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My Outro For My 20th Birthday

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Coming up on Destination Tomorrow, find out about one of Saturn's moons that has one

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of the best chances for life to exist outside of Earth.

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We'll also see how spacecraft are placed into orbit around faraway planets.

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And Johnny Alonzo finds out how advanced materials are keeping us safer.

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All this and more next on Destination Tomorrow.

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Hello everyone, I'm Brad Breckenridge filling in for Steel McGonagall.

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And I'm Kara O'Brien, welcome to Destination Tomorrow.

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This program will uncover how past, present, and future research is creating today's knowledge

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to answer the questions and solve the challenges of tomorrow.

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We begin with a look at a fascinating moon called Titan, which is orbiting around the

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planet Saturn.

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This moon has become the subject of much scientific speculation in recent years since

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it was discovered to have an atmosphere roughly four times thicker than Earth's.

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About half the size of Earth, this small planet-like moon has an atmosphere that contains large

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amounts of nitrogen and carbon.

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This is important because these chemicals are considered by many scientists to be the

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building blocks for life as we know it.

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Little is known about Titan's surface because its thick atmosphere hides it from view.

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To help us learn more about Titan, NASA scientists have launched an intriguing mission to explore

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this distant moon.

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This mission, called Cassini-Huygens, was launched from Kennedy Space Center on October

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15, 1997.

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Once at Saturn, the Cassini-Huygens spacecraft will not only study Saturn's atmosphere and

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its other moons, but will also drop a small lander onto the surface of Titan.

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While Cassini-Huygens will dramatically boost our knowledge of Titan, it will likely lead

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to more questions about this interesting moon.

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Tonya St. Romain spoke with researcher Dr. Marianne Rudisil to find out more about the

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current mission and possible future missions to Titan.

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One of NASA's stated goals is to search for life and life-enabling conditions such as

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water and life-like chemistry throughout the universe.

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In recent years, the task of searching for life has become much easier with the development

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of tools like the Hubble Space Telescope and advanced sensors aboard spacecraft.

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With these technology advancements, NASA scientists are now able to better identify so-called

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hotspot locations in the universe.

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A hotspot location is simply a celestial body, that is, a planet or a moon, that may have

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conditions that are conducive to the origin and existence of life.

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Scientists have located a number of potential hotspots in our solar system, though one of

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the most intriguing is a moon orbiting the planet Saturn named Titan.

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Titan is very exciting because unlike most moons in our solar system, it actually has

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an atmosphere.

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In fact, many scientists believe that Titan's atmosphere closely resembles early Earth's

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atmosphere three and a half billion years ago, when life was just beginning on our planet.

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The chemicals that make up Titan's thick, hazy atmosphere include nitrogen and carbon,

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elements considered by scientists to be the building blocks or raw materials for life

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as we know it.

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With this in mind, NASA and European Space Agency scientists are working on a mission

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called Cassini-Huygens, which will study Saturn and some of its moons, including Titan.

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The Huygens probe will descend into the thick Titan atmosphere to study its composition

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and look for signs of prebiotic chemistry.

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I spoke with Dr. Mary Ann Rudisill at NASA Langley Research Center to find out why this

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distant moon is such an important place to study.

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Titan's a really interesting place to explore for a number of reasons.

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It's a very large moon.

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It's larger than two of our planets, Mercury and Pluto.

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But the most interesting thing about it actually is that Titan has a very dense atmosphere

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and this atmosphere has a lot of chemistry, interesting chemistry going on.

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Most of the atmosphere at Titan is nitrogen, a lot like Earth's.

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It has methane, but it also has a lot of complex organic types of molecules going on.

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And it has weather as well.

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And so we think that potentially there are actually clouds on Titan that kind of rain

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organic molecules down onto the surface and kind of lay out an organic sludge along the

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surface of Titan.

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So a lot of scientists believe that in some important ways Titan might actually be very

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much like what Earth was like in its early days prior to life on our planet.

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So it's an interesting place to go to, to kind of look at those processes and understand

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how life originated on our planet in that type of physical environment.

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One of the reasons Titan is of great interest to scientists is because it's the only moon

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in the solar system known to have clouds and a thick, planet-like atmosphere.

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Because Titan's atmosphere contains nitrogen and high percentages of smog-like chemicals

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such as methane and ethane, it may actually rain gasoline-like liquids onto the surface,

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forming shallow, methane-filled lakes.

