A U.S. satellite giving the only advance warning of incoming high-energy solar particles is getting old and is possibly on its last legs, researchers say.

But a replacement for NASA's Advanced Composition Explorer, or ACE, satellite is at least two years away, they said.

ACE provides the only advance notice of incoming high-energy particles from the sun which can wreak havoc on indispensable radio, GPS and satellite communications, researchers said.

Launched in 1997, ACE gives the National Oceanographic and Atmospheric Administration's space weather forecasting arm advance notice if a storm is headed toward Earth, as it did with the solar storm that left the sun Tuesday.

How much longer the satellite can keep working is a concern, scientists said.

"It would be a very bad day for us if that spacecraft was not working," William Murtagh, program coordinator for NOAA's Space Weather Prediction Center in Boulder, Colo., told Discovery News.

"When an eruption occurs on the sun, there are still quite a few question marks as to if it's going to hit the Earth and when it's going to hit the Earth," he said.

From about 1 million miles away, ACE provides the only early warning of what's headed toward Earth and utility operators, airlines, satellite owners, GPS users and others depend on space weather alerts from NOAA.

"ACE is a single point of failure and it's old," Murtagh said. "Every time I have a space weather storm I cringe a little bit that our very own space weather satellite doesn't succumb to the storms I'm relying on it to help forecast."

Space storm packs late punch, biggest since '04
Washington (AFP) March 9, 2012 - A strong space weather storm packed a late punch overnight and ended up being the most significant geomagnetic event since 2004, US experts said Friday, warning more disruption was coming this weekend.

The fusillade of radiation from the Sun caused limited power grid upsets, forced airlines to reroute around the poles and sparked vivid displays of the Northern Lights in some parts of the world.

The event began late Tuesday with a series of explosions on the Sun that sent charged particles hurtling toward Earth, but the storm appeared to fizzle on arrival Thursday, causing no power outages or problems with GPS navigation systems as expected.

Conditions changed late Thursday that boosted the ferocity of the storm, raising it to the initially forecast G3 level of "strong" on a scale of one to five, said Bob Rutledge who heads the space weather forecast office at the National Oceanic and Atmospheric Administration (NOAA).

"We ended up getting some of the strong storming that was expected," he said explaining that change was due to a flip in the magnetic field inside the coronal mass ejection that burst off from the Sun.

"When you look at the storm overall for length and strength, it is arguably the strongest storm since November 2004," he said.

People across the northern US states of Wisconsin, Michigan and Washington reported seeing the nighttime light show caused by the aurora borealis when highly charged particles interact with the Earth's magnetic field, creating a colorful glow.

And although power industry operators have "certainly seen these disturbances on their systems... it should all be well within what they are capable of handling," Rutledge added.

As the current storm wound down Friday, Rutledge warned there was a potential for more disruptions by Sunday due to a flare overnight from the same region on the Sun, known as 1429, that has been acting up since early in the week.

The solar flare reached a level two out of five and was not as big as Tuesday's flare but it was associated with a coronal mass ejection that Rutledge said would make its way to Earth early on March 11.

"It is going to affect the Earth. It is headed fairly directed at us," he said.

"We believe that it could cause storming levels that could reach the G3 level again. We don't believe it would have maybe quite the sustained intensity that the storm we just got out of had."

Geomagnetic and radiation storms are growing more frequent as the Sun leaves its solar minimum period and moves into a solar maximum over the coming years, but people are generally protected by Earth's magnetic field.

However, some experts are concerned that because the world is more reliant on GPS and satellite technology now than it was during the last solar maximum, more disruptions to modern life are likely.