Soyuz undocking, reentry and landing explained
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Every day, since November 1998,
the International Space Station has been orbiting the Earth at a speed
of 28000 kilometres per hour Having spent several months on-board
the International Space Station, the time has come for
three of its crew members to travel back to Earth The return journey aboard a Soyuz capsule
takes three and a half hours Before it can start,
there is a lot of preparation to do Both in space and on the ground The normal landing site
for the Soyuz is Kazakhstan A group of ground based experts prepare meticulously for this operation They take into account
the current orbit of the station and then select the most appropriate
landing site on the ground The landing site is checked by
the search and rescue team, to make sure that
the terrain is flat and free from any obstructions that
could complicate the landing The search and rescue team is able to
operate even in extreme weather conditions When all the information
has been analysed, the optimal return trajectory is calculated One week before the Soyuz
undocks from the station, the instructors and controllers located
in the Mission Control Centre near Moscow conduct a remote training session with
the crew and the on-board simulator During this session, the crew are reminded about the
most important actions they will have to perform
during the re-entry They carefully run through
the procedures for each critical step,
including the scenarios that could lead to
an emergency descent They are also briefed
on the latest details of their trip back,
such as landing conditions, and the precise timelines for
the activation of vehicle systems The on-board crew runs a test
of the Soyuz vehicle and begins packing items that will travel
with them back to the ground The Soyuz is then activated and
the crew starts preparing it for undocking When instructed by the
ground controllers, the crew say their goodbyes
to their colleagues staying behind, and close the hatch that separates the
Soyuz orbital module from the Station The hatch is carefully checked, to make sure there are
no leaks that could cause an unexpected cabin depressurization The crew members put on their spacesuits
and enter the descent module that they will occupy for the ultimate
rollercoaster ride back to Earth Former astronaut Frank
De Winne is now head of the European Astronaut Centre in Cologne He remembers clearly the
emotions he felt as he was about to leave the
International Space Station Wow! Today I’m really going home
because of course the days before, you are preparing for the descent,
you are reviewing all the procedures you are going through all the radiograms But it is only at the moment
that you are in your spacesuit and that the hatches are closing
that you know that four hours later you will be back on Earth Both crew and vehicle are now
ready for the undocking sequence The Russian segments of the station
have several docking ports for hosting Soyuz vehicles In this example,
the vehicle is going to undock from the so called Service Module In this case, the undocked Soyuz
reaches an orbit below the station The orbital velocity of
the Soyuz also increases Sometimes, however, the Soyuz is docked
to a port underneath the Station In these situations,
approximately 40 minutes before the undocking, the Station
changes its orientation The Soyuz then undocks and joins
a higher orbit and its velocity decreases In both cases, after one revolution
of the earth, the orbits intersect but because of their now
different velocities the Station and the Soyuz arrive at the
intersection point at different times This prevents any possibility of
a collision between the two vehicles When the Flight Director
is ready a “GO” is given to the crew
to initiate the undocking The crew commander
issues the command to open the Soyuz hooks These are the only mechanical devices
holding the vehicles together After approximately 3-4 minutes,
the hooks are fully opened and the Soyuz is no longer
firmly attached to the Station A set of pushers that were kept
mechanically compressed while docked, gently
ease the Soyuz away from the station at a relative
speed of 12 to 15 cm/s Being so close to the Station,
the Soyuz propulsion system is inhibited in order to avoid
contamination of the Station with residual chemical dust produced
by the Soyuz thrusters The crew gets visual confirmation of
the separation through the image provided by the external TV camera,
and also from indications displayed on their monitors ESA astronaut Paolo Nespoli, returned to earth aboard a Soyuz
spacecraft at the end of Expedition 27 I didn’t actually feel the detach,
when we detached from the Station,
physically I did not feel it The physical departure from the Station is done because of the push
of some springs that are inside You don’t want to start your
engines close to the Station, because you are going to plume everything So you are just kind of
drifting away and what you are doing, what we were doing
was just looking at the instruments, looking at the camera outside and
checking that the Soyuz would be inside the departure corridor,
this is what we were doing I did not really feel anything
The only thing is that we felt we started this long
journey back to Earth Three minutes later,
when the spacecraft has moved about 20 metres,
the crew monitors the 15 second burn that increases