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Although the smog-like atmosphere would be harmful to humans and other forms of complex

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life on our planet, the organic nature of Titan's atmosphere is much like the prebiotic

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environment from which life arose here on Earth.

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Simply put, these conditions may actually be laying the foundation for life on Titan

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sometime in the future.

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Dr. O'Doussell, is there potential for life on Titan?

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Well, that's a really interesting question, actually, and maybe yes and maybe no.

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And I say that because of this.

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Maybe yes, because Titan has, as I said, some really interesting and complex organic chemistry

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going on.

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But the problem is that chemistry isn't all that it takes to have life.

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Titan is very far away from our sun, and so it's a very, very cold place.

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So the problem is that everything is ice.

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And life, as we know, it needs access to liquid water.

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And it also needs a source of energy.

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So on the one hand, yes, the chemistry could potentially support early life on Titan, but

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it's not warm enough.

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It's too cold, and it doesn't have access to water and energy that it would need.

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But you could speculate about some other ways, perhaps, that it could have liquid water.

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We know, for example, that meteorites have come to Titan and hit the surface, generating

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heat and bringing energy with it.

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And perhaps for certain amounts of time, then that would mean that there could be pools

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of liquid water there.

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So it's really interesting to think about and speculate about the possibility of life

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in other parts and other locations of our solar system.

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And Titan is a very interesting place to look into those questions, and that's why we're

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going there.

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Once the spacecraft gets to Saturn, how will it collect data?

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Will it use rovers like the Mars rovers?

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No, actually, it's going to be rather different from the Mars mission.

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We're not sending rovers like Spirit and Opportunity.

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It won't be trundling around on the surface like we did on Mars.

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First, we're sending the Cassini spacecraft, and it's an orbiter.

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And when it reaches Saturn, it'll actually spend the next four years there kind of doing

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a grand tour through a Saturn system.

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And one of the things it will do is about 40 flybys near Titan and collect information,

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kind of a big-picture view of Titan.

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But then in addition to that, we have a Titan probe, a Huygens probe, and that was developed

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by the European Space Agency.

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And it'll drop down through Titan's dense atmosphere, and all the way down, the instruments

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will be taking all kinds of measurements like the density of the atmosphere and the temperature

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and altitude and things of that sort.

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And of course, it's going to be taking a lot of data, a lot of information about the chemistry

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of Titan's atmosphere, what kinds of things are there and how much.

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And it'll take about two to two-and-a-half hours to get all the way down through a dense

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atmosphere.

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We don't know what it will land in, but it will be able to stay on the surface and then

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in its local area kind of take some measurements and also radio that information back to the

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orbiter and back to Earth.

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The next generation of science missions to Titan will probably be much different than

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the missions of today.

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Because little is known about the moon's geology, one type of mission concept recently developed

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by NASA would rely on a dirigible-type craft to move through Titan's atmosphere, taking

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multiple measurements over time.

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This blimp would float above the surface and deploy a small probe to sample Titan's atmosphere,

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methane crater lakes, and crater rim ice.

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The probe would be able to analyze the samples on the spot and then relay the information

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to scientists back on Earth.

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With Earth nearly 800 million miles away, the probe would need to be almost completely

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autonomous.

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This type of craft could conceivably float through Titan's atmosphere for many months,

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gathering valuable evidence about Titan's chemistry and geology and what that means

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for us back on Earth.

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NASA Jet Propulsion Laboratory, California Institute of Technology

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Realistically, what are your expectations?

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Are you expecting to find life on Titan?

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Scientists try to be very objective, you know, and only have attitudes and opinions based

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upon what we know, of course.

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And so I think a lot of people are holding back and saying, I don't expect to find life

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there.

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It's too cold.

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Even though we have extremophiles here on our planet that can live in very dry or very

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cold conditions, it's really cold out there, you know, and there isn't liquid water.

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So we're not expecting to see anything there.

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But the nice thing would be is if we could find, I think a lot of people would be very,

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very happy if we saw some serious complex organic chemistry going on.

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Prebiotic, you know, clearly prebiotic chemistry would just be wonderful.

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Going to other destinations in our solar system and then gathering this kind of information

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could really help us understand how our planet formed and how life originated on our planet.

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And these were really profound questions, not just to scientists, but to everyone.

