SpaceX plans to recover their Falcon 9 rocket’s
upper stage using..
Party ballons?
This and more, now on kNews!
Hey guys Lukas here, welcome to kNews and
as always a big shout out to my kNews Boosters
on Patreon.
Thanks for your thrust.
I’m currently changing up my video format
so what you see is still work in progress.
Before I swivel to the main topic of this
video, let me quickly mention some recent
rocket launches.
For the USA we have Orbital ATK’s Antares
which launched on May 20th and SpaceX Falcon
9 on May the 22nd.
Up top Antares was a Cygnus spacecraft loaded
with cargo for the International Space Station
and and a lot of CubeSats which will be released
from the Station.
Falcon 9 on the other hand carried another
set or Iridium NEXT satellites and a secondary
payload called GRACE or Gravity Recovery and
Climate Experiment.
It was the second of its kind and shares a
ride with Iridium because the original launch
contract using a russian rocket was canceled.
GRACE main mission is to continue updating
the map for the earth’s gravity field.
The changes happening to the gravity field
surrounding us is used to figure out what
exactly is going on inside our planet.
And lastly there was surprisingly only one
rocket for China which was a Long March 4C
on May 20th as well pushing 3 satellites.
The main one is a relay satellite for the
Chinese rover that will explore the far side
of the moon named Chang’e 4.
In order to control and communicate with a
rover that has no direct line of sight to
earth, such a relay is needed.
It will be placed near the so called Lagrange
Point 2 behind the moon.
Just btw.
I recently learned that the guy who this point
is named after was actually italian so maybe
a more correct pronunciation would be Lagrangia.
Anyhow, Important to know is in this particular
region in space is where the earth’s and
the moon’s gravity add up in just the right
way, so that a satellite placed there orbits
earth at the same rate the moon does, despite
it being on a higher thus normally slower
orbit.
Now, the satellite will not hover in a stationary
point relative to the moon because it would
be blocked by it and instead orbit around
the Lagrange Point itself, so it will appear
like a Halo for those watching from the moon.
Halo orbits around Lagrange Points are some
of the strangest gravitational phenomena and
I actually wanted to make a video about but
them a long time ago but as it turns out,
they are way more complicated to explain then
it seems.
I actually think there is no really intuitive
explanation for why one can orbit that point
other than that’s just how the math works
out but I’ll keep thinking about it.
And now to the main topic of the video which
is of course Falcon’s not yet but hopefully
soon reusable upper stage.
As every space enthusiast is aware of, SpaceX
is recovering and reusing their first stage
boosters.
The first stage turns around and guides itself
like a missile after separation, using grid
fins to hit its target drone ship out in the
ocean.
Then, just before impact, up to three engines
ignite to land on the floating platform which
is stabilized and held in place by the ship’s
extremely powerful and foldable propellers.
This still one of a kind maneuver is what
makes SpaceX so different from other rocket
companies which all throw away their boosters
crashing them into the ocean.
Having figured out how to land the booster
safely SpaceX also decided to recover their
multi million dollar payload fairing.
While it looks simple this fairing pushes
against all the aerodynamic pressure during
launch to protect the payload up top.
It’s normally separated once the rocket
leaves the atmosphere to then also crash into
the ocean.
A rather simple solution SpaceX came up with
is to equip each of the fairing halves with
a parafoil and cold gas thrusters.
The thrust keeps them oriented and stable
while they re-enter back into the atmosphere
before the parafoil is released.
Operating a parafoil above such a giant piece
of hardware is extremely challenging due to
all the turbulences and SpaceX is yet not
able to land land their fairings routinely
but they’re of course working on it.
Each half is supposed to land on a second
ship out in the ocean called Mr. Steven.
It has a giant net stretched over four enormous
pillars and I assume they will have two of
those ships in the future.
That’s what Elon Musk refers to as a bouncy
castle btw..
It’s bouncy but castle mmh not so much but
let’s not start to nitpick here because
there will probably be no party balloons recovering
the upper stage either.
So the last part of the rocket that remains
crashing into the ocean is that upper stage.
Recovering and reusing it has not the highest
priority for SpaceX since they are working
on their next gen rocket, the BFR, which stands
for.
