Data from two NASA satellites is helping scientists make better predictions about the timing of solar activity that poses a threat to communications and power systems on Earth.

Marc DeRosa, a research scientist at the Advanced Technology Center (ATC) in Palo Alto, Calif., said data from the two spacecrafts — the Solar and Heliospheric Observatory (SOHO) and the Transition Region and Coronal Explorer (TRACE) — were invaluable because they made it possible to observe the Sun over a period of several days, rather than relying on the sporadic viewing times available only when the Sun is visible from a particular facility on Earth. This allowed observations that documented the length of time of a magnetic build-up on the Sun.

DeRosa and other NASA-funded scientists spoke to reporters during an Aug. 16 teleconference to discuss their findings.

The work is part of an ongoing partnership between NASA and the European Space Agency launched in 1995, said Karel Schrijver, a senior staff physicist at Lockheed Martin’s Advanced Technology Center . The conclusions were drawn from a “long record of solar observations,” Schrijver said, and officials did not quantify how much has been invested in the project so far.

TRACE captured images of the Sun’s corona, the ionized gas surrounding it. Researchers compared the images to computer models of a three-dimensional magnetic field based on images from SOHO, which also made magnetic maps of the S un using its Michelson Doppler Imager.

NASA officials participated in the press teleconference along with representatives from Lockheed Martin Solar and Astrophysics Laboratory and the National Oceanic and Atmospheric Administration to discuss recent developments in space weather observation.

Space weather is the term used to describe the presence of energized particles from the Sun and their affect on Earth or spacecraft or astronauts from Earth — the term also is used to describe debris left behind by comets. These particles can have a detrimental effect on Earth’s atmosphere, damaging satellites or disrupting power grids. They also pose a threat to the health of astronauts.

Solar flares are one important component of space weather, and NASA has gotten a “new window into flare prediction” as a result of this recent work, said Richard Fisher, director of NASA’s Sun-Solar System Connection Division here.

Solar flares happen when a sudden release of magnetic energy causes an explosion on the sun. Magnetic fields can suddenly snap into a new shape, causing an energy release as intense as a 10 billion megaton nuclear bomb, said Schrijver.

While scientists already were aware that the flares are caused by the magnetic fields on the Sun, the study determined that the magnetic fields evolve from characteristic patterns, and that it can be determined which magnetic regions are likely to flare or not flare, DeRosa said.

Scientists figured out that those regions more likely to have flare ups had new magnetic fields merge into them, which were out of alignment with existing magnetic fields. The currents caused by the fields would build up for several hours — usually between 10 and 30 — before a flare actually occurred. Schrijver said those fields that had the large currents were two or three times as likely to flare.

Schrijver said NASA had established 90 -percent accuracy in predicting whether there is a significant enough current to cause a large flare. But scientists still have a way to go in determining how frequently flares will actually happen, and why the magnetic field build-up occurs in the first place. But the new data will help astronauts know when space weather is unlikely to occur.

Joseph Kunches, director of National Oceanic and Atmospheric Administration’s Space Environment Center in Boulder, Colo., said that an “all clear” forecast could be made “a good few days” ahead of time.

NASA’s latest observation “really is a big deal” for those interested in space weather, according to Paul Dusenbery, executive director of the Space Science Institute in Boulder, Colo., whose background is in space weather research.

“As in any research, it needs to be confirmed, but certainly it’s very promising,” Dusenbery said. “Scientists have known that magnetic fields play a very critical role in solar flares, but the new research is showing the timing and the process of how these fields interconnect and erupt. It’s getting down into the details, which is very, very important.”