But how could ice form on James Webb in space?

gradually, James Webb Space Telescope (JWST) He modifies his “vision” of our universe. The observatory was launched into space at the end of 2021, and is in the process of aligning its mirrors. It should be ready for its science activities in the summer of 2022. This includes cooling the telescope, which is designed to operate in the infrared.

One of its instruments, MIRI (which must be monitored in mid-infrared), requires an operating temperature of less than -266°C. So, as indicated NASA on March 30, 2022, equipped with a refrigerator. ” But it also requires radiators to control its cooling and prevent the formation of ice in space. Agency adds. One might be surprised that ice can form like this on the observatory, right in the middle of space.

But where does this water come from?

To understand this, you have to go back a bit to when JWST was launched. ” Moist air is trapped between components, such as sunscreen films and their many insulating layers “,” highlighted space agency. To this should be added telescope materials that were able to absorb the value of the water contained in the Earth’s atmosphere. ” Most of that air escaped just 200 seconds after take-off, but some moisture remained ‘, complements NASA.

In space, water doesn’t behave like we do planet. ” In a perfect vacuum, water can only exist as a gas, but even space is not a perfect vacuum. “,” explain space agency. In this other environment, water empties (loses its gas) above -113 °C (160 K). ” If water molecules float and come into contact with a surface cooler than 140°C, [ndlr : -133°C]They will stick to it in the form of ice and it will never explode. This is very important to avoid the Webb telescope “,” Confirms NASA.

In order not to find itself in this situation, NASA planned to cool James Webb, once the heat shield was deployed. The drop in temperatures was carefully managed, and the order in which the ingredients should be cooled was not chosen at random. ” This allowed water to escape into space instead of freezing on sensitive components. »

With regards to MIRI, the refrigerator is responsible for transferring heat to the other side of the James Webb sun visor, where it is hot. It is necessary to dispose of the water in order to properly cool the MIRI, or store the water in the areas designated for this purpose. I know you can continue On-line Cool this tool. The goal is to cool the MIRI to below 6 K (-270°C), without “spoiling” it by letting the water freeze on this instrument – hence the importance of having a proper heating technique.