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Microgravity Research - Contenido educativo

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Subido el 28 de mayo de 2007 por EducaMadrid

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NASA Connect segment exploring how NASA is working with students to develop new applications for microgravity research. The segment explains buoyancy-induced convection and the relationship between density and volume.

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Super job, you guys. 00:00:00
Hey, did you know that NASA is working with students 00:00:05
to develop new products and new experiments for space research? 00:00:09
Dr. John Poiman, a professor of chemistry and biochemistry 00:00:13
at the University of Southern Mississippi, 00:00:17
has some cool applications for microgravity research, 00:00:19
which students just like you can be working on someday. 00:00:23
What is buoyancy induced convection? 00:00:26
What is the relationship between density and volume? 00:00:32
What is the trend in the density versus temperature graph? 00:00:35
Hi. 00:00:39
NASA's reduced gravity program began in 1959. 00:00:40
But in the past five years, students from over 100 schools 00:00:43
have performed experiments in a microgravity environment. 00:00:47
Several of my students and I have flown on the KC-135, 00:00:50
NASA's flying laboratory. 00:00:53
It's science that's interesting, challenging, and fun. 00:00:56
One experiment we are conducting involves 00:00:59
making new space age materials by a really cool process 00:01:01
called frontal polymerization. 00:01:04
And the other involves studying how molecules attract 00:01:07
each other in fluids that mix. 00:01:09
Everything is made up of very, very small pieces 00:01:12
of stuff called molecules. 00:01:14
Molecules attract each other. 00:01:16
How strongly they attract determines 00:01:18
if the stuff is a liquid, solid, or a gas. 00:01:19
Some materials mix completely. 00:01:22
Others do not. 00:01:24
Here's something you can try at home yourself. 00:01:25
We have water here, which has food coloring in it, 00:01:27
and syrup. 00:01:30
And as I pour the syrup in and stir it up, 00:01:31
it'll make one continuous liquid. 00:01:38
But if I take something that's immiscible with water, 00:01:42
like mineral oil, and pour it into the water with food 00:01:45
coloring, and mix this solution up, 00:01:48
it will separate into two layers with time. 00:01:53
Water molecules attract each other more strongly 00:01:56
than they attract oil molecules, and so the water 00:01:59
stays separate. 00:02:01
A monomer is a small molecule that 00:02:02
can be made to form long chains of monomers connected 00:02:04
end to end, called a polymer. 00:02:06
It's sort of like boxcars hooked together to form a train. 00:02:09
The mixing process is called convection. 00:02:11
It's the term for liquid motion. 00:02:14
There are two ways in which convection can spontaneously 00:02:16
occur in a liquid. 00:02:18
One is caused by gravity, and it's 00:02:19
called buoyancy-induced convection. 00:02:21
Differences between the densities of the liquids 00:02:24
make the lighter fluid rise and separate 00:02:26
from the heavier fluid. 00:02:29
Another type of convection is called 00:02:30
interfacial tension-induced convection. 00:02:32
Interfacial what? 00:02:34
Interfacial tension-induced convection. 00:02:36
Let's split the term up. 00:02:38
First, interfacial tension is like the surface tension, 00:02:39
which holds up a water bug when it skitters across a pond. 00:02:43
The surface is the result of the water molecules 00:02:46
attracting each other. 00:02:48
But heating a surface here on Earth 00:02:50
causes buoyancy-induced convection. 00:02:51
How can we study only the convection 00:02:54
caused by interfacial effects alone? 00:02:55
We need to eliminate gravity or its effects. 00:02:58
We can never eliminate gravity, but by free-falling, 00:03:01
we can create a system that acts as if there were no gravity. 00:03:04
Performing experiments in weightlessness 00:03:08
allows us to study phenomena we can't study on Earth 00:03:10
and to answer questions we can't answer down here. 00:03:12
By eliminating buoyancy-induced convection, 00:03:15
we sometimes can create superior protein crystals 00:03:18
in weightlessness that can help researchers design new drugs. 00:03:20
Eliminating buoyancy-induced convection 00:03:23
can also help us understand how to make better semiconductors 00:03:25
here on Earth, like the ones used in your computer. 00:03:28
