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Space Weather

Solar storms -- those roiling eruptions that occur with surprising regularity -- could prove disastrous to our increasingly technological world. At APL, scientists are working to better understand the weather just outside Earth's atmosphere, in hopes of one day improving future forecasting.

By Joanne Cavanaugh Simpson

Opening photos courtesy NASA/SOHO Sunspot cluster 5395 was so big and ugly, it dented the sun and disturbed scientists.

The most complex patch of sunspots ever recorded, this pulsating black region 54 times the size of Earth started edging its way around the eastern rim of the sun on March 6, 1989. As it came into view at observatories around the world, researchers wondered: What next?

For nearly two weeks, the region of sunspots -- areas of intense magnetic disturbances on the sun's surface -- spewed out nearly 200 solar flares, or explosions on the solar disk. One such eruption launched a stream of radiation for 10 hours. X-rays, meanwhile, roiled away from the sun's surface, reaching Earth in 8 minutes, 20 seconds.

What followed was the most dramatic space weather event recorded in modern times. By March 13, the Earth's magnetosphere, or magnetic shell, was getting pummeled by a rain of high energy protons at least 100 times the norm. Atmospheric drag in the planet's electrified and heated upper atmosphere caused satellites to drop out of orbit, and many suffered outages and scrambled communications. Satellites in the Global Positioning System (GPS), critical in navigation and the accurate launching of military missiles, in a few cases were transmitting wrong information.

In a series of spooky phenomena, North Sea oil companies halted drilling as their magnetic instruments went awry. Radio signals faded to static. And stray electrical currents caused several power grids in North America to suffer blackouts and costly damage, including the destruction of a $10 million transformer in Salem, N.J. In the most frightening outcome, a cascading outage at Canada's Hydro-Quebec power system caused tens of millions in damages in less than a day, leaving 6 million people without electricity in the dead of winter. With power cooperatives to the south relying on exports from Hydro-Quebec, the entire Northeast United States narrowly escaped a blackout.

In the decade since that geomagnetic storm, the use of satellites and other space technology has only mushroomed, with vast networks serving pagers, cell phones, wireless handheld organizers, and other technologies. On the ground, vulnerable electrical transmission networks now span longer distances. Out in space, the solar radiation that accompanies such storms can affect spacecraft lifetimes as well as the long-term health of astronauts in space stations orbiting Earth, and pilots and crews of high-altitude planes.

Sun-generated storms could in fact prove disastrous to our increasingly technological world. "There is so much more space technology being created that the likelihood of a spacecraft being in the wrong place at the right time increases dramatically," says Nicola Fox, senior professional scientist at the Hopkins Applied Physics Laboratory (APL) and a NASA project scientist. "During space weather events, spacecraft that were in a reasonably quiet environment end up in a hostile environment."

TIMED went up on Dec. 7, 2001, at Vandenberg Air Force Base.
Photo courtesy APL/TIMED
Questions about such incidents have sparked a growing scientific field focused on "space weather," essentially the study of radiation-laced storms that blow across the seemingly empty 93 million miles from the sun to Earth. To better understand this sun-Earth connection, and to lay the groundwork to help predict such weather, NASA is sponsoring a series of missions under the Living With a Star and Solar Terrestrial Probes programs. One of the primary probes has already been built and is being operated by APL's Space Science Department.

Known as TIMED, the two-year mission launched in December 2001 has been sending back the first tantalizing data to scientists studying the least-known region of the Earth's upper atmosphere -- a frontier between Earth's environment and space, where much of the first impact of solar activity is felt. This atmospheric zone -- the mesosphere and lower thermosphere/ionosphere -- is known to researchers as the MLTI region, and it resides 40 to 110 miles above the Earth's surface. "From the standpoint of basic science, the MLTI region is where the action is," says David Grant, TIMED program manager at APL. "This is where energy first hits the Earth's system. When such energy hits, it gets redistributed, causing all sorts of chemical reactions that affect life on Earth."

Life on Earth is also affecting the upper atmosphere: Steadily increasing pollution generated by humans has added methane and carbon dioxide to the upper atmosphere, which could be changing its long-term chemical composition. Scientists overseeing the TIMED mission are taking measurements of such things as temperature to create a benchmark against which future atmospheric readings can be compared to determine, for example, the extent of global warming.

