SpaceX, the aerospace company founded by Elon Musk, has worked hard on an ambitious project: to permanently settle people on Mars.
To make this vision a reality, Musk is developing a colossal, completely reusable launch system called Starship.
The starship is designed as a 180-foot-space spacecraft that will climb in orbit over the super heavy, rocket boost of about 220 feet, according to its latest descriptions. The spacecraft is designed to be fueled in low Earth orbit to propel 100 passengers and more than 100 tonnes of cargo on Mars.
But the success or failure of the launch system – and Musk's human race support plan ̵
Instead of relying on thousands of heavy ceramic tiles to protect Starship from heat, as NASA did with its space shuttle, Musk says the spacecraft will "bleed" rocket fuel through small pores to cool down. In theory, placing a liquid between the steel skin of the Star Ship and the hot plasma that is formed while it is being fired by atmospheric gases will prevent the ship from being destroyed.
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But if SpaceX can pull a system to launch this unprecedented size and design – says Walt Engelund, aerospace engineer and director of NASA Langley Space and Technology Research.
"Massive entry, descent and landing is something NASA has caused for decades, we spent a lot of time thinking about doing it on Mars," Engelond said. Business Insider. "We've arrived at the metric-tonal rover" Curiosity "- that's the biggest thing we ever put on the surface of Mars.
Moving from landing a car-sized Martian robot to a size-filled ship filled with people, Engelund said, is "on a few orders of magnitude" – about 100 times – harder than the landing of curiosity , which he said "is one of the toughest things we've done in NASA." "It will not be easy for us or for SpaceX," Engelond said.
Why starships became a ship with a heavy metal rocket
Musk believes he can build a self-sufficient city on the red planet from 2050 . He wants individual tickets for Mars to be cheap as a house on Earth, and for return trips – free of charge. The Starship-Super Heavy starter system is the way Musk plans to achieve this goal, and said the move to stainless steel alloys is a way to reduce costs and build the system more quickly. "The starship will look like liquid silver," said Musk for the change in December, adding that the ship would have a mirror coating to reflect the heat – a literal case of a cool factor.
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The steel problem, however, is that the material is dense and heavy. At least one early version of General Dynamics' Atlas Racket, which was made of metal crushed at its own weight on the launch rocket.
But Musk suggests that the use of SpaceX steel is very different and will make the stronger, more durable and not so heavy a revised star ship. After all, he said, material change will improve the performance of the rocket ship over the old design. "I am confident that the stainless steel vessel will be lighter than advanced aluminum or carbon fiber because of its weight-to-temperature weight and the reduced need for thermal protection," Musk said in January. But no matter how hard it is steel, it is not invincible, especially when it forms the skin of a spacecraft screaming through the atmospheric gases.
Sweating and Bleeding for Survival
It's enough heat to destroy the steel alloy that Musk said SpaceX could use for Starship's outer skin. Called 310S, the material is often invoiced as a heat-resistant metal because it has a lot of chrome and nickel. (Not unlike the steel used in kitchen utensils and pots.) But 310S still starts to react with oxygen and corrodes at about 2000 degrees and melts at about 2400.
The rocket ship needs protection from the intense heat, so Musk's plans call the body of the spacecraft to cool using liquid fuel during landing.
Musk told Popular Mechanics that he has decided to give up space-like thermal shuttles to save weight and avoid the risk of damage or loss of the tile.
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Instead, he explained, the Star ship will "bleed" fuel from small holes in steel skin, and that the liquid layer will carry the hot heat to the atmospheric inlet. "On the wind side, I want to have the first heat-generating heat shield, a double-walled stainless steel envelope – like a stainless steel sandwich," Musk said. – You pour either fuel or water between the sandwich layer, then you have micro perforations from the outside – very small perforations – and you basically drop water or you can bleed through the microperforations from outside. he would not see them if you did not get close.
He added that the heat shield would make a double duty by reinforcing the Star's steel body.
"To my knowledge, it has never been offered before," Musk said. Experts told Business Insider that Musk is right that a spacecraft never went into orbit and was returned to Earth with such a heat shield. But the concept of sweating or "transpirational" thermal protection is not new, and it has a history of being an extremely challenging engineering challenge.
Transponder cooling for lunar men and MBP
Active cooling has existed for millions of years in the form of mammalian skin. When the temperature of the human body rises too high, for example, microscopic pores push sweat. This liquid then evaporates to transfer excess heat and prevent overheating. As for space-sucking devices, NASA began playing with the nature-inspired cooling system before the astronauts of the moon landed.
