The lightweight, translucent composite membrane doesn't absorb visible light. This lets light from the four bulbs inside pass through the balloon's skin without any color distortion.

Large-diameter balloons are used to light up sporting events, rock concerts, construction work, and film sets without the harsh shadows associated with glaring floodlights.
To make the balloon gas-tight without using light-absorbing graphite fillers, engineers at Noelle Industrielle Umwelttechnik GmbH of Rheinberg, Germany, selected a composite made with silica-filled, UV-resistant EVM rubber from Bayer Polymers, a div. of Bayer AG, Leverkusen, Germany (www.bayerpolymers.com). Controlling the relatively small amounts of silica filler alters the strength of the Levapren rubber and gives the membrane its light-scattering properties.

A polyamide-fabric layer protects the membrane from abrasions and makes the HeliMax Powermoon balloon stronger than those made from silicone rubber, notes Stefan Kisser, a designer at ContiTech. Because of their strength, the balloon membranes can be kept very thin and thus lightweight.

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The largest HeliMax Powermoon has a 5.5-m diameter and contains four 4-kW HQI lamps, which are as bright as 35-kW halogen lamps (over 1,000,000 lumens). Floating 50 meters high, the balloon illuminates everything in an 800-m radius. And at 1.5 km from the balloon provides dusklike illumination. Once unpacked, the ÒmoonÓ can rise within just 10 min.