Physics world. Hello, and welcome to the Physics
world stories podcast.
And lift off.
Decollage.
Lift off from a tropical rainforest to the
edge of time itself.
James Webb begins a voyage back to the
birth of the universe.
On the 12/25/2021,
the James Webb Space Telescope launched for a
twenty year mission exploring our solar system, solar
systems around other stars,
and distant galaxies in greater detail than we've
ever seen.
It can see objects in space 100
times fainter than the Hubble Space Telescope could.
In today's episode of the Physics World Stories
podcast, we're gonna hear from two of the
project scientists at NASA
behind the James Webb Space Telescope. I'm Andrew
Glester, and if you've heard any of these
episodes before when we've talked to astronomers over
the last two or three years and beyond,
then you'll know that the answer to the
question, when will we know more, is when
the GENS Webb Space Telescope
launches.
Well, now it has. And the telescope which
looks
something like a boat with a sail on
it is 20
meters by 14 meters in its largest point.
That's the sunshield.
And the main telescope's diameter is 6.5
meters.
It's on its way now to l two,
one of the points in space
where because of orbital mechanics and the way
that gravity works,
spacecraft can be balanced between the pull of
the gravity of the Earth and the pull
of the gravity of the sun. The telescope
has had to unfurl
once it's in space, and we'll hear all
about that, the journey
to Lagrange two, and what we can expect
to see beyond that right now as we
go
to NASA
to hear from those two project scientists.
I'm Jonathan
Gardner. I am the deputy senior project scientist
for the James Webb Space Telescope
at the NASA Goddard Space Flight Center.
I've worked on the project in my current
role for almost twenty years starting in 02/2002.
Wow. And,
my role on the project or generally the
the role of the project scientist team
is to watch over the science
of the observatory.
As we have gone through the process of
building it, we need to make sure that
the engineers and managers are building the right
the the things that will do the best
science. And now in the exciting part with
the with the launch and the commissioning,
we continue that that process of watching over
the science.
I'll now hand it over to my colleague,
Stephanie Milam, who,
was
during the process of developing the observatory,
we realized
that about ten years ago
that,
Webb was going to be very powerful
in the solar system for studying solar system
objects, and we needed to bring an expert
onto the team. So I'll turn it over
to Stephanie. Yeah. Thanks. Thanks, Jonathan.
So I'm Stephanie Milam. I'm the deputy project
scientist
planetary science on the James Webb Space Telescope,
as
was just sort of introduced.
And I have been on the project for
about a decade.
So,
the the gist of my role, well, yes,
making sure we have solar system science capabilities
with the James Webb Space Telescope
was, to make sure that we could actually
do these observations in a
in
in a way that, the telescope wasn't originally
designed to do. So we have this massive,
extremely sensitive,
floppy telescope, you know, that's designed to look
at the first stars and galaxies across the
universe.
And I wanna look at the brightest thing
in the infrared sky that's,
you know, flying by the Earth.
So we have to be able to track
targets that move with respect to the stars,
and other galaxies,
like Mars or any other planets,
but also things like comets
and near the asteroids.
As well as making sure that we had
capability to look at these really, really, really
bright objects. So making sure we had modes
with our instruments that we wouldn't saturate everything
and and not have that capability.
Okay. So I'm a amateur astronomer. I have
a telescope in my back garden. If I'm
looking at
a planetary
nebula or something and then I want to
turn to look at the moon, I'm gonna
have to really
refocus the telescope. Is that something you're gonna
have to do with JWST?
So it's not a focus,
per se.
Basically, what we're we're doing is, we'll we'll
be tracking an object that's bright and big.
But we have subarrays on our cameras. So,
basically, we're not exploiting the full, you
know, sensitivity and capability, all the pixels,
so that, you know, we can detect really,
really, really faint things. We only need a
handful of them, so some subcomponent.
And that's how we actually do our imaging.
And spectroscopy,
we usually don't need to have any any
major,
concerns,
unless it is something like Mars, in which
case we have to make sure we use
the right resolution so that we're not saturating
the spectra.
