Showing posts with label sun. Show all posts
Showing posts with label sun. Show all posts

Wednesday, 22 June 2011

Getting Ready for the Next Big Solar Storm

June 21, 2011: In Sept. 1859, on the eve of a below-average1 solar cycle, the sun unleashed one of the most powerful storms in centuries. The underlying flare was so unusual, researchers still aren't sure how to categorize it.  The blast peppered Earth with the most energetic protons in half-a-millennium, induced electrical currents that set telegraph offices on fire, and sparked Northern Lights over Cuba and Hawaii.

This week, officials have gathered at the National Press Club in Washington DC to ask themselves a simple question: What if it happens again?

Modern power grids are vulnerable to solar storms.
"A similar storm today might knock us for a loop," says Lika Guhathakurta, a solar physicist at NASA headquarters. "Modern society depends on high-tech systems such as smart power grids, GPS, and satellite communications--all of which are vulnerable to solar storms."

She and more than a hundred others are attending the fifth annual Space Weather Enterprise Forum—"SWEF" for short.  The purpose of SWEF is to raise awareness of space weather and its effects on society especially among policy makers and emergency responders.  Attendees come from the US Congress, FEMA, power companies, the United Nations, NASA, NOAA and more.

As 2011 unfolds, the sun is once again on the eve of a below-average solar cycle—at least that’s what forecasters are saying.  The "Carrington event" of 1859 (named after astronomer Richard Carrington, who witnessed the instigating flare) reminds us that strong storms can occur even when the underlying cycle is nominally weak.

In 1859 the worst-case scenario was a day or two without telegraph messages and a lot of puzzled sky watchers on tropical islands.

In 2011 the situation would be more serious. An avalanche of blackouts carried across continents by long-distance power lines could last for weeks to months as engineers struggle to repair damaged transformers. Planes and ships couldn’t trust GPS units for navigation.  Banking and financial networks might go offline, disrupting commerce in a way unique to the Information Age.  According to a 2008 report from the National Academy of Sciences, a century-class solar storm could have the economic impact of 20 hurricane Katrinas.

As policy makers meet to learn about this menace, NASA researchers a few miles away are actually doing something about it:
"We can now track the progress of solar storms in 3 dimensions as the storms bear down on Earth," says Michael Hesse, chief of the GSFC Space Weather Lab and a speaker at the forum.  "This sets the stage for actionable space weather alerts that could preserve power grids and other high-tech assets during extreme periods of solar activity."





They do it using data from a fleet of NASA spacecraft surrounding the sun.  Analysts at the lab feed the information into a bank of supercomputers for processing.  Within hours of a major eruption, the computers spit out a 3D movie showing where the storm will go, which planets and spacecraft it will hit, and predicting when the impacts will occur.  This kind of "interplanetary forecast" is unprecedented in the short history of space weather forecasting.

"This is a really exciting time to work as a space weather forecaster," says Antti Pulkkinen, a researcher at the Space Weather Lab.  "The emergence of serious physics-based space weather models is putting us in a position to predict if something major will happen."

Some of the computer models are so sophisticated, they can even predict electrical currents flowing in the soil of Earth when a solar storm strikes.  These currents are what do the most damage to power transformers.  An experimental project named "Solar Shield" led by Pulkkinen aims to pinpoint transformers in greatest danger of failure during any particular storm.

"Disconnecting a specific transformer for a few hours could forestall weeks of regional blackouts," says Pulkkinen.

Another SWEF speaker, John Allen of NASA's Space Operations Mission Directorate, pointed out that while people from all walks of life can be affected by space weather, no one is out on the front lines quite like astronauts.

"Astronauts are routinely exposed to four times as much radiation as industrial radiation workers on Earth," he says.  "It's a serious occupational hazard."

Astronauts are on the front line of stormy space weather.

NASA keeps careful track of each astronaut's accumulated dosage throughout their careers.  Every launch, every space walk, every solar flare is carefully accounted for.  If an astronaut gets too close to the limits ... he or she might not be allowed out of the space station!  Accurate space weather alerts can help keep these exposures under control by, e.g., postponing spacewalks when flares are likely.

