NASA has been planning on sending humans back to the Moon for a long time now. The space agency’s plans changed when the Trump administration demanded that NASA astronauts return to the surface of the Moon by 2024. That deadline was, and still is, largely unrealistic, especially in light of the delays posed by the coronavirus pandemic, but NASA now has another reason to expedite its return of humans to the Moon, and it’s coming from the Sun itself.
A new study published in Solar Physics explains that the Sun might not want to cooperate with a Moon return if the dates get pushed back to the late 2020s. Our star goes through a regular cycle of high activity and low activity. The solar maximum and minimum are on a pretty predictable schedule, and within that schedule, the intensity of the solar maximum appears to be in a pattern of its own. The maximum is more intense earlier in the cycle during even-numbered cycles and more intense later in odd-numbered cycles, based on the current method of cataloging its behavior. Unfortunately for NASA, this new finding suggests that intense space weather events are likely to occur during Moon return missions if they slip into the late 2020s.
Space travel is fraught with many risks. That’s the nature of shot into space on the nose of a rocket, after all. But there are certain dangers that can be mitigated if astronauts travel into the cosmos at certain times. During a period of low solar activity the chances of encountering extreme space weather — the outflow of charged particles from the Sun — is much lower than during windows of increased solar activity. This new research attempts to paint a clearer picture of when would be the best and worst times to send humans to the Moon if NASA wants the best chance of avoiding such weather.
“Until now, the most extreme space-weather events were thought to be random in their timing and thus little could be done to plan around them,” Professor Mathew Owens of the University of Reading, lead author of the research, said in a statement. “However, this research suggests they are more predictable, generally following the same ‘seasons’ of activity as smaller space-weather events. But they also show some important differences during the most active season, which could help us avoid damaging space-weather effects.”
The study’s warning to NASA is clear: If you can’t make it to the Moon by the mid-2020s, you should probably wait until the risk of intense solar weather is over.
“These new findings should allow us to make better space weather forecasts for the solar cycle that is just beginning and will run for the decade or so,” Owens says. “It suggests any significant space missions in the years ahead—including returning astronauts to the Moon and later, onto Mars—will be less likely to encounter extreme space-weather events over the first half of the solar cycle than the second.”