An official website of the United States Government 
Here's how you know

Official websites use .gov

A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS

A lock ( lock ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Photos

Snapshots of what’s happening in the Defense Department.

A person wearing a white protective suit stands in front of six big, hexagon-shaped mirrors.

Mirror Segments

Recently, technicians at NASA's Marshall Space Flight Center in Huntsville, Ala., completed a series of cryogenic tests on six James Webb Space Telescope beryllium mirror segments at the center's X-ray & Cryogenic Facility. During testing, the mirrors were subjected to extreme temperatures dipping to -415 degrees Fahrenheit, permitting engineers to measure in extreme detail how the shape of the mirror changes as it cools.

Photo Gallery