The innovation described in this proposal will permit the rapid assessment of new superpressure balloon materials for use as an envelope in the Martian atmosphere and/or in the Earth's stratosphere. The use of scrim reinforced thin films has been considered for many years and occasionally used with polyethylene films. However, the high modulus property, required for superpressure balloons to prevent unstable deformations and resulting altitude excursions, limits the choice of materials significantly. The requirement to "design to cost" for the delivery of a balloon to Mars further limits the choice of materials to those that possess known, reliable properties. Polyester film has been successfully bilaminated to form a composite structure with the necessary strength, weight, and permeability at low temperatures. Although, the scrim reinforcement adds weight, it gives the resulting composite material the tear strength that is absent in the base material. This Phase I research will demonstrate the effect of packing density on the gas loss properties of two layers of three micron polyester film bilaminated with light weight scrim reinforcement.