the separation speed up to 2 km/h This leads the Soyuz to a safe position
relative to the Space Station After the undocking,
the ground controllers upload the data needed by
the on-board computer to autonomously perform the descent The crew is in constant
communication with the ground They verify the validity of the data,
before allowing the computer to use it. At this stage, the crew must pay special attention to
prepare for the next critical operation: the Deorbit Burn As can be seen,
although the Soyuz is now far away from the Station,
it is still orbiting the Earth at an altitude
close to that of the ISS The purpose of the Deorbit Burn is to
force the Soyuz to decrease its speed As a result, the trajectory of the vehicle
changes and it re-enters the atmosphere The atmosphere acts as a natural
brake and does most of the work in slowing the Soyuz down
until a set of parachutes opens and ensures a relatively soft landing This braking is achieved by using the main engine located
in the rear side of the spacecraft to push against the
direction of travel The required orientation
and duration of the braking impulse must be
precisely calculated and achieved because
it directly influences the steepness of
the re-entry path If we don’t burn enough, then we have still too much speed
and we will still be too high in the atmosphere and we can
actually skip off the atmosphere and then go further into space and that
of couse would not be a successful re-entry On the other hand, if we burn too
much and we come in too steep then we will have too much speed when
we are in the lower parts of the atmosphere the heat that is normally
around 2000 degree Celsius will be much higher and we
have the risk of burning up So also therefore is very critical that
we do the correct deorbit burn and that we really
fix this around 120 m/s To achieve the correct burn,
the main engine fires for exactly four minutes
and forty five seconds The Soyuz now follows a
trajectory that will lead it to intercept the dense
layers of the atmosphere, leading to a safe re-entry and landing,
about 55 minutes later As the vehicle travels along its
trajectory, about 30 minutes before landing and at an altitude
of roughly 140 km, it separates into three parts: the orbital
module, the descent module and the instrument compartment There is no chance of the individual
modules colliding with each other, this is called
impact-less separation Only the descent module hosting the crew
will make it back safely to Earth The other two will disintegrate and
burn up in the atmosphere The separation of the spacecraft into
three parts is happening through several seconds, because
there are several parts that get detached
one after the other All this action is done with explosive
bolts or with explosive implements Seen from the inside of the
spacecraft, it felt like there was somebody outside the
spacecraft with a sledgehammer that was hammering here and there,
up and down so every few milliseconds the spacecraft
was shaking with this BANG! BANG! BANG! BANG! It felt really interesting actually! The descent module experiences
extreme high temperatures during re-entry, so to protect it,
and the crew inside, it is fitted with a
special protective coating and has a heat
shield on its base As the atmosphere becomes
more dense, the descent module positions itself so that its heat
shield points forward The capsule is about to enter
the Earthís atmosphere This will be the most stressful
part of its journey home By the time we were
supposed to re-enter the atmosphere, I actually
looked out from our window and I actually looked we were
tumbling and I was a little bit puzzled because I thought we needed
to re-enter with a special angle, so I started looking at procedures, we did
a few things and when I looked out again I saw that we were already inside
this plasma, it was getting really red and actually the
window was getting pretty dark what was happening was that the plasma stream was actually
burning the outside layer of the window which has a protective cover So it was kind of interesting, at that
point I did not feel that much I mean the gravity starts
grabbing you but it is very gentle at the beginning
and you actually use it to feel or go into the
seats and buckle up, pull your straps so that you
really lay into the seat It was an interesting feeling The descent module follows a path
that is similar in shape to that made by a surfer
riding a big wave Like a surfer, the Soyuz is able to make
small adjustments to keep itself on track So, how is the trajectory of a
free falling capsule controlled? Even though it does not
have wings, the Soyuz capsule is able to change the
way it flies through the air The design of the Soyuz
enables it to do this The capsuleís lift increases
when it rotates in one direction and decreases if it rotates
in the opposite direction In this way, the capsule is able to
keep to its planned trajectory As a side effect,
this rotation also induces a sideways displacement
of the module This effect is very
useful because it gives more flexibility for the selection
of the landing site This sideways manoeuver
has already been taken into account when selecting
the optimum trajectory During the descent in the atmosphere,
the crew feels the effect of the deceleration when
their weight exceeds several times their own
weight on the ground The maximum G-load (4G) is experienced
when the capsule reaches an altitude of roughly 35 km while it has already been travelling
