STEP Team Produces Large Aerogel Samples for Tests

The Satellite Test of the Equivalence Principle (STEP) team is performing a number of feasibility experiments to test the use of aerogel for controlling helium tides. They advanced the production of silica aerogel for these new applications by the fabrication of uncracked, regularly shaped annular cylinders of 0.100 g/cc silica aerogel. Previous testing of the confinement of helium tides for the STEP project, done by researchers at the University of Trento in Povo, Italy was conducted with 1-cm machined pieces of aerogel. Samples have now been produced at JPL that are more than 14 cm in diameter with a precast 5-cm hollow bore running through the center. Prior to this work, the ability to manufacture large, high-density aerogel involving a toroidal geometry had not been demonstrated. Initial attempts at producing these samples resulted in complete fracturing and then extensive cracking of the aerogel structure. Eventually, a method has been achieved that results in uncracked, monolithic annular cylinders. These pieces, and others that have temperature probes embedded in them, are being used for liquid helium immersion tests in preparation for the STEP Project.