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WEBB CAM : Watch us build the Webb Telescope at NASA Goddard Space Flight Center!

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Chamber A to Begin Warming

In late September, engineers will begin to warm Chamber A to bring the Webb telescope back to room temperature — the last step before the chamber’s massive, monolithic door unseals and Webb emerges in October. Everyone can watch the temperature of Chamber A rise during the next few weeks by checking out the temperature overlay on the online Webbcam. The overlay shows the temperature of the gaseous helium shroud, the innermost of two shrouds that were used to cool the telescope to cryogenic (extremely cold) temperatures. The two shrouds are thin, cylindrical, metal shells that envelope the telescope.

The engineers are using heaters to incrementally warm the inside of the chamber. In addition to this, they will warm the two enveloping shrouds, which previously had frigid cryogens (substances used to produce extremely cold temperatures) flowing through them.

Carl Reis, the test director for Webb's cryogenic testing at Johnson, explained the engineers will gradually raise the temperature of the helium gas flowing through the innermost shroud. The temperature of that shroud, which is the temperature displayed on the Webbcam overlay, will reach about 68 degrees Fahrenheit (about 20 degrees Celsius / 293 kelvins) before the Chamber A door opens. He added that the engineers will stop the flow of liquid nitrogen into the outermost shroud, allowing the liquid nitrogen already inside the shroud to “boil off” as it warms. Liquid nitrogen begins to evaporate at about minus 321 degrees Fahrenheit (about minus 196 degrees Celsius / 77 kelvins).

The team tested Webb in the airless cold of Chamber A because, in the vacuum of space, the telescope must be kept extremely cold in order to be able to detect the infrared light from very faint, distant objects. Warm objects emit infrared radiation, and any excess warmth could give false signals to the telescope. The cryogenic testing ensured all of Webb's components, including its science instruments and mirrors, worked as expected in a space-like environment.

In the overall warming process, temperatures will go up in a number of steps, including at least one intermediate cooling step.

More information about Chamber A

The Webbcam Views

On our Webbcams are views of "Chamber A" at NASA's Johnson Space Center. Chamber A is a massive thermal-vacuum chamber. This means that it can mimic the vacuum of space, and can also be cooled to extremely low temperatures, like the ones at which the James Webb Space Telescope will be operating. Webb is currently at NASA Johnson for an end-to-end test of the telescope at cryogenic temperatures in Chamber A.

In more technical terms, the end-to-end test on Webb's telescope involves passing light through the entire assembled telescope using test point sources of light from precision-placed fiber optics and using reflecting mirrors (three auto-collimating flat test mirrors). This will re-check alignment of all the telescope optics assembled together and demonstrate that the individual primary mirror segments can be aligned to each other, and it will re-check the figures of the mirrors.

Although there is no view of Webb once it is inside the chamber during the actual cryo-optical testing, there will be much activity on Webb in the cleanroom itself for several weeks before and after.

The image is updated once per minute. The webcam pages and widgets update at the same rate to keep the latest image on screen. You can view the webcam on our Home page or on our webcam page at various sizes up to 1920px wide.

Those who work in cleanrooms (like the one in front of Chamber A) must dress in the outfits you see them in on the webcam (known unofficially as "bunny suits"). This is to ensure that any particles or contaminants on their persons are contained, in order to keep the room as clean as possible. The process of getting suited up is not trivial and the cleanroom workers often spend very long hours in the cleanroom without an easy way to leave for breaks. We on the project are very appreciative of the hard work they put into building and testing the hardware in such a challenging work environment.

You can read more about how the testing is different for Webb and Hubble's mirrors, and what Hubble taught us on our FAQ.

You can read about upcoming milestones on our "What's Next" page.

Webb-cam Time-Lapse Movies

Note that our webcam was at NASA Goddard for many years. Be sure to check out our playlist of Webb-cam time-lapse movies that compress hours and even days of Goddard Webb-cam footage into a few minutes. Many of the recent significant events are captured in time-lapse.

Related Images

About the Spacecraft Components

To learn more about the various components of the Webb Telescope, see the Observatory page as well as our interactive 3d spacecraft model (new window) (requires flash).


(There is always the possibility that the webcam may not function properly. Please bear with us if that is the case.)