It’s the Big Fa...con Rocket.
However, they are going to try it, improving
it progressively.
Similar to the fairings the upper stage is
supposed to land on a ship probably also using
a parafoil of some sort only bigger.
The most difficult part though is to re-enter
back into the atmosphere without breaking
up which is a completely different endeavour
flying at orbital speeds.
One important thing to keep in mind is every
kilogram added to the upper stage means a
kilogram less payload since the upper stage
goes where ever the payload goes naturally.
So I assume this is only an option for either
light Falcon 9 payloads or the Falcon Heavy.
The most popular method on the internet to
get the upper stage back is a so called ballute.
Not that balut guys from the philippines.
This one is a fusion between a balloon and
a parachute.
Ha!
It inflates itself like a parachute without
the need of any gas while providing a huge
surface area to act as a giant drag brake
essentially.
The idea is to decrease the speed as fast
as possible during reentry and keep the nose
of the stage pointing downward.
Without it the heaviest part would face the
hot plasma which would be the engine section.
It could then double to either land the upper
stage safely on a ship, or maybe even allow
to catch it with a giant drone like the United
Launch Alliance plans to do with their Vulcan
rocket’s engine section.
However, latter sounds a little too complex
for SpaceX as this recovery is not a priority
right now.
But who knows.
I’m not quite sure how all of that would
work out especially since the ballute had
to be heat resistant.
But that’s just one way they could do it
and I want to explore a more crazy method.
While the ballute idea sounds really good
and was even tried before, I’m still a bit
sceptical about this approach.
The reason is it can only be used during reentry
and they couldn’t deorbit and lose speed
before that happens.
Such a ballute also had to be mounted next
to the engine which could have unknown consequences
to a launch and I doubt they will do a test
launch with it or recertify their upper stage.
Mounting inflatable stuff as a secondary payload
inside the fairing on the other hand should
be no big deal.
So I think they will at least start putting
stuff there to gain experience before they
make changes in more dangerous areas.
So what could they do in order to reenter
without destroying the expensive engine?
The solution is to get rid of as much speed
as possible while still in space.
It’s of course highly speculative at this
point but the upper stage tanks are pressurized
with Helium gas as they drain.
Once the mission is over this gas is vented
into space to make sure the upper stage tanks
do not rupture from heating up in the sunlight.
As you can imagine this gas could also be
used to inflate a giant balloon.
To make things a little less complicated and
stable SpaceX could omit the rope and mount
the balloon or multiple balloons directly
to the payload adapter.
However, doing it like this they had to mount
a pipe at the side of the vehicle since all
the necessary connections are at the bottom
where the engine is.
I’m not sure if SpaceX is willing to do
changes to its fuel piping system to reuse
the upper stage but for this video I assume
they do.
If not it’s probably going to be a self
inflating ballute as mentioned in the beginning
that does not require internal gas.
A benefit of such side mounted balloons would
be they could act like giant inflatable fins
basically.
Varying the pressure and size they could even
steer the upper stage and point the bottom
section in the right direction to bounce off
the atmosphere a little like the Space Shuttle
used to do in order to lose as much velocity
as possible before they hit the thicker more
dense layers where the real heating begins.
Whatever they come up with and which orientation
the upper stage will reenter, they will not
be able to get rid of all the velocity so
some kind of heat shield will be needed.
SpaceX plan is to add more and more insulation
to its upper stage similar to what they’ve
done to their Block 5 booster.
They covered all the parts that are exposed
to the reentry heat with their black insulating
material.
They will either shield more of the engine
or come up with a payload adapter shielding
solution, where they can still mount the payload
safely.
Though, I personally only see it as a backup
plan should the development of BFR not go
as smoothly and take much longer than expected.
Having a completely reusable rocket would
make a big difference and would drop the costs
to launch Falcon down to single digit million
values competing with even the smallest of
launchers.
Even if it was Falcon Heavy.
Do you have some thoughts on it as well?
Feel free to leave a comment below the video
I read all of them.
Okay, that shall conclude this episode, I
hope to see you in the next one if you like
and become a Patreon.
Auf Wiedersehen and Thank you for watching!
It’s the Big Falcon Rocket!
