As the National Aeronautics and Space Administration continues to point the way towards space exploration and manned missions to neighboring planets and beyond, a key problem for long-term spaceflight is that of basic life-support and energy efficiency.
A successful manned trip to Mars would require that the mission be untethered to a supply line such as the one needed by the International Space Station.
Many of those life-support issues - such as growing food, recycling water and air, and energy efficiency (both in electrical power and propulsion) - have solutions that can also be applied to obvious problems on Earth. Solving for one can be the solution for both if NASA makes these solutions available and patent free.