"One of the biggest challenges facing humanity is understanding our environment," says Victoria Elsbernd, Solar Terrestrial Probes program executive for NASA. "If we didn't have a sun, we wouldn't have life on Earth. But how does the sun function? What are the physics? What kind of impact does it have on Earth? A lot of nasty stuff gets thrown at us, and the Earth's atmosphere sort of blows that off," Elsbernd adds. "We need to understand what we are doing on Earth that could contribute to the deterioration of that protective atmosphere."

In late April, scientists at APL, NASA, and elsewhere across the country watched as the TIMED spacecraft's payload of instruments -- a complex equivalent of Galileo's telescope -- for the first time chronicled global fallout in Earth's upper atmosphere. Their observations began soon after a sunspot cluster marked the face of the sun.

Mary Mellott, TIMED program scientist at NASA, was at agency headquarters in Washington, D.C., when the data started streaming in. "For the first time," she says, "we are really able to picture what is going on in this region 60 miles above our heads."

The two-year mission known as TIMED has been sending back the first tantalizing data to scientists studying the least-known region of the Earth's upper atmosphere -- a frontier where much of the first impact of solar activity is felt. Michael J. Carlowicz is not an astronomer, solar physicist, or even a scientist who studies aeronomy, that is, a planet's upper atmosphere. He's a writer.

Having earned his master's degree at the Hopkins Writing Seminars in 1994, he reports stories about science for newspapers, magazines, and Web sites. In the mid-1990s, he became fascinated with the phenomenon of space weather at a conference in San Francisco. "A scientist started talking about geomagnetic storms affecting telegraph lines and railroads and all this 19th-century stuff," says Carlowicz, who also has taught science writing in Hopkins' part-time graduate writing program.

Then in 1997, a solar storm knocked out the AT&T Telstar 401 communications satellite, disrupting TV networks and part of the U.S. earthquake-monitoring network. "I realized this wasn't just a basic curiosity," Carlowicz says. "It really had some real-life impact. There are all sorts of everyday conveniences we don't realize are connected to satellites. It still seems like a fairly distant, weird phenomenon, but when you go to the gas station and use a Speed Pass or use your credit card, they often beam your information through a satellite to check it."

What's more, pagers, cell phones, and other electronic devices have become increasingly critical in health care, emergency response, and other safety-oriented fields. "Policemen, firemen, surgeons, or the OB doctor about to deliver your baby are going further afield because they can stay in touch by cell phone or pager," notes Carlowicz, now editor of Currents magazine at the Woods Hole Oceanographic Institution in Woods Hole, Massachusetts.

Carlowicz's first book, Storms from the Sun: The Emerging Science of Space Weather (Joseph Henry Press, 2002) -- co-written with Ramon Lopez, a University of Texas physics professor and former APL scientist -- details recent major space weather events, including the March 1989 geomagnetic storm. The authors also chronicle scientific discoveries about the sun, and explore the vagaries of space weather. As Carlowicz and Lopez note, "The key to space weather is the transformation of energy, a transformation from magnetic energy and intense heat on the sun to plasma energy in interplanetary space to magnetic and electrical energy around the Earth."

The TIMED payload, illustrated at left, includes:

The Global Ultraviolet Imager (GUVI), which tracks UV light to measure chemical composition and temperatures in the MLTI region, as well as auroral energy.

SABER (Sounding of the Atmosphere using Broadband Emission Radiometry), which measures heat emitted by the atmosphere and tracks global temperature and sources of atmospheric "cooling" as energy is radiated back into space.

SEE (Solar Extreme Ultraviolet Experiment), which records the primary energy that ends up in the region, including soft X-rays and UV radiation. And the last, TIDI (or TIMED Doppler Interferometer), globally measures wind, among other profiles.
Courtesy APL/TIMED

Solar influence on our planet's atmosphere is, of course, as old as Earth's sun-basking existence. Mostly, civilizations witnessed dancing auroras, or night sky glows, later linked to geomagnetic activity in the upper atmosphere. Such displays near the Earth's poles were believed to be omens of good or ill, depending on the era's religious teachings or communal mood. Only in modern times have Cassandra-like predictions of chaos actually come to pass, oddly enough because of technology born in the scientific age. Before the advent of electricity and radio, there were few space weather "events" to notice.

