Create a small, affordable aerosol sensor for use in reduced-gravity space habitats. Long-duration human space missions need the ability to monitor airborne particle matter. Equally, having low-cost, small aerosol sensors would be beneficial to humans on Earth. The NASA Earth & Space Air Prize is open to U.S. citizens and permanent residents age 18 and over. Three finalists will be awarded $50,000 each, with a final winner being awarded $100,000. The deadline to register to compete is December 13, 2017.