A typical sterilisation process for a lander, in this case Beagle 2

Previous planetary flight projects indicated a clear need for an alternative sterilization method, complementary to the standard dry heat process. The best identified candidate is the hydrogen peroxide vapour process which is a low temperature sterilisation process. To a certain extent, hydrogen peroxide plasma processes have already been used for sterilizing spacecraft subsystems (e.g., Beagle II, Russian Mars missions). However, there is no hydrogen peroxide vapour processes certified for use on spacecraft systems.
 
ESA has to provide the sterilization process parameters so that industry can define their approach to meet the planetary protection requirements. Industry will then have to evaluate the impact on material/component selection, and the potential use of this surface sterilization process at subsystem level or as terminal sterilization process for the entire spacecraft. This process is particularly important for a MSR mission as it not only inactivates microorganisms but also removes their organic residues.

The steps to qualify the low temperature sterilization process are:

• Definition of a biological challenge that can be used to verify the process based on isolated strains from the spacecraft environments and compare it to the standard biological challenge used in the health care industry;
• Definition of process parameters for use on spacecraft systems. This has to include the definition and process control of temperature, humidity, time of exposure, concentration, pre- and post conditioning, and applicability limits for materials, components, and systems;
• Scale up from the engineering model to the use as terminal sterilization process;
• Formulation of standard documents, including application and verification methods and procedures.