The James Webb Space Telescope is fueled stacked atop the Ariane five launch vehicle
and encapsulated in its fairing for a Christmas Eve launch. Now the fact is
is that a December 24th launch is a delay from the previously announced December 22nd
launch, which was itself a delay from December 18th, which was a delay from, well, you
know, the rest. But since arriving in Kourou, French Guiana,
Webb's launch campaign has, believe it or not, gone fairly smoothly. Only what's considered
fairly smooth for a typical mission is a cause for delay with Webb. In November, there was
an incident when a clamp band sprang loose as Webb was being fitted to its payload adapter.
The launch prep was halted while they figured out just how they would resolve the situation.
That pushed launch back from December 18 to December 22nd. Then, just last week,
after they stacked Webb atop the Ariane five, there was another problem getting Webb's ground
support system to communicate with the spacecraft. That held up the final aliveness test, which
in turn held up encapsulating Webb in its launch fairing, which pushed its launch back another
two days to December 24th. Now you might think that Webb is somehow cursed or the whole thing
is doomed to failure. But the truth is is that problems like these happen all the time, only
we just never hear about them. And that's because these kinds of problems aren't necessarily
showstoppers. For example, NASA's DART asteroid deflection and its IXPE astronomy missions
each had similar communication problems with Space X's ground systems. In both cases, managers
determined that in spite of those problems, it was still safe to launch, so there were no schedule
slips. But Webb is on a whole other level. with 144 release mechanisms and more than 300 single
points of failure. Webb is the highest risk mission of its kind ever attempted. There's no
way NASA's going to launch it without addressing every last risk while it's still here on Earth.
Fortunately, this newest problem was just resolved, and now Webb is fuel stacked on
top of the rocket and is sealed in its fairing awaiting launch. From this point
forward, it's all about getting the rocket out to the launch pad and sending Webb on its way.
And since this is perhaps the last video I'll make about Webb while it's still here on Earth,
I thought it'd be cool to take a look at one of the amazing launch
campaign that NASA, ESA and Arianespace had been working on just to get us to this point,
and we're going to look ahead to Webb's
departure from this planet. But first, I'd like to thank Magellan TV for sponsoring today's video.
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Simply click on the link in the description of this video. After Webb arrived at ESA's Space
Center in October., it was unboxed and raised vertical. After passing some initial checks,
Webb was lowered into its payload adapter. The next step was to tighten a spring-loaded
clamp band that would hold Webb in place during launch and then release
the telescope once in space. But as this band was being tightened, it unexpectedly sprang off.
By this point, Webb was otherwise safe and sitting in his payload adapter. So
after some initial assessment, Webb was transported into the fueling station, while the
Anomaly Review Board decided what to do about the clamp band. Before NASA allowed fueling to begin,
.they wanted to verify that all of Webb's subsystems
hadn't been rattled in the incident and ordered some additional testing.
It turns out that despite snapping off, though, the clamp band itself appeared
to be in good shape. It passed additional fit checks and release testing without any problems.
However, there just happened to be another spare clamp band still in its box,
sitting there on the floor of the fuel depot. You know where extra clamp bands are
apparently kept? It turns out the spare band passed its fit checks and release testing as well.
Well, since the spare band was also flight qualified, NASA decided to use the spare
rather than refurbish the original band. The spare clamp band was installed without anomaly,
and the observatory subsystems were rechecked to make sure nothing was shaken.
After passing all of its tests, the ARB gave the go ahead to proceed with propellant loading.
This is the propellant Webb will use throughout its mission. Some of it is used early on to make
critical course corrections after it separates from the Ariane five.
Then later, more of it gets used to maintain its orbit around the L2 and
occasionally re-point the observatory during the course of its mission.
This fuel will ultimately determine how long Webb's mission will last.
So getting every last drop loaded was a critical step, but also an extremely dangerous one.
