File:Prep for Mechanic Shock Test.jpg

English: This is the Spacecraft Element of the James Webb Space Telescope, which includes the spacecraft bus and the tennis court-sized sunshield. Here it is shown folded in a launch configuration, encasing a mock-up of the telescope. The telescope is the part of the observatory that includes the golden mirrors and instruments. The flight telescope is complete and successfully finished its testing at NASA Goddard before being shipped to Northrop Grumman where it will be mated with the Spacecraft Element. The mock unit is used to simulate weight, size and mass of the flight telescope for test purposes.

In this photo, the Spacecraft Element is being prepped and lifted for a mechanical shock test in Northrop Grumman's facilities. Why was this test done? After the second stage of the rocket gives Webb a final nudge to send it on its way to its orbit at the second Sun-Earth Lagrange point (L2), the two halves of the payload adapter separate, releasing Webb from the rocket. The release sends a mechanical shock — a series of high-frequency vibrations — through the observatory. “Mechanical shock is a quick jolt to the system, a lot like when you shut your car door and the car shudders a little,” explained Keith Parrish, the Observatory Manager for Webb at NASA Goddard. The electronics in Webb are designed to withstand this shock just as a laptop is designed to withstand the bangs and drops of everyday life.

To simulate this separation on Earth, engineers at Northrop Grumman first suspended the spacecraft element in the air with the payload adapter attached to it. They then remotely released the bottom half of the payload adapter, which is the half that will be attached to the rocket during launch. The bottom half fell approximately 8 inches (about 20 centimeters) onto a padded catch area on the floor of the cleanroom where the test was being performed.

The engineers monitored the forces caused by the release to ensure they were within expected values, and high-speed video cameras recorded the separation to make sure it was smooth. During the actual flight and separation, 12 springs will gently push Webb away from the Ariane 5 rocket.

Image credit: Northrop Grumman