Image: NASA clean room gets a heart-full of Webb

The James Webb Space Telescope's team welcomed back the "heart" of the observatory, known as the Integrated Science Instrument Module or ISIM, to the world's largest clean room at NASA's Goddard Space Flight Center in Greenbelt, Md.

After months-long cryogenic testing inside a thermal vacuum chamber, Engineering Technician Mick Wilks inspects ISIM.

ISIM will soon house all of Webb's science instruments.