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>> Behind me is the latest

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in a series of tests of

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a new type of propulsion system

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called a solar sail.

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Uh, this particular sail

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is very large.

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Uh, it's about

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4,000 square feet,

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and this is only

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one fourth of it.

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In its full size,

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when it's deployed in space,

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it'll be almost 17,000

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square feet in area,

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and the thickness

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of a human hair.

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Now a solar sail

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is a propulsion system.

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It's not a propulsion system

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that'll get a spacecraft

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or a rocket off the ground,

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but once you get into space,

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and you're away from

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Earth's gravity,

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having all that thrust

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of a rocket engine

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isn't what's as important.

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What's important is efficiency,

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and being able to get

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a lot of thrust to travel

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from one position to another.

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And a solar sail

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achieves that by reflecting

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sunlight, just like a sailboat

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on the lake reflects the wind.

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So this solar sail

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with its large, lightweight

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shiny aluminum coating

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behaves just like

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that sailboat.

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We've had several test flights

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of solar sails.

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The first was in 2010,

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and it was a small sail

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called Nano Sail D.

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It was about 10 square meters.

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Um, I am the principal

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investigator for NASA's

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first interplanetary

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solar sail mission,

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which is called

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Near Earth Asteroid Scout,

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which is set to launch

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on the Artemis 1 rocket

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in the next several weeks.

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That mission will deploy

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a 925 square foot sail,

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again, the thickness

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of a human hair,

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and use that reflected

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sunlight pressure to take

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this spacecraft and its science

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camera, provided by NASA JPL,

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to study an asteroid

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after two years of flight.

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The sail deployment test

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that we just completed here

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at NASA Marshall was really

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a test of functionality

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of the sail.

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Could you get these two

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hundred-foot long booms

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coiled up, put in a deployer,

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attached to a sail that has

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the area of over

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4,000 square feet when

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it's all folded and rolled,

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put it in a small box,

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and get it to deploy un-aided.

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And the answer is, yes.

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We had a very successful test,

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and the results are evident

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in the pictures that

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have been taken

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and the data we collected

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during the test.

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And the key to enabling

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some of these missions

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is having larger

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and larger sails

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that are very lightweight.

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And that's why we're

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moving from sails

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the size of NEA Scout,

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925 square feet,

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to 17,800 square feet

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with Solar Cruiser,

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and in the future,

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we'll make sails that

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are even larger still.

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And the larger the sail,

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generally speaking,

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the better it has

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a capability to do propulsion

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and higher thrust.

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Some of the missions

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that are of interest

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for solar sailing are

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things like space weather.

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Most people on the ground

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don't really think about it,

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but spacecraft in space

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are affected by activities

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on the sun.

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And there are solar storms

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that spread out into

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the solar system

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that require advance warning

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so that our spacecraft

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can essentially batten down

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the hatches and be ready

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to weather the storm.

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A solar sail craft

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can continually thrust

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along the sun/Earth line

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between the Earth and the sun,

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closer to the sun

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than the current

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warning satellites,

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and increase that warning time

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by up to 50%.

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Solar sailing captivates

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the imagination.

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It's the ultimate

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green propulsion system.

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What we're doing is

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we're maneuvering in space

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without any fuel,

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just using the natural

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environment to get from

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point A to point B.

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As long as the sun is shining,

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we can get propulsion.

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And the significance

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of that is there are

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a lot of science missions

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that need to be accomplished

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that cannot be done

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any other way.

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It will allow scientists

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to gain views of the sun's

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north and south poles

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on future missions,

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which we can't study right now.

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The reason why that's

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so exciting is I can't

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imagine trying to understand

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the Earth's weather systems

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if we don't know what's

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happening at the North

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and South Pole.

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Scientists are similarly

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handicapped when

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they try to study the sun,

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because they don't have

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near continuous observations

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of the Poles.

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Now solar sails are obviously

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not for everything.

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Sails are limited to

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small spacecraft

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and small payloads.

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We won't be flying humans

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with them anytime soon.

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But that doesn't mean

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they can't be used

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to support human missions.

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In near-Earth space,

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going to the moon,

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they can be put into

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novel orbits to give

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near-continuous communications

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coverage to the moon.

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They can give us

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observations of what's

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happening on the lunar

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far side, continuously.

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They give us the capability

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to maneuver in

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near-Earth space,

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and take spacecraft from

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point A to point B, repeatedly,

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over years, because they don't

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run out of gas, and eventually

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the descendents of this sail,

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that are much larger

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and much more durable

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will fly very close to the sun