How do you decide who gets time on
the the telescope? Are the astronomers all over
the world sort of clambering over each other?
You know, I want time on it. I
wanna point it in this direction, etcetera.
So I'll take that. It is a competition,
and, it's a very hard fought competition.
So what we do is,
once a year, we put out a call
for proposals.
And scientists from around the world,
will form their teams
and write their very best proposals. So a
proposal contains
a description of the science question that they
want to answer
and how Webb will do that,
and then also a detailed description of the
observations
themselves. How long of an exposure,
which filters, which which of the four instruments.
Sometimes we can use two instruments at once,
and,
sometimes a single proposal will successively
use the the different instruments.
Some of these teams are very big,
more than a hundred people.
International teams, there's certainly a a strong
component of,
scientists in The UK who are working on
this this telescope. And
and so these proposals then
went in
last November, and they were reviewed
by,
a peer review. So panels of scientists
would read these proposals
and,
pick out the best projects
and
put those forward to be to be done.
And what we what we do is we
have a year of time
that can be allocated to the proposals
at one time. And then
we'll in our first year, we'll do those
programs
that were selected.
There were 276
programs selected,
ranging from
fairly short time periods, you know, one or
two hours, all the way up to, I
think, the biggest one we picked was, just
over two hundred hours.
And then, we'll do those in the first
year. But during that first year, we'll run
the competition for the second year
and, let people,
both propose new ideas and also follow-up,
the the initial discoveries that we're getting with
the telescope. So you're right. It is a
hard fought competition,
very prestigious
to win win time with the web, and,
you know, they'll get great data and be
able to start answering the important questions in
astronomy.
Among all of those different uses for it,
have you got favorites out of the proposals?
Besides my own science, obviously.
So So as far as the solar system
goes, my my my own area of research
actually involves studying comets and interstellar objects.
So we're we're trying to see, you know,
what what these basically icy relics of our
our solar system are actually made of, you
know, what processes
are driving them, you know, crazy
physics and dynamics and planetary astronomy, but also
the really cool stuff like, oh, did it
deliver water to Earth or other planets and,
you know, organics,
maybe something that looks like, prebiotic chemistry.
If you think about, like, Miller Urey kind
of kind of craziness,
and fun. But, another things that I think
is gonna be a really compelling project, for
not only science but also for the general
public is we have some programs that are
gonna be looking at ocean worlds in our
solar system. So like Europa and Enceladus. Just
in case you're not completely up to speed
on your solar system moons, Europa is a
moon of Jupiter,
and Enceladus
is a moon of Saturn.
So with UST, we have the capability to
not only observe these objects and image them,
but we're also gonna be collecting the spectra.
And so we're looking for fingerprints of molecules
that are gonna be,
indicative of a unique kind of chemistry,
maybe some bio biochemistry,
maybe some prebiotic chemistry.
So looking for things like water, carbon dioxide,
what processes are happening in these ocean worlds,
studying the plumes that are coming out, seeing
if those
volcanic like eruptions are putting,
new molecules or, you know, you can almost
think like a lava flow except for the
ice on the surface of these bodies,
and really trying to understand what's what's happening
with them. It's gonna be really critical to
do this for especially Europa,
with JWST
early on because they're developing the Europa
Clipper Clipper mission as we speak. And so
optimizing the instrumentation for future missions is is
something that JWST really has in its wheelhouse
for planetary science. I look at my own
research is to look at the other end
of the universe.
So Stephanie looks at the closest things that
Webb will observe, and I look at some
of the farthest things.
So we do that by,
by what's called deep surveys.
So
to look at something really far away, of
course, we need to be able to see
something that's really faint, and Webb was designed
to to look at things that are really
faint.