for 6 to 7 minutes in the atmosphere Gravity is a very,
very strong force We do not understand
here on Earth how gravity has such a hold on our body
and what is around us You do feel it when you
come back from space because now you have been in
a non-gravity environment for a long time and then you see
all these forces grabbing you You look at stuff and you feel
your hands are heavy, you feel your watch weights a ton,
your books, the materials around you, your head
is extremely heavy It is really a very strong feeling In the unlikely event that the
automatic control system fails, the crew is able to use a manual
hand controller as a backup They train extensively to
prepare for this possibility Another option is the ballistic descent The spacecraft starts spinning and
flies a much steeper trajectory without any additional
sideways displacement The G-load in this case
will increase up to 9 When the capsule reaches an
altitude of 10.5 km, its speed has already decreased
from 28000 to 800 km/h In order to further decrease the speed,
the parachute cover is jettisoned and a series
of parachutes are deployed At the end of the atmospheric re-entry,
you really start hearing the noise of the wind and the sound,
you are almost breaking the sound barrier Then, in the opposite direction of course
you are coming back into the normal area of flying This is around 30000 feet that
the parachute has to open This is actually a very critical
moment and is one of the only things in the Soyuz where the
crew does not have a manual override So this is only an automated system So far, it has always worked and we
also have a backup parachute that can help us in case that
the main will not open But it is also a very
violent moment, you can imagine this
2000 kilogram capsule that is soaring at the speed of
sound through the atmosphere and then all of the sudden
you have a parachute that opens on the side and that
pulls on you, like a little swing, It is almost like a yo-yo and you
see the capsule going all around It is much worse than in
a roller coaster because the motion is in all directions
and it is a little bit scary for some of us,
for some others it can also be fun because they are like “Wow this
is the best ride I’ve ever had!” Then, a few minutes later, at a
height of 8.5 km, the drogue chute finally deploys the 1000 square
metre canopy of the main parachute This slows the capsule down
to a speed of 22 km/h The capsule is suspended
under the parachute with a specific angle
relative to the ground This angle helps the capsule to
dissipate the heat accumulated on its surface and structure
during the re-entry But then everything calms down,
of course once that the main parachute has deployed you really come to the
calm air after this whole violent re-entry, the violent
opening of the parachute, then you are hanging safely,
slowly descending to the Earth underneath your parachute and this is actually the
first time that you know: Yes, I am safe, we are going to make it! At an altitude of roughly 5.5 km, the frontal heat shield and external
window glass are jettisoned The capsule vents excess fuel
and oxygen from pressurised tanks, to reduce any chance of an
explosion when it hits the ground In order to position the spacecraft
adequately for the landing, the main canopy switches
to symmetric suspension This setup ensures that the
cosmonauts’ seats are now perfectly positioned to absorb
the landing impact shock The retrorockets that were
hidden behind the heat shield are prepared for firing Inside the capsule, the crew
seats automatically raise in order to prepare
shock absorbers Usually, the Search and Rescue
Team equipped with aircraft and helicopters starts
tracking the Soyuz capsule even before the very first
parachute is deployed The helicopters land next to the capsule
shortly after touch down and the team help the crew to exit Finally, 70 cm above the ground,
the six retro rockets fire to further reduce the capsule
speed to approximately 5 km/h The capsule hits the ground
but the crew seats continue moving down and shock absorbers help
to make the landing softer for the crew The soft landing is not really soft, You prepare for it by putting your arms
against your body, not touching any of the metallic parts, hold your books
against you, you are not talking not to put the tongue in the middle of your
teeth and you are lying there trying to be as inside your
seat as well as you can and you are waiting for
this “soft landing” to happen, which for me felt like a head-on collision
between a truck and a small car and of course I was in the small car,
so when this happened it was like BA-DA-BOOM! everything shook, I was
kind of shaking in there, everything was, and then…
silence everything was stopped So I looked a little bit around, I looked
at my crew members and then I said: Hey guys,
Welcome back to Earth! Once landed,
one of the first actions of the crew commander
is to release one of the two ropes that connect
the capsule to the parachute This is important, as in
windy conditions, it prevents the capsule from being dragged away on
the ground by the inflated parachute You know that you are on the ground,
you hear the voices of the rescue troops that are next to you and you know that 5
minutes later they will open up the hatch and you can breathe fresh air The crew is now safely back on Earth They will soon be reunited with
their families and begin the rehabilitation process,
after their extraordinary journey