Over the centuries, meanwhile, sporadic advances in astronomy have shed some light on the sun itself. According to Carlowicz and Lopez, the oldest known human record of sunspots dates from 28 B.C.E. in China. Greek philosophers Anaxagoras and Theophrastus may have viewed several in the fourth century B.C.E. Yet even by the early 1600s, when Galileo Galilei and other astronomers used telescopes to sketch out sunspot shadows, discussion about blemishes on the celestial orb was considered heresy by the Catholic Church. Solar eclipses, meanwhile, sparked peace treaties and royal marriages. And awed populaces linked the darkened face of the sun to natural disasters and even the death in 840 of Emperor Louis I, son of Charlemagne. As the authors note: "Legend holds that he was so 'perplexed' by the eclipse that he died of fright."

It wasn't until 1859 that the study of sun-born space weather really began in earnest. On September 1 of that year, English astronomer Richard Carrington was studying the progression of sunspots, which by then had become an accepted occurrence. Projecting the sun's image onto a screen -- the only safe way to look at the sun using telescopes of the day -- he noticed a "sudden conflagration" of white blotches around the spots. He thought light might have leaked through a filter, but months later he described the event in the Monthly Notices of the Royal Astronomical Society. What Carrington had witnessed was the first known sighting of a solar flare, according to Carlowicz and Lopez, and it was a big one. About 18 hours after the sighting, magnetic instruments at the Kew Observatory in London "went wild." As noted in Storms from the Sun, "Earth was in the throes of one of the strongest magnetic storms ever recorded -- a storm which lasted more than six days and which zapped the most advanced communications system of the day, the telegraph."

Carrington and others glimpsed the sun-Earth connection at a time when an increasing number of scientists were linking an 11-year cycle of sunspot activity to subsequent storms buffeting our planet. Yet even 150 years later -- with the study of Earth's upper atmosphere limited by ground-based instruments or rockets measuring isolated atmospheric samples -- science's ability to fathom and predict space weather still lags far behind attempts to predict its earthly counterpart. As APL's Fox notes: "You don't know which clouds will bring rain until you've done research on clouds, until you know what rain clouds look like and how and why they move."

During recent solar storms, TIMED captured data tracks of an intense aurora (red) over the Earth's northern polar region, superimposed here over an Earth image.
Courtesy APL/TIMED
On the APL campus in Laurel, Maryland, down a dusty asphalt road, sits a low, tan-and-brown corrugated metal building. This is Mission Operations Center for TIMED. The most impressive view of the operation from here is straight up - - the 60-foot satellite dish that collects data each day from the APL-built spacecraft orbiting the edges of Earth's atmosphere.

The freezer-cold temporary building features gray cubicles and neutral carpet in quarters that could pass for the offices of a computer software start-up in Seattle, except for a few details: a framed photo of the Dec. 7 rocket launch of TIMED from Vandenberg Air Force Base in California, a mission poster hanging near an American flag, and a red LCD clock set to Greenwich Mean Time. It's three hours until next contact with the spacecraft, and the middle of lunch. Mission Operations is empty.

TIMED (an acronym for Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics) is exploring a pivotal link in the sun-Earth connection. "The eventual goal is to understand the processes, just like when we first tried to understand terrestrial weather," says Sam Yee, TIMED project scientist at APL. "We need to improve models to know what will happen with solar storms in a particular spot in the Earth's atmosphere. What we learn from the Earth can be applied to other planets as well."

So far, what's known about the sun has mostly generated more questions in scientists' minds. "One of the mysteries of the sun is why the corona is much hotter than the surface," notes Fox, referring to the sun's outer atmosphere. "The surface might read 6,000 degrees [kelvin], but the corona reads millions of degrees. No one understands this."

There is one unequivocal fact, Fox notes: "The sun has so much energy to get rid of, it has to flare."

Energy from the sun's interior is released via numerous forms of electromagnetic energy -- including ultraviolet and infrared light, X-rays, radio waves, gamma rays, and visible light. The seething sun in fact continually spews such radioactive energy outward in what is known as solar wind. This solar wind is essentially highly ionized gas, a plasma of protons and electrons defined as the fourth state of matter, and Earth is in its path. Usually, the Earth's magnetosphere can deflect much of the solar wind, and the energetic particles and magnetic fields that accompany it. But during times of violent solar activity such as flaring, and when other conditions are right, the steady rain can become a storm. (Flares occur daily on the sun, but the bigger, more problematic eruptions usually follow the appearance of sunspots.)

