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The SWEAP investigation consists of
three separate instruments and a central

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electronics box most of the instruments
within sweep sit on either side of the

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spacecraft stare out over the entire sky
and make maps of all the different

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particles and what energies they're
moving at what types of particles they

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are the purpose of sweep is to measure
the bulk of the solar wind and a solar

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atmosphere one of the biggest questions
we want to resolve with Solar Probe is

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how the corona in the solar wind are
heated in order to do that we need to

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see if there are waves that are coming
from the Sun and depositing energy

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within the solar atmosphere in the solar
wind so we have a series of sensors

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across the spacecraft that will collect
individual particles electrons fully

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ionized hydrogen helium which we call
protons and alphas and other minor ions

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and make maps of the number of particles
as a function of their speed and energy

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and type we take those maps on the
ground and we can interpret them to

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figure out the temperature the density
the pressure of the solar wind and the

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solar atmosphere on the RAM side of the
spacecraft so that's in the shadow of

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the heat field in the direction that
Solar Probe is moving around the Sun we

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have Span A. Span A looks ahead of the
spacecraft it has an electron and an ion

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instrument and they can see the entire
sky on that side of the spacecraft on

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the other side the anti ram side of the
spacecraft we have Span B which

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basically looks behind our direction of
motion Span a and Span B are each able

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to take an inventory of electrons coming
from any direction in the sky their

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fields of view stitch together like the
seams on a baseball the spans combined

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to give us a field of view that covers
nearly the entire sky and we have one

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large gap in our field of view and it's
produced by the heat shield at the front

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of the spacecraft
so we have the Solar Probe Cup is the

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final instrument within SWEAP. The Solar
Probe cups sits on a strut it looks

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around the heat shield and faces
directly into the Sun when our solar

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wind or solar atmosphere comes blowing
into the cup

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if those particles which are charged
don't have enough energy they get

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reflected out by that electric field
we've set up the particles with enough

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energy to make it past the
could feel come in and strike a plate

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and we record the current all we have to
do in an individual measurement is sweep

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in voltage and measure the number of
particles that can make it in as a

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function of the voltage that's sweep
when we interpret it lets us figure out

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the average speed direction energy
temperature density of individual

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populations of particles