Extreme heat and liquid hydrogen and liquid oxygen propellants are not a good combination, and so a successful preliminary design and development of an in-space inflatable sun shield for the Atlas V launch vehicle’s upper stage has been presented by United Launch Alliance (ULA) engineers. The work was performed in partnership with engineers from ILC Dover in Delaware, and with support from NASA engineers at Kennedy Space Center in Florida and Glenn Research Center in Cleveland. The sun shield is designed to inflate and deploy after jettison of the launch vehicle payload fairing to reflect the sun’s rays away from the upper stage tanks, thereby minimizing the liquid boil-off of the two super-cold propellants.  United Launch Alliance is studying concepts for propellant depots that would be derived from upper stages, their contents kept cold by sunshields. (credit: ULA)

The Atlas V upper stage uses liquid hydrogen and liquid oxygen propellants, both of which are very cold ­– minus 420 degrees F and minus 290 degrees F, respectively.  Both liquids vaporize quickly in the presence of heat from the sun’s rays in space. Although the initial design of the sun shield is for use on the Atlas V upper stage, the same concept could be used for ULA’s Delta IV, other rockets or for in-space propellant depots. Propellant depots are long-term storage tanks or refueling stations for space vehicles on their way to earth orbit, to the Moon or to Mars.

“The sun shield project is an excellent opportunity to collaborate with our NASA partners to develop and test technologies that will further the goals of both the Agency and industry,” said Dr. George F. Sowers, ULA vice president of Business Development.  “We look forward to continuing the project and flying the sun shield on a future Atlas or Delta mission.”

Following the initial component design and test work performed to date, the next step in the project will be to design and build a flight test article that will be deployed around the Atlas V upper stage in space. The test article will be instrumented with temperature and pressure sensors to further understand its operation in a vacuum, at low temperature and under zero gravity.  An on-board digital camera will also record its deployment.

Funding for the project is being provided by the NASA Innovative Partnership Program (IPP), which brings together industry, colleges, government agencies and national laboratories to solve technical problems in support of NASA’s goals in space exploration, space science, aeronautics and space operations.  Funding is also provided by the companies and NASA centers.