"One of the mysteries of the sun is why the corona is much hotter than the surface," notes Fox. "The surface might read 6,000 degrees (kelvin), but the corona reads millions of degrees." The results down in our neighborhood: Earth's magnetosphere responds to the storms, especially the direction of a storm's magnetic field, stirring up energetic particles and setting off chain reactions, including the expansion of the aurora. "Solar wind can affect the magnetosphere, pushing it in and out, and energizing it," says Elsayed Talaat, APL staff research scientist. "The magnetosphere then becomes unstable, which can trigger geomagnetic storms. This causes the aurora to be stronger and to move lower in latitude, instead of just appearing in the polar regions."

Even more dramatic energy releases, known as coronal mass ejections, or CMEs, are the equivalent of high-powered hurricanes and have been described as gargantuan bubbles of plasma that erupt from the sun's corona. Such CMEs, which often pair with flares, release billions of tons of matter and have helped spark various space weather events on Earth over the past few years. These have included the 1989 geomagnetic storm, the 1997 event that knocked out the AT&T Telstar 401 satellite, and a May 1998 storm that scientists believe zapped a communications satellite, downing pager networks in North America for a full day.

In recent years, several spacecraft have started to study the space weather phenomenon. One satellite developed by APL and managed by NASA -- the Advanced Composition Explorer (ACE) -- measures the speed, density, and magnetic orientation of solar wind. Another cutting-edge craft sponsored by NASA and the European Space Agency -- the Solar & Heliospheric Observatory (SOHO) -- studies the structure of the sun to understand the origins of such energy, in part by measuring the velocity and direction of acoustic waves on the sun's surface. SOHO's round-the-clock images of the sun and ACE's measurements also help scientists monitor the highs and lows of the 11-year sunspot cycle, and, to some degree, predict storms.

Meanwhile, the Colorado-based Space Weather Operations Center -- run by the U.S. Air Force and the National Oceanic and Atmospheric Administration (NOAA) -- broadcasts solar storm warnings that can help companies shut down vulnerable technology on satellites or power grids. Yet even the spacecraft that forecasters now rely on can be affected by the sun's volatility. ACE, SOHO, and others were temporarily blinded by waves of solar particles unleashed by a huge coronal mass ejection on Bastille Day, July 14, 2000.

In the end, any hope of accurately forecasting the outcome of solar wind, flares, or CMEs resides in more fully understanding Earth's own atmosphere, including the interactions between the various layers. That's where the TIMED mission comes in.

Assembly of the TIMED spacecraft
Photo courtesy APL/TIMED
TIMED orbits 388 miles above Earth, well above the MLTI region (an area of the atmosphere too dense to support satellites or spacecraft). It's a unique craft, even by NASA standards. Using remote sensors, TIMED takes measurements via four instruments, recording sun-influenced spikes in X-rays or UV light, tracking wind, and detecting temperature and other changes in the region. The 1,300-pound spacecraft's payload, for example, includes a Global Ultraviolet Imager (GUVI), which measures chemical composition, temperature, and auroral energy. Tapping the instruments are researchers based at the Aerospace Corporation in El Segundo, California; Hampton University in Hampton, Virginia; and the University of Colorado and the National Center for Atmospheric Research, both in Boulder.

At a cost of $195 million, plus $42 million for operations and data analysis, TIMED is considered a low-cost space mission, a priority for NASA. Of late, APL has become a substantial player in such endeavors, including the recent $224 million NEAR Shoemaker mission, in which the lab operated the first spacecraft to orbit and study an asteroid. APL also is developing, building, and is slated to operate the NASA-sponsored Solar Terrestrial Relations Observatory, or STEREO. That craft, set for launch in 2005, will use two identical observatories to provide the first 3-D stereoscopic images of coronal mass ejections. In part, APL scientists are adept at lower-cost space science because they develop or adapt groundbreaking technology to make the crafts lighter, smaller, and more self-reliant -- requiring less funding and operations staff. Says NASA's Elsbernd: "The TIMED spacecraft is more autonomous than other spacecraft before it. We see that as being a trend."

A few technological advances on the craft are especially exciting to APL researchers, including a satellite-tailored GPS navigational system that lets the craft determine exactly where it is and where it's headed at any given moment. TIMED also uses large 17-by-4-foot solar panels to tap energy from the sun, avoiding a need to "power down" one instrument to use another. "We sized the solar panels to power all of the instruments and the spacecraft simultaneously," says David Kusnierkiewicz, TIMED mission system engineer. Because of these and other measures, principal investigators at the University of Colorado and elsewhere also can send instructions directly to the instruments (via APL Missions Operations) and quickly and efficiently receive the data. Once analyzed, the data is accessible over the Internet and fed into a database that will reside with NASA.

