The flight of the James Webb Space Telescope (JWST) suffered initial delays. Because some sensors failed, the deployment of the sun protection was delayed by several hours.
The sun shield has an area of around 22 by 10 meters and was opened on New Year’s Eve. It consists of five aluminum-coated special foils and was fixed in twelve layers with over a hundred actuators at the start. The actuators opened according to plan. However, some sensors that were supposed to display the unfolding of the film subsequently failed, so that the telescopic rods only extended several hours later and the protective films were put on, as NASA did here in one Video demonstrated.
Due to the delay, the slides could not be stretched so far, as it was actually on the plan for the seventh day of the mission. This next step is considered to be a delicate one because there is a risk that the film could tear when it is stretched. That is why the engineers want to take at least two days for the process to stretch the foils one after the other with over 90 cables.
Flight to the second Lagrange point
Eight days after the launch on December 25th in French Guiana, it had already covered more than 800,000 kilometers from Earth and thus more than half of the so-called L2 orbit. In contrast to the Hubble telescope, the JWST will not circle around the earth, but around the sun – at a distance of 1.5 million kilometers from the earth at the second Lagrange point (L2).
At this point the telescope orbits the sun – in sync with the earth, which is located at the first Lagrange point. This means that the telescope can always turn its rear side towards the sun, which is protected from its radiation by a large screen. According to NASA, the sun protection heats up to around 85 degrees Celsius. It is necessary to keep the telescope’s sensors cool to around -233 degrees Celsius. They are supposed to detect waves from particularly old stars and galaxies from the early days of the universe in the infrared range.