In Lightyear, them studio Pixar explore Buzz’s pastFlash (Buzz Lightyear in the original version), theastronaut well known from the saga Toy Storyfamous in particular for his famous cult replica “ to infinity and beyond “. The story follows Buzz and his crew on T’Kani Prime, a fictional planet located 4.2 millionlight years of the earth. But as they explore the planet on behalf of society Star Command, the crew is attacked from all sides by living beings from the planet (we won’t say more), and their ship is then destroyed! They therefore need to establish themselves long enough to rebuild it. And this famous ship, how does it work? In a press release fromAriane Group which analyzes in detail the “Star Cruiser 42”, engineers have looked into several aspects of the ship. Whether it’s his propulsion technique, acceleration, or even the way he slows down, every element is interesting. The processes used for Lightyear are more so in many other works of science fiction.
Trailer of Lightyear. © Pixar, YouTube
A magnetic ramp to reach escape velocity
First, the way the ship takes off and then accelerates enough to reach the speed release of T’Kani Prime. As the engineers explain, it uses “the magnetic force of a ramp much like that of a roller coaster”. Indeed, the vertical ramp, visible in the trailer, is strangely reminiscent of that of SpaceMountain. This method of transport by magnetic way is currently used for trains, in particular the Maglev train for Magnetic Levitationwhere the magnetic levitation trains which can reach prodigious speeds! The very first of its kind was built in Germany and dates from 1979. Since then, many developments have taken place, which have made it possible to reach a speed record of 603 km/h.
The principle: whether for the Maglev or magnetic levitation, powerful electromagnets are arranged all along the rails. Then the train has eithermagnets classic but powerful, either magnets superconductors. The movement of the train induces a current in the track, and the resulting force causes it to levitate. This process is also used for some droneand for small appliances in general. But, small problem: reaching a speed sufficient to free itself from Earth’s attraction (approximately 11.2 km/s) is currently not achievable with this technology, and even less so for a large machine that weighs several hundred tons!
For all our young space fans, our engineers have watched “#Lightyear”, the movie telling the story of Buzz Lightyear, to find out whether the space technologies he uses could work in real life.
Have you seen it yet? https://t.co/FqXcfDMK86@Pixar@ChrisEvans@AngusMacLanepic.twitter.com/3lKzt0r4H5— ArianeGroup (@ArianeGroup) July 21, 2022
The crystals of Lightyear, to jump into hyperspace
But after taking off, it remains to reach hyperspace, that is, to reach and exceed the speed of light. Small reminder: according to the theory of relativity established by Einstein to the XXe century, it is simply impossible, at least in a vacuum as is the case in space. But in science fiction, hyperspace is very real, and used regularly. In the case of Buzz Lightyear, the latter uses a very particular fuel. As it says in the press release, it’s a science fiction classic that has been reused here by Pixar studios: crystals. Previews as dilithium in star trek or naqahdah in Stargatethey are made in Lightyear from liquids colored whose nature is not specified in the animated film. The Ariane Group engineers have, however, likened them to propellants liquids and they serve, like their analogues in the other works, to reach superluminal speeds: this is called hyperpropulsion.
But small problem: create crystals from liquids requires special conditions of pressure and temperature. It all starts with mixing a chemical element to one aqueous solution. The crystal forms either when the water evaporates or when the mixture cools and hardens. The process then proceeds through accretion to others molecules which compose it, following the unit cell of the crystal, and the typical regular organization of the crystals is done little by little. “Crystallization can occur when a magma hardens or when water evaporates from a natural mixture (especially for salt crystals)”, explain the engineers.
Create a crystal as in Lightyear, which contains a sufficient quantity to propel an entire ship is currently not feasible, far from it. Where a few liters of propellant are enough, so a mass of a few kilograms for Buzz Lightyear, in reality, the quantity needed is in the hundreds of tons. Moreover, as Ariane Group engineers explain, “Although scientists have already attempted to store thehydrogen in molecular “cages”, made up of chains ofatoms of carbonofoxygen and hydrogen connected by ions metallic (in practice, a liquid mixture of sugarofalcoholsalt and water), it is not possible today to make crystals from propellants like those we use for our launchers (oxygen and liquid hydrogen)”.
Deceleration rings
Once Buzz Lightyear has finished his journey, or almost, he is left with one important element: thelanding ! For this, he uses “deceleration rings”, which slow him down as he passes through them and then allow him to land safely, finally with a lower speed. Placed in orbit around the alien planet T’Kani Prime, the technology behind is not specified in Lightyear, but engineers assume they would generate a powerful magnetic field capable of slowing down the vessel which is heading speed of light. The idea may appeal, because currently space travel mainly uses the gravitational attraction of stars to speed up or slow down, but ” even if this process saves a lot ofenergy and makes possible some flights that otherwise could not be launched, it is quite a long method. For example, for the mission BepiColombo launched by Ariadne 5 as of 2018, the journey takes seven years to 2025 and requires nine planetary crossings (called gravity assists), including six above Mercuryits final destination, to slow down and go into orbit around the planet”, explain the engineers.
Ultimately, Lightyear uses well-known processes from science fiction, between hyperspace, original methods of propulsion, fuel… but also the Time travel ! Not directly related to the ship this time, but rather to its speed. Without revealing too many elements of the film, Buzz Lightyear must carry out tests of his ship, so that he then transports all his crew out of the alien planet. But a four-minute hyperspeed test flight for him is like many years on this planet, so when he returns victorious after a successful test, many decades have passed! Even more, the animated film depicts, in a moment that will not be mentioned, the paradox of time travel! But these time travels will be developed in another episode.
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