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And so I think it's really interesting and great that NASA can send spacecraft and gather

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these kinds of data to help us answer those kinds of questions.

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Many astrobiologists are skeptical as to whether life as we know it exists on Titan.

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Although many of the building blocks for life are there, temperatures average a numbing

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minus 290 degrees Fahrenheit.

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However, Titan might provide a habitat for life if scattered sources of heat from geysers

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or volcanoes are discovered.

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Coming up, we'll find out how NASA has been using a technique called aerobraking to insert

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spacecraft into extraplanetary orbits.

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First, did you know that Saturn's density is the lowest in the solar system?

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Although Saturn has a diameter of about 75,000 miles, it's made up of primarily hydrogen

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and helium gases.

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The presence of these gases makes Saturn's specific gravity at about 0.7, less than that

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of water.

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In fact, Saturn's density is so low that if it were placed in an imaginary gigantic

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bathtub, it would float.

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In the past, entering into orbit around a planet or moon required precise navigation

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and the ability to slow a spacecraft with thrusters.

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Of course, thrusters require large amounts of fuel to slow the craft down to orbital

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speeds.

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The fuel carried on these missions takes up valuable space, which can be used to store

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science instruments.

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To help reduce costs and create more room, NASA researchers have developed an alternative

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to using fuel to slow the craft, called aerobraking.

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Aerobraking uses the atmosphere of the target planet as both a brake and a steering wheel

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to slow the craft.

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Jennifer Pulley spoke with Dr. Mary Kay Lockwood to find out more about aerobraking and how

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NASA is using this technique in space travel.

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The sight of spacecraft flying out of the atmosphere on the way to a distant destination

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is a familiar one to most of us.

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In order to break free of the Earth's gravitational field, a typical spacecraft needs to be traveling

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at speeds close to 25,000 miles per hour.

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Once the spacecraft does break free, it is able to continue traveling to its destination

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at high speeds because there is very little friction to slow it down.

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Once the craft reaches its destination, the craft must decelerate from very high speeds

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to much lower speeds in a relatively short period of time.

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In the past, additional thrusters would be fired to help the craft decelerate as it approached

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its target.

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But a major problem with this method is that the fuel needed for these thrusters takes

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up valuable space and weight, which could be used to house additional science instruments.

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More recently, NASA has been using an aero-assist technique called aerobraking, which adds the

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use of atmospheric drag to slow the craft, rather than using thrusters alone.

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This technique allows additional science instruments to be delivered to a distant target, while

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also reducing costs.

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I spoke to Dr. Mary Kay Lockwood at NASA Langley Research Center to find out more.

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Well, when we first approach a planet on a trajectory from Earth, we do a small firing

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of the thrusters and capture into a very large elliptical orbit about that planet.

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We then do several passes through the upper atmosphere of that destination to slow the

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spacecraft down into the final science orbit.

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Aerobraking is accomplished when a vehicle makes multiple passes around a planet or moon

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and uses the atmosphere to slow down the vehicle.

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This process is very slow, sometimes taking several months, because the vehicle is only

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exposed to the upper layers of the atmosphere.

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This procedure is very similar to how a rock reacts when it is skimmed across the top of

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water.

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With each skip, the rock slows down until it finally stops.

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The spacecraft is similar, because with each pass through the atmosphere, it slows down

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more and more until it finally reaches the appropriate orbital speed.

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Has the aerobraking technique ever been flown on a mission?

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Well, aerobraking was first demonstrated in the Magellan mission at the very end of the

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mission at Venus, and it has since flown in two successful Mars missions, both the

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Mars Global Surveyor mission and Mars Odyssey.

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It's also going to be used in the future on the Mars Reconnaissance Orbiter mission.

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Once a vehicle nears its destination, how does the atmosphere slow it down?

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Well, an atmosphere slows a vehicle down in the same way that if you were to put your

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hand out the window of a car while it's moving, you can feel the force of the air on your

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hand, and that is the same force that's slowing the spacecraft down when it passes through

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the atmosphere.

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Aerobraking is a good way to slow a vehicle down at a destination and capture into an

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orbit, but we're also looking at another approach called aerocapture.

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Aerocapture is similar to aerobraking because it uses the atmosphere to slow a vehicle down.

