NASA’s Advanced Composition Explorer, which is critical to space-weather forecasting, is nearing its end of life. Satellite operators fear the end could come at any time, according to Irene Klotz of Discovery News.

ACE provides advanced warning of high-energy particles from solar storms and changes in the solar wind. This information is critical for space-weather predictions that help ensure the safety of ISS astronauts, high-latitude airline flights, and future suborbital space travelers as well as unmanned satellites and the terrestrial power grid. Pipelines are also vulnerable, especially those at high latitudes like the Alaska Pipeline.

There is currently no backup for the satellite. The National Oceanic and Atmospheric Administration and the US Air Force are hoping to launch a replacement, the Deep Space Climate Observatory (DSCOVR), before ACE fails. At the moment, however, the launch its not yet scheduled and the DSCOVR satellite is in storage at NASA’s Goddard Spaceflight Center.

This report is especially timely. The news came just as Earth was being hit by the biggest solar storm in years.

When scientists someone mentions “planetary defense,” most people think about asteroid impacts. Asteroids are not the only space hazard that poses a risk to life and civilization here on Earth, however.

Space weather, caused by the unstable behavior of the sun, affects life on Earth in many ways. It creates the colorful auroras that are enjoyed in higher latitudes, but it can also interfere with communications. Space weather can create increased radiation risks for space travelers and even air travelers. Most people don’t realize that airlines routinely monitor space weather forecasts and sometimes need to reroute flights that normally go over the polar regions, due to increased solar activity.

Large solar storms could have much more serious effects. They could damage or destroy communications, weather, and GPS navigation satellites, as well as the terrestrial power grid. In 1989, a solar storm took down the Quebec power grid leaving 6 million customers temporarily without power. A larger storm could create more widespread, catastrophic damage which could take years to repair. A single storm could damage or destroy electrical power plants throughout an entire hemisphere. The economic impact of such an event is estimated at one trillion dollars per year. Fortunately, we have not seen a really large storm since 1859.

IEEE Spectrum looks at the potential effects of a solar superstorm and some measures that might be taken to protect the planet. There are some relatively simple modifications that can be made to protect power plants, but we also need better space weather forecasting and monitoring.