Kasper>>What happens to metals when they're at
1700 degrees C being hit by sunlight and
particle radiation? How do you know it
won't just evaporate? How do you convince
NASA and reviewers that it will actually
survive? The Sun is one of the most
fascinating mysteries in our solar
system, and thanks to the Parker Solar Probe,
we may start to understand it a little
better. The plan is to send a spacecraft
the Sun's corona to measure the electric
and magnetic field, image the solar wind,
and collect high-energy solar particles.
Then, it will send back the solar data to
help researchers better forecast Solar
Flare activity and how that might affect
us here on earth. The probe team needed
to prove that their instruments could
withstand the harsh conditions of the
Sun. Justin Kasper is responsible for the
probe's Faraday cup which is designed to
scoop up the solar wind. >>So a French
colleague of mine in Paris said, you know,
'Okay. Meet me in Perpignan (which is a
small town on the on the coast in
southern France).' So like a couple months
later, I hop on the plane, I fly down
there and I meet him. We hop in a car
three hours later were up in the
Pyrenees. Get out of the car, there's a half a
foot of snow.
I'm in shorts, miserable, but we're
looking at the largest solar furnace in
the world.
The Audeo solar furnace is located in
the Pyrenees Mountains in southern
France. There are 63 mirrors on the
mountainside that reflect the sun's rays
to a seven-story parabolic structure
fitted with ten thousand mirrors. The solar
rays are then reflected and focused to a
central tower. >> My colleague and the
people that work there said, 'Come with a
prototype of your instrument, stick it in
this chamber, and we'll expose it up to,
you know, the full amount of sunlight it
would experience at closest approach. We'll heat it to the full temperatures. We can
simultaneously hit it with the radiation
of an experience close to the Sun, and
will do it for you for free.' And they
showed me a memorandum from the 1970s
and it said you know we the French Space
Agency would love to be involved in the
Solar Probe one day if it ever happens.
So here's the agreement we've made: we're
gonna go off and we're gonna figure out
how you can show these things can
survive that's a kind of extreme
environment, and if one day,
Solar Probe really happens and you want
to design these instruments, you come to
us and and we will have a facility where
you can test these materials. And so
they'd been waiting for like 40 years
for someone to show up and say, you know,
okay, I've got it. And so it was a
wonderful experience. In the end they
wound up testing more than 300 different
material samples for us, you know, all
using this light bouncing off these
mirrors and the Pyrenees. NASA needed
further testing to ensure the probe
could withstand days of exposure to the
solar elements in space. >>So we're just
three months away from the launch of
Parker Solar Probe. We have one last test
to do for our instruments on the
spacecraft, and that's to take our
qualification model the Solar Probe cup,
put it in this chamber behind me, and
simulate an encounter with the Sun.
Researchers put the Faraday cup in a
vacuum chamber and blasted it with light
and radiation as powerful as the Sun.
Then the team bought four used IMAX film
projectors on eBay, and hacked them to
create the intense focused light. "If you
look at an old-school analog 70
millimeter IMAX film projector that has
a bulb full of xenon it heats up to
about the same temperature as the
surface of the Sun, we have to combine
four projectors to get the total amount
of sunlight and the the angular size of
the Sun correctly, but we shine that
merged sunlight in through this window
into the chamber and illuminate the
instrument with it. Outside the vacuum
chamber, we have this dull-looking metal
box here, which is actually a replica of
the spacecraft. So the instrument
actually thinks it's on the spacecraft,
talking to the spacecraft, sending it telemetry. We're now very much
simulating the real Sun environment. The
next steps, now that the chamber pressure
is dropping, we can bring our ion gun or
particle accelerator on and see if the
instrument functions. So now that we've
turned on the instrument it's reporting
internal Diagnostics, and one of the
things we're seeing is the electronics
are actually pretty warm. We really don't
have a lot of time to do our tests
before the electronics risk overheating,
so we're gonna have to move pretty
quickly. Chamber pressure is a little on
the high side, which is fine, but the
particle accelerator actually has its
own circuit that won't allow us to
enable the accelerator if it thinks the
pressure is too high. So, we've got to
basically flip a switch to override that
interlock device so we can turn the
particle accelerator on. Meanwhile, the
temperature of the electronics box keeps
rising. We managed to just correctly
reprogram the
interlock, so the particle accelerator
is not being inhibited from turning on.
We're gonna set up a data display, so as
the instrument scans through voltage,
we'll see if there's an IM beam or
not. Done? Yay! Alright! Haha.
That's a nice, really strong signal. If
you look, you know, the signal is coming in
really clear, really strong, coming in at
the exact same energy every time, and
we've reached a point where the
instrument is able to outperform the
conditions that the chamber is capable
of recreating. It's just about as good as
it gets.
What more do you want when you're trying
to show that an instrument is gonna
operate in an extreme environment than to
build the best test facility you can to
recreate that environment, then see if
the instrument is able to outperform that.
Yeah! We're going to the sun. We're going to the sun.
That's exciting.