So following up to,
the faintest picture that humanity has ever taken,
which is the Hubble Ultra Deep Field taken
with the Hubble Space Telescope,
following that up with with other,
projects like that, we're gonna point Webb at
a few places on the sky for a
really long time just to kinda see what's
there. And what we expect to see
is,
when we when we find the most distant
galaxies we can see, of course, because of
the light travel time, we're looking backwards in
time to when the universe was much, much
younger. And we're trying to look back to
within
a couple or
a few million years of the big bang,
13 and a half billion years ago,
to when the first
galaxies formed in the early universe. And that's
that's my research. That's what I'm most excited
about. There's actually a number of different projects
that are that have been selected that are
taking different approaches. I'm involved with a couple
of them. I like to watch the the
results of of the other projects.
And, there's a lot of synergy between these
projects as well because you wanna if you
if you see something in one part of
the sky, you wanna know whether it's typical.
So you look in a different part of
the sky to see whether you see similar
types of objects. But I also wanna throw
in something,
where I'm not involved
and I'm just kind of a fan of
the research, and that's exoplanets.
So Stephanie looks at the planets in our
own solar system, but there's loads of planets
around other
stars that we are
really just,
there's a flood of of information
since the discovery of the first exoplanets,
about
twenty five,
twenty seven years ago.
And,
Webb is just gonna do some really amazing
things with with exoplanets.
So I do I I study the the
distant galaxies. I I think exoplanets are cool,
and I like what Stephanie is doing too.
Yeah. You and me both. One of the
things that I'm really looking forward to is
that ability
to look into, peer into the atmospheres of
exoplanets.
Can you tell me a bit about how
that's gonna work? So it's basically the same
way we can look at our own planets
in the solar system. So we're we're studying
those atmospheres. Basically, the planet goes in front
of its star. You can think of an
eclipse. And
what we do is we can see how
puffy the planet is. So maybe it has
a really big atmosphere like Jupiter,
you know, Saturn, or maybe it doesn't have
an atmosphere at all like Mercury,
or Mars. And we can study the composition
of that atmosphere as it goes through this,
phase of its, you know,
orbit.
And by doing that, we can study the
chemistry of that atmosphere. So as I was
telling you, like, these wavelengths, we can study
really important molecules for,
understanding
atmospheric conditions
and what processes could be occurring
in or on that planet.
So
even though, you know, everyone wants to look
for life, we're not looking for life itself.
We're looking for evidence of some perturbation in
in an atmosphere.
So we wanna know whether or not the
chemistry is unique, and that can be caused
by various things, you know, geologic
processing,
impact events,
weather,
all kinds of things causes crazy things, and,
you know, life can as well. And so
just by getting, you know, some indicators
of what the chemistry looks like, that'll be
something we can follow-up with and, you know,
get a short list of planets around other
stars that we think are really compelling as
far as their chemistry goes
and follow that up with future facilities.
And, you know, maybe one day we'll we'll
get to a point where we can start
saying, oh my goodness. There's satellites or whatever
there that that are crazy.
I I just is there something? Is it
possibly something that's so odd, so
peculiar and crazy that
you might go back to that one year
of planning and say, actually, we've gotta go
back to this sooner, or do they everybody
has to wait for the next year? That's
what the annual,
call for proposals is is all about.
We do have a small amount of time,
a few hundred hours that's set aside for
the
discretion of the director of our science operations
center,
to,
to respond to things that are happening.
A a
a supernova goes off,
and we wanna get the telescope onto that
as quickly as possible.
We actually have two ways of doing that
kind of thing. If people can anticipate that,
they can write what's called a target of
opportunity
proposal to the regular call and say, if
certain conditions are met during the year,
activate our program and go and look at
it, Or we have as a backup if
something's really
if really happens and we wanna get the
telescope onto it, we have this what's called
director's discretionary
time
that,
the the director
of our science center can,
say, you know, this is so important. I'm
gonna use some of this discretionary time, and
we'll get on to it. A prime example
of that
process with Hubble was when comet Shoemaker Lee
Levy
impacted into Jupiter.
