The American space agency NASA has successfully completed a test in which the primary mirror of the James Webb telescope is fully extended and integrated into a whole. This was a crucial test.
NASA conducted the test in early March in a Northrop Grumman Space Systems cleanroom in Redondo Beach, California. For the test, the spacecraft’s internal systems were used to fully extend the transom. For the test, equipment was attached to the transom to simulate a zero-gravity situation. Such a test will then be performed once more on the ground.
When fully unfolded, the mirror has a diameter of 6.5 meters. This makes it significantly larger than the mirror of the Hubble telescope, which has a diameter of 2.4 meters and is not on the outside of the spacecraft like the James Webb telescope. Such a large mirror is necessary to capture as much light as possible, which is directly related to the sensitivity of the telescope and thus how much detail becomes visible.
To fit into the nose cone of the chosen Ariana 5 rocket, the eighteen beryllium hexagons that make up the mirror could not fit into a solid structure. An origami solution was chosen for the design. The twelve middle segments sit in a solid structure, with two ‘wings’ each containing the three outer hexagons on the left and right sides. Once in space, the unfolding of the primary mirror will be preceded by the positioning of the secondary mirror, which is positioned opposite the primary.
The gold coating of the hexagons should increase the sensitivity to infrared. The James Webb Telescope focuses mainly on the infrared part of the spectrum, because it can also be used to look at very distant objects, such as the first stars that formed after the Big Bang. In addition, infrared light is able to penetrate nebulae and gas clouds, allowing the telescope to reveal many more stars and reveal features of nebulae.
Officially, the telescope must still go up in the air at the end of March next year, but it is questionable whether that deadline will be met, partly due to the influence that the corona virus has on the work. Apart from that, this international project, in which the ESA and the Canadian Space Agency also participate, has been associated with delays and high costs for some time. The launch has been delayed several times and the United States Government Accountability Office estimated in January that there is only a 12 percent chance that the current official launch date will actually be met.