20 Nov 2018

Professor Craig Rodger: The hazards of space weather

From Nine To Noon, 10:07 am on 20 November 2018

Explosions on the sun can cause storms that shut down satellites and electric systems on earth - thankfully, University of Otago's Craig Rodger says, New Zealand is ahead of the curve.

Earth and the sun, but what else is out there?

Earth and the sun, but what else is out there? Photo: Pixabay

Professor Rodger specialises in what's known as "space weather" and he tells Nine to Noon's Kathryn Ryan it's a hazard the modern world needs to prepare for.

He is head of physics at the University of Otago and his high energy, dynamic lectures - putting complicated physics concepts into exciting language like 'zombie satellites' and 'killer electrons' - are described as "unforgettable" by his colleagues.

His research looks into what could happen if a solar storm disrupts human technology.

"New Zealanders know that one day the Southern Alpine fault is going to go off, we know that there are volcanic threats, we know that tsunamis can come out and negatively impact us.

"Lots of people have got their disaster kits at home and have got that plan of what they would do ... space weather is something that needs to be added to the list of hazards that we think about as a country."

He explains that while space weather is an imperfect term, it does help to explain things. 

"The ‘weather’ weather - the weather that we’re used to, that the MetService provides us forecasting of ... encapsulates lots of different physical processes: whether it's’ wind, whether it’s thunderstorms, whether it’s hail, whether it’s rain. 

"The sun is the most important provider of energy heat and light to humanity and so it’s always the best starting point, but it turns out that … it also acts as a hazard in our increasingly technological society. 

This handout illustration shows an artist’s conception of NASA’s Parker Solar Probe, the spacecraft that will fly through the Sun’s corona to trace how energy and heat move through the star’s atmosphere.

This handout illustration shows an artist’s conception of NASA’s Parker Solar Probe, the spacecraft that will fly through the Sun’s corona to trace how energy and heat move through the star’s atmosphere. Photo: AFP PHOTO / NASA / Johns Hopkins APL

"All over the world there’s this realisation that processes that start from the sun - which have been given the broad name of space weather - can interfere with our technology."

Start with an explosion on the sun's surface

He says this space weather comes in a variety of forms.

"Some people have ended up linking all space weather to solar flares, which is not physically accurate, but in a cartoon sense it’s not so bad.

"Not always, but an awful lot of the processes that we're interested in start with an explosion on the sun’s surface." 

"We have an explosion on the sun which lets out a blast of X-rays. It can also let out a blast of hot protons, which is a radiation risk, and it might - depending on where on the surface the explosion is - lead to what we call a coronal mass ejection ... that’s like a billion tonnes of matter being thrown outwards from the sun out into space." 

They can have a variety of effects on the earth, particularly because it's hard to predict which direction they'll go. 

"The outer atmosphere of the sun is so hot that it’s boiling off into space at all times, this is just the background normal condition, and this creates what we call the solar wind. 

"That’s effectively a highway that a cloud of plasma like a coronal mass ejection has to follow the magnetic field of the sun, it has to follow that highway. 

The sun with a coronal mass ejection happening

A coronal mass ejection from the Sun has the power to create a powerful geomagnetic storm that could disrupt power supplies on earth. Photo: NASA

"Normally there’s just light traffic on the highway and that goes past the earth at 400km a second, but sometimes there’s faster traffic on the highway and that can trigger a geomagnetic storm just because of the speed … and we’re only talking about a factor of two change to like 700km a second, that sort of speed, coming past earth. 

"Another possibility is these huge trucks on the highway that are going to crash into the earth ... they’ve got lots of matter and they're moving at high speed, and that’s the coronal mass ejections."

At war with space?

Prof Rodger says the military has been dealing with space weather for a long time. For example, there was one account - declassified in 2016 - of a storm in 1967 during the Cold War. 

"It was in the lead-up to the six-day war in the Middle East ... the sun exploded, there was a solar radio noise burst and that took out the United States NORAD (North American Aerospace Defense Command) early warning defence system. 

