Cryogenic Phase Change Material Development

Project Objective

Develop a cryogenic phase change material (PCM) to be incorporated into FROSTE (Frozen Return of Samples to Earth) hardware.

Project Description

The FROSTE (Frozen Return of Samples to Earth) project is developing a mobile deep cryogenic cold stowage system that will preserve scientific samples in pristine condition from extraction on the lunar surface through return to Earth’s surface. The primary concept requires a phase change material (PCM) to extend the time samples can be kept at cryogenic temperatures passively, as opposed to continuously actively cooling samples. PCMs are commonly used as passive thermal management solutions, particularly for sensitive scientific samples. However, there are currently no PCMs capable of providing cooling at the cryogenic temperatures needed to enable lunar sample return with volatiles intact (<120 K). Two candidate materials were proposed in an earlier Advanced Concepts Office (ACO) study: 2-methylpentane and 2-methylbutane, both of which are considered flammable and hazardous to human health. The goal of this Center Innovation Fund (CIF) project is to advance development of these materials as cryogenic PCMs by testing their performance at engineering scale and gaining experience with handling.

The basic concept is to create simplified proxy hardware for the FROSTE system’s Secondary Sealed Container (SSC), which would contain the PCM and lunar regolith samples. The proxy SSC containing the PCM will be subjected to thermal cycling in a space relevant environment (thermal vacuum chamber), while behavior is recorded and characterized. This information will be fed back into the design effort for the flight-like SSC to optimize performance.

Outside of this CIF, the FROSTE project provided additional support to purchase hardware as well as quality and facilities support. FROSTE continues to support this effort, which is ongoing into FY25 and beyond.

Project Results and Conclusions

This project has a produced number of significant accomplishments. Although the goal of fully characterizing both materials under a space relevant environment was not met (yet), the CIF funding positioned the project to conduct not only this test (in the upcoming year), but future tests for the FROSTE project (and more widely, for the Artemis infrastructure).

Accomplishments:

• A new test system has been stood up, based on a vacuum chamber that was moved from Building 4711 to Building 4605. New capabilities include:
• Vacuum chamber (diameter 4’, length 5’), which has been checked out in its new location through an extensive leak checking process. The chamber is now capable of reaching pressures down to 2 x 10^-6 Torr.
• A liquid nitrogen shroud is on order, which will be used to more realistically simulate the cold radiative (thermally) environment of deep space.
• Room 13D is waiting for installation of a vent system needed to exhaust potential vapors from the hazardous PCMs. Design and bidding is complete.
• A flammable chemical storage refrigerator was purchased to store the candidate PCMs, which have boiling points just above room temperature. Five liters of each chemical were procured (proactively) and are stored here.
• The proxy SSC and additional hardware have been built and installed in the vacuum chamber. This includes:
• Two portable reservoirs needed to contain the PCM during transitions between storage and testing. When installed, these connect to the room’s venting system to remove any potential exposures to personnel from vapors;
• Lines for filling and draining the proxy SSC with PCM, lines for running liquid nitrogen to freeze the PCM (with cryogenic flow meters), and heaters for contingency states; and
• Many thermocouples for characterizing thermal behavior both inside and outside the proxy SSC.

Additionally, our in-house LabVIEW data acquisition and control system was upgraded (by Erin Hayward writing new software), and new cDAQ modules were purchased to support the new lab.

One of the goals of this CIF project was to gain experience working with these hazardous chemicals. We have gained a much better understanding of the required processes and how they can introduce delays into the planned test schedule. Much of the early focus of the CIF project was on designing an appropriate test setup and associated procedures that would reduce, as much as possible, any potential exposure of personnel to chemical vapors.

Although we are still waiting for final installation of the room vent and for the actual testing to be conducted, much of the groundwork has been laid, and testing will be completed in FY25 with further support from the FROSTE project [currently in the MCO (Mars Campaign Office)].

This is an enabling technology for lunar sample return, as there are currently no phase change materials (PCMs) capable of performing at the cryogenic temperatures needed for the Artemis missions. Returning lunar samples in pristine conditions at cryogenic temperatures will allow scientists, engineers, and technologists to better understand the Moon’s composition and geotechnical properties. This, in turn, can lead to advances in a wide variety of technologies, including in-situ resource utilization (ISRU) and dust mitigation, as well as advances in science, helping us understand space weather and how our solar system was formed.

Other Artemis and Moon to Mars programs have expressed interest in using passive cryogenic storage for biological sample return as well. Although Artemis is the direct mission pull, many additional uses of a cryogenic PCM can be envisioned, including both in-space and on-Earth applications.

There is a clear path to infusion of this technology within the FROSTE project, which will enable pristine regolith sample return from the Moon. However, this technology also has the potential to be utilized for other science returns (biological, material) from space, or even in terrestrial cold storage applications.

This is early/mid-stage (TRL 2) — the most realistic path in is NASA SBIR/STTR, which funds small businesses and research institutions to develop technology aligned with NASA's needs (equity-free, phased funding). Check whether a current SBIR/STTR solicitation topic overlaps with this project's technology area, or contact the project directly (above) to ask.

None of these are guaranteed paths for this specific project — TechPort itself doesn't have an "apply" button. Reaching out to the contact(s) above with a specific question is usually the fastest way to find out what's actually open.