That was an activation of of, you know,
all of the telescopes in the world. I'll
I'll point it at that that,
at Jupiter at that time. And they got
Hubble onto it as well,
just within
the time from when it was predicted to
when it when it actually happened and and
got some great results out of that. So,
yeah, we we can do it if it's
if it's important and if it's rare, but
we also have our process where we make
sure that the competitive process lets us do
the very best follow-up observations
to,
to the discoveries. And, you know, likewise, if
if Hubble discovers something,
because Hubble's still gonna keep going. If Hubble
discovers something,
we'll follow it up with with Webb in
the following year unless it's really time critical.
Okay. So we've known and loved the Hubble
Space Telescope
for some time now.
JWST
is often spoken about as the successor to
it. So where is it different? Where is
the instrumentation
different,
and how are things improved? The differences
between Webb and Hubble are that Webb has
a bigger mirror.
Webb is,
optimized for the infrared,
whereas Hubble is
ultraviolet, visible light, and a little bit into
the near infrared.
So there is some overlap.
Hubble can can pick up in in the
ultraviolet and can see blue light and
blue visible light red and then into the
infrared.
Webb
has gold coated mirrors, and gold
absorbs all of the colors,
bluer than gold.
So,
so gold gold is very reflective in the
infrared,
and it reflects gold colored light and red
colored light. So so Webb can see
red visible light and goes into the infrared
out to,
the the wavelength range is point six microns
to 28 and a half microns,
into the infrared.
28 and a half is is where we
can see things
that see the heat
from things that are room temperature or a
little bit
little bit colder than that. So,
so that's that's the big difference.
Webb has four
cameras,
four instruments.
The near infrared camera is gonna be our
main imager taking a lot of the the
pretty pictures that you will see.
And, even though it's infrared,
we're still gonna get great pictures just like
Hubble. So so the the the, the people
who are addicted to looking at Hubble pictures
every day will get that from Webb, and
they'll get it from both together,
as long as both are operating together.
So that's the near infrared camera is our
is our,
imager. It goes from point six microns gold
colored light out to five microns,
in the near infrared.
We have a near infrared spectrograph
is,
provided by the European Space Agency. So it
was built in Europe.
There is a couple of components that we,
we made in The United States, but it's
a European instrument.
That's got a really cool thing in it
called a micro shutter array
in which we have a quarter of a
million little windows
on a computer chip.
And we can open those windows where there's
something that we wanna look at, and we
can close the windows to cut down the
background and the overlap of the spectra.
So with this micro shutter array, we can
get spectra of a hundred galaxies at once,
like in, for example, in the Hubble Ultra
Deep Field region. We can do a hundred
at once, whereas
with Hubble, it could only do one or
because it was a long slit, we could
maybe line it up with two,
at times. So that's a huge advantage.
We have,
the mid infrared instrument, which picks up at
five microns and goes out to 28 and
a half
microns and can do both imaging pictures and
spectroscopy,
at the longest wavelengths.
That's,
that's good for studying the molecules that Stephanie
was talking about and,
things like forming stars and planetary systems within
our own galaxy, and then also looking at
at, all the other things that that Webb
looks at. And then the the fourth instrument
was provided by the Canadian Space Agency as
It's part of our it's our Canadian contribution,
and it does two things.
One is that it's the guider,
which means that this camera will lock onto
a bright star and keep the telescope
pointed
perfectly at our targets.
But the Canadians didn't just want to be
part of the,
of enabling the science. They wanted to have
their instrument do their do science as well.
So on the other side of the optical
bench,
they stuck a science camera,
and this has,
three specialized
instrument modes for particular
projects.
One is to find distant galaxies,
with,
particularly with the fundamental transition of hydrogen,
which is called Lyman alpha,
red shifted out into the, into the infrared
because the galaxies are so distant.
There's a second
mode
that,
you wouldn't think we would do this with
the space telescope, but it takes the image
and puts it out of focus.
So we will point this this camera at
a bright star, maybe even bright enough that
you can actually see it with your naked
eye,
and,
spread the light,
take it out of focus, spread the light
over the whole detector.
And this way and then look for,
for,
the the dip in the total amount of
light when a planet goes across the face
of that star.
