By Janice Kleinschmidt
Jeffery Hall, a staff engineer at Jet Propulsion Laboratory (JPL) in Pasadena, Calif., has been testing fabrics to be used as far as 750+ million miles from Earth: on balloons for exploring Venus and Saturn’s moon, Titan.
“Both of those balloons have involved the use of high-strength fabric materials,” he says. “We have designed and fabricated prototype balloons and done testing under laboratory conditions on Earth. For Venus, we have been making a pressurized helium balloon that uses a laminate material, one part of which is a Vectran® fabric.” The laminate includes aluminum foil to reflect sunlight and prevent balloon overheating and an outer layer of Teflon® film to protect against the sulfuric acid clouds that surround Venus.
“For Titan, we came up with a different kind of laminate material that’s geared toward the very, very cold temperature: a polyester fabric laminated to polyester film,” Hall says. “In both cases, we did not go back to the chemistry lab and invent a new material. We were able to find fabrics that had been developed by other companies for other purposes, and then we did fairly exhaustive laboratory testing of all kinds of materials to figure out the ones that were able to do the job the best.”
JPL gets fabric from one company, has the fabric and film laminated by another company and then has a third company cut the laminated product into pieces and glue them into a 3-D balloon.
“We pick fabrics that have a high strength-to-weight performance, which is certainly a key to why we picked Vectran for the Venus balloon,” Hall says. “For Titan, we were driven to polyester fabrics. They’re not the highest in strength to weight, but they remain flexible at very cold temperatures.”
JPL continues to submit proposals to get funding for both missions, but, as Hall says, “In terms of maturity of the technology, these two balloons are close to ready to go.