Webb Telescope Snapshot: Cryo-Testing

The James Webb Space Telescope

The ISIM structure is inspected inside NASA’s Space Environment Simulator at the Goddard Space Flight Center after enduring weeks of temperatures less than minus 300 degrees Fahrenheit; the same temperature it will see for the duration of its mission inside the James Webb Space Telescope.

The James Webb Space Telescope (JWST) is a large, infrared-optimized space telescope, scheduled for launch in 2014. JWST will find the first galaxies that formed in the early Universe, connecting the Big Bang to our own Milky Way Galaxy. JWST will peer through dusty clouds to see stars forming planetary systems,connecting the Milky Way to our own Solar System. JWST’s instruments will be designed to work primarily in the infrared range of the electromagnetic spectrum, with some capability in the visible range. JWST will have a large mirror, 6.5 meters (21.3 feet) in diameter and a sunshield the size of a tennis court. Both the mirror and sunshade won’t fit onto the rocket fully open, so both will fold up and open once JWST is in outer space. JWST will reside in an orbit about 1.5 million km (1 million miles) from the Earth. The James Webb Space Telescope was named after a former NASA Administrator.

Watch the Webb In Progress on the NASA “Webb-cam”! http://www.jwst.nasa.gov/webcam.html

Currently on The Webcam Page

The Near-InfraRed Camera Engineering Test Unit (NIRCam ETU), the Near-InfRared Spectrograph Engineering Test Unit (NIRSpec ETU), and the Mid-InfraRed Instrument Structural Thermal Model (MIRI STM) are currently in the cleanroom. They are visible near the left side of the below image. The NIRCam ETU will go through electrical interface checks as well as mechanical fit checks. The NIR Spec ETU will undergo a series of electrical tests to confirm its operation as well as mechanical interface checks with the Integrated Science Instrument Module (ISIM) Structure. The MIRI STM serves as the engineering test unit for MIRI and will be integrated into the ISIM Structure.

(Left Side of the Clean-Room)

The ISIM Structure, the large, black, square, “latticed” structure was temporarily moved out of the cleanroom and into Cryo Set Testing, but now it is back, as you can see on the webcam. The testing it underwent was designed to observe the ISIM structure with high precision photogrammetry equipment as it is cooled from room temperature (20 C or 68 F) to -233 C (-388F) and ensure the amount the structure shrinks is within the allowable and predicted bounds. The test cycles between these two temperatures five times to show that the structure behaves in a repeatable fashion over these cycles. The ISIM Structure will contain all of the Webb’s instruments and will sit right behind the primary mirror. Also in the cleanroom right now is the OSIM (Optical Test Element Simulator), visible in the lower right (along with part of the balcony the camera is on) below. This equipment provides a high fidelity representation of the Webb telescope section and is used for performing detail optical testing of the ISIM and its instruments.

(Right side of the Clean-Room)

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