Scientists Solve Decades-Long Mystery Behind Solar Probe Fogging

The phenomena of solar probe fogging weaken the aluminum filters on satellites intended to investigate the Sun. This phenomenon has puzzled scientists for decades. Extreme ultraviolet (EUV) emissions are crucial for understanding solar flares and coronal mass ejections. These events can affect our daily existence on Earth. These filters are essential for detecting EUV emissions. Nevertheless, the filters have been becoming cloudy. The occurrence is due to the existence of water, which has decreased their efficiency. In addition, it has jeopardized the accuracy of the data they gather.

The origin of the fogging was long assumed to be carbon. However, new research has revealed that it is actually aluminum oxidation brought on by the presence of water. It is stimulated by ultraviolet radiation. The Synchrotron Ultraviolet Radiation Facility (SURF) at the National Institute of Standards and Technology (NIST) was utilized by a research team. Physicist Charles Tarrio led the team to produce EUV radiation and direct it toward an aluminum filter in a vacuum chamber. The vacuum chamber had been filled with water vapor.

The research demonstrated that water is to blame for filter degradation. This is because it interacts with aluminum to generate a layer of oxide. The layer stops the filter from letting through the light waves that the sensor is meant to detect. The scientists also discovered that the thermal blanket material had likely been the source of the water. The thermal blanket material had been designed to shield the sensitive probe equipment from extremely hot temperatures. These blankets are constructed from layers of a thin polyethylene terephthalate (PET) sheet that can capture and hold onto water vapor from the air. The aluminum EUV filter oxidizes when solar heat strikes it. This is because the water vaporizes and progressively outgases into the spacecraft.

Future solar probe missions must identify the underlying cause of solar probe fogging. This is to enable the development of more durable filters and probes that can resist the harsh conditions of space.  It can also assist in preventing disruptions to radio and satellite communications, as well as power grids. This will be achieved by providing early warning and forecasting the size of the geomagnetic storms that can be sparked by solar flares and coronal mass ejections.

The team wants to investigate strategies to stop the oxidation of the filters in their future work. This includes creating a new filter that can function in the appropriate wavelength range or working to safeguard the aluminum. This investigation is important for comprehending the Sun and how it affects our daily lives on Earth. It is proof of the potency of scientific inquiry and discovery.