Long Duration Balloons
{"Image DocumentName": "Long Duration Balloons", "Image ImageDescription": "Polyethylene Zero Pressure. If vented, can stay aloft at float altitude for several days with ballast drop each night. Expensive to buy. - Difficult to make.", "Image XResolution": "37", "Image YResolution": "37", "Image ResolutionUnit": "Pixels/Centimeter", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}