Radioisotope Sample Sterilization for Low-Mass Return Containment
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Solution Overview
Problem
Current sample return missions face challenges in ensuring planetary protection against backward contamination by using complex and heavy sterilization systems, which increase mass and cost, and there is a need for an efficient and low-mass sterilization method to ensure no extraterrestrial life is introduced to Earth.
Innovation Solution
Utilizing radioisotope sources, such as Cs-137, Am-241, or Tl-204, for ionizing radiation sterilization within sample containers or on their surfaces to achieve sterilization assurance levels (SAL) of 10−12 to 10−24, with doses of 50-100 kGy over a prolonged period, minimizing mass and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex sterilization systems are used to ensure planetary protection, then sterilization effectiveness is improved, but system mass increases
Solution Approach 1:
The patent extracts the sterilization function from complex external sterilization systems and implements it through a simple radioisotope source placed directly within the sample container. This eliminates the need for heavy external sterilization equipment while maintaining sterilization effectiveness through the natural radiation emission of the radioisotope source.
Solution Approach 2:
The radioisotope source performs sterilization autonomously through its natural radiation emission without requiring external control systems, power sources, or complex operational mechanisms. The source self-regulates the sterilization process by emitting radiation at a rate determined by its radioactive decay, eliminating the need for active system management.
2Reliability
If complex sterilization systems are used to ensure planetary protection, then sterilization effectiveness is improved, but device complexity increases
Solution Approach 1:
The patent extracts the sterilization function from complex external sterilization systems and implements it through a simple radioisotope source placed directly within the sample container. This eliminates the need for heavy external sterilization equipment while maintaining sterilization effectiveness through the natural radiation emission of the radioisotope source.
Solution Approach 2:
The radioisotope source performs sterilization autonomously through its natural radiation emission without requiring external control systems, power sources, or complex operational mechanisms. The source self-regulates the sterilization process by emitting radiation at a rate determined by its radioactive decay, eliminating the need for active system management.
3Productivity
If intense radiation sources are used for sterilization, then sterilization speed is improved, but mass increases
Solution Approach 1:
The patent applies a low-activity radioisotope source that delivers radiation at a moderate rate over an extended period (hundreds of days during the return journey). This dynamic approach distributes the total sterilization dose over time, achieving the required sterilization effect without requiring a high-mass intense source that would deliver the dose too quickly.
Solution Approach 2:
The sterilization process begins immediately upon sample collection and continues throughout the return journey. By utilizing the available time window of hundreds of days, the system accumulates the required sterilization dose progressively, eliminating the need for a high-intensity source that would be needed to achieve the same effect in a shorter time.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method provides effective sterilization with minimal mass and cost, adhering to planetary protection guidelines, preserving sample integrity, and reducing the mass of the Mars Capture and Containment Return System by up to 625 kg.
Implementation Method 1
the present disclosure focuses primarily on the use of ionizing radiation. This form of irradiation sterilization is useful because it directly affects nucleic acid (DNA and RNA associated with viruses and bacteria), while leaving the bulk material unaffected
Implementation Method 2
A sterilization method may include: (a) providing a sample container, (b) inserting a sample collection tube, containing a sample, into the sample container, (c) inserting a radioisotope source into the sample container, and (d) irradiating the sample with radiation emitted by the radioisotope source
Data Source
AI summary
The present disclosure teaches methods and devices for using radioisotope sources to sterilize samples of soil, rock, atmosphere or atmosphere, which may be collected from an extraterrestrial planet, moon, or asteroid, or other body. A sterilization method may include: (a) providing a sample container, (b) inserting a sample collection tube, containing a sample, into the sample container, (c) inserting a radioisotope source into the sample container, and (d) irradiating the sample with radiation emitted by the radioisotope source. A sterilization apparatus may include: a sample container, a sample collection tube, a sample disposed inside of the sample collection tube, and a radioisotope source disposed inside of the sample container. Alternatively, an outside surface of the sample container may be irradiated with radiation emitted by a radioisotope source that is attached, or coated onto, the outside surface of the sample container. The radioisotope source may be Cesium-137, Am-241, or Tl-204, or combinations thereof.