The TPS materials were of two basic types. One was a hard tile intended for the underside of the X-38, very similar to a Space Shuttle TPS. This type is sometimes referred to as "TUFI". These tiles were bonded to a backing of composite honeycomb sandwich material. The second type of TPS sample was an AFRSI (Advanced Flexible Reusable Surface Insulation) blanket meant for the upper surface of the X-38. The AFRSI blanket panels were bonded to the same type of honeycomb backing as the TUFI tiles.

Projectiles used in these test series were aluminum spheres, fired from light gas guns at impact velocities of approximately 7 km/sec. Most tests were conducted with the velocity vector normal to the TPS surface (which we define as 0° impact angle); one in the second series was conducted at an impact angle of 45°.