well.
This will cause large amounts
of a cooler fluid to sink
because it is denser
than the warmer fluid surrounding it.
In oceans, the convection of warm water
rising near the equator
and sinking of cooler water
near the poles
feeds oceanic currents
that circulate the ocean water
all over the world.
This aids in the migration of sea
life as they ride these currents
and stay within channels of water
at certain temperatures
to maintain homeostasis.
However, this is not the case
on the orbiting laboratory.
In microgravity,
the density of an object
does not affect its motion.
So a pocket of warm air
created by computers,
a warmed up meal or even our body heat
just kind of stays there.
That's why
we use a series of fans
and ducts
to mix and circulate
the air on space station
to keep us in homeostasis.
The final method of
thermal energy transfer,
radiation, is vital for our oceans
and the space station.
Radiant energy
from the Sun
in the form of visible
and UV light is absorbed
by the oceans during the day
and is converted to thermal energy,
warming the water.
Thermal energy
is also radiated away from the ocean
in the form of infrared light.
This energy radiated
from the oceans, warms
our atmosphere and cools
oceanic temperatures,
keeping them both stable.
The temperature on space
station is regulated through radiation.
The space station is outfitted
with large radiators,
which have a large surface
area of panels to radiate away
the excess thermal energy of station,
keeping the station
in a type of homeostasis.
Maintaining the right temperature
using thermal energy
transfer is a big job,
both aboard the space station
and in our oceans.
What methods
are you using to stay in
thermal homeostasis right now?
Convection?
Convection? Radiation?
All three?
Share your observations
as you work on the corresponding
classroom connection.
Thank you for exploring thermal energy
transfer with me today.
See you next time!