Apparatus for Measuring the Thermal Conductivity of Returned Samples from Asteroid Bennu

Project Goal: Measure the thermal conductivity of irregularly shaped geologic samples without contaminating or altering them.

Conventional thermal conductivity measurements require a sample that is cut and polished to a specific shape. The samples retrieved from the asteroid Bennu by OSIRIS-REx, once they arrive for analysis on Earth, connote altered or contaminated in any way, making it difficult to take conventional measurements. The team performed thermal conductivity experiments in a high vacuum environment to minimize sample contamination. Accordingly, they used radiation as the primary method of heat transfer to the sample.

The students designed a spherical aluminum apparatus to hold a geological sample at its center. The top hemisphere of the apparatus was exposed to heat flux, while the bottom hemisphere was cooled to a known temperature. This caused the heat to flow through the sample to the bottom. The team then measured the temperature of the top hemisphere. Because the sample’s thermal conductivity determines the amount of heat transferred, this measurement, along with finite element software, established the sample’s thermal conductivity.