So far, TIMED is helping researchers learn how the various forms of energy are transferred in and out of the MLTI region, which will lead to a greater understanding of how the upper atmosphere functions during times of high and low solar activity. The TIMED mission, though scheduled for two years, will likely be extended for another two, according to NASA and APL officials. But, like SOHO and the other research satellites now orbiting, its life span is limited.

"Scientists start out with a set of questions they want to answer, but then they usually get a whole lot of new questions so they design new spacecraft," says space engineer Kusnierkiewicz, who jokes that it keeps people like him in a job. "The knowledge does seem to grow."

Online Resources

NASA's Goddard Space Flight Center's Web site, which features the April solar event

APL's TIMED Web site

Another NASA site, The Space Weather Center, has an online exhibition, "Living in the Atmosphere of the Sun"

For real-time space weather observations, check out NOAA's Space Weather Now or The Space Weather Bureau

In late April, the TIMED spacecraft chronicled its first substantial solar event. This time, scientists were not disturbed. They were downright excited.

Soon after a sunspot region appeared on the sun's western rim, a series of solar flares and CMEs erupted, accompanied by a massive blast of X-rays and electrically charged particles heading toward Earth.

Over the next few days, TIMED began taking measurements of various repercussions in Earth's upper atmosphere. Researchers were particularly interested in a few especially intense flares, a sort of Goldilocks selection. "Of three different flares, one was small, one medium-sized, and one quite large," says NASA's Mellott. "The first two had significant effects on our magnetosphere and ionosphere. The biggest one wasn't pointed at Earth, but we got clipped by it."

To scientists' delight, after the largest flare on April 21, TIMED's Solar Extreme Ultraviolet Experiment (SEE) instrument detected a spike in irradiance, or brightness of the sun -- a nearly tenfold increase in solar X-ray radiation in the Earth's upper atmosphere. Thomas Woods, principal investigator for SEE at the University of Colorado, watched the data being downloaded from TIMED the day after.

"It's very exciting to have something that large happen," Woods says. By collecting such data, Woods and other researchers are learning more about solar ultraviolet irradiance, including how much it varies and how it affects the atmosphere. "Solar radiation and extreme ultraviolet are very dynamic," he says. "This study will be ongoing for years to come."

The GUVI instrument, meanwhile, revealed an expanded aurora borealis that extended 10 degrees further south than usual -- down to 60 degrees latitude. The satellite's readings of UV light, as well as a recorded increase in nitric oxide and other gases linked to auroras, will help researchers track and explain long-term atmospheric changes.

Though the April event generated little fallout on Earth, and TIMED's measurements drew scant media attention, scientific conferences over the spring and summer were abuzz. Until TIMED began beaming back data, scientists could only model, or make educated guesses, about Earth's outer atmosphere. "We now have data on a solar event all the way from the surface of the sun down to where it interacts with the upper atmosphere," notes Mellott. "This is the fist time the complete chain of events has been observed."

The year is 2012 -- and the sun is flaring up again.

"Forecasters are warning the power companies to brace for a wicked magnetic storm, which likely means that many cities along the East Coast will be forced to endure preventative rolling blackouts, disrupting commerce for the day," pen the authors of Storms from the Sun, in the book's final chapter.

In such scenarios, the NASDAQ and other trading houses have shut down because of satellite outages; planes are being diverted because of distorted GPS signals tracked by air traffic controllers; TV broadcasts and Webcasts of the Euro 2012 soccer championships have been disrupted -- causing riots in Turin, Italy, and Liverpool, England; and people traveling farther and farther from home are out of touch as their personal communication devices go on the fritz.

Whether or not there will be a 24-hour Space Weather Channel on cable TV remains to be seen. But as humans move into space, erecting orbiting hotels and pursuing commercial space travel in crafts vulnerable to sun-born radiation, the weather outside of the Earth's protective atmospheric shell will become increasingly important to our everyday life.

In some ways, TIMED and other spacecraft today are precursors to future space weather forecasting devices that will let us know what kind of solar blowouts to expect. For now though, it's all still on science's frontier. Says Elsbernd: "What's so exciting about all this to me is the opportunity to learn something new that nobody on this earth has ever known before."

Joanne Cavanaugh Simpson is a senior writer for Johns Hopkins Magazine. Contact her via e-mail:

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