And that's partly because fuel has a tendency of damaging hardware if it ignites
in an uncontrolled fashion. But it's also because this particular propellant is a deadly
combination of hydrazine fuel and die nitrogen tetroxide oxidizer. Both are extremely toxic -
a whiff of this stuff will kill you. So, specially trained technicians
must wear Self-Contained Atmospheric Protective Ensembles, or SCAPE suits. These three individuals
were the only ones permitted in the fueling bay. Over the next ten days. Webb's propellant
tanks would be loaded with 133 kilograms of oxidizer and 168 kilograms of hydrazine fuel.
Meanwhile, the Ariane launch vehicle was being prepped in the Launcher Integration Building
or BIL. In Kourou. French acronyms are used, so the letters get reversed from English. On
November 29th, the Ariane five was transported to the Final Assembly Building, or BAF.
Meanwhile, Webb's fueling operations went flawlessly,. With its tanks pressurized with
liquid death, Webb was loaded into its transport container to meet its rocket.
Even its transporter container is a mobile clean room on wheels. In fact, we should take a moment
to talk about how hard people work just to keep the environment around Webb insanely clean.
Of course, keeping spacecraft clean is always a priority, which is why they're
assembled in climate controlled clean rooms and everyone wears those cute bunny suits.
But when it comes to cleanliness, Webb is once again on a whole other level.
Remember, the observatory has to be extremely sensitive to detect very faint infrared radiation.
But that also makes it extremely sensitive to even the slightest contamination levels.
For example, plastics can release hydrocarbons into the air, adhesives can release phthalates,
and water in particular absorbs infrared radiation at 3.1 microns.
That's a critical science observing wavelength, so even tiny water droplets are a contaminant.
Now, to be clear, a couple of contaminants here and there will not blind Webb or anything,
but they will degrade its sensitivity. If that were to happen, then you'd have to take longer
exposures to compensate. Longer exposures mean fewer observations over its mission lifetime,
and fewer observations means a reduced science output.
And that's why Webb has to be kept so ridiculously clean while still on the
ground at all times. But even Webb's own design makes it prone to contamination.
Traditional observatories like Hubble and Kepler enclose their telescopes inside
tubes that are sealed while they're on the ground. And that goes a long way towards protecting its
optical systems. But Webb needs to be much larger than Hubble, while weighing only half as much.
As a result, the telescope is largely exposed,
and that's why NASA's sent a crack team of contamination control engineers to help ESA,
an Arianespace prepare every facility and crew ahead of Webb's arrival. Not only was every
surface in every room custom cleaned, but all of the facilities had to be modified as well.
For example, NASA's supplied two portable HEPA filter walls to control contamination
levels near the spacecraft. Contamination engineers cleaned, covered, bagged, sealed,
and even removed anything that couldn't meet Webb's cleanliness requirements.
They turned every facility Webb visited - including the fueling station and the
final assembly building - into state of the art clean rooms.
They even cleaned the living hell out of every surface near Webb each night after everyone
else went home. If cleanliness is next to godliness, then these people are saints.
On December 7th, Webb arrived at the Assembly Building and was removed from
its transport container. Then, in an anxiety -ueling maneuver,
Webb was lifted three stories up to a platform above the Ariane five second stage.
After some more checks, the telescope was carefully - and I mean
carefully - lowered through a hole in the platform to be stacked atop the Ariane five.
At long last, Webb was sitting on top of its rocket. But this is Webb, so there is no such
thing as just sitting on top of a rocket. The next steps were to do a round of aliveness checks
before encapsulating Webb and its fairing. But before the aliveness test could be run,
Webb had to be connected to its ground support equipment system,
or GSE. The GSE is located on the launch pad near the base of the rocket
and talks to the payload at the top of the rocket through a 100 meter cable.
But when engineers attached this cable to the spacecraft, they found intermittent data drop
outs between the spacecraft and the GSE. In other words, the communications were spotty.
They soon realized that the problem wasn't really with Webb,
but rather somewhere between the cable and the ground system.
They worked around the clock to get everything working, but they used
up their one day of contingency without any success. As a result,
NASA announced that the launch would slip from December 22nd to no earlier than the 24th.