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But unlike aerobraking, which only skims the top layers of the atmosphere, the aerocapture

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technique allows the vehicle to go deep inside the atmosphere of the target.

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The vehicle maneuvers through the atmosphere using drag to decelerate to the desired orbital

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speed.

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After the vehicle exits the atmosphere, a very small thruster firing occurs to achieve

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the desired orbit around the target planet or moon.

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One of the major differences between aerobraking and aerocapture is that for aerocapture we

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need an aeroshell, and an aeroshell is very much the same as the aeroshell used on the

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Mars Exploration Rover missions you may be familiar with.

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But for aerocapture, of course, we're maneuvering through the atmosphere and then exiting the

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atmosphere and finally achieving an orbit at a destination, where with the Mars Exploration

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Rovers we were landing on the surface of that destination.

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For aerobraking you do not need an aeroshell because you're passing through the very upper

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part of the atmosphere, so the heating environment on the vehicle is not nearly as severe as

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it is with aerocapture.

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So do different planets need different shaped aeroshells, or will one design work in all

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situations?

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The aeroshell shape for the aerocapture missions at places like the Earth or at Mars or at

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Titan can be very similar to those that are used with the Mars Exploration Rover missions.

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But if we're going to destinations such as Neptune, that would require a different vehicle

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shape, different aeroshell shape, and that would be more shaped like a bullet that flies

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at an angle.

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To achieve a successful aerocapture we have to stay within a very narrow corridor.

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If we don't stay within that corridor we would have a flyby, we wouldn't capture into the

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orbit, or on the other side we would land.

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So it's very important to stay within a particular corridor through that destination.

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At Neptune the corridor is narrower.

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It's kind of like a little highway.

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It's like a little highway.

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And so at Neptune in order to make the highway bigger we need to have a different shape.

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So Dr. Lockwood, in addition to aeroshells, what are some other techniques that can be

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used to slow a vehicle down?

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We're looking at other techniques that might be second generation techniques that would

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use an inflatable aeroshell or even a balut.

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A balut basically looks like a giant donut.

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It's got tethers similar to a parachute, but it has a giant ring behind it and that allows

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a spacecraft to fly shallower in the atmosphere to still slow down.

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We are always working to achieve the science and exploration goals for NASA and being able

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to reduce the cost of these systems and being able to improve the performance of the systems

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is a very important part of achieving that goal.

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It's very exciting and challenging work.

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Coming up, we'll find out how specialized materials are saving lives, but first, did

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you know that aerobraking was first tested on the Magellan mission to Venus in 1994?

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Although the Magellan mission used propulsion to slow the craft, aerobraking was tested

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at the end of the mission to validate the theory.

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With the success of this test, NASA researchers decided to use aerobraking as the primary

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deceleration method on one of its next missions, the Mars Global Surveyor.

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On February 4, 1999, history was made when the Mars Global Surveyor successfully obtained

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stable circular orbit of Mars using aerobraking as the primary method of deceleration.

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Researchers at NASA have a long and significant history of materials technology development.

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With an impressive list of new lubricants, lightweight alloys and composites, these materials

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have revolutionized our world.

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Since the 1960s, the process of creating new materials has rapidly advanced.

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Today, NASA scientists are continuing to develop new materials that are hundreds of times stronger

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than steel at a fraction of the weight.

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These advanced materials are becoming so strong and lightweight, they can stop bullets and

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even keep debris from puncturing space vehicles.

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But how are these materials made and what else can they be used for?

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Our own Johnny Alonzo finds out how it works.

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Specialized protective clothing has been around for thousands of years.

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From ancient warriors to medieval knights, protective garments were worn to help prevent

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injuries and save lives.

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The materials that were used to make these types of clothing, like metal and leather,

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worked well in those early days, but as weapons became more sophisticated, the usual materials

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began offering less protection.

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The types of materials that were used to make protective clothing remained relatively unchanged

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until about the mid-1960s, when a research scientist named Stephanie Qualik introduced

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a revolutionary new material called Kevlar.

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This material was not only lightweight and durable, but was about five times stronger

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ounce for ounce than steel.

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With this development, the world of protective materials changed forever.

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Today, stronger, lighter synthetic structures have opened up new and exciting avenues in

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the development of protective materials.

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These materials are being used in everything from sporting goods to space applications.

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To help shed some light on how these materials have changed our lives, I spoke with Dr. Jeffrey

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Hinckley at NASA Langley Research Center to find out how it works.

