>>This is flight number 223. A special flight.
>>Ok, we're gonna take off, and Pluto is right
here, we're gonna make sure we're on time straight to this point.
>>Basically, we have
three objectives. The first is to observe Pluto occulting a star. We should be able
to get a pressure and temperature profile for Pluto's atmosphere, which is particularly
interesting right now because we can directly compare it to the one derived from New Horizons
and that will let us to calibrate all the observations we've been making for 20 years.
And secondly, if we can do this occultation in multiple wavelengths simultaneously, we
will be sensitive to particle dust haze in the atmosphere, in a way that we're not in
any single wavelength. And, finally, the biggest objective is, if we can hit the center point
of the shadow, within say 75 kilometers, then we can get an actual global view around the
entire planet.
>>Tonight we're planning on observing the Pluto occultation over the South Pacific.
We have a very finite amount of time to catch the shadow as it streaks across the Earth.
>>Let's go do it.
>>Let's go.
[SOFIA taking off]
>>We started this process at MIT for this particular event about
three years ago. Basically, you just have to spend a lot of time observing both Pluto
and the star. As Pluto moves across the sky, we're constantly updating its ephemeris. Each
night, we measure it, we measure its position, see which direction it's moving, and project
that ahead until it intersects with the star. Simultaneously, we're measuring where the
star is, trying to firm up the coordinate system of the other stars around it, so we
can get a very careful measurement of how closely they will intersect, and more importantly,
from where on the earth we'll be able to see that occultation. SOFIA is the only observatory
that can actually get to the center of the shadow, as the center line is going to be
over the ocean. And now we're here to actually observe the occultation and see what we can
learn about Pluto's atmosphere.
>>And, coming up on 5 minutes, pilots- it's gonna be a left-hand
turn to 253.
[Music/Radio Chatter]
>>Update dot txt. Print that one-
This particular mission looms large in importance
because of the synergy with New Horizons. What I've been doing tonight is receiving
updates on Pluto's position relative to the stars. I received that update first as a very
simple text message. That the center line of the shadow had moved north by 227 kilometers.
The good people upstairs were able to adjust these legs going back and forth, kind of like
a trombone, so we wound up at the right place at the right time.
>>Each stays the same...but now they're just shifted up and over.
Headed in there, there, then up here, then down...
All right?
>> Yeah, that's good.
>>There it is.
>>My collegue Karina
at the other console, is closely monitoring where the plane is compared to where it's
supposed to be crossing this shadow path.
>>Two minutes, crew.
[Music]
>>One degree left.
>>One left.
>>How's our cross elevation looking?
>>Good, right in the center.
>>Ah! Did it just? It's going down!
Woohoo!
>>Nice.
>>That's so cool!
>>They're right on top of each other.
>>It's just about right on.
>>Wow!
>>Congratulations! That's so cool!
>>Oh, it's coming back.
>>Oh, yep I see it.
>>That is so bizarre.
>>That's probably close to 90 seconds...
>>So they may have really gotten right in the middle.
>>So this graph is signal
over time plot. We see the signal of the occulting star before Pluto is moving right in front
of it. At this point, Pluto is moving in front of the star and the signal drops down. And,
here at the bottom of the curve, we see this central flash, which means that we were very
close to the center line of the shadow.
>>Everyone just jumped for joy when we actually saw that
star occulted by Pluto. I think of Pluto as being kind of a small body, but we saw it
and it was just amazing. One of the highlights of my career, I gotta say, working on this
project.
[Music]