Our communications and GPS satellite constellations are vulnerable in multiple ways. The charged particles of the storm can disrupt the small electronic microchips in computer systems on satellites by causing differential charging in the electronics causing them to malfunction, this means guidance systems and operations can be effected if not overloaded and burned out completely. Also when the solar storms radiation reaches the Earth's ionosphere it causes the gas to expand by heating and it can rise up to 700 miles higher than usual, this causes drag on low orbiting satellites and space craft like the ISS, this causes something called orbital decay and the satellites if not boosted into higher orbits will fall back to Earth. GPS satellites use their constellations to mark positions on Earth in relation to each other, during solar storms there are fluctuations in the data do to electrical flux interference caused by the charged electrical particles in the storm. This throws off the information being sent to those on the ground using the system to navigate, shipping industries, the military, and air craft all use these systems to find their way to where they are going. Though back up systems can be implemented of the need should arise.