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If you look at the history of materials in humankind, you see the Stone Age, the Bronze

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Age, and then the Age of Steel, which is sort of the Industrial Revolution.

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We're in the course of another revolution now of high-performance materials that combine

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the strength, the stiffness of steel with other properties, electrical conductivity,

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the ability to be formed in plastically and to even stop bullets.

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Another example is Kevlar, which is used in armor protection for our troops.

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And of course, glass fiber is familiar to some people and glass fiber boats and so on.

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So we talk about Kevlar.

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How does a thin material like that stop bullets?

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We have here the flexibility of a fine fiber, a very tough, resilient material, and twice

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as strong as steel at a fifth the weight.

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And Kevlar is also a good material for penetration resistance, cut resistance.

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Because of the way it's fabricated, actually, the molecules that make up the polymer are

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stretched and aligned such that in order to break this material, you actually have to

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break the molecules.

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To understand how a flexible material like Kevlar can stop bullets, just think of a net

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on a soccer goal.

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The net strands are interlaced together, which are in turn attached to the frame of the goal.

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When the ball is kicked into the goal, each tether extends from one side of the frame

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to the other, dispersing the energy from the point of impact over a wide area.

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This forces the ball to stop.

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The same basic principle applies to bulletproof vests.

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The vest is made up of layers of fabric containing incredibly strong fibers.

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When a bullet hits this material, the energy is dissipated, forcing it to stop before it

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can penetrate the vest.

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Why is NASA interested in using these materials?

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Kevlar as a bulletproof vest material is essential to protecting the astronauts and the equipment,

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for example, on the space station.

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Space is a very hostile environment.

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Extreme temperatures, radiation, and small meteorites can make working there very dangerous.

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For example, the International Space Station is orbiting the Earth at close to 18,000 miles

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per hour.

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At these speeds, even a piece of debris the size of a grain of sand can damage the station.

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To help decrease the chance of an object penetrating the outer skin, the space station wears a type

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of bulletproof vest.

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Layers of aluminum, ceramic fabrics, and Kevlar form a blanket around each module's aluminum

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shell.

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If an object strikes the station, this blanket of protective materials helps to dissipate

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the energy of the object, helping to keep the crew safe inside.

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I know that composite materials are still relatively new.

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How do you think they will change in the future?

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Maybe one of the most exciting examples is carbon nanotubes.

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These are pure carbon and unbelievably small, but they're in the form of a fiber.

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This is a material that was discovered in the 1990s and is probably stronger than anything

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we've known up until now.

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It's perhaps stronger than diamond.

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The trick is to figure out how to make something useful out of these tiny, tiny tubes.

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This is 10,000 times smaller than the human hair.

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And so the trick is to use this material, which, even under a microscope, just looks

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like soot, into a strong, lightweight composite material.

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And so our chemists are working on that.

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An idea that's really on the drawing boards is the idea of a self-healing material.

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You can imagine a spacecraft that's going to be in orbit for 20 years, it would be nice

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not to have to service it.

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So we conceived the idea of a material that would heal itself after it was damaged.

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And I have an example here.

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This is sort of a conventional plastic material that was struck by a 9mm bullet.

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And as you can see, it shattered and left a hole that's just a little over 9mm in diameter.

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This is a new material that was invented here at NASA.

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And this also was struck by a 9mm bullet.

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The bullet went right through, the bullet was not stopped.

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But there's no hole.

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We can imagine that self-healing materials would be useful on aircraft, too.

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Right now, when an aircraft is brought in for service, they look all around it for cracks.

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And they're looking for a critical crack, which on some commercial jets might be as

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much as 4 inches long.

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When they get to the critical crack size, they can repair it.

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Well, we can imagine a composite material made with a self-healing matrix, a self-healing

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plastic, that could heal itself and the cracks would never grow.

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The exciting thing about working for NASA is that it is always something new.

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And we get to sometimes see the results of our work coming into commercial use.

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So the next time you hear about somebody getting their life saved by a bulletproof vest, you

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know how it works.

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I wonder if these things work well with paintballs.

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That's all for this edition of Destination Tomorrow.

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Thank you for joining us.

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I'm Brad Breckenridge.

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And I'm Kara O'Brien.

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For all of us here at NASA, we'll see you next time.

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