00:00Imagine yourself floating in the infinite immensity of space.
00:04There is no edge, no corner, no top, no bottom, no left, no right.
00:08It's as if you were lost in a galactic desert.
00:11Except that, to guide you, you cannot rely on any natural reference point,
00:16not even on your usual sense of direction.
00:19And without gravity, you could even find yourself making turns in all directions,
00:24as if you were caught in a celestial skydive.
00:27So, what to do?
00:29How to know where to go? How to avoid getting lost?
00:32The question is not simple.
00:34First of all, let's go back to our good old planet Earth,
00:37where orientation is something that we often take for granted.
00:41Imagine that you are hiking in a dense forest.
00:44You are surrounded by gigantic trees, mossy rocks, and birds chirping.
00:49But there is neither a well-defined path, nor a signpost to guide you.
00:53What should you do?
00:55The first thing that comes to mind is a compass, isn't it?
00:58A little magic device that always knows how to find the North,
01:01wherever you are on the planet.
01:04And this, thanks to a very small magnet.
01:07It reacts to the attraction of the Earth's magnetic field,
01:10which covers our planet like a blanket.
01:13This field draws its arrow to the north pole of the planet.
01:16Once you know where the North is,
01:18you know where the East, West and South are.
01:21And now, you can orient yourself in nature like a chevronned explorer.
01:26This is what we call a reference point.
01:29But it's not just forests.
01:31Think of the reference points that you use in your daily life.
01:35When you follow the indications on a map,
01:37consult your GPS navigation system,
01:40or simply when you tell someone the direction to take at the corner of a street.
01:44And in the air, we use water.
01:49Imagine that you are embarking on an exciting adventure in Montgolfière.
01:53As you climb,
01:55you discover wavy landscapes and sparkling oceans.
01:58It's breathtaking.
02:00But how do you know how high you are?
02:03Well, that's where the sea level comes into play.
02:06You have probably already heard the expressions
02:09above the sea level,
02:11or below the sea level in your daily life.
02:14This is the average level of the oceans on the planet.
02:18A universal reference that serves as a starting point
02:21for measuring heights and depths.
02:24When you climb in your Montgolfière,
02:27you can use, for example, an altimeter
02:30to measure your altitude in relation to the sea level.
02:33This instrument tells you how far you have climbed in the sky.
02:37And it's not just useful for adventures in Montgolfière.
02:41We calculate the altitude in relation to the sea level
02:44in many areas,
02:46from aviation to meteorology,
02:48through geography.
02:50It helps us to know the height of the mountains,
02:52the depth of the oceans,
02:54the altitude of cities,
02:56and even the flight trajectories of airplanes.
02:58We have reference points all around us on Earth.
03:01But when we take altitude,
03:03all this becomes much more complicated.
03:06In space, there are no natural landmarks,
03:09no compass, no universal altimeter.
03:12And in the absence of fixed reference points,
03:15determining the orientation is a real challenge.
03:18Even the stars, which are often used for navigation on Earth,
03:22can be misleading in space.
03:24On Earth, the stars seem to move
03:27according to a fixed diagram due to the rotation of our planet.
03:31But in space, they seem to move
03:33and change position as you travel.
03:37So what should we do?
03:39A point technology and precise calculations are necessary.
03:42Our intrepid ships have ingenious solutions
03:45to navigate in the seas of the galaxy.
03:48One of the most amazing tools
03:50used by space ships for navigation
03:52is the star tracking system.
03:54It's a bit like a cosmic GPS.
03:56Cameras scan the night sky,
03:59draw up a map of the stars,
04:01and use it as a reference point.
04:03Just as we use signaling panels
04:06to find our way to a new city,
04:08our ships use the position of the stars
04:11to determine their orientation and direction in space.
04:15Other celestial objects can also be used
04:18to locate themselves in space,
04:20like planets, moons, and even asteroids.
04:24All this allows us to determine our position
04:26and the direction to take.
04:28We can establish our trajectory
04:30on the basis of these data,
04:32for example, to go from Mercury to Mars,
04:34passing through Venus.
04:35It's like a game of points to connect,
04:37but with planets and moons.
04:39But it's not just about finding your way.
04:42Spacecraft also use these navigation methods
04:46to perform precise maneuvers,
04:48like orbiting around a planet
04:50or landing on a moon.