"The idea of cooling with transpiration is not new, it has been happening for decades," Engelond said. A patent filed by NASA in 1965 suggested the use of astronaut urine to cool the heat shield at the bottom of the space capsule. It was not until 2006 that the space agency spent at least $ 70,000 on an inflatable, transpiration-cooled heat shield that could help Mars spacecraft.
The space ship "sweating" also plays a role in the Cold War race. In March 1976, the US Department of Defense tested airborne chillers for incoming vehicles. Such tugs are made to fly into the space of the intercontinental ballistic missiles, re-enter the earth's atmosphere at thousands of kilometers per hour, and hit distant targets with nuclear warheads.
But, according to the US Air Force's historical records, the project was canceled later in the 1970s, due to limited funding and "design problems that hampered development efforts." Instead, engineers have chosen simpler "ablative" heat shields that isolate the vehicle by burning during re-entry.
Information on problems in defense-related transhipping heat shields is mostly classified. But George Herbert, an aerospace engineer who has investigated the military needs of spacecraft, told e-mail that "reported and known problems include blocked transpiration openings." In other words, a challenge common to teen skin: clogged pores.
"What happens if a bird intervenes on your rocket?"
Dwayne Day, who helped investigate the loss of NASA's space shuttle and Colombia's crew, imagined an annoying scenario in front of which the Star Ship would have stood up in every place to launch the Earth.
"What if a bird gets out of your rocket and it picks up a few holes, and then when things get back, there is no coolant coming out of those holes and that part of the vehicle overheating?" Day wrote in Business Insider email.
Engelund said he had problems with clogged cooling systems in tests performed in NASA's hyper-sonic aerodynamic tunnels. During such experiments, large-scale vehicle models are placed in a tunnel that can blow the air at thousands of kilometers per hour to study how they are running. Some of the tests include heat shields that pump liquids through the channels just below the model skin to cool it, but not all models have survived.
"I have seen cases where you will get a clogged channel … and it will immediately cause burnout," Engelond said. "The model will disappear in the hypersonic aerodynamic tunnel, almost evaporating, so much energy and so much heat."
Musk says that using methane as a cooler can be better than water.
"Rapid evaporation of water can cause intuitive freezing and blocking cooling channels," he said .
But Engelund also sees challenges with the methane option. When exposed to high temperatures, the carbon atoms in the hydrocarbon fuel (such as methane) can "coke" or stick and become stiff. Such debris can then block subtle structures such as pores. "I'm going to worry about it," Engelund said, adding that other major concerns would be impurities in fuels, which could also cause obstruction. One of the possible ways to solve these problems, Engelund said, may be simply adding more pores than it seems necessary, "only if a small percentage of the perforations are blocked or the channels flow coolant to these perforations."
Along with problems like bird fertilizer and clogging, there is the fine dust that blows on Mars. It may fall inside the fuel pores and it may be difficult to detect and remove these locks while on the red planet.
"Inspection and certification, in general, would be a concern for such a large-scale active system – especially on Mars where you do not have access to a large portal or towers to climb up and check," Engelund said. use the drones Maybe it's something he thinks about
Can the starship take the heat
Musk shared only parts of the newest star ship design and did not present a complete picture to the audience as he did in the past (The pictures shown in this story Ori Musi said in December that it would provide a detailed explanation in March / April, "pending successful prototype shots the "test bunker" the company is building in Texas.
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Meanwhile Musk shared a video (above), which appears to be testing the metal heat shield for Starship. It is not yet clear how many SpaceX studies have implemented the concept of transpiration cooling. "It's a huge risk if they have not worked to qualify and confirm what they want to do," Herbert said. "But if they did, they could be a real winner for their new design.
If it does not work, Engelund said, it is not necessarily a dead end for Musk's star ship. "He can understand that he is untenable or too expensive for certification or testing, and can find a better idea," Engelond said. "He's really good at this in his career."
SpaceX also expects constant tweaks and changes as engineers work to make Starship a reality.
"We use the same quick iteration in the design approach that led to the success of Falcon 1, Falcon 9, Falcon Heavy and Dragon," a company spokesman said in an email quoting the latest company missiles and spacecraft.
But SpaceX rejects any comparison between the Starship Shackle and Science.
"Courage implied the boundaries of Mars technology of 1970 [entry, descent, and landing] including a specific EDH architecture based on parachutes," said SpaceX. "We use a very different approach using what we did with Falcon 9 and we have enough opportunities to demonstrate it on Earth before we fly to Mars."
In spite of the high hurdles that SpaceX seems to have encountered in trying to land and land the Star Mars, none of the experts we talked to was implausible. "They have surprised many people and have a lot of smart people working for them, and Elon seems really engaged and committed to it," Engelond said. "Maybe there are some things we can do with them. I suspect there will be.