Falafel is everywhere in this city. Along with asking when someone moved here and what they pay in rent, arguing over where to grab the best bite for any given occasion and location is a time-honored conversation.
My friend, Jason (who moved here a long time ago and pays far too little for his lovely one bedroom), and I were recently having just such a conversation. He was singing the praises of Cafe Rakka in the East Village.
Their falafel, he said, isn’t anything special in terms of price or flavor, but it is the perfect bite to counteract an evening spent having ‘just one more drink’ in any one of the poorly lit bars in the neighborhood. What does make them special is that they poke holes in the middle of their falafel. Those holes, according to Jason, give each piece “the perfect crisp to innard ratio.”
Naturally, this reminded of the Space Shuttle.
Take a moment to soak in the beauty that is Atlantis on its way to the launchpad.
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| Are you soaking in all this beauty? Are you? |
The Space Shuttle flew as part of the 30 year long Space Transportation System Program--NASA's ambitious program to build the world's first reusable manned spacecraft.
The whole thing is amazing, but that siren-song of nerdy admiration will have to wait for another time. For now, let’s focus on the two white towers on either side of the orange External Tank. Those are the Solid Rocket Boosters or--because no one appreciates a good acronym like the folks at NASA--SRBs.
Their name, as you may have guessed, alludes to the fact that the SRBs were filled with solid rocket fuel. The explosive bit of the fuel was powdered aluminum, not entirely unlike the foil on those leftovers you brought for lunch. Said aluminum was mixed with ammonium perchlorate, a compound only too happy to donate some oxygen to that whole combustion thing. Those two things were mixed with a catalyst (to get the party started), a binding agent, and a curing agent that gave the fuel its characteristic look and feel said to be reminiscent of a hardened eraser.
Each booster was filled with more than a million pounds of this stuff, in addition to structural elements, instrumentation, and parachutes. The parachutes were there so that they could safely land in the ocean and be recovered once they had been jettisoned from the Shuttle.
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NASA had two recovery ships and several trained crews of
divers whose job it was to retrieve the rockets and send
them back to Utah to be refurbished and refilled.
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The SRBs were a big part of what got the Shuttle going fast enough--ahem, 17,500 miles per hour--to be able to bust free from the gravity that keeps mere mortals like you and me firmly attached to the planet.
Even though they only burned for two minutes, they provided over 70% of the thrust needed for liftoff. They did that by burning nine tons of fuel every second. Nine tons of fuel every second.
Here's where the falafel comes in. Burning that much propellant that quickly is no easy feat. Engineers needed to come up with a way to ignite as much of it at once as possible (while remaining within the structural abilities of the vehicle).
Their solution was simple, elegant, and, though they didn’t know it, falafel-like. They cut a core through the fuel--it's an 11-point star at the tip, a straight cylinder lower down.
Just like creating a hole mid-falafel allows the East Village joint to
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One section of an SRB meets another section during processing.
Go ahead and admire that simple geometry. I'll wait.
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increase the crispy to innard ratio, cutting a core through the propellant inside the SRBs increased the amount of surface area that could be burned at any given time.
The star at the top of the rocket, by the way, created even more surface area than the cylinder below, allowing more fuel to burn, and more thrust to be generated in the critical first moments of a launch.
There’s so much that is so complicated about rocketry and spaceflight, but I love the SRBs because they are a reminder that sometimes even the most complicated machines can benefit from some clean, elementary geometry.