We take a lesson from computer chip manufacturers 00:03:31
who use light to make the circuit patterns. 00:03:34
Microgravity research shows us that we 00:03:36
can create patterns on fluids which would not 00:03:38
be allowed on Earth, where buoyancy convection mixes 00:03:41
up the patterns due to gravity. 00:03:43
My students and I are studying how forces between molecules 00:03:45
in fluids that mix can cause convection. 00:03:48
We use light as an initiating agent 00:03:51
to make the monomer turn into the polymer. 00:03:52
By exposing the monomer to light with a specific pattern, 00:03:55
we hope to observe how the monomer and polymer 00:03:58
molecules pull on each other. 00:04:00
For many minutes, we predict that the two fluids 00:04:02
will act like oil on water. 00:04:04
But in the long run, the molecules 00:04:06
will diffuse into each other and make a single fluid. 00:04:08
Why can't we do the experiment in the lab? 00:04:10
Because buoyancy-driven convection 00:04:12
will smear everything out. 00:04:14
So there really is no way on Earth to do the experiment. 00:04:15
We also study a process called frontal polymerization, 00:04:18
in which plastics and foams can be 00:04:21
made with a chemical reaction that 00:04:23
spreads out like a liquid flame. 00:04:25
Gases can be released by the hot reaction 00:04:27
that makes bubbles, which can form the foam. 00:04:29
Of course, bubbles float in a liquid because of gravity. 00:04:31
But without the buoyant force, bubbles 00:04:34
can become larger in a microgravity environment. 00:04:36
How do you use math in your work? 00:04:39
Math is essential to our work. 00:04:41
For example, in order to predict how gravity will cause 00:04:43
convection in our systems, we need 00:04:46
to prepare graphs of the density of our materials 00:04:47
as a function of temperature. 00:04:50
We use a special instrument called a densitometer. 00:04:51
But we have to know how to use the math to make 00:04:54
sense of what it tells us. 00:04:56
Let's look at some of the data from my lab. 00:04:58
Here, we have plotted the densities 00:05:00
of the monomer and the polymer on the y-axis 00:05:02
and the temperature on the x-axis. 00:05:04
First, notice that the density of the polymer 00:05:06
is higher than the monomer. 00:05:08
Next, we can draw straight lines through the points. 00:05:11
The slope of each line is the ratio 00:05:14
of the change in density to the change in temperature. 00:05:15
The density of the polymer decreases 0.03 grams 00:05:19
per cubic centimeters for a 50 degree centigrade 00:05:23
increase in temperature. 00:05:26
The density of the monomer also decreases, 00:05:28
but it decreases 0.04 grams per cubic centimeter 00:05:31
for the same temperature change. 00:05:34
Remember that we said buoyancy-driven convection 00:05:36
happens because of differences in density 00:05:38
and that the less dense liquids will float to the top. 00:05:41
Information from this graph tells us 00:05:44
how the density changes when we heat the monomer and polymer. 00:05:46
And so we can predict how much buoyancy-driven convection will 00:05:49
occur during experiments on Earth. 00:05:52
The graph also tells us how much the volume changes 00:05:55
as we heat the liquids, essential information 00:05:57
for designing our experiment on the International Space 00:06:00
Station. 00:06:02
As we go farther and farther from Earth into space, 00:06:03
we're going to be required eventually 00:06:06
to make our own materials in space. 00:06:08
Foams are just one of the things we need to look at. 00:06:10
Gaining an understanding of the opportunities in microgravity 00:06:12
research today will be valuable knowledge 00:06:15
for you, young researchers of tomorrow, 00:06:17
when we are ready for our first manned flight to Mars. 00:06:20
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Idioma/s:
en
Materias:
Matemáticas
Niveles educativos:
▼ Mostrar / ocultar niveles
      • Nivel Intermedio
Autor/es:
NASA LaRC Office of Education
Subido por:
EducaMadrid
Licencia:
Reconocimiento - No comercial - Sin obra derivada
Visualizaciones:
270
Fecha:
28 de mayo de 2007 - 16:52
Visibilidad:
Público
Enlace Relacionado:
NASAs center for distance learning
Duración:
06′ 23″
Relación de aspecto:
4:3 Hasta 2009 fue el estándar utilizado en la televisión PAL; muchas pantallas de ordenador y televisores usan este estándar, erróneamente llamado cuadrado, cuando en la realidad es rectangular o wide.
Resolución:
480x360 píxeles
Tamaño:
38.37 MBytes

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