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Hi, I'm Chris and this is NASA Now.
Imagine the coldest temperature on Earth,
now go a couple hundred degrees lower than that.
Our expert today, explains why NASA researchers study fluids
and materials at super cold temperatures
for applications in space.
That's ahead, but first here's what's happening at NASA Now.
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Space Shuttle Discovery arrived at its new home.
After 39 missions, 365 days in space, 5,830 orbits of Earth,
and over 148 million miles traveled,
Discovery reached its final destination.
A NASA modified Boeing 747 carried Discovery
on it's back during the transport
to Washington Dulles International Airport.
Discovery will be on permanent public display
at the Smithsonian's National Air
and Space Museum Steven F. Udvar-Hazy Center
in Chantilly, Virginia.
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Just how cold is cold?
How about -269 degrees Celsius or 4 Kelvin?
That's the temperature you'll find in some parts of space.
Today, our expert Wesley Johnson
from Kennedy Space Center will talk about the use
of super cold liquids and insulating materials
for space exploration.
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Cryogenics is the study of both fluids and materials
at super cold temperatures, as cold as absolute zero
and sometimes going up to about negative 190 degrees Fahrenheit.
Some of the applications that we use cryogenics here
at NASA involve liquid propellants for launch vehicles.
We use liquid oxygen and liquid hydrogen,
both which are several hundred degrees below zero in all
of our propulsion applications.
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This is some flowers that I picked at my house this morning.
They are bendable and pliable.
In fact, they were alive this morning when I picked them.
So now we're going to put them in liquid nitrogen
and see what happens to them.
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So when I chilled down the flower, the properties
of the molecules in the flower changed
and they became very brittle and it broke apart.
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Some of the applications that you might see cryogenics here
on Earth are on MRI machines, which use liquid helium,
which is even colder than liquid hydrogen.
The liquid helium is wrapped
around the superconducting magnet
as it takes high intensity images.
Also, most cell phone towers have a liquid nitrogen cooling
system to allow for better reception
and wider transmission ranges.
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What we do at the cryogenics test laboratory is we develop
insulation systems for ground applications here on Earth
and also for space flight applications in orbit.
On Earth there's three modes of heat transportation.
The first is just solid conduction along any
solid material.
The material has the affinity to conduct heat.
The second is called convection.
It's caused by a gas motion where the gas can pick
up the heat from a solid object and then leave.
The third mode is called radiation and this happens both
on Earth and in space.
In fact, it's the only mode of heat transportation in space.
Radiation occurs when electro-magnetic waves travel
between a high temperature system
to a different low temperature system
and this can happen through a vacuum.
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So for in space applications where we only have to deal
with radiation, we use what's called multi-layer insulation
and that's just like this highly reflective blanket right here,
and you can see the spacer material in between it
that we use to keep the reflective layers
from touching each other.
Just, for instance, this blanket in my hand has 25 layers,
25 layers of reflector and 25 layers of spacer material.
On Earth, we use a couple materials.
One type of material that we use is these aerogels I have
in my hand.
I have a powderous form on my right hand,
and a blanket form on my left hand.
Aerogel is the best thermal insulation that we have
on the Earth right now in an atmosphere and it was also,
actually developed here in the cryogenics test lab
at Kennedy Space Center.
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Shielding a craft from the extreme temperatures
of space is a real challenge.
See how well you can do with this project.
Teachers, you and your students can develop your own thermal
protection system with this featured lesson.
Look for Heat, Temperature and Energy: Messenger -
Cooling with Sunshades.
You'll find it on the NASA Explorer Schools'
Virtual Campus.
Well that's it for NASA Now,
be sure to visit our Facebook page and leave a comment.
We'll see you next time on NASA Now.
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NASA Now comes to you from the Virtual Campus
at NASA Explorer Schools.