We need to talk about the sun, a vital if middle-aged dwarf star
The sun, about which we need to know more, ‘drives everything’, and there is a 12% chance over a decade of an extreme solar event striking Earth
Dallas — On the list of “bad stuff that could happen”, a huge plasma ejection from the sun is not an everyday worry, falling somewhere between an irrevocably warming climate and a shortage of soy milk in the office fridge.
Yet our star’s output plays a critical role in space weather, which carries potentially large implications for satellites, mobile phones, airlines and electrical grids — in other words, the underpinnings of 21st-century society. In March 1989, a solar storm that struck Earth zapped the grid in Quebec, Canada, causing most of the province to lose electricity and doing billions of dollars in damage.
Three decades on, a similar solar outburst could do a lot more damage. Even the US National Intelligence Council in 2012 called such an event, if severe enough, one of its “black swans”, along with nuclear war, a global pandemic, collapse of the EU and US disengagement.
Scheduled to lift off this weekend from Cape Canaveral in Florida, a joint $1.5bn mission by the European Space Agency and Nasa is aimed at expanding our understanding of the sun at a critical time for both space exploration and space commerce. Safely negotiating the solar system — rife with radiation and other highly charged particles — is essential for any long-duration human endeavours in deep space.
There’s a definite case for protecting against future outages of the sun-made variety. There’s one big problem, however: enormous scientific mysteries remain about how the sun operates
Along with protecting vulnerable systems on the ground, a more thorough understanding of space weather may also allow us to better protect flocks of new satellites (not to mention the 2,000 operational satellites already up there) filling up the night skies.
The probability of an extreme solar event striking Earth is akin to a 100-year flood, with a 12% chance over a decade, according to a 2014 research paper by Peter Riley, a co-investigator on the Solar Orbiter mission and senior scientist at Predictive Science, a San Diego-based solar astrophysics research firm.
The US National Oceanic and Atmospheric Administration’s (NOAA) geomagnetic storm scale rates such events on a five-level scale, with a G5, or extreme storm, having the capacity to cause electrical grid “collapse or blackouts” and degraded satellite navigation.
For perspective on how expensive such disruptions could be, tallies of the economic cost of the electrical outage in the northeastern US back in August 2003 (courtesy of a utility software bug) range as high as $10.3bn, according to ICF Consulting Services.
As a result, there’s a definite case for protecting against future outages of the sun-made variety. There’s one big problem, however: enormous scientific mysteries remain about how the sun operates.
“Everything is driven by the sun,” Nicola Fox, director of Nasa’s heliophysics division, said at a January 27 news conference. “So we really, really want to understand this star.”
The Solar Orbiter, weighing only 118kg, carries 10 instruments and will become the first spacecraft to capture images and other data from the sun’s poles. It will fly as close as 41-million kilometres from the solar surface (the Earth is, on average, about 140- million kilometres away). The orbiter will work in concert with another Nasa mission, the Parker Solar Probe, to provide complementary measurements and context on the data.
Solar Orbiter is scheduled to launch on Sunday, February 9, aboard a United Launch Alliance Atlas V rocket configured with only a single solid booster to optimise for the thrust needed to head towards the sun. The probe will collect data starting in May with its primary mission beginning in November 2021.
Middle-aged with sunspots
About 4.5-billion years old, the sun is a middle-aged yellow dwarf star. Scientists began paying close attention to its sunspots back in 1755, using 11-year activity cycles that alternate between periods of minimal and maximal sunspot activity. Increased sunspot activity is usually a harbinger of solar flares and coronal mass ejections. These can in turn cause magnetic storms that could affect Earth.
The current cycle, the 24th we’ve measured, has been one of the least active. In December, the US Space Weather Prediction Centre, part of NOAA, forecast an average intensity for cycle 25 (predicted to begin this year) that may include about 115 solar storms.
Maximum intensity for this cycle is seen occurring around July 2025.
The largest extreme solar event to strike Earth occurred in 1859. Called the Carrington event, it caused telegraph lines to catch fire and made the Aurora Borealis visible as far south as Cuba and Australia. A similar-sized coronal mass ejection on July 23 2012, though not aimed at Earth, served as a warning for many of the potential global economic catastrophe that could result.
It even got Wall Street’s attention, via a prominent mention in a 2014 investor letter from New York hedge fund Elliott Management. “If that had hit the Earth,” said Riley of Predictive Science, “there would have been major consequences.”
While the Solar Orbiter is aimed at conducting science without any real-time monitoring functions, the mission “will indirectly help us understand extreme solar events”, said Riley’, whose work involves the craft’s magnetometer, which will make detailed readings of the magnetic fields at and near the sun.
The research will also inform work on how to forecast solar activity more precisely, with one of Solar Orbiter’s key goals to try to learn how coronal mass ejections form and how they’re accelerated into space. Said Riley, “I am excited about this mission because it’s going to address some really basic science questions.”
With Brian K Sullivan