Mystery of the Solar Filter Degradation

NIST scientists have used experiments and modeling to explain why aluminum filters on certain sun-facing satellites have become mysteriously obstructed over time. In the new NIST model, water vapor is released, possibly from thermal blankets near the instruments. The work improves on previous models which did not take into account the effect of UV radiation and therefore predicted much less oxide growth. To fix the problem, the NIST team proposes future instruments contain a layer of carbon to stop the movement of aluminum ions and also be fitted with tubes that block incoming water vapor. Credit: Sean Kelley/NIST<br>