Outgassing

Definition

Outgassing is the process by which volatile substances escape from solid or liquid materials into a gas phase, particularly in a vacuum or low-pressure environment. This phenomenon is significant in the space environment, as materials used in spacecraft can release gases that may interfere with sensitive equipment and impact overall mission success. Understanding outgassing is crucial for designing spacecraft materials and thermal control systems to ensure their reliability in the harsh conditions of space.

5 Must Know Facts For Your Next Test

1. Outgassing can lead to contamination of sensitive instruments on spacecraft, which may impair their functionality and accuracy.
2. Materials such as plastics, adhesives, and coatings are common sources of outgassing in space applications.
3. The rate of outgassing can be quantified using a parameter called the Total Mass Loss (TML), which measures how much mass is lost due to outgassing under specified conditions.
4. NASA has developed a set of outgassing standards to evaluate materials before they are used in spacecraft design, ensuring that they meet strict requirements.
5. Outgassed materials can condense on cooler surfaces within a spacecraft, potentially creating issues like fogging on windows or affecting thermal control systems.

Review Questions

• How does outgassing affect the operation of sensitive instruments on spacecraft?
  • Outgassing can release volatile compounds that may deposit on sensitive instruments, leading to contamination. This contamination can obscure optical sensors, degrade electronic components, and interfere with measurements. As a result, understanding and mitigating outgassing is crucial for ensuring the reliability and accuracy of scientific instruments operating in the harsh conditions of space.
• Discuss the importance of thermal vacuum testing in evaluating outgassing behavior of materials used in spacecraft.
  • Thermal vacuum testing is vital because it simulates the extreme conditions of space, allowing engineers to observe how materials behave under high temperatures and low pressures. This testing helps identify potential outgassing issues before launch, ensuring that materials do not release harmful gases that could compromise mission objectives. By assessing material performance in a controlled environment, engineers can select appropriate materials that minimize outgassing risks.
• Evaluate the potential impacts of outgassing on thermal control systems within a spacecraft and propose solutions to mitigate these effects.
  • Outgassing can significantly impact thermal control systems by causing unwanted condensation on surfaces that need to maintain specific temperatures. This can lead to inefficiencies and potential failures in maintaining temperature regulation. To mitigate these effects, engineers can select low-outgassing materials during the design phase and implement effective thermal management strategies such as insulation and active heating systems. Additionally, regular monitoring for signs of outgassing during mission operations can help address any emerging issues promptly.

Related terms

Volatile Compounds: Substances that can easily vaporize at relatively low temperatures, often contributing to outgassing when materials are heated or subjected to vacuum conditions.

Thermal Vacuum Testing: A process used to simulate the space environment on Earth, where components are exposed to high temperatures and vacuum to assess their performance, including any outgassing characteristics.

Material Compatibility: The ability of different materials to coexist and function together without adverse reactions, which is critical in assessing how outgassing can affect spacecraft systems.