So this is specialized for doing transiting planets
of really
bright or really nearby
stars. Some of these stars, you know, are
are stars that have names.
And
so that's gonna be our our,
most powerful way of studying the atmospheres of
exoplanets
because,
if it's a bright star, it's nearby. It's
got lots of light, lots of photons. We
can get a really good signal
for when the planet goes across the face
of the star and the light goes from
the star goes through the atmosphere
of the planet and then into our telescope.
And then the final,
specialized mode for the Canadian instrument
is,
a a way of seeing planets that are
or
planets or or dust discs that are really
close to the star. It's a
a type of interferometry
for boronography.
Brilliant. And we're we're talking on the January
18.
So by the time people are listening to
this, the telescope is gonna be 1,500,000.
Or by the time it gets to
l two, it's gonna be 1,500,000
miles
away from Earth.
Can you tell me about that journey from
launch
to that point in space? And are we
safe now? Well, Stephanie's in the mission control
center, so I think she should answer that
question. Sure. Sure. We're we are safe.
Right.
We're on our journey.
As as I'm sitting here working in operation
center,
we'll be in orbit around a a point
called the second Lagrange point. So it's a
Earth sun gravitational,
that
makes it
far easier for us to stay in that
position because of this gravitational
attraction,
so we don't have to, you know, burn
fuel constantly to stay in orbit.
But it also protects us. It's far enough
away from the Earth and the moon,
that we don't get radiation from the Earth
and the moon. So as John was saying
or excuse me. As Jonathan was saying, we're
very sensitive to thermal radiation, so any heat.
So being further away, it kinda gives us
a a nice barrier from being too close
to to heat sources such as the Earth
and, the moon. And also in this orbit,
we can maintain
our our position in the sky so that
we always have the sun on one side
of the spacecraft and, you know, the dark
cold sky on the other side. So this
is why we have a funny looking boat
shaped telescope.
So we we can always make sure we're
protected and and keep the optics and the
instruments cold.
We will have to unfortunately
use fuel to stay in that orbit, but
we don't have to do it quite as
regularly as we would if we weren't in
a gravitational set point.
But that's mostly to unload momentum. We will
be, you know, building momentum as we turn
and point the telescope.
But also because we have this giant solar,
you know,
sunshield, it it acts like a solar sail.
So the sun radiation pressure actually pushes on
it. So we have to maintain that orbit
and and correct it so that we know
where we are in the sky,
and also just to stay there and,
maintain.
But, it's already been announced that, we've we've
really been able to manage our fuel
very well,
throughout the launch and as we're going
to this point.
So it's,
unfortunately, we are a fuel limited lifetime,
for the mission.
So we
once it runs out, obviously, we can't stay
in L2 anymore. We can't unload momentum. We
can't control the telescope.
So, once we are out of fuel, we
don't have a mission. But, by managing the
fuel efficiently,
we'll have longer operations than what we originally
planned. So it's gonna be well over ten
years. So it's gonna be great. Oh, it
certainly is. Now
getting a telescope to that point in space
from Earth is is difficult. Right? Can you
talk me through that? The the telescope was
launched
on Christmas day, Christmas morning,
Christmas morning in,
in The United States, Christmas Afternoon
in The UK.
It was launched on Christmas day on a,
Ariane five rocket,
that was part of the European contribution to
the mission,
very,
important contribution.
And,
we got a beautiful launch.
And most of the,
energy
that the
observatory tape will need to get to L
2 was provided by that rocket. We started
out really fast,
and,
we're kind of climbing a gravitational
hill. And as we go, we're slowing down
because we're climbing up that hill.
So but but we started off with a
whole lot of momentum, and we're,
we're using that momentum to get to L
2. There were
two burns
of the onboard rockets,
to correct this,
trajectory.
The first one so
the the l two point is it's what's
called a saddle point. If you can picture
a saddle that, you fall down in one
direction, but towards the earth and away from
the earth, you're climbing the hill. And we
wanna climb that hill, but we don't wanna
go over the top and start drifting
too far away
past the l two point. That's because our
our the onboard rockets are on the
sun side or the earth side of our
sunshield.