100 thoughts on “Soyuz undocking, reentry and landing explained

  1. "The soft landing is not really soft" 😀. "Felt like a head on collision between a truck and a small car" Bravo Cosmonauts 👏👏👏. Welcome back to Earth.

  2. Now i understand why people say "This is not Rocket Science" Enjoyed every frame of it. Thanks for Posting

  3. Wow, look at their pale faces after landing. I've never thought that the force of gravity can be that extreme

  4. Why it needs to be 2 ton. Why there is no Manually opening opetion for capsul. How to escape in case or emergency. Does this desing makes any sense.
    We have recently seen some people just directly jumping from the space to eath and they Safely landed with Parachute. They are without any capsul.
    https://youtu.be/vvbN-cWe0A0

  5. Fascinating! Cool that these folk are so deadpan about things – they use words like interesting and puzzling instead of 'scared out of your wits'.

  6. A lots of beautiful happens are occured in 2019 about the space. What a unique year .So fast only in 10 minutes .👌👍✌

  7. I am very curious to know how ISS is protected by the other satellites and destroyed satellites that are there in the orbit and have a high speed due to destroy force.

  8. 😥❤️😢

    THSOUNDS OF KILO METERS AWAY Our feelings To EARTH LIKE HOME, AND THE PEOPLES LIKE BROTHERS AND SISTERS,
    BUT WHEN REACH TO EARTH

    LET START THE HATE, JEALOUSY, FIGHTING AND WAR ,
    KEEP SAFE THE WORLD SAFE , SECURE LIKE HOME.

  9. AND WHEN YOU REACH TO EARTH AND HEARD, OH HE CROSS OUR BORDERS , SHOW PASSPORT, SHOT A BULLET,

    YOU ARE NOT ALLOWED,
    WICH NATIONALITY YOU ARE?
    AHH

  10. What happens if a parachute of metal or other fabric is used to slow down the speed just when the Soyuz enters the atmosphere

  11. Very beautiful how all nations work together to make this happen. Y can’t we use same concept to leave together happily on earth.

  12. I could never be an astronaut for ONE reason and only ONE REASON. I am waaaay to claustrophobic. I would panic and completely screw everything up!

  13. no es tan fácil como pensaba, pero vamos bien, de seguro en un futuro sera mejor el aterrizaje de una nave espacial

  14. Infact all of the background music is so good I trying to find the artists or music but there is no information . ESA please help.

  15. 9:08 That is one of the 72 Island in the Philippines, I live in that island, It's name is Panay Island. Now I know that the precise trajectory of reentry was over our head.

  16. This program made my day. Thanks for your wonderful explanation 🙏🙏, We always loves you from India 🇮🇳🇮🇳

  17. I was wondering how did they feel as soon as the module's locks were opened……
    It's now did I understood that gravity is really a mighty force. And here on Earth we realize this fact very rarely

  18. This is perhaps one of the extraordinary achievement of Russians to bring humans back to Earth from ISS.

    Loved it…..love from India🇮🇳

  19. "You can actually skip off the atmosphere and launch further into space."
    That's the stuff nightmares are made of. That's a hard nope from me, chief.

  20. It must be so scary being trapped in a capsule so small going so fast. Burning up in that would be scarier than in a space shuttle imo

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