The US Air Force's 846th Test Squadron is on a bit of a roll when it comes to breaking world speed records. A couple of years ago, the unit set the speed record for magnetic levitation at 510 mph. Then earlier this year on March 2nd, the squad broke the record again at Holloman's Air Force Base in New Mexico, sending a 2,000 pound, magnetically levitated, rocket-powered sled down a nearly frictionless track at 513 mph. But that record only stood for two days, when the 846th set a new one at an incredible 633 mph.





The sled covered a distance equal to seven football fields in about two seconds. Whoever wrote the official Air Force press release about this achievement clearly earned their MFA from the Iowa Writers' Workshop, because this is pure poetry:

"Ten, nine, eight, seven, six..."

A steady voice reads through a crackling radio atop a roughly hewn 2x4 wooden shelf, adding lumber to the smells of coffee and aftershave inside the enclosed trailer. Red LED numbers attached to the radio flash their faint light as they drop toward zero.

"...five, four, three..."

Rolling chairs anxiously scrape across the trailer floor as the four men position themselves to better see through a dirty window. They train their eyes toward the track a quarter of a mile away.

"...two, one..."

Half a year of long days in the New Mexico sun brought them to this moment. Now, a heartbeat away, they will find out if it has been worth it.

"...fire."

Everyone in the trailer holds their breath in anticipation for t...

BOOM!

A violent explosion from the track rocks the trailer and everyone inside.

This squad uses powerful magnets to steady the sled on a 2,100 foot-long track. In order for the magnets to work properly, engineers must first cool them using liquid helium to four degrees Kelvin above absolute zero — or four degrees above the coldest an object can possibly get. This ensures the smoothest ride possible. "It's a few months of preparation," said 2nd Lt. Natalia Ocampo, the rocket sled project manager for the launch. "We all work really hard to get the procedures very clear and step by step. Then everything seems to go very smooth."

"Go Mach 10"

Its unclear how long this current record will stand, though, as the 846th's commander says, his engineers are already back to drawing board looking for ways to go even faster. The squad's motto is "Go Mach 10," or hypersonic speed of 7,672 mph. "What we have planned to do after this test is refine the design of the sled itself," Lt. Col. Shawn Morgenstern said. "We want to look at some lighter materials and continue to see what kind of capability we can get out of this system in terms of the speeds that we're capable of going."

Obviously, the Air Force is interested in maglev for military purposes, but the engineering has mass transit implications as well. Several high-speed rail systems across the globe use maglev. The fastest commercial train currently in operation, in Japan, has a top speed of 375 mph. Elon Musk's Hyperloop proposal envisions aluminum pods traveling through frictionless tubes at up to 760 mph, some forms of which using magnetic levitation.

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