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medli is a set of instrumentation that

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we're installing on the Mars Science

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Laboratory spacecraft so we went to take

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data during the entry MSL through the

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Martian atmosphere

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medli data is really going to provide an

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order magnitude more information than

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engineers have had in the past we've

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never instrumented a Mars entry vehicle

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to this extent we make a lot of

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assumptions and our simulations and our

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vehicle models for instance since MSL is

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so big we expect the flow on the front

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of the vehicle during entry to

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transition to a turbulent state which

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will raise the heating on the front of

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the vehicle we're not sure where on the

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vehicle or when that will happen we're

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also not sure how the vehicle is

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aerodynamic characteristics will change

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as the TPS material burns away so these

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are all things that we can use our data

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for to improve our knowledge for the

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next Lander we also have a temperature

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subsystem and that was developed at the

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Ames Research Center and it's actually a

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plug of thermal protection system

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material that has contained in it for

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thermocouples at different depths in the

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heat shield and also a recession sensor

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that sticks up to the surface and will

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tell us how much the heat shield will

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burn away as it flies through the

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atmosphere this is an actual piece of

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simulated MSL aeroshell structure the

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thermal protection system would be down

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here as the vehicle enters the

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atmosphere and here is our pressure

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transducer connected via stainless steel

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tube through the structure and then

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that would extend through the thermal

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protection system where we would sense

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the pressure the Mars Science Laboratory

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has a heat shield that is the biggest

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one ever flown to Mars and it's about

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four and a half meters or about fifteen

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feet in diameter and across the vehicle

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we have seven pressure transducers and

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we also have seven thermal plugs and

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those were located very carefully by our

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scientist and principal investigators to

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look at some specific things for the

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pressure system the transducers are

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located in a cross configuration down

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the centerline of the vehicle and that

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allows us to then look at the different

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measurements and determine what the

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attitude of the vehicle was the angle of

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attack and also the angle of sideslip

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and this gives us an independent measure

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from the inertial measurement unit

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that's on the spacecraft for the thermal

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plugs the seven thermal plug located

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those in areas where we expected the

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flow to transition from laminar to

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turbulent so that we can predict where

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and when that transition would occur and

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where the heating might increase on the

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vehicle we're looking for additional

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information how the vehicle performs

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that we can use to apply to the design

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of the next generation of vehicles and

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maybe will help define what the

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technology should be as well as

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understand where the design assumptions

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that we've made for MSL are conservative

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or not conservative enough so it'll

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allow us to make designs that can land