James Webb Space Telescope inside Chamber A
![](https://cdn.sci.esa.int/documents/34594/35357/1567214670724-Webb_telescope_inside_ChamberA_20180131_625.jpg)
Date: 15 September 2017
Satellite: Webb
Depicts: Optical Telescope element / Integrated Science instrument module (OTIS)
Location: NASA's Johnson Space Center, Houston, Texas
Copyright: NASA/Chris Gunn
The James Webb Space Telescope's combined optical and science instrument element (OTIS) undergoing cryogenic testing inside Chamber A at NASA's Johnson Space Center in September 2017. The temperature inside the chamber was approximately 40 kelvin (-233 degrees Celsius).
A photogrammetry camera was placed inside the chamber to measure the telescope's alignment and to monitor the effect of extremely cold temperature on the black Kapton® material that is fitted to block unwanted light from behind the telescope. Also visible are the hexagonal primary mirror segments. The bright "stars" shining in this long-exposure photograph are photogrammetry targets that were used to measure extremely precise movements of the telescope as it cooled.