04:52They use complex calculations
04:54and precise measurements
04:56to determine their altitude, speed,
04:58and trajectory
05:00by using the position of celestial objects
05:02like a compass.
05:04It's like a dance in which the ship
05:06follows directions to perform movements
05:08in the vastness of space.
05:10The gyroscope is another ingenious gadget.
05:13It's a kind of space compass.
05:15Gyroscopes are incredibly sensitive.
05:18They can detect the slightest change in orientation.
05:21They help spacecraft to remain stable
05:24and keep them on the right track.
05:26Our ships also use cameras and lasers
05:29to record images
05:31and measure the distance between objects
05:33such as planets, moons, or asteroids.
05:37And let's not forget all the sophisticated software and algorithms.
05:41Inside each spacecraft
05:43is a brilliant computer brain
05:45that solves complex equations
05:47and calculates trajectories.
05:49But we've only talked about orientation.
05:51What about altitude?
05:53In space, altitude has a different meaning.
05:56It's like trying to measure the height of a skyscraper
05:59without a roof.
06:01This cosmic riddle requires creativity at all costs.
06:05In general, we measure it
06:07with respect to the position of a spaceship or a satellite.
06:10If you're floating near a moon or another celestial body
06:13and you want to know what altitude you're at,
06:15you have to measure the distance
06:17that separates you from the surface of that body.
06:19For example,
06:21astronauts from the International Space Station
06:23calculate their altitude
06:25by referring to the distance that separates them
06:27from the surface of the Earth
06:29far in our atmosphere.
06:31And if the star has no solid surface,
06:33like Jupiter,
06:35which is just a huge ball of gas,
06:37well, all you have to do is pray.
06:39Another method
06:41is to measure the altitude
06:43with respect to the orbit of the spaceship.
06:45You can measure the distance
06:47that separates you from the center
06:49or the plane of your orbit
06:51and use it as a reference point.
06:53These methods may seem complex,
06:55but they are the simplest way
06:57to navigate and maneuver in space.
06:59They allow spacecraft
07:01to accurately control their altitude,
07:03their speed and their trajectory.
07:05Thanks to these methods,
07:07it is possible to perform maneuvers
07:09such as mooring, landing
07:11or synchronization.
07:13Space agencies and missions
07:15also play the role of controllers
07:17of interstellar traffic.
07:19They must ensure that the ships
07:21of different nations and organizations
07:23do not crash into each other.
07:25To organize all this,
07:27they use standardized systems and protocols.
07:29Just as we use signposts
07:31and a road code
07:33to travel on Earth.
07:35In addition to normalized systems,
07:37space agencies and missions
07:39use a code to determine
07:41the direction and orientation in space.
07:43For example, the rule of the right hand.
07:45It is a kind of secret hand
07:47that allows you to understand
07:49in what sense things are
07:51in the fields of physics and engineering.
07:53Imagine that you have
07:55a magic glove capable of
07:57telling you the direction
07:59things will take in certain situations.
08:01Suppose this glove is
08:03on your right hand.
08:05Now, raise your thumb.
08:07It represents the direction
08:09of the force, the thrust
08:11or the traction of an object.
08:13Then, wrap your fingers around
08:15your thumb as if you were closing the fist.
08:17Your fingers now represent
08:19the direction of a magnetic field
08:21or the object in question.
08:23And now, the grand finale.
08:25Point your index finger straight
08:27as if you were pulling a laser beam.
08:29Your index finger now represents
08:31the direction of a movement or a current.
08:33And that's it.
08:35The rule of the right hand
08:37is to use your magic glove
08:39to make the link between the direction
08:41of the force, the thrust,
08:43the magnetic field or the rotation,
08:45fingers, and the movement
08:47or the flow of current, index.
08:49It's a fun and practical trick
08:51that helps scientists
08:53to solve complex problems
08:55in physics and engineering.
08:57Space exploration is a field
08:59that questions our perception
09:01of direction and orientation
09:03and makes us realize
09:05how much we depend on our planet.
09:07Who knows what other madness
09:09awaits us in the future?
09:11For example, quantum navigation
09:13or when we create
09:15distortion speeds like in Star Trek.
09:17These are not only practical
09:19but also very impressive methods.
09:21I can't wait to see them.
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