Satellite protection

Scientists working on NASA's twin Stereo spacecraft have made a discovery that could help protect satellites from the damage caused by solar explosions, known as coronal mass ejections (CMEs).

CMEs are powerful solar explosions that can have damaging effects when hitting Earth’s upper atmosphere at speeds of nearly 1,000,000mph. These giant clouds of electrically charged gas – called plasma – can disrupt satellite communications, GPS and/or cell-phone signals, or induce large currents in power grids, which can cause power disruptions or black outs.

But now, researchers have shown that they can capture 3D images from the spacecraft that then enable them to track a CME all the way to the Earth and predict its arrival at least 24 hours beforehand. This allows more time for preventative measures to be put in place to minimise the damage that might be caused.

Dr Chris Davis, of the Science and Technology Facilities Council's Rutherford Appleton Laboratory (RAL), explained that this has been made possible because of the UK-built Heliospheric Imagers onboard the twin Stereo spacecraft that view the space between the sun and the Earth.

Davis said: 'The images taken from the UK-built Heliospheric Imagers represent a major step forward in predicting the arrival of these solar storms at Earth.'

The NASA Stereo mission was launched in October 2006. Two identical probes are now in solar orbit – one flying ahead of the Earth and one behind the Earth – from where they look back at the sun and the space between the sun and the Earth.

This two-platform view allows 3D images of the sun to be produced. However, it is the RAL-led Heliospheric Imagers on Stereo that look at the space between the sun and the Earth. In addition to leading the Heliospheric Imagers instruments, all of the imaging instruments onboard the two Stereo spacecraft use a novel CCD-based camera system developed at RAL.

Stereo is sponsored by NASA Headquarters' Science Mission Directorate, Washington, DC. NASA Goddard Space Flight Center's (GSFC) Solar Terrestrial Probes Program Office, in Greenbelt, Maryland, manages the mission, instruments and science centre.