They're not on the telescope side. So we
can always speed up, but we can't slow
down.
We would have to point, you know, turn
the telescope towards the sun in order to,
slow down. We don't wanna do that. So
we're constantly
trying to just get to where we need
to go, but not go too far.
So we did that with the rocket.
This was all planned, and the rocket went
went perfectly.
The,
there was a correction
twelve hours after launch
to, get just the right amount of energy
at that that we needed at that point.
Then two days after that, there was the
second correction.
And then at launch plus twenty nine days,
which is coming up not too long from
now, we're gonna have the third correction,
the third firing of the thrusters to put
us into our final
orbit.
So those three
burns of the onboard thrusters,
are are just kind of tweaking up all
of the energy that the that was given
to us by the rocket.
So mostly and if if you wanna if
you wanna see where Webb is, we have
a web page that says, where is Webb?
And lots of people have been watching this.
That tells you how how close we are
to where we're we're going, how fast it's
going, and then also a whole lot of
information about what's happening day to day on,
the
the what we call commissioning, the deployments, and
commissioning of the telescope.
Quite a Christmas present for the world's astronomers
as the James Webb Space Telescope
begins its life
heading towards deep space.
So we need to talk about the launch.
And it obviously happened on Christmas day, and
it was delayed from Christmas Eve to Christmas
day fairly last minute. And there were a
few delays before that, of course. But that
timing on Christmas day, it just felt like
for nerds like me. Right? It just felt
like a wonderful
Christmas present. And I wonder how it was
for you who've been working on it for
all that time.
I cried. Go
ahead.
It so, with the pandemic, unfortunately,
launch viewing opportunities
and events and things have all kind of
been put on the hiatus, and that was
really unfortunate to not get to be with
all of our colleagues and, you know, sharing
the excitement of the law, especially with people
like Jonathan,
that's been working on it for decades.
I've only been on the project for ten
years, and I'm already very emotionally attached.
So his perspective is probably
well beyond
but I I definitely
I was very emotional about it.
For the success of the team, for the
success of the mission, the success of NASA,
for the success of ESA, the Canadian Space
Agency,
and all of astronomy
and planetary science.
This is going to as you said, it's
it is the next thing. This is how
we learn more, and
it's very, very exciting.
And being a part of it and watching
the success of it and more importantly, watching
the the solar array actually deploy, which was
amazing capture
an extreme amount of fun.
I cried again when that happened.
So, yeah, I I was very thrilled, and
I'm sure Jonathan's
experience was beyond. Yeah. I I think one
thing that's really telling is that,
at the launch site itself,
when the launch happened,
everybody cheered. And I think, you know, worldwide,
lots of people were cheered. But I I
wasn't in the control center, but in the
control center, the launch happened
and people were still kinda watching.
And then half an hour later, when that
solar
array
folded out,
that's when it the the control center went
into bedlam.
Because,
you know, without that solar array,
we would have a seven hour mission.
That's how long the batteries would last without
without additional,
charging power. So,
the fact that we actually could could see
that on the camera,
was just amazing. And, yeah, it the whole
thing was was very moving.
I I personally actually was watching with my
family,
went to stay with my parents for,
for the holiday and for the launch. And,
you know, I I
that that,
that was also important because,
you know, your family,
on a mission like this
supports,
provides a whole lot of support for,
you know, like, this current period where we're
doing shifts in the control center.
Sometimes, you know, missing missing dinner like I
will tonight because Stephanie's in there till four,
and I'm picking up from four until midnight
tonight.
And,
everybody's a part of this. This this is
a
a a mission that belongs to the world.
We have,
you know, the NASA, European, and Canadian Space
Agencies all working together. There are scientists
around the world that are waiting for,
for the data.
