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Wednesday April 18 10:57 AM EDT
Solar Forecasters on Full Alert
By Leonard David
Senior Space Writer, SPACE.com
BOULDER, Colo. -- The Sun has a mean side. Space weather churned out by old Sol can be wicked and worrisome, not only here on Earth but also for civilian and military satellite operators.
Currently in the midst of an active solar storm period, Earth has recently been on the receiving end of energetic particles heaved out by the Sun. These powerful punches can whip up aurorae, increase radiation levels and stir up geomagnetic storms that disrupt telecommunications here on Earth.
Sometimes it’s rough sailing for Earth-circling spacecraft. They can become "drenched" in nasty bouts of space weather.
For instance, a weather satellite operated by the U.S. National Oceanic and Atmospheric Administration (NOAA) failed in 1982 due to space weather. In 1994, two Canadian communications satellites died, disrupting phone, TV and radio traffic. In 1998, space weather is thought to have crippled a Galaxy 4 commercial satellite, leaving millions of customers without service.
Even more recently, an expensive, super-secret spy satellite in geosynchronous orbit was blasted by a solar storm. Hardware that correctly oriented the spysat was fouled. The spacecraft began wobbling as ground controllers tried to regain control, only to compound the problem. It is believed the intelligence-gathering satellite was eventually put back on duty, but the event was a nail-biter for all concerned.
The Sun is going through solar maximum at present -- an 11-year cycle in which increasing numbers of sunspots serve as signposts for possible episodes of flares and coronal mass ejections, or CMEs. A large CME can contain a billion tons of matter, spit out at high speed, that hits anything and everything in its way. On occasion, Earth is in the strike zone.
Solar storm watching and forecasting is a pretty dicey business, said Joseph Kunches, acting chief of space weather operations here at NOAA’s Space Environment Center (SEC). The current solar maximum hasn’t coughed up as much activity as predicted, he said.
"The Sun has broken a pattern that existed for 150 years," Kunches said. "It looks like, from the sunspot numbers, the maximum was about a year ago. This March and April, while the sunspot number is high, it still has got a lot of catching up to do," he told SPACE.com.
Kunches said that he feels the Sun has reached a plateau in terms of uproarious behavior. "But it’s not unusual for a couple of years after sunspot maximum to get episodes of strong activity," he said.
"I wouldn’t be surprised to see, perhaps, four or five episodes over the next year," Kunches said.
Streams of data
The key to space weather forecasting is timeliness of data.
Now planted in space are numbers of probes that make the job of understanding the Sun-Earth interaction feasible, such as the joint European Space Agency/NASA (news - web sites) Solar and Heliospheric Observatory (SOHO) and the NOAA Geostationary Operational Environmental Satellite series, which includes the agency’s Advanced Composition Explorer (ACE) and several pole-to-pole, Earth-circling spacecraft.
Streams of data from various sources -- ground, as well as space-based -- pour into the Space Environment Center.
"If we can’t get the data, no matter how good it is, within a few minutes of when it is sampled, it’s of little value," Kunches said. "So many things happen so quickly…we need data as fast as possible," he said.
A new NOAA Geostationary Operational Environmental Satellite is to be lofted in a few months, Kunches said. It will carry an x-ray imager designed to relay pictures of the Sun every minute to a couple of minutes, day or night Earth time.
"We’ll be able to watch in x-ray all kinds of things, at a cadence that we’ve never seen before," Kunches said.
NASA’s Solar Terrestrial Relations Observatory (STEREO) mission is slated for launch in 2004. By doubling up on the Sun, separate STEREO sentinels can provide 3-D views of coronal mass ejections thanks to their unique positions in space.
"They could give us much better information about where CMEs are going relative to the Earth, and when they’ll get there. That would be terrific," Kunches said.
During solar storms the number and energy of electrons and ions increase. When a satellite zips through such an energized environment, the charged particles can wreak havoc with electronic components, harming and possibly disabling them.
"You can get phantom commands," said David Desrocher, director of The Aerospace Corporation’s Space Operations Support Office in Colorado Springs, Colorado. "That could result in attitude-control loss. Most of these upsets are momentary and are not typically fatal or very destructive," he said.
However, such problems can impact day-to-day operations and efficiencies in managing spacecraft, Desrocher said.
The Aerospace Corporation has been busy at work helping the U.S. Air Force Space Command to better deal with and understand space weather phenomena, Desrocher said. Ferreting out what’s background from the space environment to discern an attack on military space assets is part of the assignment, he said.
The idea that manufacturers are cranking out spacecraft that feel no pain from space weather effects is not true, Desrocher said.
"That’s not the case. They can do a pretty good job and there are several things you can do design-wise to mitigate the effects. But you're not going to build an impervious satellite," Desrocher said.
There is a booming business in watching solar explosions.
Sun-triggered geomagnetic storms and increased solar ultraviolet emission heat Earth’s upper atmosphere, causing it to expand. This results in increased drag on satellites in space. Unless low Earth satellites are regularly boosted to higher orbits, drag slows down the spacecraft, causing them to eventually tumble to terra firma.
"Space weather affects the performance and certainly the rate at which you repopulate your satellites," said Larry Plummer, managing partner for Earth2Sun International LLC, in Westminster, Colorado -- an association of companies offering a variety of space weather services.
"Space weather is a real issue for the investment community," Plummer said. The science of space weather is meshing with economics, he said, with a correlation between sizes of storms and their impact in terms of dollars.
Keeping tabs on space environmental changes can enable satellite operators to reboost their assets at a time when Earth’s atmosphere is thinnest, thus saving precious propellant. That adds more life to the satellite, in turn, yielding added revenue, Plummer said.
Plummer said that satellite operators think spacecraft builders have "designed out" troublesome problems that might be spurred by space weather. "That’s like saying we’ve made mobile homes safe from tornadoes," he said.
Also, you have spacecraft operators that don’t publicly signal use of weather data for fear of implying to customers there’s anything at risk for their systems, Plummer said.
"Your spacecraft may not blow up due to space weather. But if you interrupt five minutes of the Super Bowl being broadcast through your satellite, that’s a huge financial loss," Plummer said.
-- (Sp@ce.weather), April 18, 2001