Welcome back to Launch Pad, I'm Christian Ready, your friendly neighborhood
astronomer. Well, I wanted to talk with you a little bit about the situation
going on with the Hubble Space Telescope. As an astronomer, the Hubble Space
Telescope is of course very near and dear to my heart, but personally I'm very
connected to it because I worked on the Hubble program for about five years back
in the 1990's when the Hubble telescope had that awful haircut. So let me try to
explain what's going on with Hubble and what it means for the spacecraft going
forward. The telescope entered safe mode last Friday due to the failure of a
gyroscope. Now in order for Hubble to point very precisely at objects in the
sky, it has to be able to know exactly where it's pointing down to a very high
level of precision. In order to do that, gyroscopes are used which are spinning
at 19200 rpm, so these things are really moving. A spinning gyroscope is very
resistant to forces acting on it, so let me just give you a quick demonstration
of a gyroscope and then we'll talk about the failure that happened here on the
spacecraft. All right, so I have a gyroscope here and as you can see it's
held by some string. If I let go of it, it just dangles just like it expected to do.
The thing that makes these gyroscopes so sensitive to motion is what happens when
they start spinning ,so I've got a spinner right here, and we're gonna go ahead
and get this going. [machine whirrs] Let's see what happens when this thing's spinning.
[machine stops] So you notice that the gyroscope's now, you know, almost standing up on its own.
And if I try to move it, I really gotta give it...I gotta give it
some force so that means that when these things are spinning, they're really
resistant and are sensitive to attempts to move it, so when the telescope is
moving the gyroscope feels that motion and it reports back to the computer how
fast the spacecraft is turning. So a spinning gyroscope is very resistant to
motion and when the telescope pushes on the gyroscope as it points to a new
location the gyroscope basically pushes back and that tells the computer onboard
the telescope how fast it's moving and in what direction. Now for Hubble to work
most efficiently, there needs to be three gyroscopes spinning at 19,200 rpm.
These three gyroscopes are essential for keeping Hubble pointed in exactly
the right direction for long durations so it can take these very long deep
exposures. On Friday one of the three gyros failed. Now normally that wouldn't
be a problem because Hubble is outfitted with six gyroscopes. But since it
was launched in 1990, Hubble has been upgraded on five different occasions.
These servicing missions would be used to upgrade the telescope, giving it new
capabilities, new instruments and on almost every single mission, at least one
pair of gyroscopes had to be replaced. In fact, on the last servicing mission all
three pairs, or all six gyroscopes, were replaced. Over time, two of the gyroscopes
failed and one gyroscope started acting up so they turned it off. Now of the
three gyros that remain functional ,one of them started to show signs of wear
and tear and it was expected to fail. As a matter of fact, it ended up lasting
about six months longer than the team originally expected it to, so the fact
that it failed on Friday is really not a surprise. But it's not good news, either.
So the plan is in place to take Hubble down to just one gyro and keep the
remaining operational gyro as a spare. At least that's the worst-case
scenario. But there may be some alternatives, and that's what the mission
management team wants to do - they want to figure out what are the possible options.
So far they've attempted to reactivate the previously fuzzy but not yet dead
gyro. It didn't respond too well. It came back on but it wasn't delivering the
performance necessary for proper science operations. So now the team has to figure
out what is possible; can that funky gyro be reactivated and re-commanded to
perform better from the ground, or will the spacecraft have to go to a single
gyro mode? Or is there be some other option that's available? Unfortunately,
the one option that everybody would like to have is another servicing mission, but
that's just not going to happen. There are no more space shuttles with which to
service the Hubble telescope. Neither are there any manned or unmanned vehicles in
operation today that are up to doing the job. There are some people looking at
maybe using SpaceX's crewed Dragon or Boeing's Starliner or maybe SpaceX's BFS
to fix Hubble, but it's not going to get Hubble back to full operational
capability anytime soon. That's partly because the spacecraft were never designed to
service the Hubble telescope, and also because they haven't ever actually flown into
space. So what does it mean for Hubble to operate on just one gyro? Well first it
means that the Hubble mission will continue for a number of years. Even if
this single gyro fails there will be another operational backup left so this
will at least preserve Hubble doing science for some time to come. But how
that science is going to be executed, how much science, and the type of science
that's going to be done right now is in doubt. Operating on one gyro means that
Hubble may not be sensitive to all three motions at once and therefore there may
be certain parts of the sky that the telescope could not observe at any given
time. Or it could mean that the telescope cannot be certain of its pointing for
long-duration exposures, so the spacecraft might be limited to taking
shorter exposures, or limit itself to observing brighter targets.
Undoubtedly, there will be some workarounds and some new ways of using
the telescope. But the telescope will still continue to be used, and that's
really important. NASA is planning to launch the James
Webb Space Telescope which has been delayed yet again until 2021. At the
earliest. You know, I really wish Lockheed Martin would figure out how to do
what they said they knew how to do and actually get the telescope's thermal
protection system working...[sighs]. Anyway, point being is that yes, there will be a
successor to Hubble. But even when James Webb is operational,
it won't be able to do what Hubble can do. Hubble is sensitive to ultraviolet
and visible light, and near-infrared. James Webb on the other hand is a mid
infrared telescope. It will not be able to see the way Hubble sees; no
telescope in space will be able to do what Hubble is able to do, so it's vital
that we keep this important astronomical research going for as long as possible.
And maybe, just maybe, we can muster up the political will to build a copy and
put it up as well. It would have been great if Hubble and James Webb
could be operational both at the same time, but right now Hubble's days are
numbered. It's on borrowed time and there are no more servicing missions scheduled.
So that's the long-term view, but let's just get back to the short-term problem
at hand, and that is figuring out under what mode Hubble will return to service.
That's currently being looked at by the experts so we have to let them work
through the problem and come up with the plan. And as they do, and more information
is released I'll be sure to update you on this because I want to see my old
telescope back in service and I know you do too. So if you'd like to learn a
little bit more about how telescopes work I've got some videos on them and
I'll put a link to some of those videos right here and I'll even have a link in
the description below. I'd like to know what you think though. What do you think
about Hubble's options going forward and what would be a really cool way to save
this telescope? Let me know in the comments below and I'll be sure to check
them out. And if you'd like to join me on this journey through this amazing
universe of ours, well please make sure to subscribe and ring that notification
bell so that you don't miss out on any new videos. Until next time, I'm Christian
Ready. Keep watching the skies.
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