And,
I think we are also
able to bring the public along because this
is a a fantastic
accomplishment
for the world where,
we're able to work together
and do something
that turns out to be really, really, really
hard. Yeah. It is hard, isn't it? I
I was gonna talk to you about
the delays and things, but it sort of
feels
now we're in this post launch phase that
it's just all in the past. At least
that's how it is to me. So I
would say, yeah, I would say that,
when you put a telescope in space, it
has to work.
And
that's what that's what we did. We,
we have
spent years testing
this thing.
The process for building up a a complex
observatory like the, you know,
detector,
and we test it. We make sure it's
gonna work in a vacuum, work at the
operating temperature,
and we shake it, and we blast it
with sound like it's gonna get on the
launch.
And then we put that detector into the
camera,
and we shake that, and we blast it
with sound, and we test it in vacuum.
We put the camera into the instrument box.
We go through the testing process. We add
it together with the telescope,
more testing,
put it onto the spacecraft.
And that process takes a long time. But
because we've tested it at every level,
we've now we're now getting the payback
When when it's out there in space and
we're doing the deployment and they all went
perfectly,
that means that we did the right amount
of testing,
and we took the time we needed in
order to make sure that that was go
smoothly.
So that's that has to do with the
the schedule.
We we kept working on it until we
were sure it was going to work, and
now we're we're getting the benefit of all
of that testing.
Yeah. I suppose. I mean, that certainly, that
final delay put it onto Christmas day, didn't
it? It was just it was just too
special. It was too brilliant. I was well,
that I well, it was for me. I
suppose you were both working, were you? So
I was I was online. I was watching
it. I was, checking my email, you know,
but I also managed to spend spend the
holiday with my family. So I I think
I had six interviews that day.
Really?
So, I was working.
I was watching the telemetry, and
watching everything up until
midafternoon, I guess, Christmas day. And then I
finally got to Christmas with my my family.
But, yeah, it it
and it you know, as much as I
wanna say, you know,
I'm not working when I'm not working.
I'm lying because I'm so excited about it.
I'm always I'm always
checking my email. I'm always logging in just
to see where we are, what's going on,
what's happening.
Can't help yourself. It's it's I mean, it's
an obsession now. Oh, yeah. I can imagine.
And you've waited, but you're personally ten years
working on this project, and we've got a
few days as we're recording this to getting
to l two. But how long is it
after that before we start getting data? So
we won't get data until about next summer
or sorry. This summer.
We have to fully commission the telescope. So
we have to turn the instruments on,
make sure that they're working properly. We have
to focus the mirror.
We have to make sure that all the
modes of the telescope are working.
You know, it's
down enough,
that
we get sufficient signal to noise.
We have to understand the contamination. We have
our calibration.
And all of that takes up quite a
while. I'm just considering the complexity of the
observatory.
We're we're still kind of in the deployment
phase even though they're not major deployments where,
you know, getting the mirrors ready so that
we can start focusing them.
And that's sort of what we're doing right
now is is getting them ready to to
start working on them.
And that process is is iterative once we
start focusing it. You know, you take an
image and then you have to move the
mirrors
and then you have to take another image
and make sure you move them the right
way.
And, you know, there's a whole optimization
process. And so it's quite a long time,
unfortunately.
But once we, you know, give our final
blessing of the telescope,
next summer science operations begin or the summer.
Excuse me. I'm still still in 2021.
It's not, you know, March yet, so even
my checks say 2021.
So Yeah. So let me let me jump
in and tell tell you a little bit
more about this process of what,
Stephanie called focusing the telescope.
So the primary mirror is made up of
18
individual
mirror segments, hexagonal
segments. You know, you can kind of see
in the iconic pictures.
Each of those segments
is supported,
by six
actually, seven actuators
that can move it in,
seven different ways.
So
what does that mean? Seven different ways. So
the first six are
kind of the x y z of,
the the normal
positioning,
but we can also tip them in one
direction and tilt it in the orthogonal
direction,
and we can rotate
the the mirror segment. And that six of
the actuators
do those six different motions. We have a
seventh actuator
that kind of pokes it at the back
and changes the radius of curvature.
So we can actually change the shape
of each of these mirror segments. And then
the secondary mirror also has,
the six actuators.
