The proposed HELIX mission will provide stereoscopic images of solar mass ejections from their origins on the Sun to their arrival at Earth. With an array of telescopes and plasma detectors, it will investigate magnetic helicity conservation in the heliosphere. Helicity conservation, which has been used successfully to describe the behavior of plasmas in fusion experiments, may explain why there are solar ejections and how they evolve in interplanetary space. HELIX uses two identical spacecraft in heliocentric ecliptic orbits. One remains near Earth and the other drifts so that it will see solar features up to five days before they are visible from Earth. This will provide advance warning of areas on the Sun that can provide geomagnetic storms at Earth.