“We need to pay attention to radio bursts now.” This is the message given by solar physicist Tamitha Skov, and this message, in a nutshell, reflects the actual concern raised by the recent X-class solar flare: not the solar flare itself, but its impact on communication at a time when space flight operations depend on communication.
The X-class solar flare, rated at X1.4 on the NOAA scale of X-ray intensity, briefly disrupted high-frequency communication on the sunlit side of the Earth. This, in itself, is a normal event at a time when we are in the solar maximum season. However, in the context of the Artemis 2 mission, we must remember that, far from being isolated, space flight operations take place within a context of space weather.
The overall space weather program at NASA has been formulated with a specific purpose: to understand the role of space weather as an integral part of the space environment, not only affecting space exploration but also affecting the Earth itself. Space weather is an aspect that influences various facets of life on Earth, such as GPS-based farming, electric power grids, air travel, and the space environment for human exploration beyond Earth.
The science behind space weather is not complex. Although the effect on space flight operations is not simple to understand, the science behind the X-class solar flare is simple. The X-class is the biggest category of solar flares. It happens when the magnetic fields in the sunspot areas reconnect suddenly. As a result, the Sun releases energy. The issue with the X-class solar flare is not the flow of particles to the Earth. It is the emission of X-rays from the Sun to the ionosphere. As per the NOAA recommendations, the high frequency radio signal is blocked on the dayside as the lower part of the ionosphere is unusually absorptive. It is the frequency used in aviation, maritime operations, emergency communication, and government communication.
It is important because space flight operations involve many layers of communication. Understanding one’s surroundings is also important. Skov’s comment is not only about the HF communication. It is also about the VHF and satellite communication during the critical phase of the space flight. Even if the safety is not directly impacted by the solar flares, the invisible infrastructure of the space flight is impacted. Nevertheless, there is one more layer to this. Solar flares can actually cause coronal mass ejections. Moreover, intense flares can actually cause geomagnetic storms. A NASA mission to understand the magnetic reconnection phenomenon actually brought out the chain effect. It includes auroras, satellite communication, GPS, and power grids. As the Artemis program is moving into deep space, this chain effect is becoming increasingly important.
The flare, in fact, is symptomatic of a broader issue, which is not related to the dramatic event on the Sun but is instead related to the fact that, in the modern world, the Moon program requires us to forecast the Sun with the same gravity that we used to require to forecast the weather for the launch pad. And as the areas on the Sun where activity is happening start to rotate more into our view from Earth, this is an increasingly hard thing to ignore.