tech2 News StaffJan 23, 2019 13:37:55 IST
SpaceX's Starship rocket — a prototype for a shuttle to the moon and Mars won't just look like the coolest steel flying machine ever built – it'll actually stay pretty cool thanks to the shiny steel.
Starship is made of stainless steel, as SpaceX CEO Elon Musk said in a tweet long ago — a material that is capable of resisting heat well, with a generous coat of polish to give it a shiny, reflective surface.
Skin will get too hot for paint. Stainless mirror finish. Maximum relfectivity.
— Elon Musk (@elonmusk) December 24, 2018
This makes it a superior choice to the usual, carbon-fibre body that SpaceX has gone with to build its other rockets, including its workhorse, the Falcon 9.
Musk also elaborated on the unusual choice of stainless steel over carbon fibre in a recent interview with Popular Mechanics.
In Musk's own words, "The thing that’s counterintuitive about the stainless steel is...it’s obviously cheap, it’s obviously fast, but it’s not obviously the lightest...But it is actually the lightest. If you look at the properties of high-quality stainless steel, what isn’t obvious is that at cryogenic temperatures, its strength is boosted by 50%."
He also used some other words to explain himself, but they ended up prompting more questions and confused memes than provide an ounce of clarity.
When going to ~1750 Kelvin, specific heat is more important than latent heat of vaporization, which is why cryogenic fuel is a slightly better choice than water
— Elon Musk (@elonmusk) January 22, 2019
But that's just half of what makes Starship so very badass. Musk has also attempted something with the rocket that no one thought was actually possible: a regenerative heat shield.
"A stainless-steel sandwich, essentially, with two layers...that are joined with stringers. You flow either fuel or water between the sandwich layers, and then have micro-perforations on the outside—very tiny perforations...you essentially bleed water, or you could bleed fuel, through the micro-perforations," Musk told Popular Mechanics.
These tiny perforations won't be visible to observers till you get up close to the rocket's body. Much like water evaporating from a leaf's surface, the cooling that comes from the process (transpiration) is part of what gives the rocket's heat shield its 'regenerative' property.
Starship will look as chrome and cocktail mixer-like as it does now. A closer look will reveal the rocket's outside (or the windward side) are double-walled for a double purpose – to cool the rocket using a whole new heat shield technology and giving the rocket added stiffness so it doesn't crumble mid-flight like the last rocket that featured a stainless steel body – the Russian Atlas.
"You have a heat shield that serves double duty as structure...To the best of my knowledge, this has never been proposed before," Musk said.
Innovative use of kitchenware alloys and teasers every few weeks are leading up to what space junkies are really waiting for – to see the glitzy mammoth fly.
We can expect to see that happen in a matter of weeks, plus a "technical presentation of Starship" after the prototype's maiden flight in March or April this year.
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