Removal of waste heat generated via Joule heating during the operation of electronic devices is critical to overall system performance and reliability. A significant fraction of the overall thermal budget is consumed by heat transfer across the interface of contacting materials. To enhance the flow of heat from source to sink, thermal interface materials (TIMs) are used to reduce thermal contact resistance (TCR) by increasing real contact area at the interface. In space systems, TIMs are exposed to high doses of gamma radiation not encountered in typical terrestrial applications. With typical design lifetimes of 5 years or more, total radiation exposure can be significant and can affect the structure and performance of the TIM. Here, we report measurements of the pressure-dependent TCR of metallic foils and carbon nanotube TIMs (CNT-TIMs) in both vacuum and ambient air environments. The TIMs were irradiated in a gamma cell at a rate of 200 rad/s to a total dose of 50 Mrad. TCR was measured before and after gamma-ray irradiation using a one-dimensional steady-state calorimetric technique at room temperature and contact pressures ranging from 0.5 to 10 MPa. Additionally, the potential for vibration transmission through these interface materials into sensitive electronic equipment is investigated, which is of critical importance during launch when space systems can be subjected to high levels of shock and broad-band vibration. The vibration transmission characteristics of the TIMs were measured from 200 to 4,000 Hz at vibration levels ranging from 1 to 20 g's using an electrodynamic shaker table. CNT-TIMs are shown to exhibit the lowest TCR of any of the tested interface materials, about 38% lower than a plain copper foil. Additionally, all of the TIMs offer little vibration isolation and therefore, care must be taken to isolate sources of vibration that may be transmitted into the electronic components via the TIMs.