Speaking at the forum, Allen called for a new kind of forecast: "We could use All Clear alerts. In addition to knowing when it's dangerous to go outside, we'd also like to know when it's safe.  This is another frontier for forecasters--not only telling us when a sunspot will erupt, but also when it won't."
The educational mission of SWEF is key to storm preparedness. As Lika Guhathakurta and colleague Dan Baker of the University of Colorado asked in a June 17th New York Times op-ed: "What good are space weather alerts if people don’t understand them and won’t react to them?"
By spreading the word, SWEF will help.


Monday, 7 February 2011

Nasa Warns of Solar Storms

Solar Storm Warning


March 10, 2006:
 It's official: Solar minimum has arrived. Sunspots have all but vanished. Solar flares are nonexistent. The sun is utterly quiet.
Like the quiet before a storm.
This week researchers announced that a storm is coming--the most intense solar maximum in fifty years. The prediction comes from a team led by Mausumi Dikpati of the National Center for Atmospheric Research (NCAR). "The next sunspot cycle will be 30% to 50% stronger than the previous one," she says. If correct, the years ahead could produce a burst of solar activity second only to the historic Solar Max of 1958.
see captionThat was a solar maximum. The Space Age was just beginning: Sputnik was launched in Oct. 1957 and Explorer 1 (the first US satellite) in Jan. 1958. In 1958 you couldn't tell that a solar storm was underway by looking at the bars on your cell phone; cell phones didn't exist. Even so, people knew something big was happening when Northern Lights were sighted three times in Mexico. A similar maximum now would be noticed by its effect on cell phones, GPS, weather satellites and many other modern technologies.
Right: Intense auroras over Fairbanks, Alaska, in 1958. [More]
Dikpati's prediction is unprecedented. In nearly-two centuries since the 11-year sunspot cycle was discovered, scientists have struggled to predict the size of future maxima—and failed. Solar maxima can be intense, as in 1958, or barely detectable, as in 1805, obeying no obvious pattern.
The key to the mystery, Dikpati realized years ago, is a conveyor belt on the sun.
We have something similar here on Earth—the Great Ocean Conveyor Belt, popularized in the sci-fi movie The Day After Tomorrow. It is a network of currents that carry water and heat from ocean to ocean--see the diagram below. In the movie, the Conveyor Belt stopped and threw the world's weather into chaos.
see caption
Above: Earth's "Great Ocean Conveyor Belt." [More]
The sun's conveyor belt is a current, not of water, but of electrically-conducting gas. It flows in a loop from the sun's equator to the poles and back again. Just as the Great Ocean Conveyor Belt controls weather on Earth, this solar conveyor belt controls weather on the sun. Specifically, it controls the sunspot cycle.
Solar physicist David Hathaway of the National Space Science & Technology Center (NSSTC) explains: "First, remember what sunspots are--tangled knots of magnetism generated by the sun's inner dynamo. A typical sunspot exists for just a few weeks. Then it decays, leaving behind a 'corpse' of weak magnetic fields."
Enter the conveyor belt.
see caption"The top of the conveyor belt skims the surface of the sun, sweeping up the magnetic fields of old, dead sunspots. The 'corpses' are dragged down at the poles to a depth of 200,000 km where the sun's magnetic dynamo can amplify them. Once the corpses (magnetic knots) are reincarnated (amplified), they become buoyant and float back to the surface." Presto—new sunspots!
Right: The sun's "great conveyor belt." [Larger image]
All this happens with massive slowness. "It takes about 40 years for the belt to complete one loop," says Hathaway. The speed varies "anywhere from a 50-year pace (slow) to a 30-year pace (fast)."
When the belt is turning "fast," it means that lots of magnetic fields are being swept up, and that a future sunspot cycle is going to be intense. This is a basis for forecasting: "The belt was turning fast in 1986-1996," says Hathaway. "Old magnetic fields swept up then should re-appear as big sunspots in 2010-2011."
Like most experts in the field, Hathaway has confidence in the conveyor belt model and agrees with Dikpati that the next solar maximum should be a doozy. But he disagrees with one point. Dikpati's forecast puts Solar Max at 2012. Hathaway believes it will arrive sooner, in 2010 or 2011.
"History shows that big sunspot cycles 'ramp up' faster than small ones," he says. "I expect to see the first sunspots of the next cycle appear in late 2006 or 2007—and Solar Max to be underway by 2010 or 2011."
Who's right? Time will tell. Either way, a storm is coming.