Houston Chamber A: The Big Cool Down
The temperature of Chamber A at NASA’s Johnson Space Center in Houston is steadily dropping, creating a frigid environment for NASA’s James Webb Space Telescope that is in stark contrast to the heat of the city.
You can view this contrast yourself by checking out the new temperature overlay on the Webbcam. With the Webb telescope locked away inside Chamber A, you won't see Webb itself on the Webbcam for several months. Now, however, you can see how the chamber’s temperature compares to that of Houston.
The temperature of the Chamber A will continue to steadily drop until it reaches about 20 kelvins (minus 424 degrees Fahrenheit/minus 253 degrees Celsius), but it will take a little while longer for the Webb telescope and its instruments to reach the same temperatures they will be when operating in space.
The telescope and its instruments must transfer their heat to the surrounding liquid nitrogen and cold gaseous helium shrouds in Chamber A to achieve their operating temperature of about 37 kelvins (minus 393 Fahrenheit/ minus 236 Celsius). Because the Webb telescope’s mid-infrared instrument (MIRI) must be kept colder than the other research instruments, it relies on a cryocooler to lower its temperature to less than 7 kelvins (minus 447 degrees Fahrenheit/minus 266 degrees Celsius).
In space, the telescope must be kept extremely cold in order to be able to detect the infrared light from very faint, distant objects. To protect the telescope from external sources of light and heat (like the sun, Earth and moon), as well as from heat emitted by the observatory, a five-layer, tennis court-sized sunshield acts like a parasol that provides shade. The sunshield separates the observatory into a warm, sun-facing side (reaching temperatures close to 185 degrees Fahrenheit/85 degrees Celsius) and a cold side (minus 400 degrees Fahrenheit/minus 240 degrees Celsius). The sunshield blocks sunlight from interfering with the sensitive telescope instruments.
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.
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.)