So in all, there's a 32,
actuators
that that we use to move all of
these 18
segments.
And what we need to do is we
need to take these 18 individual mirrors and
turn them into one perfect mirror. And by
perfect, I really mean perfect
because,
we have to get the overall
bouncing of the light off of each of
these mirrors
to be, one seventh of a wavelength
of light. So 150
nanometers,
one seventh of a of a,
of a micrometer
accuracy.
And to do this, each of these,
each of these actuators can go in steps
of
10 nanometers.
And and that's kind of a a number
that or a a unit that we don't
use a whole lot, 10 nanometers.
But to put that in perspective, if we
took the primary
mirror of Webb
and it was the size of The United
States,
so the distance between, like, Los Angeles and
New York,
we blew it up to that size, we
could move the,
actuators by
10 centimeters for
you. Wow.
Okay. Overall, we have to get them to
within position,
their their perfect position of about a meter.
Yeah. So this is over over the size
of The United States. So this is, this
is the process that will take, three months,
starting pretty soon at about launch plus thirty
days. For the next three months,
we're going to be going through what what's
called mirror phasing. And it's not just focus.
It's it's getting the mirrors
to be in focus
to within this fraction of a wavelength
of the the focus of the of the
all the other mirrors.
That's gonna take three months and then two
months for the,
for turning on the instruments, and that takes
us to,
kind of the June,
early July. Well, this is clearly a massive
undertaking, and it's
led the whole project is led by NASA
with contributions
from ESA and the Canadian Space Agency. But
the how many people would be involved in
in something like that process over the coming
months? We typically I think we're typically gonna
have something like,
between one and two hundred people
working
during commissioning.
Some of them
will be at the Mission Operation Center,
and, others will be,
remote online.
Due to COVID, we did have to change
our plan. The original plan was basically have
everybody there in one big room with each
their little cubicle.
Those cubicles are looking pretty sparse as we
keep people, you know,
two meters apart. And,
so we spread out within the operation center,
and and then also a lot of people
are supporting,
remotely either from their home or from their,
their home company.
But one to 200 people are involved in
the,
will be involved kinda day to day.
But I think you also need to include
this couple of thousand people that have been
working on our
telescope for the last two decades.
For this process of lining up the mirrors,
we actually
built a one sixth scale model of the
telescope
to, to test out the algorithms just to
develop the computer programs that that we're gonna
go through this. One sixth scale was
big enough to have full sized actuators
working in the in the way that they,
they were gonna
do it. And then, you know, we shine
in just in a in a laboratory, we
shine light down onto that mirror and ran
out the cameras and and,
developed
the process
that we're gonna be going through
on this mission over the years. Oh, it's
a wonderful, wonderful thing. I I often think
when I talk to people like you that
I really did choose the wrong career, but
it's wonderful to talk to you about it.
You know, like I said, I was watching
the launch with,
with my family.
And,
my sister was kind of, you know, posting
pictures on on on social media.
And one of her friends,
came back with the comment, wow. Your brother
is a whole lot cooler than my brother.
Thank you so much to Stephanie and Jonathan,
project scientists for the James Webb Space Telescope
at NASA for talking to me. And, of
course, we'll be back next month with something
else from this wonderful world of physics. If
you are interested in this telescope,
then you should definitely check out the January
edition of the Physics World magazine, where you'll
find a host of articles and features all
about it and the science that it's doing.
And, of course, be sure to check out
the Physics World website, physicsworld.com,
where you'll find many of those features and
articles
and a video
made by James Dacey,
which features footage from that launch in French
Guiana, as well as animations
demonstrating
how the telescope has unfolded and is going
to go about its work now it's out
there in space.
And as James is the very person who'll
be posting this episode of the Physics World
Stories podcast onto the website,
I'll just take this moment to remind James
to post a link to that video on
the page where you'll find this episode.
And thank you very much to NASA's Goddard
Space Flight Center for the audio
of that launch. And most of all, thank
you very much for listening.
Physics
world.