Studies have been made of the parameters of time, pressure, and temperature that influence adhesion of structural metals in vacuum. The objective was to provide spacecraft designers with engineering data to ensure separation of instrument capsules and other components from spacecraft in the space environment. These studies were conducted at an environmental pressure of5×10−9Torr over a temperature range of 25 °C (77 °F) to 500 °C (932 °F) and at compressive stresses within the elastic limits of the materials. Surface finishes and cleanliness of the test specimens simulated spacecraft hardware. Loading was applied by both static and dynamic modes and the adhesive forces were measured. Data are presented showing the extent of adhesion of a wide variety of materials under these conditions. With static loading, no adhesion occurred except at elevated temperatures. With dynamic loading, adhesion occurred at lower temperatures and lower compressive loads than under static conditions.