When Sierra Nevada Corporation’s (SNC) Dream Chaser spacecraft flies through the atmosphere, it will encounter a wide variety of environmental conditions. Any spacecraft traveling at hypersonic velocities must have a robust thermal protection system (TPS) to protect astronauts and cargo from the extreme temperatures associated with ascent and re-entry.
NASA's Langley Research Center in Hampton, VA, recently conducted hypersonic testing of Dream Chaser models for SNC as part of the agency's Commercial Crew Program in order to obtain necessary data for the material selection and design of the TPS. The Dream Chaser, based on NASA's HL-20 lifting-body design, combines years of NASA analysis and wind tunnel research with SNC engineering, resulting in a reusable spacecraft that could ferry astronaut crews to and from low-Earth orbit.
The Dream Chaser models tested were approximately 10 inches long and made of cast ceramic. They were fabricated at Langley to measure heating levels the Dream Chaser spacecraft would experience during re-entry, including the lower- and upper-body flaps, elevons and a rudder. The heating data were measured using phosphor thermography, which allowed researchers to see a global view of the surface being investigated. Each pixel in the image acts as its own data point.
With this technique, an image of each model is acquired before each wind tunnel run and then multiple images are taken during the run itself. The temperatures and heating rate information then will be used to help determine appropriate thermal protection system materials and also will be compared with computational predictions.