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(Music)

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(Music)

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Bruce Jakosky: I want to start my story with this picture not

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of the Earth but of an early Mars. We know that

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Mars had a thicker atmosphere, was warmer, a much wetter environment

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than we see today. Because we see crater lakes

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on the surface, ancient lakes, valley networks that were carved by

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by liquid water. Over time though, the environment

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changed. Today, we see a much colder, dryer desert

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and we have to ask, "What's responsible for that change?" On early Mars

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we think that there was a lot more water. We think that the atmosphere was

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a thick CO2, carbon dioxide atmosphere that

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somehow changed over time, that Mars has undergone significant climate change.

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Where did the water go? Where did the carbon dioxide go?

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It might have gone down into the crust where it can be locked up as

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minerals or as ice, or it might have gone up to the top of the atmosphere and been

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lost to space. That latter option is the one that MAVEN is going to be

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exploring. Looking at the role that loss to space may have

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played in the changing Mars climate. We think that this loss to space was

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driven by the Sun, by the solar wind hitting the planet

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by solar storms that eject out from the Sun hitting

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the planet, and stripping the atmosphere off. So we have to start with

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the Sun. When we look here at the quiet Sun we don't see the

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solar winds streaming out, out beyond that corona though it's going out

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at 500-1000 kilometers per second. And when it hits Mars

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it has the possibility of stripping some of the gas off.

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The more energetic Sun is much more interesting though, the

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solar wind is more intense, the solar storms that you can see here,

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are more intense, and the ability to strip off the gas is more

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significant. We're going to measure the properties of the sunlight

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hitting the planet, the solar wind, and the response of the atmosphere.

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When these solar storms eject from the Sun and head out

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through the solar system, seen here in this artist's representation,

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we want to know what effects they can have when they get to Mars. And when they

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do, we can see here in a representation from

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observations from spacecrafts spread throughout the solar system

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that they can hit Mars, they can have a significant effect.

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We know these storms happen, we need to see what happens when they get to

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Mars. So we're going to study the upper atmosphere which is the place form which

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gas is removed. And this image shows a representation

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of the upper atmosphere and what might happen when the solar wind hits it.

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The arrows represent streamlines; the colors represent the top of the

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atmosphere being stripped off by the solar wind when it hits the planet.

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That was to my mind was such a cool video I want to show this

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again, because I had to talk through the first time. When we

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see the atmosphere and the solar wind hitting it,

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it strips the gas off, and over geologic time that may have been

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responsible for changing the atmosphere, for

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driving the climate change that we see evidence for at Mars.

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We're going to do this now with the MAVEN spacecraft. It's a solar powered

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spacecraft. That bus in the middle, that almost cube like thing

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is about 7 feet across, to give you a sense of the scale. Most of the instruments

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are mounted around the edge of the high gain antenna

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seen in the middle, because they want to look at the Sun in order to capture the solar

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wind, the solar particles that hit it. And then at the

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bottom and the top are the instruments that measure the properties of the upper atmosphere.

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The ones at the bottom measure it in situ, at the location of

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the spacecraft. The ones at the top measure it both in situ and

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remotely, so we can get a global picture of what's happening with the

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Mars upper atmosphere today and how escape to space occurs.

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We've just finished building the spacecraft, unfortunately we're not

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really flying 4 of them, this just shows it at different steps.

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And fortunately they were more careful in building it than moving as fast

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as they are here. The spacecraft was built by Lockheed Martin

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in Denver, and I have to say they've provided us with what looks like it's going to be a honey

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of a spacecraft. Once it was built it goes into testing. Here we're seeing

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the deployment test of the solar arrays. We want to

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make sure that everything that the spacecraft is going to

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experience and do, it does on Earth. It experiences on

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Earth first, because we want to make sure it works. One of the

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most exciting tests is what's called thermal vacuum testing. We

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put it in a large chamber, you'll see it going in in just a minute,

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and pump it down to vacuum and put it through its paces.

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MAVEN spent 3 weeks in thermal vacuum testing, going

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through everything it's going to do once it's in orbit at Mars.

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The science instruments were cycled. The platform that holds

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them was moved. The spacecraft thought it was in orbit around Mars, again

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they didn't really move it this fast. They took a lot of care with it.

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You can imagine dropping it would not be a good thing. Once

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the testing was complete at the beginning of August,

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just a month and a half ago we shipped the whole thing down to Cape Canaveral,

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in Florida, that's where we're going to launch it from. We started off

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by driving it in a truck, in this big shipping

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container out to Buckley Air Force Base. Put it on a C-17,

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Air Force cargo jet and flew it down to Florida.

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Here in the C-17, it was so cool to me

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to ride along with it and just accompany it on the start of

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its trip to Mars. The launch vehicle, an Atlas V,

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is now at the Cape. It was delivered at the end of

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August and now we're in the process of integrating it all together.

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This isn't ours on the pad, but ours is going to look a lot like this.

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On November 18, we're going to launch into space,

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we have a 10-month cruise phase to get to Mars. We go into orbit with a

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rocket motor burn for 38 minutes. It takes us about a month

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then to commission the spacecraft; deploy the booms, test all the

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instruments, make sure everything is working right, and then we can begin

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our 1 Earth year science mission. In that year,

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we anticipate seeing enough variability of the solar input,

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of the solar wind input, of the solar energetic

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storms, to really understand what effects they have on the atmosphere.

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What this is going to do is going to tell us, coming back to the science now,

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"Where did that water go?" Where did the carbon dioxide go,

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from that early thick, warm wet environment? And this really isn't just

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about Mars, it's telling us about the evolution of the

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habitability of a planet by microbes. What is it that causes a planet to be

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habitable? And what is it that makes it not habitable?

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That's what MAVEN is going to be exploring. I hope you guys are going to see this with us.

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Thank you.

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(clapping)

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(music)

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(beeping)

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(beeping)

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