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mars phoenix lander is headed for the

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north polar region of mars and its goal

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will be to search for habitable regions

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places where life may have existed in

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the past the phase that we're in now is

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called cruise which sounds really easy

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and laid-back although it's actually a

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very busy time for the spacecraft teams

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we're busy making sure the systems of

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the spacecraft are are working as they

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should the teams are busily preparing

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for the science is going to occur after

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landing the navigation team is getting

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ready to make sure that the spacecraft

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actually gets to its target on Mars it's

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very similar to the sport of archery in

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archery you have archer who's standing

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some distance away from the target and

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and that person's job is to make sure

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that the arrow hits the target an archer

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will have to draw back the bow with a

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certain amount of force secondly the

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Archer has to make sure that he aims the

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arrow at a certain angle and then that

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arrow actually has to to traverse the

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correct amount of distance so that it

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hits the target these three things have

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to come together just right we're

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watching a spacecraft to Mars it's a

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little different the bow in this case is

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a 250 ton rocket our arrow is the

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Phoenix spacecraft it has to travel over

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420 million miles to its target that's

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70 miles long by 15 miles wide this is

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like trying to shoot your arrow from

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Dodger Stadium and hitting home plate at

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this seems almost like an impossible

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shot to take just in one single shot so

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we actually make it a little more fair

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by having six opportunities to correct

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that trajectory along the way imagine if

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stop it in its path check to make sure

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it's on course for the target and if not

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be able to nudge it back to its target

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so that it's headed for the right place

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now of course our spacecraft is moving

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at about 60,000 miles per hour it never

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stops so the corrections have to be

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performed along the way while the

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spacecraft is still in motion we track

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the spacecraft using the deep space

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network of antennas and we figure out

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exactly where the spacecraft is where

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it's heading and then compute where it

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actually needs to be we develop commands

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to fire the thrusters on board the

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spacecraft to make any corrections that

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when you can make 22 hours prior to

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entry we have one last chance to make a

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fine tuning of where we're going to land

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the arrow hitting a target is a decent

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analogy for what the navigation team

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does but in reality it's a lot more

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complicated than that Earth and Mars are

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rotating around the Sun at at various

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speeds and constant motion the

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spacecraft itself is moving very fast

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across the solar system it's trying to

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hit a moving target and that target is

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also spinning on its axis and we have to

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keep all of these things in mind while

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we're attempting to hit this target it's

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pretty challenging all these things that

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you have to take into account and

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actually get get done during this