Now you might be thinking that all of this is just ridiculous. I mean, was Webb's launch really going
to be held up by a faulty data cable? Yes. Yes, it was. And that's because the data cable is really
not a single cable, but it seems to be more like a bunch of individual cables, each with their own
special connector. It turns out that it's really not that uncommon for one or more of
these connectors to not correctly function. Now, sometimes that's OK. As long as the GSE is getting
enough telemetry data, managers may determine that it's safe enough to proceed with launch.
And that's apparently what happened with the DART and IXPE missions,
even though there were similar problems with Spac X's ground support
equipment. But this is Webb we're talking about; it carries enough risk all by itself,
and NASA's not going to let it go anywhere without eliminating as much of that risk as possible.
So the launch was slipped and engineers took a couple of extra days to troubleshoot each of
those interface connections. Once that was done, Webb would spend the next half a day
going through a rigorous set of aliveness checks with the GSE.
After its test results were analyzed, NASA gave the OK to encapsulate Webb in its fairing. Now,
the Ariane five launch fairing is the only one large enough to accommodate Webb,
and this is a big reason why it was designed to launch aboard the Ariane five in the first place.
But even then, the fairing just barely fits around Webb, and that's why they used a special laser
alignment system to precisely control the fairings position as it was lowered around the spacecraft.
It's hard to overstate what an important milestone this launch campaign has achieved.
Webb is no longer at risk of anybody or anything crashing into it.
The launch vehicle is secured to its launch pad, so it's not going to tip
over or anything, and no living being will ever view Webb again with their own eyes.
Webb is now as safe as it's ever been or ever will be. Until it launches.
At T-0, the Ariane five lifts off from the launch pad at the Kourou spaceport.
Because of its proximity to the equator, Earth's surface is rotating at nearly
1700 kilometers an hour, and that gives the Ariane five an extra free boost it
can't get from anywhere else. The Ariane five's twin socket (solid) rocket boosters
will generate something like 80% of the thrust during the first three minutes.
After their expended, the boosters separate and the core stage powers onward,
sending Webb into the upper atmosphere where protection is no longer needed.
The payload fairing jettisons and falls away. The core stage continues,
accelerating Webb until it expends its fuel, shuts down, and separates from the upper stage.
At this point, Webb is starting to fall back to Earth until its second stage engine ignites,
resuming its upward climb. With the telescope exposed to direct sunlight,
it must be protected against overheating even as it's accelerating. So the second
stage executes a specially designed series of oscillating rolls to prevent
any part of the telescope's structure from getting too hot. With its fuel expended,
the second stage shuts down the clamp and releases and Webb springs forward.
Now, the second stage has a camera on board that will let us watch this release sequence.
But after separation, the second stage executes a special avoidance maneuver
to prevent contamination, and that will be the last time we'll ever see Webb.
As it cruises out to L2, Webb will spend the next few months unfolding itself,
cooling down to its operational temperature, and transforming itself into an observatory.
I'll save those details for later video. But for now, the next order of business is launch.
Webb has daily half hour launch windows beginning on December 24th at
7:20 a.m. Eastern Time. If they can't launch after two days,
then they'll need to stand down for a third day to replenish the rocket's supply of liquid oxygen.
If for some reason it can't launched by January 6, then they'll have to wait another week until
the 13th because the Moon will be coming too close to Webb's flight path. If Webb gets too close to
the Moon, then it has to expend extra fuel to counter the Moon's gravity and stay on course.
Still, that leaves Ariane about eight launch opportunities between the 24th and the 6th,
with the first launch window opening on Christmas Eve at 7:20 a.m. Eastern Time. So far, though,
there is no word on whether or not that might interfere with Santa's flight plan.
But there are thousands of people who've been very, very good and worked super hard to launch
the James Webb Telescope, so hopefully the Big Guy can alter course. And speaking of great people,
how about these folks who are helping to keep Launch Pad Astronomy going?
And I'd like to welcome Rosstlav Hulka and Not Who You Think as my newest patrons. And
if you'd like to join me on this journey through this incredible Universe of ours,
well, please make sure you subscribe and ring that
notification bell so that you don't miss out on any new videos. Until next time,
stay curious, my friend. And Go Webb!