NASA was forced to submit a new budget and a new development plan for the Webb, one that culminates in a fast-approaching launch date in 2018. “It is very important for us to stay on schedule,” NASA engineer Begoña Vila recently told me. “We need to finish on time.”

Even if it means working through a blizzard.

NASA has already put the telescope’s sensors through acoustic testing, to make sure they can withstand the deep, bone-jarring roar of lift-off. The fully-assembled Webb will be 75 feet wide, but when the telescope leaves Earth it will be bundled up and stuffed into the tip of a rocket that will deposit it nearly one million miles away.

Once it reaches its new home, the Webb will attempt an unprecedented feat of reverse origami. Over a period of months, it will unfurl its giant sunshade, its instruments, and its 18 gold-coated mirrors, becoming, in the process, the largest space observatory in the known universe.

The stakes for this metamorphosis are high. Astronauts have flown out to service the Hubble Space Telescope several times since it reached orbit in 1990. But the Webb is being sent to deep space, some three times the distance of the Moon. Even with tomorrow's technology, repair at such a remove from Earth will be extremely difficult. If for any reason the Webb should fail after launch, it will likely be left to idle out of reach, a stillborn in the void.

That’s why testing is so important. Engineers at NASA Goddard have been working around the clock to make sure that the Webb will function in the frigid, airless environment it will soon call home.

Back in October, its instruments were lowered into the center’s Space Environment Simulator. At more than 40 feet tall, the cylindrical simulator is itself an impressive specimen of the technological sublime. After the instruments were sealed in, the simulator’s interior was transformed into an artificial abyss. Vacuum pumps sucked out its air until the interior pressure was only a billionth as strong as Earth’s atmosphere.

When I visited NASA Goddard in early January, I could see ice forming on the pipes that feed into it. Liquid nitrogen and helium had been released into the chamber, to cool it to the -387 degrees Fahrenheit temperature the Webb will experience in deep space. The most powerful of the telescope’s four instruments will need to be cooled even further, to just north of absolute zero, the point where all motion ceases. Only in the grips of that deep chill will it be able to detect faint, long-journeying starlight from galaxies more distant and ancient than any that have ever been glimpsed.

The Space Environment Simulator requires constant monitoring—even through the weekend—to ensure the stability of the chamber, and the priceless instruments it holds. The team typically divides each Saturday and Sunday into three eight-hour shifts. But with a blizzard looming, they worried that the region’s impassable roads would make shift changes impossible.