X-Ray Specs

Columbia astrophysicist Chuck Hailey is building a telescope to view stars so hot they’ve never been seen.

by David J. Craig Published Spring 2010
  • Comments (1)
  • Email
  • ShareThis
  • Print
  • Download
  • Text Size A A A

Glass onion

Hailey was chosen to oversee NuSTAR’s optics team in part because of improvements he’s made to the way cylindrical mirrors are manufactured: First, thin sheets of glass similar to the glass used in computer screens and cellular phone displays are cut into long strips, heated in an oven, and melted into concave molds. Next, the curved glass pieces are coated with a metal film, which makes them reflective. Technicians then assemble the glass pieces into concentric cylinders, which are separated one layer from the next by tiny graphite spacers whose thicknesses are determined — to the nearest micron — by a computer-driven grinder wheel.

The optic device is assembled in a dust-free room, as any stray particles could hinder its performance.“There’s no way you could get 133 layers on this thing if you were determining the spaces between each shell by hand, which is the way this used to work,” says Todd Decker, a mechanical engineer at Columbia’s Nevis Laboratories. “Every tiny inaccuracy would add up and become huge. Even with the computer’s help, this work isn’t for the faint of heart.”

Perfecting the process took years. Hailey tried hundreds of epoxies before finding one suitable for gluing together the glass strips. “It had to be able to withstand temperature changes in space, even when applied in a layer one-micron thin,” he says. “I’m not joking when I say that I’m now considered one of the world’s top experts on epoxy. This was never my intention, and some of my physics colleagues think it’s pretty funny. But it’s what the work demanded.”

The assembly of mirror encasements should be finished by this fall. Hailey’s team has already built two prototypes, each having about 10 cylinders. Researchers shoot hard X-rays at them every day to see how they perform. “So far, they’re perfect,” says Jason Koglin, a research scientist in the Columbia physics department. “But when we finish all 133 layers this summer, we’ll likely have to do some extremely difficult calibrations to make sure it focuses properly.”

This work all takes place in a brightly lit, dust-free room that Hailey constructed in a gymnasium-sized work space at Nevis Laboratories. The space once housed a large cyclotron particle collider and now resembles an airplane hangar. It’s cluttered with welding equipment, nitrogen tanks, scaffolding, and small cranes. Hailey strolled about this Metropolis-like facility recently and discussed the heritage of scientists, from Sir Isaac Newton to the late Columbia X-ray astronomy pioneer Robert Novick, who, in order to peer into the cosmos, picked up hammers and metal-working tools.

“If you want to do important work in astrophysics, you can’t spend all of your time thinking about neutron stars and black holes,” said Hailey. “You also have to think about electronics and mechanical engineering and optics and the physical properties of glass and epoxy. To get the data, you have to go into the garage.”

  • Email
  • ShareThis
  • Print
  • Recommend (82)
Log in with your UNI to post a comment


Keep up the great work, Chuck!


The best stories wherever you go on the Columbia Magazine App

Maybe next time