60 New Zealand MPs have called on the world's nuclear powers to disarm.

File photo. Photo: Wikicommons

"The initial response from NORAD and the US was to think that the Soviets were jamming them, not that the sun was doing it: that’s the thing that you do right a the start of a war is take out your opponent's eyes."

Geomagnetic storms through history

And there are other examples of damage done on earth as a result of these geomagnetic storms.

"Just a couple of years ago there was a solar radio burst that disrupted air traffic control systems in Sweden and Norway and Greenland.

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Photo: Pixabay

"March 1989, which caused the hydro Quebec power system to fail in 92 seconds ... that led to a blackout across all over Quebec. 

There are records of more historical storms too, including big ones in 1921 - which knocked out telegraph communications - and 1859. 

"The funny thing is that the storm that everybody agrees on as being truly extreme is actually back in 1859, so somehow we know more about 1859 event than we do about the 1921 event." 

Burnt out transformers

He explains that while coronal mass ejections are very unlikely to hit the earth, merely passing by is enough to cause disruption. 

"When the coronal mass ejection crashes into the earth’s magnetic field, it triggers a whole lot of processes that boosts up the radiation environment."

That can cause all sorts of problems for electronic equipment. 

"It comes down to this thing called 'Faraday’s Law'. So, Michael Faraday - very famous physicist, he identified a law which is that a changing magnetic field introduces an electrical current on an electrical conductor. 

"When you have a coronal mass ejection crashing into the earth’s magnetic field, it’s going to change the magnetic field on the surface of the earth. 

"Any conductor will have a current induced in it - and electrical networks all over the world are these long conductors.

"Currents that weren’t designed to be there end up coming into the transformers ... those currents are, let’s just say 'not good' for the transformer. If we had an extreme storm the expectation is that we would have burnt out transformers - physically written off." 

Zombie satellites

Another effect of these geomagnetic storms is on satellites, which society is increasingly reliant on.

"The classic one would be that the inside of the satellite gets charged up then it discharges internally, so you get a spark inside the satellite and that’s just not good for the on board electronics.

"On planet Earth ... if we have a charge build-up we would just ground it by touching the ground, touching what we would call an earthed object.

"Now, that’s difficult if you’re flying around in space because you can’t touch the ground ... you can get very large currents because after all that’s what a thunderstorm is, that’s just lots and lots of charge building up and then eventually a gigantic spark leaps to earth."

No caption

Photo: creative commons - pixabay - Free-Photos

Satellites have just dropped dead, he says and Galaxy 15 went into a zombie state.

"It drifted around the world out of control broadcasting madly and it just drifted around the world for about six months before it ran out of power and rebooted itself. 

Mitigating risks and space weather forecasting

He says people are trying to design GPS - which much of modern technology has become so reliant on - with the risk of geomagnetic storms in mind

"One of the ways of mitigating risks to GPS technology is to use multiple radio frequencies  in the hope that while one frequency might be very badly affected, not all of them will be. 

Sentinel-5P satellite.

Sentinel-5P satellite. Photo: Supplied/European Space Agency.

"In the extreme case it’s very likely that all of the frequencies will be affected, but one can try and make the system more resilient by doing those sorts of things."

Another approach, he says, is trying to design a warning system. 

Prof Rodger says in New Zealand, Transpower is fairly advanced in its thinking about preparing for geomagnetic storms, and in an effort to do so has shared its data with him and his team. 

"We’ve started off with the more easy questions like identifying some hotspots where it’s more likely to be a problem and also helping Transpower develop mitigation strategies for big but not extreme storms."

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Photo: PHOTO NZ

He says the problem is in preparing for an extreme case like the Carrington event of 1859. 

"We’ve been able to come up with some estimates of what the extreme currents might be in a Carrington-level storm for some off the locations where Transpower’s been collecting data for a long time. 

"We’ve also been in the process of developing a model for the electrical network, particularly in the South Island, and validating it for geomagnetic storms so we can predict hopefully across the entire network."

While the technology for prediction and mitigation seems a long way off, it's on its way, he says. 

"There’s lots of things that we do today that were regarded as being extremely difficult in previous decades… now, honestly, that is in the process of happening in space weather forecasting as we speak.

"There are efforts under way and ... stuff is happening."