Extreme space weather threatens manned trip to the Moon

Nasa’s Artemis mission is already underway and plans to return humans to the moon in 2024, but the likelihood of delays pushing this back to the late 2020s is high.

University of Reading researchers have studied 150 years of space weather data to investigate patterns in the timing of the most extreme events, which can be extremely dangerous to astronauts and satellites and can even disrupt power grids if they arrive at Earth.

They found, for the first time, that extreme space weather events are more likely to occur early in even-numbered solar cycles and late in odd-numbered cycles - such as the one just starting.

They are also more likely during busy periods of solar activity and in bigger cycles, mirroring the pattern for moderate space weather.

The Sun goes through regular 11-year cycles of its magnetic field, which is seen in the number of sunspots on its surface. During this cycle, the Sun’s magnetic north and south poles switch places. Each cycle includes a solar maximum period, where solar activity is at its greatest, and a quiet solar minimum phase.

Previous research has shown moderate space weather is more likely during the solar maximum than the period around the solar minimum and more likely during cycles with a larger peak sunspot number.

This study goes one further by showing the same pattern is also true of extreme events which were found to be more likely to occur late in odd-numbered cycles, such as cycle 25, which began in December 2019.

The findings suggest that any major operations planned beyond the next five years will have to make allowances for the higher likelihood of severe space weather late in the current solar cycle between 2026 and 2030.

A major solar eruption in August 1972, between Nasa’s Apollo 16 and 17 missions, was strong enough that it could have caused major technical or health problems to astronauts had it occurred while they were en route to or around the Moon.

Professor Mathew Owens, a space physicist at the University of Reading, said: “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.

“However, this research suggests they are more predictable, generally following the same ‘seasons’ of activity as smaller space-weather events. They also show some important differences during the most active season, which could help us avoid damaging space-weather effects.

“These new findings should allow us to make better space weather forecasts for the solar cycle that is just beginning and will run for a decade or so. 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.”

In October, the UK Space Agency signed an agreement with Nasa to play a key role in the Artemis project by helping to construct the service module and habitation module of the Lunar Gateway, a new space station orbiting the Moon.