Ask scientists why Mars is cold and dead and they'll usually point to the death of its magnetic field some 4.2 billion years ago. Without that protection, solar winds gradually stripped it of most of its atmosphere. A NASA-led team, however, thinks there's still a chance to protect what's left -- and human explorers in the process. The scientists have proposed a magnetic shield that would sit at the L1 Lagrange Point beyond the planet, creating an artificial magnetosphere that would deflect solar winds and incoming radiation. Simulations even suggest that the atmosphere would get thick enough to melt carbon dioxide ice at Mars' northern pole, sparking a greenhouse gas effect that would melt water ice and restore some of Mars' oceans. Needless to say, that would be much friendlier to any long-term visitors.